Development of hybrid biomicroparticles: cellulose exposing functionalized fusion proteins

BACKGROUND

One of the leading current trends in technology is the miniaturization of devices to the microscale and nanoscale. The highly advanced approaches are based on biological systems, subjected to bioengineering using chemical, enzymatic and recombinant methods. Here we have utilised the biological affinity towards cellulose of the cellulose binding domain (CBD) fused with recombinant proteins.

RESULTS

Here we focused on fusions with 'artificial', concatemeric proteins with preprogrammed functions, constructed using DNA FACE™ technology. Such CBD fusions can be efficiently attached to micro-/nanocellulose to form functional, hybrid bionanoparticles. Microcellulose (MCC) particles were generated by a novel approach to enzymatic hydrolysis using Aspergillus sp. cellulase. The interaction between the constructs components - MCC, CBD and fused concatemeric proteins - was evaluated. Obtaining of hybrid biomicroparticles of a natural cellulose biocarrier with proteins with therapeutic properties, fused with CBD, was confirmed. Further, biological tests on the hybrid bioMCC particles confirmed the lack of their cytotoxicity on 46BR.1 N fibroblasts and human adipose derived stem cells (ASCs). The XTT analysis showed a slight inhibition of the proliferation of 46BR.1 N fibroblasts and ACSs cells stimulated with the hybrid biomicroparticles. However, in both cases no changes in the morphology of the examined cells after incubation with the hybrid biomicroparticles' MCC were detected.

CONCLUSIONS

Microcellulose display with recombinant proteins involves utilizing cellulose, a natural polymer found in plants, as a platform for presenting or displaying proteins. This approach harnesses the structural properties of cellulose to express or exhibit various recombinant proteins on its surface. It offers a novel method for protein expression, presentation, or immobilization, enabling various applications in biotechnology, biomedicine, and other fields. Microcellulose shows promise in biomedical fields for wound healing materials, drug delivery systems, tissue engineering scaffolds, and as a component in bio-sensors due to its biocompatibility and structural properties.

The Application of Peptide Nucleic Acids (PNA) in the Inhibition of Proprotein Convertase Subtilisin/Kexin 9 (PCSK9) Gene Expression in a Cell-Free Transcription/Translation System

Proprotein convertase subtilisin/kexin 9 (PCSK9) is a protein that plays a key role in the metabolism of low-density lipoprotein (LDL) cholesterol. The gain-of-function mutations of the PCSK9 gene lead to a reduced number of surface LDL receptors by binding to them, eventually leading to endosomal degradation. This, in turn, is the culprit of hypercholesterolemia, resulting in accelerated atherogenesis. The modern treatment for hypercholesterolemia encompasses the use of biological drugs against PCSK9, like monoclonal antibodies and gene expression modulators such as inclisiran-a short, interfering RNA (siRNA). Peptide nucleic acid (PNA) is a synthetic analog of nucleic acid that possesses a synthetic peptide skeleton instead of a phosphate-sugar one. This different structure determines the unique properties of PNA (e.g., neutral charge, enzymatic resistance, and an enormously high affinity with complementary DNA and RNA). Therefore, it might be possible to use PNA against PCSK9 in the treatment of hypercholesterolemia. We sought to explore the impact of three selected PNA oligomers on PCSK9 gene expression. Using a cell-free transcription/translation system, we showed that one of the tested PNA strands was able to reduce the PCSK9 gene expression down to 74%, 64%, and 68%, as measured by RT-real-time PCR, Western blot, and HPLC, respectively. This preliminary study shows the high applicability of a cell-free enzymatic environment as an efficient tool in the initial evaluation of biologically active PNA molecules in the field of hypercholesterolemia research. This cell-free approach allows for the omission of the hurdles associated with transmembrane PNA transportation at the early stage of PNA selection.

Regenerative Drug Discovery Using Ear Pinna Punch Wound Model in Mice

The ear pinna is a complex tissue consisting of the dermis, cartilage, muscles, vessels, and nerves. Ear pinna healing is a model of regeneration in mammals. In some mammals, including rabbits, punch wounds in the ear pinna close spontaneously; in common-use laboratory mice, they remain for life. Agents inducing ear pinna healing are potential regenerative drugs. We tested the effects of selected bioactive agents on 2 mm ear pinna wound closure in BALB/c mice. Our previous research demonstrated that a DNA methyltransferase inhibitor, zebularine, remarkably induced ear pinna regeneration. Although experiments with two other demethylating agents, RG108 and hydralazine, were unsuccessful, a histone deacetylase inhibitor, valproic acid, was another epigenetic agent found to increase ear hole closure. In addition, we identified a pro-regenerative activity of 4-ketoretinoic acid, a retinoic acid metabolite. Attempts to counteract the regenerative effects of the demethylating agent zebularine, with folates as methyl donors, failed. Surprisingly, a high dose of methionine, another methyl donor, promoted ear hole closure. Moreover, we showed that the regenerated areas of ear pinna were supplied with nerve fibre networks and blood vessels. The ear punch model proved helpful in testing the pro-regenerative activities of small-molecule compounds and observations of peripheral nerve regeneration.

Interaction of Arginine-Rich Cell-Penetrating Peptides with an Artificial Neuronal Membrane

Arginine-rich cell-penetrating peptides (RRCPPs) exhibit intrinsic neuroprotective effects on neurons injured by acute ischemic stroke. Conformational properties, interaction, and the ability to penetrate the neural membrane are critical for the neuroprotective effects of RRCCPs. In this study, we applied circular dichroism (CD) spectroscopy and coarse-grained molecular dynamics (CG MD) simulations to investigate the interactions of two RRCPPs, Tat(49–57)-NH2 (arginine-rich motif of Tat HIV-1 protein) and PTD4 (a less basic Ala-scan analog of the Tat peptide), with an artificial neuronal membrane (ANM). CD spectra showed that in an aqueous environment, such as phosphate-buffered saline, the peptides mostly adopted a random coil (PTD4) or a polyproline type II helical (Tat(49–57)-NH2) conformation. On the other hand, in the hydrophobic environment of the ANM liposomes, the peptides showed moderate conformational changes, especially around 200 nm, as indicated by CD curves. The changes induced by the liposomes were slightly more significant in the PTD4 peptide. However, the nature of the conformational changes could not be clearly defined. CG MD simulations showed that the peptides are quickly attracted to the neuronal lipid bilayer and bind preferentially to monosialotetrahexosylganglioside (DPG1) molecules. However, the peptides did not penetrate the membrane even at increasing concentrations. This suggests that the energy barrier required to break the strong peptide–lipid electrostatic interactions was not exceeded in the simulated models. The obtained results show a correlation between the potential of mean force parameter and a peptide’s cell membrane-penetrating ability and neuroprotective properties.

PTD4 Peptide Increases Neural Viability in an In Vitro Model of Acute Ischemic Stroke

Ischemic stroke is a disturbance in cerebral blood flow caused by brain tissue ischemia and hypoxia. We optimized a multifactorial in vitro model of acute ischemic stroke using rat primary neural cultures. This model was exploited to investigate the pro-viable activity of cell-penetrating peptides: arginine-rich Tat(49–57)-NH₂ (R⁴⁹KKRRQRRR⁵⁷-amide) and its less basic analogue, PTD4 (Y⁴⁷ARAAARQARA⁵⁷-amide). Our model included glucose deprivation, oxidative stress, lactic acidosis, and excitotoxicity. Neurotoxicity of these peptides was excluded below a concentration of 50 μm, and PTD4-induced pro-survival was more pronounced. Circular dichroism spectroscopy and molecular dynamics (MD) calculations proved potential contribution of the peptide conformational properties to neuroprotection: in MD, Tat(49–57)-NH₂ adopted a random coil and polyproline type II helical structure, whereas PTD4 adopted a helical structure. In an aqueous environment, the peptides mostly adopted a random coil conformation (PTD4) or a polyproline type II helical (Tat(49–57)-NH₂) structure. In 30% TFE, PTD4 showed a tendency to adopt a helical structure. Overall, the pro-viable activity of PTD4 was not correlated with the arginine content but rather with the peptide’s ability to adopt a helical structure in the membrane-mimicking environment, which enhances its cell membrane permeability. PTD4 may act as a leader sequence in novel drugs for the treatment of acute ischemic stroke.

Development of a Peptide Derived from Platelet-Derived Growth Factor (PDGF-BB) into a Potential Drug Candidate for the Treatment of Wounds

Objective: This study evaluated the use of novel peptides derived from platelet-derived growth factor (PDGF-BB) as potential wound healing stimulants. One of the compounds (named PDGF2) was subjected for further research after cytotoxicity and proliferation assays on human skin cells. Further investigation included evaluation of: migration and chemotaxis of skin cells, immunological and allergic safety, the transcriptional analyses of adipose-derived stem cells (ASCs) and dermal fibroblasts stimulated with PDGF2, and the use of dorsal skin wound injury model to evaluate the effect of wound healing in mice. Approach: Colorimetric lactate dehydrogenase and tetrazolium assays were used to evaluate the cytotoxicity and the effect on proliferation. PDGF2 effect on migration and chemotaxis was also checked. Immunological safety and allergic potential were evaluated with a lymphocyte activation and basophil activation test. Transcriptional profiles of ASCs and primary fibroblasts were assessed after stimulation with PDGF2. Eight-week-old BALB/c female mice were used for dorsal skin wound injury model. Results: PDGF2 showed low cytotoxicity, pro-proliferative effects on human skin cells, high immunological safety, and accelerated wound healing in mouse model. Furthermore, transcriptomic analysis of ASCs and fibroblasts revealed the activation of processes involved in wound healing and indicated its safety. Innovation: A novel peptide derived from PDGF-BB was proved to be safe drug candidate in wound healing. We also present a multifaceted in vitro model for the initial screening of new compounds that may be potentially useful in wound healing stimulation. Conclusion: The results show that peptide derived from PDGF-BB is a promising drug candidate for wound treatment.

Imunofan-RDKVYR Peptide-Stimulates Skin Cell Proliferation and Promotes Tissue Repair

Regeneration and wound healing are vital to tissue homeostasis and organism survival. One of the biggest challenges of today's science and medicine is finding methods and factors to stimulate these processes in the human body. Effective solutions to promote regenerative responses will accelerate advances in tissue engineering, regenerative medicine, transplantology, and a number of other clinical specialties. In this study, we assessed the potential efficacy of a synthetic hexapeptide, RDKVYR, for the stimulation of tissue repair and wound healing. The hexapeptide is marketed under the name "Imunofan" (IM) as an immunostimulant. IM displayed stability in aqueous solutions, while in plasma it was rapidly bound by albumins. Structural analyses demonstrated the conformational flexibility of the peptide. Tests in human fibroblast and keratinocyte cell lines showed that IM exerted a statistically significant (p < 0.05) pro-proliferative activity (30-40% and 20-50% increase in proliferation of fibroblast and keratinocytes, respectively), revealed no cytotoxicity over a vast range of concentrations (p < 0.05), and had no allergic properties. IM was found to induce significant transcriptional responses, such as enhanced activity of genes involved in active DNA demethylation (p < 0.05) in fibroblasts and activation of genes involved in immune responses, migration, and chemotaxis in adipose-derived stem cells derived from surgery donors. Experiments in a model of ear pinna injury in mice indicated that IM moderately promoted tissue repair (8% in BALB/c and 36% in C57BL/6 in comparison to control).

Data regarding a new, vector-enzymatic DNA fragment amplification-expression technology for the construction of artificial, concatemeric DNA, RNA and proteins, as well as biological effects of selected polypeptides obtained using this method

Applications of bioactive peptides and polypeptides are emerging in areas such as drug development and drug delivery systems. These compounds are bioactive, biocompatible and represent a wide range of chemical properties, enabling further adjustments of obtained biomaterials. However, delivering large quantities of peptide derivatives is still challenging. Several methods have been developed for the production of concatemers - multiple copies of the desired protein segments. We have presented an efficient method for the production of peptides of desired length, expressed from concatemeric Open Reading Frame. The method employs specific amplification-expression DNA vectors. The main methodological approaches are described by Skowron et al., 2020 [1]. As an illustration of the demonstrated method's utility, an epitope from the S protein of Hepatitis B virus (HBV) was amplified. Additionally, peptides, showing potentially pro-regenerative properties, derived from the angiopoietin-related growth factor (AGF) were designed and amplified. Here we present a dataset including: (i) detailed protocols for the purification of HBV and AGF - derived polyepitopic protein concatemers, (ii) sequences of the designed primers, vectors and recombinant constructs, (iii) data on cytotoxicity, immunogenicity and stability of AGF-derived polypeptides.

A vector-enzymatic DNA fragment amplification-expression technology for construction of artificial, concatemeric DNA, RNA and proteins for novel biomaterials, biomedical and industrial applications

A DNA fragment amplification/expression technology for the production of new generation biomaterials for scientific, industrial and biomedical applications is described. The technology enables the formation of artificial Open Reading Frames (ORFs) encoding concatemeric RNAs and proteins. It recruits the Type IIS SapI restriction endonuclease (REase) for an assembling of DNA fragments in an ordered head-to-tail-orientation. The technology employs a vector-enzymatic system, dedicated to the expression of newly formed, concatemeric ORFs from strong promoters. Four vector series were constructed to suit specialised needs. As a proof of concept, a model amplification of a 7-amino acid (aa) epitope from the S protein of HBV virus was performed, resulting in 500 copies of the epitope-coding DNA segment, consecutively linked and expressed in Escherichia coli (E. coli). Furthermore, a peptide with potential pro-regenerative properties (derived from an angiopoietin-related growth factor) was designed. Its aa sequence was back-translated, codon usage optimized and synthesized as a continuous ORF 10-mer. The 10-mer was cloned into the amplification vector, enabling the N-terminal fusion and multiplication of the encoded protein with MalE signal sequence. The obtained genes were expressed, and the proteins were purified. Conclusively, we show that the proteins are neither cytotoxic nor immunogenic and they have a very low allergic potential.

Epigenetic inhibitor zebularine activates ear pinna wound closure in the mouse

BACKGROUND

Most studies on regenerative medicine focus on cell-based therapies and transplantations. Small-molecule therapeutics, though proved effective in different medical conditions, have not been extensively investigated in regenerative research. It is known that healing potential decreases with development and developmental changes are driven by epigenetic mechanisms, which suggests epigenetic repression of regenerative capacity.

METHODS

We applied zebularine, a nucleoside inhibitor of DNA methyltransferases, to stimulate the regenerative response in a model of ear pinna injury in mice.

FINDINGS

We observed the regeneration of complex tissue that was manifested as improved ear hole repair in mice that received intraperitoneal injections of zebularine. Six weeks after injury, the mean hole area decreased by 83.2 ± 9.4% in zebularine-treated and by 43.6 ± 15.4% in control mice (p < 10^-30). Combined delivery of zebularine and retinoic acid potentiated and accelerated this effect, resulting in complete ear hole closure within three weeks after injury. We found a decrease in DNA methylation and transcriptional activation of neurodevelopmental and pluripotency genes in the regenerating tissues.

INTERPRETATION

This study is the first to demonstrate an effective induction of complex tissue regeneration in adult mammals using zebularine. We showed that the synergistic action of an epigenetic drug (zebularine) and a transcriptional activator (retinoic acid) could be effectively utilized to induce the regenerative response, thus delineating a novel pharmacological strategy for regeneration. The strategy was effective in the model of ear pinna regeneration in mice, but zebularine acts on different cell types, therefore, a similar approach can be tested in other tissues and organs.

Identification of potentially mobile and persistent transformation products of REACH-registered chemicals and their occurrence in surface waters

Transformation of industrial chemicals might be a significant source of hitherto unknown persistent and mobile organic contaminants (PMOC, PM chemicals) present in the aquatic environment. Herein we depicted a three-step strategy consisting of (I) the prioritization of potential PMOC precursors among REACH-registered chemicals, (II) their lab scale transformation through hydrolysis, photolysis, MnO₂ oxidation, and biotransformation and subsequent structural elucidation of derived transformation products, and finally (III) the assessment of their environmental relevance. The proposed procedure was utilized to investigate eleven chemicals, for nine of which a concentration reduction was observed. For six of these chemicals transformation products were at least tentatively identified and partially confirmed with a commercially available reference standard. Retrospective assessment of high-performance liquid chromatography - high-resolution mass spectrometry data as well as a target screening method for the identified TPs and some of the prioritized REACH chemicals revealed the widespread presence of the following chemicals in the environment: 2-pyrrolidone (hydrolysis product of vinylpyrrolidone), TP 216 (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-acetic acid, biotransformation product of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-ethanol), and 1,3-diphenylguanidine (prioritized chemical with experimental evidence of environmental stability). 2-Pyrrolidone was detected in 23/25 investigated surface water samples and present in concentrations of up to 400 ng/L. TP 216 was detected in 20/25 surface water samples and an additional sampling of a waste water treatment plant and the receiving surface water confirmed that TP 216 is formed in waste water treatment plants. The vulcanisation agent 1,3-diphenylguanidine was present in all investigated samples. A leaching experiment with a tire suggested that tires and thus tire wear particles are a potential source of 1,3-diphenylguanidine. With these data the depicted approach was proven successful and suitable for true unknowns like TP 216, and thus an alternative to non-target screenings or suspect-screenings with predicted TPs to identify environmentally relevant transformation products.

TP10-Dopamine Conjugate as a Potential Therapeutic Agent in the Treatment of Parkinson's Disease

Parkinson's disease (PD) is a common progressive neurodegenerative disorder for which the current treatment is not fully satisfactory. One of the major drawbacks of current PD therapy is poor penetration of drugs across the blood-brain barrier (BBB). In recent years, cell-penetrating peptides (CPPs) such as Tat, SynB, or TP10 have gained great interest due to their ability to penetrate cell membranes and to deliver different cargos to their targets including the central nervous system (CNS). However, there is no data with respect to the use of CPPs as drug carriers to the brain for the treatment of PD. In the presented research, the covalent TP10-dopamine conjugate was synthesized and its pharmacological properties were characterized in terms of its ability to penetrate the BBB and anti-parkinsonian activity. The results showed that dopamine (DA) in the form of a conjugate with TP10 evidently gained access to the brain tissue, exhibited low susceptibility to O-methylation reaction by catechol- O-methyltransferase (lower than that of DA), possessed a relatively high affinity to both dopamine D₁ and D₂ receptors (in the case of D₁, a much higher than that of DA), and showed anti-parkinsonian activity (higher than that of l-DOPA) in the MPTP-induced preclinical animal model of PD. The presented results prove that the conjugation of TP10 with DA may be a good starting point for the development of a new strategy for the treatment of PD.

Monitoring the Transcriptional Activity of Human Endogenous Retroviral HERV-W Family Using PNA Strand Invasion into Double-Stranded DNA

In the presented assay, we elaborated a method for distinguishing sequences that are genetically closely related to each other. This is particularly important in a situation where a fine balance of the allele abundance is a point of research interest. We developed a peptide nucleic acid (PNA) strand invasion technique for the differentiation between multiple sclerosis-associated retrovirus (MSRV) and ERVWE1 sequences, both molecularly similar, belonging to the human endogenous retrovirus HERV-W family. We have found that this method may support the PCR technique in screening for minor alleles which, in certain conditions, may be undetected by the standard PCR technique. We performed the analysis of different ERVWE1 and MSRV template mixtures ranging from 0 to 100% of ERVWE1 in the studied samples, finding the linear correlation between template composition and signal intensity of final reaction products. Using the PNA strand invasion assay, we were able to estimate the relative ERVWE1 expression level in human specimens such as U-87 MG, normal human astrocytes cell lines and placental tissue. The results remained in concordance with those obtained by semi-quantitative or quantitative PCR.

Immunophenotyping and transcriptional profiling of in vitro cultured human adipose tissue derived stem cells

Adipose-derived stem cells (ASCs) have become an important research model in regenerative medicine. However, there are controversies regarding the impact of prolonged cell culture on the ASCs phenotype and their differentiation potential. Hence, we studied 10 clinical ASCs replicates from plastic and oncological surgery patients, in six-passage FBS supplemented cultures. We quantified basic mesenchymal cell surface marker transcripts and the encoded proteins after each passage. In parallel, we investigated the differentiation potential of ASCs into chondrocytes, osteocytes and adipocytes. We further determined the effects of FBS supplementation and subsequent deprivation on the whole transcriptome by comprehensive mRNA and miRNA sequencing. Our results show that ASCs maintain differentiation potential and consistent profile of key mesenchymal markers, with apparent expression of distinct isoforms, in long-term cultures. No significant differences were observed between plastic and oncological surgery cohorts. ASCs in FBS supplemented primary cultures are almost committed to mesenchymal lineages as they express key epithelial-mesenchymal transition genes including early mesenchymal markers. Furthermore, combined mRNA/miRNA expression profiling strongly supports a modulatory role for the miR-30 family in the commitment process to mesenchymal lineages. Finally, we propose improvements to existing qPCR based assays that address alternative isoform expression of mesenchymal markers.

The application of strand invasion phenomenon, directed by peptide nucleic acid (PNA) and single-stranded DNA binding protein (SSB) for the recognition of specific sequences of human endogenous retroviral HERV-W family

The HERV-W family of human endogenous retroviruses represents a group of numerous sequences that show close similarity in genetic composition. It has been documented that some members of HERV-W-derived expression products are supposed to play significant role in humans' pathology, such as multiple sclerosis or schizophrenia. Other members of the family are necessary to orchestrate physiological processes (eg, ERVWE1 coding syncytin-1 that is engaged in syncytiotrophoblast formation). Therefore, an assay that would allow the recognition of particular form of HERV-W members is highly desirable. A peptide nucleic acid (PNA)-mediated technique for the discrimination between multiple sclerosis-associated retrovirus and ERVWE1 sequence has been developed. The assay uses a PNA probe that, being fully complementary to the ERVWE1 but not to multiple sclerosis-associated retrovirus (MSRV) template, shows high selective potential. Single-stranded DNA binding protein facilitates the PNA-mediated, sequence-specific formation of strand invasion complex and, consequently, local DNA unwinding. The target DNA may be then excluded from further analysis in any downstream process such as single-stranded DNA-specific exonuclease action. Finally, the reaction conditions have been optimized, and several PNA probes that are targeted toward distinct loci along whole HERV-W env sequences have been evaluated. We believe that PNA/single-stranded DNA binding protein-based application has the potential to selectively discriminate particular HERV-W molecules as they are at least suspected to play pathogenic role in a broad range of medical conditions, from psycho-neurologic disorders (multiple sclerosis and schizophrenia) and cancers (breast cancer) to that of an auto-immunologic background (psoriasis and lupus erythematosus).

Synthesis and hybridization studies of a new CPP-PNA conjugate as a potential therapeutic agent in atherosclerosis treatment

The objective of this study was to design and synthesize a new CPP-PNA conjugate that would be able to penetrate endothelial cells, bind STAT1 mRNA and thereby block the activity of STAT1 (the Signal Transducer and Activator of Transcription 1), which is important in cases of vessel inflammation. In the course of the study, the TAMRA-PTD-4- Hal(traziole-Gly-PNA)-conjugate was successfully synthesized using a specific 1,3-dipolar Huisgen cycloaddition reaction known as a "click reaction". The hybridization properties of the conjugate to complementary hSTAT1 mRNA and hSTAT1 ssDNA fragments was verified by capillary electrophoresis (CE). Studies have shown that the attachment of a fluorescence-labeled peptide to a PNA sequence via a 1,2,3-triazole ring did not alter the binding properties of the PNA to the complementary hSTAT1 mRNA or hSTAT1 ssDNA fragments maintaining similar binding affinity. Furthermore, the data obtained suggest that the use of such a conjugate to modulate the activity and expression of STAT1 could provide a new therapeutic strategy for atherosclerosis treatment.

Cell-penetrating peptides as a promising tool for delivery of various molecules into the cells

Many biologically active compounds, including macromolecules that are used as various kinds of drugs, must be delivered to the interior of cell or organelles such as mitochondria or nuclei to achieve a therapeutic effect. However, very often, lipophilic cell membrane is impermeable for these molecules. A new method in the transport of macromolecules through the cell membrane is the one based on utilizing cell-penetrating peptides (CPPs). Invented 25 years ago, CPPs are currently the subject of intensive research in many laboratories all over the world. CPPs are short compounds comprising up to 30 amino acid residues, which penetrate the cell membrane but do not cause cell damage. Additionally, CPPs can transfer hydrophilic molecules (peptides, proteins, nucleic acids) which exceed their mass, and for which the cell membrane is generally impermeable. In this review, we concentrate on the cellular uptake mechanism of CPPs and a method of conjunction of CPPs to the transported molecules. We also highlight the potential of CPPs in delivering various kinds of macromolecules into cells, including compounds of therapeutic interest.

A peptide nucleic acid (PNA)-mediated polymerase chain reaction clamping allows the selective inhibition of the ERVWE1 gene amplification

A new peptide nucleic acid (PNA) mediated QPCR technique for the detection and quantification of the Multiple Sclerosis-Associated Retrovirus (MSRV) belonging to the human endogenous retrovirus-W (HERV-W) family has been developed. The assay utilizes a PNA probe which is fully complementary to the ERVWE1 sequence, another member of the HERV-W family which is closely related to MSRV. Due to its excellent affinity to a completely matched template, PNA probe selectively blocks the amplification of ERVWE1 thus allowing the specific and exclusive detection and quantification of the MSRV as PNA does not interfere with the amplification of MSRV. Using this newly developed method we found that MSRV is predominantly expressed over ERWVE1 in astrocyte-derived U-87 MG cell line but not in human umbilical vein endothelial cells or human placental cells.

Functional recognition of the modified human tRNALys3(UUU) anticodon domain by HIV's nucleocapsid protein and a peptide mimic

The HIV-1 nucleocapsid protein, NCp7, facilitates the use of human tRNA(Lys3)(UUU) as the primer for reverse transcription. NCp7 also remodels the htRNA's amino acid accepting stem and anticodon domains in preparation for their being annealed to the viral genome. To understand the possible influence of the htRNA's unique composition of post-transcriptional modifications on NCp7 recognition of htRNA(Lys3)(UUU), the protein's binding and functional remodeling of the human anticodon stem and loop domain (hASL(Lys3)) were studied. NCp7 bound the hASL(Lys3)(UUU) modified with 5-methoxycarbonylmethyl-2-thiouridine at position-34 (mcm(5)s(2)U(34)) and 2-methylthio-N(6)-threonylcarbamoyladenosine at position-37 (ms(2)t(6)A(37)) with a considerably higher affinity than the unmodified hASL(Lys3)(UUU) (K(d)=0.28±0.03 and 2.30±0.62 μM, respectively). NCp7 denatured the structure of the hASL(Lys3)(UUU)-mcm(5)s(2)U(34);ms(2)t(6)A(37);Ψ(39) more effectively than that of the unmodified hASL(Lys3)(UUU). Two 15 amino acid peptides selected from phage display libraries demonstrated a high affinity (average K(d)=0.55±0.10 μM) and specificity for the ASL(Lys3)(UUU)-mcm(5)s(2)U(34);ms(2)t(6)A(37) comparable to that of NCp7. The peptides recognized a t(6)A(37)-modified ASL with an affinity (K(d)=0.60±0.09 μM) comparable to that for hASL(Lys3)(UUU)-mcm(5)s(2)U(34);ms(2)t(6)A(37), indicating a preference for the t(6)A(37) modification. Significantly, one of the peptides was capable of relaxing the hASL(Lys3)(UUU)-mcm(5)s(2)U(34);ms(2)t(6)A(37);Ψ(39) structure in a manner similar to that of NCp7, and therefore could be used to further study protein recognition of RNA modifications. The post-transcriptional modifications of htRNA(Lys3)(UUU) have been found to be important determinants of NCp7's recognition prior to the tRNA(Lys3)(UUU) being annealed to the viral genome as the primer of reverse transcription.

Sequence-altered peptide adopts optimum conformation for modification-dependent binding of the yeast tRNAPhe anticodon domain

Amino acid contributions to protein recognition of naturally modified RNAs are not understood. Circular dichroism spectra and predictive software suggested that peptide tF2 (S1ISPW5GFSGL10 LRWSY15), selected from a phage display library to bind the modified anticodon domain of yeast tRNAPhe (ASL), adopted a beta-sheet structure. Ala residues incorporated at positions Pro4 and Gly6, both predicted to be involved in a turn, did not alter the peptide binding affinity for the ASLPhe, although major changes in the peptide's CD spectra were observed. Substitutions at three positions Pro4, Gly6, and Gly9, the latter not predicted to be in a turn, reduced the peptide's binding affinity to 4% of that of the unsubstituted tF2 and strongly influenced the peptide's secondary structure. The results suggest that peptides with different conformations, but similar affinities, adopt the optimal binding conformation, indicative of a structurally adaptive model of binding in which the modified RNA serves as a scaffold.

Using capillary electrophoresis to study methylation effect on RNA-peptide interaction

Methylation of RNA and proteins is one of a broad spectrum of post-transcriptional/translational mechanisms of gene expression regulation. Its functional signification is only beginning to be understood. A sensitive capillary electrophoresis mobility shift assay (CEMSA) for qualitative study of the methylation effect on biomolecules interaction is presented. Two RNA-peptide systems were chosen for the study. The first one consists of a 17-nucleotide analogue (+27-+43) of the yeast tRNA(Phe) anticodon stem and loop domain (ASL(Phe)) containing three of the five naturally occurring modifications (2'-O-methylcytidine (Cm(32)), 2'-O-methylguanine (Gm(34)) and 5-methylcytidine (m(5)C(40))) (ASL(Phe)-Cm(32),Gm(34),m(5)C(40)) and a 15-amino-acid peptide (named t(F)2: Ser(1)-Ile-Ser-Pro-Trp(5)-Gly-Phe-Ser-Gly-Leu(10)-Leu- Arg-Trp-Ser-Tyr(15)) selected from a random phage display library (RPL). A peptide-concentration-dependent formation of an RNA-peptide complex was clearly observable by CEMSA. In the presence of the peptide the capillary electrophoresis (CE) peak for triply methylated ASL(Phe) shifted from 18.16 to 20.90 min. Formation of the complex was not observed when an unmethylated version of ASL(Phe) was used. The second system studied consisted of the (+18)-(+44) fragment of the trans-activation response element of human immunodeficiency virus type 1 (TAR RNA HIV-1) and a 9-amino-acid peptide of the trans-activator of transcription protein (Tat HIV-1) Tat(49-57)-NH(2) (named Tat1: Arg(49)-Lys-Lys-Arg(52)-Arg-Gln-Arg-Arg- Arg(57)-NH(2)). In the presence of Tat(49-57)-NH(2) a significant shift of migration time of TAR from 18.66 min to 20.12 min was observed. Methylation of a residue Arg(52)-->Arg(Me)(2), crucial for TAR binding, strongly disrupted formation of the complex. Only at a high micromolar peptide concentration a poorly shaped, broad peak of the complex was observed. CE was found to be an efficient and sensitive method for the analysis of methylation effects on interaction of biomolecules.

Aminoacyl-tRNA synthetases and aminoacylation of tRNA in the nucleus

This review is focused on findings concerning the presence of translation apparatus components (aminoacyl-tRNA synthetases, aminoacyl-tRNA, elongation factors) as well as translation itself in the nucleus. A nuclear role of these molecules is unknown. New findings suggest that well-accepted model of spatial segregation of transcription and translation in eukaryotic cell may be oversimplifcation. Nuclear coupling of both these processes show us how exciting and surprising may be the world of the living cell.

Using capillary electrophoresis to study methylation effect on RNA-peptide interaction

Methylation of RNA and proteins is one of a broad spectrum of post-transcriptional/translational mechanisms of gene expression regulation. Its functional signification is only beginning to be understood. A sensitive capillary electrophoresis mobility shift assay (CEMSA) for qualitative study of the methylation effect on biomolecules interaction is presented. Two RNA-peptide systems were chosen for the study. The first one consists of a 17-nucleotide analogue (+27-+43) of the yeast tRNA(Phe) anticodon stem and loop domain (ASL(Phe)) containing three of the five naturally occurring modifications (2'-O-methylcytidine (Cm(32)), 2'-O-methylguanine (Gm(34)) and 5-methylcytidine (m(5)C(40))) (ASL(Phe)-Cm(32),Gm(34),m(5)C(40)) and a 15-amino-acid peptide (named t(F)2: Ser(1)-Ile-Ser-Pro-Trp(5)-Gly-Phe-Ser-Gly-Leu(10)-Leu- Arg-Trp-Ser-Tyr(15)) selected from a random phage display library (RPL). A peptide-concentration-dependent formation of an RNA-peptide complex was clearly observable by CEMSA. In the presence of the peptide the capillary electrophoresis (CE) peak for triply methylated ASL(Phe) shifted from 18.16 to 20.90 min. Formation of the complex was not observed when an unmethylated version of ASL(Phe) was used. The second system studied consisted of the (+18)-(+44) fragment of the trans-activation response element of human immunodeficiency virus type 1 (TAR RNA HIV-1) and a 9-amino-acid peptide of the trans-activator of transcription protein (Tat HIV-1) Tat(49-57)-NH(2) (named Tat1: Arg(49)-Lys-Lys-Arg(52)-Arg-Gln-Arg-Arg- Arg(57)-NH(2)). In the presence of Tat(49-57)-NH(2) a significant shift of migration time of TAR from 18.66 min to 20.12 min was observed. Methylation of a residue Arg(52)-->Arg(Me)(2), crucial for TAR binding, strongly disrupted formation of the complex. Only at a high micromolar peptide concentration a poorly shaped, broad peak of the complex was observed. CE was found to be an efficient and sensitive method for the analysis of methylation effects on interaction of biomolecules.

Structural requirements for conserved Arg52 residue for interaction of the human immunodeficiency virus type 1 trans-activation responsive element with trans-activator of transcription protein (49-57). Capillary electrophoresis mobility shift assay

A sensitive capillary electrophoresis mobility shift assay (CEMSA) for qualitative study of the interaction between the trans-activation response element (TAR) and the trans-activator of transcription protein (Tat) has been presented. The human immunodeficiency virus type 1 (HIV-1) Tat promotes elongation of viral mRNAs binding to the TAR. It has been suggested that a single, conserved arginine residue (presumably Arg52) within the arginine-rich region (ARR) of Tat plays the major role for the Tat-TAR recognition. To study structural requirements of the Arg52 position, Tat(49-57)-NH2 analogues substituted with nonencoded amino acids at the Arg52 position have been synthesized and their interaction with TAR has been studied by CEMSA. Using a linear polyacrylamide-coated capillary and a sieving polymer containing separation buffer, well separated and shaped peaks of free and bound TAR RNA were obtained. In the presence of Tat1 peptide bearing the native sequence of Tat(49-57) a significant shift of migration time of TAR from 18.66 min (RSD=1.4%) to 20.12 min (RSD=2.4%) was observed. We have found that almost every substitution within the guanidino group of the Arg52 [L-Arg52-->Cit, -->Orn, -->Arg(NO2), -->Arg(Me2)] strongly disrupted or abolished the TAR-Tat peptide interaction. Enantiomeric substitution, L-Arg52-->D-Arg was the only one which notably promoted TAR-Tat peptide interaction. The results demonstrate that the specific net of hydrogen bonds created by the guanidinio group of conserved Arg52 plays a crucial role for TAR-Tat HIV-1 recognition. The newly developed procedure describes for the first time use of CE to monitor RNA-peptide complex formation. The methodology presented should be generally applicable to study RNA-peptide (protein) interaction.

Interaction of RNA with phage display selected peptides analyzed by capillary electrophoresis mobility shift assay

A sensitive capillary electrophoresis mobility shift assay (CEMSA) to analyze RNA/peptide interactions has been developed. Capillary electrophoresis (CE) has been adapted for investigating the interaction between variously methylated 17-nt analogs of the yeast tRNAPhe anticodon stem and loop domain (ASL(Phe)) and 15-amino-acid peptides selected from a random phage display library (RPL). A peptide-concentration-dependent formation of RNA/peptide complex was clearly visible during CEMSA. In the presence of peptide, the UV-monitored CE peak for ASLPhe with three of the five naturally occurring modifications (2'-O-methylcytidine (Cm32), 2'-O-methylguanine (Gm34) and 5-methylcytidine (m5C40) shifted from 18.16 to 20.90 min. The mobility shift was observed only for methylated RNA. The negative effects of diffusion, electroosmotic flow and adhesion of molecules to the capillary internal wall were suppressed by using a buffer containing a sieving polymer and a polyacrylamide-coated capillary. Under these conditions, well-shaped peaks and resolution of RNA free and bound to peptide were achieved. Peptide tF2, the most populated ligand in the RPL, specifically bound triply methylated ASLPhe in a methylated nucleoside-dependent manner. CE was found to be an efficient and sensitive method for the qualitative analysis of RNA-peptide interaction and should be generally applicable to the study of RNA-peptide (protein) interactions.

Aminoacyl-tRNA synthetases and aminoacylation of tRNA in the nucleus

This review is focused on findings concerning the presence of translation apparatus components (aminoacyl-tRNA synthetases, aminoacyl-tRNA, elongation factors) as well as translation itself in the nucleus. A nuclear role of these molecules is unknown. New findings suggest that well-accepted model of spatial segregation of transcription and translation in eukaryotic cell may be oversimplifcation. Nuclear coupling of both these processes show us how exciting and surprising may be the world of the living cell.

Anticodon domain methylated nucleosides of yeast tRNA(Phe) are significant recognition determinants in the binding of a phage display selected peptide

The contributions of the natural modified nucleosides to RNA identity in protein/RNA interactions are not understood. We had demonstrated that 15 amino acid long peptides could be selected from a random phage display library using the criterion of binding to a modified, rather than unmodified, anticodon domain of yeast tRNA(Phe) (ASL(Phe)). Affinity and specificity of the selected peptides for the modified ASL(Phe) have been characterized by fluorescence spectroscopy of the peptides' tryptophans. One of the peptides selected, peptide t(F)2, exhibited the highest specificity and most significant affinity for ASL(Phe) modified with 2'-O-methylated cytidine-32 and guanosine-34 (Cm(32) and Gm(34)) and 5-methylated cytidine-40 (m(5)C(40)) (K(d) = 1.3 +/- 0.4 microM) and a doubly modified ASL(Phe)-Gm(34),m(5)C(40) and native yeast tRNA(Phe) (K(d) congruent with 2.3 and 3.8 microM, respectively) in comparison to that for the unmodified ASL(Phe) (K(d) = 70.1 +/- 12.3 microM). Affinity was reduced when a modification altered the ASL loop structure, and binding was negated by modifications that disfavored hairpin formation. Peptide t(F)2's higher affinity for the ASL(Phe)-Cm(32),Gm(34),m(5)C(40) hairpin and fluorescence resonance energy transfer from its tryptophan to the hypermodified wybutosine-37 in the native tRNA(Phe) placed the peptide across the anticodon loop and onto the 3'-side of the stem. Inhibition of purified yeast phenylalanyl-tRNA synthetase (FRS) catalyzed aminoacylation of cognate yeast tRNA(Phe) corroborated the peptide's binding to the anticodon domain. The phage-selected peptide t(F)2 has three of the four amino acids crucial to G(34) recognition by the beta-structure of the anticodon-binding domain of Thermus thermophilus FRS and exhibited circular dichroism spectral properties characteristic of beta-structure. Thus, modifications as simple as methylations contribute identity elements that a selected peptide specifically recognizes in binding synthetic and native tRNA and in inhibiting tRNA aminoacylation.

Specific induction of Z-DNA conformation by a nuclear localization signal peptide of lupin glutaminyl tRNA synthetase

Recently we have sequenced cDNA of plant glutaminyl-tRNA synthetase (GlnRS) from Lupinus luteus. At the N terminal part the protein contains a lysine rich polypeptide (KPKKKKEK), which is identical to a nuclear localization signal (NLS). In this paper we showed that two synthetic peptides (20 and 8 amino acids long), which were derived from lupin GlnRS containing the NLS sequence interact with DNA, but one of them (8aa long) changing its conformation from the B to the Z form. This observation clearly suggests that the presence of the NLS polypeptide in a leader sequence of GlnRS is required not only for protein transport into nucleus but also for regulation of a gene expression. This is the first report suggesting a role of the NLS signal peptide in structural changes of DNA.

Experimental models of protein-RNA interaction: isolation and analyses of tRNA(Phe) and U1 snRNA-binding peptides from bacteriophage display libraries

Peptides that bind either U1 small nuclear RNA (U1 snRNA) or the anticodon stem and loop of yeast tRNA(Phe) (tRNA(ACPhe)) were selected from a random-sequence, 15-amino acid bacteriophage display library. An experimental system, including an affinity selection method, was designed to identify primary RNA-binding peptide sequences without bias to known amino acid sequences and without incorporating nonspecific binding of the anionic RNA backbone. Nitrocellulose binding assays were used to evaluate the binding of RNA by peptide-displaying bacteriophage. Amino acid sequences of RNA-binding bacteriophage were determined from the foreign insert DNA sequences, and peptides corresponding to the RNA-binding bacteriophage inserts were chemically synthesized. Peptide affinities for the RNAs (Kd approximately 0.1-5.0 microM) were analyzed successfully using fluorescence and circular dichroism spectroscopies. These methodologies demonstrate the feasibility of rapidly identifying, isolating, and initiating the analyses of small peptides that bind to RNAs in an effort to define better the chemistry, structure, and function of protein-RNA complexes.

Conformation of Systemin, a Polypeptide Activator of Proteinase Inhibitor Synthesis in Plants

An 18-amino acid polypeptide systemin was synthesized by the solid-phase method and its conformation was studied by circular dichroism spectroscopy. The peptide in solution is a mixture of random coil structure with β-sheet and β-turn motifs as has been previously suggested with NMR spectra. Free zone capillary electrophoresis analysis proved purity and chemical stability of systemin at different pH.

Interaction of HIV Tat model peptides with tRNA and 5S rRNA

New data are presented on the interaction of model synthetic peptides containing an arginine-rich region of human immunodeficiency virus (HIV-Tat), with native RNA molecules: tRNA(Phe) of Saccharomyces cerevisiae and 5S rRNA from Lupinus luteus. Both RNA species form complexes with the Tat1 (GRKKRRQRRRA) and Tat2 (GRKKRRQRRRAPQDSQTHQASLSKQPA) peptides, as shown by electrophoretic gel shift and RNase footprint assays, and CD measurements. The nucleotide sequence UGGG located in the dihydrouridine loop of tRNAPhe as well as in the loop D of 5S rRNA is specifically protected against RNases. Our data indicate direct interactions of guanine of RNA moieties with arginine residues. These interactions seem similar to those observed in DNA-protein complexes, but different from those previously observed in the TAR RNA-Tat complexes.

Interaction of HIV Tat Peptides With tRNAPhe from Yeast

We present data on the interaction of arginine-rich peptides of human immunodeficiency virus (HIV-Tat) with tRNAPhe of Saccharomyces cerevisiae. We have found that tRNA forms complexes with the Tat1 peptide of amino acid sequence GRKKRRQRRRA and its mutants where R is replaced by D-arginine, citrulline or ornithine. The structure of tRNA-Tat1 complex was probed by specific RNases digestions and Pb2+-induced cleavage of phosphodiester bond of guanosine. The nucleotide sequence UGGG located in the dihydrouridine loop of tRNAPhe binds to Tat peptide and therefore is specifically protected against RNases and is not hydrolyzed by Pb2+ ion. It seems that the peptide-RNA complex formation depends on direct recognition of guanine moieties of tRNA with arginine residues. These interactions are similar to those observed in many DNA-protein complexes, but are different from those previously observed for TAR RNA-Tat complexes.

Lysine14galanin(1-15)-NH2: a partial agonist at galanin receptors in rat isolated gastric fundus

The study was undertaken to characterize the effects of the porcine galanin [pGal(1-29)-NH2] analogue [Lys14]pGal(1-15)-NH2 on rat gastric fundus. [Lys14]pGal(1-15)-NH2 is a less potent contractile agent than pGal(1-29)-NH2 (EC50 74.1 vs. 43.7 nmol/l, respectively) and shows a significantly lower maximal response than pGal(1-29)-NH2. Concentration-contraction curves were constructed for pGal(1-29)-NH2 alone (control) and pGal(1-29)-NH2 in the presence of 10, 100, and 1,000 nmol/l of [Lys14]pGal(1-15)-NH2. [Lys14]pGal(1-15)-NH2 shifted the concentration-contraction curves of pGal(1-29)-NH2 significantly to the right, whereas their linear portions remained parallel to that for the pGal(1-29)-NH2 control. [Lys14]pGal(1-15)-NH2 markedly increased the EC50 of the respective pGal(1-29)-NH2 concentration-contraction curves. It did not substantially change the maximal response of the muscles to pGal(1-29)-NH2 and the form of the respective concentration-contraction curves. Schild's plot gave a straight line with a slope of 0.84. The pA2 value for [Lys14]pGal(1-15)-NH2 was 8.23. [Lys14]pGal(1-15)-NH2 seems to be a partial Gal receptor agonist. Since the lack of specific Gal receptor antagonists in the gastrointestinal tract makes a precise characterization of its role as a motility modulator difficult, the position 14 in the pGal(1-29)-NH2 molecule looks as an attractive target in the search of a pure Gal receptor antagonist in the smooth muscles of the gut.

Interaction of HIV Tat model peptides with tRNA and 5S rRNA

New data are presented on the interaction of model synthetic peptides containing an arginine-rich region of human immunodeficiency virus (HIV-Tat), with native RNA molecules: tRNA(Phe) of Saccharomyces cerevisiae and 5S rRNA from Lupinus luteus. Both RNA species form complexes with the Tat1 (GRKKRRQRRRA) and Tat2 (GRKKRRQRRRAPQDSQTHQASLSKQPA) peptides, as shown by electrophoretic gel shift and RNase footprint assays, and CD measurements. The nucleotide sequence UGGG located in the dihydrouridine loop of tRNAPhe as well as in the loop D of 5S rRNA is specifically protected against RNases. Our data indicate direct interactions of guanine of RNA moieties with arginine residues. These interactions seem similar to those observed in DNA-protein complexes, but different from those previously observed in the TAR RNA-Tat complexes.

The clinical usefulness of routine stacked multiplanar reconstruction in helical abdominal computed tomography

RATIONALE AND OBJECTIVES

The authors evaluate the usefulness of stacked multiplanar reconstructions in routine, thick-section abdominal computed tomography.

MATERIALS AND METHODS

Twenty-five routine, thick-section contrast abdominal CTs performed with equivalent technique were reformatted by multiplanar reconstructions in sagittal and coronal planes sequentially from side-to-side and front-to-back. The image sets were submitted, first axial images only followed by axial plus multiplanar reconstructions (MPRs), to 5 separate physician readers including 2 radiologists and 3 nonradiologists. These readers graded the visualization of a variety of normal and up to 5 pathologic lesions per patient on a scale of 1 to 5 (5 = best).

RESULTS

The addition of sagittal and coronal multiplanar reconstructions significantly improved the visualization of all normal anatomic structures (mean axial only, 3.8; mean axial plus MPR, 4.1; P < 0.0001). In addition, most pathologic lesions were statistically better visualized with the addition of multiplanar reconstructions (mean axial images only, 3.9; mean axial plus MPR, 4.1; P < 0.0001). All five readers found improved visualization in nearly every category with the addition of the multiplanar reconstructions. However, in only 7% of cases, did a reviewer find new diagnostic information with the addition of MPR images.

CONCLUSIONS

Stacked multiplanar reconstructions of routine, thick-section abdominal CT has clinical value in both the display of normal anatomic and pathologic lesions. Further studies, however, are required to confirm these findings before it is commonly used.

Galanin, galantide and galanin (1-14)-[alpha-aminobutyric acid8]-scyliorhinin-I: structure dependent effects on the rat isolated gastric fundus

The study was undertaken using selected pharmacodynamic parameters to describe the effects of porcine galanin(1-29)-NH2; porcine galanin fragments; galantide; porcine galanin(1-14)-[alpha-aminobutyric acid8]scyliorhinin-I and the analogues of the latter peptides on rat isolated gastric fundus muscle. All tested peptides, apart from galanin(16-29)-NH2 evoked reproducible concentration-dependent contractions with significantly decreased activities in comparison to the potency of the native galanin(1-29)-NH2 molecule. The order of the contractile ability in the group of galanin(1-29)-NH2 short fragments was as follows: [lysine14]galanin(1-15)-NH2 > galanin(1-15)-OH > galanin(1-15)-NH2 > [glycine5] galanin(1-15)-NH2 > galanin(2-15)-NH2 > [glycine5,lysine14]galanin(1-15)-NH2. Aside from [lysine14]galanin(1-15)-NH2 which had a lower efficacy, none of the peptides showed significant changes in this respect in comparison to the intact galanin(1-29)-NH2 molecule. The concentration-response curves of the tested peptides were to the right and their slopes besides from: galanin(1-15)-OH; galanin(2-15)-NH2; [glycine5]galanin(1-15)-NH2 remained not significantly different from galanin(1-29)-NH2. Hill's coefficient for galanin(1-29)-NH2 is 1.03 indicating an interaction of one galanin(1-29)-NH2 molecule with one receptor, fulfilling criteria of classical receptor theory. For galanin fragments Hill's coefficients are < 1 implying that the rules of classical theory may not apply. Galantide and analogues exhibited a subsequent decrease in potency: [cycloleucine4] galantide > galantide > [homoserine6]galantide > [phenylalnine(4fluor)17] galantide. Galanin(1-14)-[alpha-aminobutyric acid8]-scyliorhinin-I and its analogues contracted the gastric fundus with a decline in strength: galanin(1-13)-[norleucine10]-scyliorhinin-I(3-10) > galanin(1-13)-[phenylalanine(4fluor)7]-scyliorhinin-I > galanin(1-14)-[alpha-aminobutyric acid8]-scyliorhinin-I > galanin(1-13)-[alpha-aminobutyric acid8, norleucine10]-scyliorhinin-I(3-10). They all displayed a greater efficacy than galanin(1-29)-NH2, and the concentration-response curves were slightly to the right, almost parallel to that of galanin(1-29)-NH2. Slopes of the curves were not significantly different from galanin(1-29)-NH2. Hill's coefficient for the galantide, [cycloleucine4]galantide; [homoserine6]galantide; [phenylalanine(4fluor)17]galantide and galanin(1-13)-[phenylalanine(4fluor)7]-scyliorhinin-I are < 1. Hill's coefficients for galanin(1-13)-[norleucine10]-scyliorhinin-I(3-10); galanin(1-14)-[alpha-aminobutyric acid8]-scyliorhinin-I; galanin(1-14)-[alpha-aminobutyric acid8, norleucine10]-scyliorhinin-I(3-10) are > 1. A Hill's coefficient markedly different from 1 might indicate that an activation of more than one type of receptors, negative or positive receptor cooperativity or multiple-step agonist-receptor reaction.

Nonoperative management of the ruptured spleen: a revalidation of criteria

BACKGROUND

Our goal was to revalidate this institution's original criteria for safe nonoperative management of splenic injury.

METHODS

This was a prospective series between October 1991 and December 1995 entering all patients with splenic injury to a modified algorithm. Patients were taken to the operating room if hemodynamically unstable (systolic blood pressure less than 90 mm Hg; pulse greater than 110 beats per minute) after 2 liters of fluid resuscitation, positive abdominal examination findings, American Association for the Surgery of Trauma Organ Injury Scale Grade IV or V injuries by computed tomographic scan (unless younger than 15 years old), or associated severe head injuries (unless younger than 15 years old), or age greater than 55. The remainder of the patients were closely observed.

RESULTS

One hundred seventy-three patients were entered-six were excluded by death before operating room salvage, and one was excluded because of operation for a ruptured thoracic aorta. Therefore 166 patients were reviewed. Seventy splenectomies and 18 splenorrhaphies were performed, and 78 patients were treated nonoperatively (58% splenic salvage). Two failures occurred in the nonoperative group: a 16-year-old with a grade IV hilar injury was operated on on the eighth day after injury because of a continually falling hematocrit, and a 25-year-old with unresolved tachycardia was operated on at 6 hours (97% success rate). The patients in the operative group had a greater severity of injury as determined by mean Injury Severity Score of 32, 18 deaths, a mean transfusion requirement of 14 units of blood compared with mean injury severity score of 21, two deaths from brain injury, and no transfusions given in 58 of the 78 nonoperative cases.

CONCLUSIONS

Prospectively applied, these guidelines allow the safe nonoperative management of patients with blunt splenic injury.

Contractile action of galanin analogues on rat isolated gastric fundus strips is modified by tachyphylaxis to substance P

This study was undertaken to characterize the interaction of porcine galanin (Gal) and some of its analogues with their receptors on rat gastric fundus muscle strips. Gal, galantide (M15) and Gal(1-14)-[Abu8]SCY-I evoked concentration-dependent contractions of gastric smooth muscle strips. Reproducible effects were observed in concentrations of 1-300, 3-1000 and 100-3000 nM, respectively. Specific EC50 for the contractile effect equalled 13.70 and 187 nM. Hill's coefficient for Gal is 1.03 indicating an interaction of one Gal molecule with one receptor, fulfilling the criteria of classical receptor theory. For M15 and Gal(1-14)-[Abu8]SCY-I Hill's coefficients are different from 1, namely 0.73 and 1.56, pointing out that the principle of interaction of one drug molecule with one receptor may not apply. The contraction induced by 300 nM of Gal was not significantly modified by tachyphylaxis to substance P (SP). On the contrary the introduction of tachyphylaxis to SP decreased the contractile effects of M15 and Gal(1-14)-[Abu8]SCY-I by about 57.7 +/- 3% and 39.6 +/- 5%, respectively. The findings suggest that contractile actions of M15 and Gal(1-14)-[Abu8]SCY-I are probably not only due to their agonist activities at Gal receptors but may result from a subsequent stimulation of receptors for SP or release of endogenous SP.

Mechanism of the activation of proteinase inhibitor synthesis by systemin involves beta-sheet structure, a specific DNA-binding protein domain

We analyzed a tertiary structure of systemin, the first identified polypeptide plant hormone, using two-dimensional NMR spectroscopy. From these data and molecular dynamics calculations we concluded that the peptide can adopt a Z-like-beta-sheet structure, which has previously been found in many specific DNA-binding proteins. Using DNA-cellulose affinity chromatography, we showed that systemin binds strongly to DNA. We suggest that the specific systemin-DNA interaction, particularly in a promoter region of the proteinase inhibitors, could effect gene expression and thus explain the biological activity of systemin.

Long-term outcome of cholecystoenterostomy as a definitive biliary drainage procedure for benign disease

Our aim was to examine the long-term success of cholecystoenterostomy performed for the relief of benign extrahepatic biliary obstruction. Concern about the ability of cholecystoenterostomy to provide reliable long-term biliary decompression has led many to abandon its use for benign biliary obstruction. Thirty-four patients who underwent cholecystoenterostomy for benign biliary obstruction over a 17-year period were reviewed. Patients were followed until cholecystoenterostomy failure, death, or to date. Failure was defined as recurrent biliary obstruction or cholangitis requiring therapeutic intervention. Mean follow-up was 8.0 years. Early postoperative morbidity occurred in 11 patients (32%), but only one early complication (cholangitis) was related directly to the cholecystoenteric anastomosis. Five patients (15%) experienced late biliary tract complications related directly to the cholecystoenterostomy including recurrent biliary stones with biliary obstruction in four and anastomotic stricture in one. All required reoperation and conversion to choledochoenterostomy at a mean of 112 months. Cholecystoenterostomy can provide reasonably effective long-term biliary decompression in selected patients with benign biliary obstruction.

Prevention of infection in critically ill patients by selective decontamination of the digestive tract

OBJECTIVE

To determine whether selective decontamination of the digestive tract using oral and nonabsorbable antimicrobial agents and parenteral cefotaxime prevents infection in critically ill patients.

DESIGN

Randomized, controlled trial without blinding.

SETTING

Surgical trauma and medical intensive care units in a tertiary referral hospital.

PATIENTS

One hundred fifty patients admitted to surgical trauma and medical intensive care units during a 3-year interval, whose condition suggested a prolonged stay (greater than 3 days).

INTERVENTION

Patients were randomly allocated to an experimental group (n = 75) that received cefotaxime, 1 g intravenously every 8 hours for the first 3 days only, and oral, nonabsorbable antibiotics (gentamicin, polymyxin, and nystatin by oral paste and oral liquid) for the entire stay in the intensive care unit. Control patients (n = 75) received usual care.

MEASUREMENTS

The number of infections, total hospital days, and deaths, as well as the number of days in intensive care unit, were recorded.

RESULTS

Control patients experienced more infections (36 compared with 12, P = 0.04), including bacteremias (14 compared with 4, P = 0.05) and pulmonary infections (14 compared with 4, P = 0.03). Although total hospital days, days in intensive care, and the overall death rate all were lower in the treatment group, these differences were not statistically significant. Clinically important complications of selective decontamination of the digestive tract were not encountered.

CONCLUSIONS

Selective decontamination of the digestive tract decreases subsequent infection rates, especially by gram-negative bacilli, in selected patients during long-term stays in the intensive care unit.

Blunt colonic injury--a multicenter review

During the past decade there has been a shift in the management of injuries of the colon to primary repair without a protective diverting colostomy. Unfortunately, reports concerning this practice contain relatively few patients with blunt trauma and it is unclear whether the principles established for penetrating injury should be applied in the setting of blunt colon injury. A retrospective review of 54,361 major blunt trauma patients admitted to nine regional trauma centers from January 1, 1986, through December 31, 1990, was conducted. Statistical analysis of the data collected regarding 286 (0.5%) of these patients who suffered colonic injury revealed: (1) injury to the colon is found in more than 10% of patients undergoing laparotomy following blunt trauma; (2) available diagnostic modalities are unreliable in detecting isolated colonic pathology; (3) primary repair of full-thickness injuries or resection and anastomosis may be safely performed without diversion; (4) gross fecal contamination is the strongest contraindication to primary repair. Further, delay of surgery, shock, and the timing of antibiotic administration were not associated with significantly increased morbidity.