SEARCH · PubMed Health

Results for “Packaging”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources

PubMed1991

Differences in secondary structure between packaged and unpackaged single-stranded DNA of bacteriophage phi X174 determined by Raman spectroscopy: a model for phi X174 DNA packaging.

The single-stranded packaged genome (ssDNA) of bacteriophage phi X174 is shown by Raman spectroscopy to lack both the ordered phosphodiester backbone and base stacking, which are demonstrated for unpackaged, protein-free ssDNA. In solutions of moderate ionic strength, unpackaged ssDNA contains 36 +/- 7% of deoxyribosyl phosphate groups with conventional B-type backbone geometry [i.e., gauche- and trans orientations, respectively, for the 5'O-P (alpha) and 3'O-P (zeta) torsions], indicative of hairpin formation and intramolecular base pairing. Additionally, the bases of unpackaged ssDNA are extensively stacked. Estimates from Raman band hypochromic effects indicate that unpackaged ssDNA contains approximately 70% of the maximal base stacking exhibited in the linear, double-stranded, replicative form III of phi X174 DNA. Conversely, for the packaged phi X174 genome, ordered (B-type) phosphodiester groups are not present, and only 40% of the base stacking in RFIII DNA is observed. These results are interpreted as evidence that the substantial hairpin-forming potential of ssDNA is eliminated by specific and extensive ssDNA-protein interactions within the phi X174 virion. Comparison of the present results with studies of other packaged single-stranded nucleic acids suggests that proteins of the capsid shell (gpF + gpG + gpH) do not fully account for the conformational constraints imposed on ssDNA of phi X174. Accordingly, we propose a model for ssDNA packaging in which the small basic gpJ protein, which is packaged along with the genome, is involved stoichiometrically in binding to the ssDNA (approximately 90 nucleotides per subunit). The proposed gpJ-DNA interactions could prevent helical hairpin formation, restrict base stacking, and disfavor fortuitous base pairing within the capsid. The present analysis is based upon use of model nucleic acids of known conformation for calibration of the Raman intensity in the region 810-860 cm-1 in terms of specific secondary structures. The calibration curve allows quantitative determination of the percentage of ssDNA nucleotides for which the 5'O-P-O3' group is configured (g-,t) as in the B-form of DNA. The method proposed here is analogous to that employed by Thomas and Hartman (1973) for ssRNA and should be applicable to single-stranded DNA and to partially denatured forms of double- and multiple-stranded DNAs.

Bacteriophage phi X 174↗

PubMed1998

Herpes simplex virus type 1 cleavage and packaging proteins UL15 and UL28 are associated with B but not C capsids during packaging.

At least seven viral genes encode proteins (UL6, UL15, UL17, UL25, UL28, UL32, and UL33) that are required for DNA cleavage and packaging of herpes simplex virus type 1 (HSV-1) DNA. Sequence analysis reveals that UL15 shares homology with gp17, the large catalytic subunit of the bacteriophage T4 terminase. Thus, UL15 may play a direct role in the cleavage of viral DNA replication intermediates into monomers. In this study, we asked whether UL15 and other cleavage and packaging proteins could be detected in capsids isolated from infected cells. Consistent with previous studies showing that UL6 and UL25 are minor protein constituents of the capsids, we detected these proteins in both B and C capsids. In contrast, the previously identified full-length version (81 kDa) of UL15 was found predominantly in B capsids and in much smaller amounts in C capsids. In addition, the UL28 protein was found predominantly in B but not C capsids in a distribution similar to that of the 81-kDa version of UL15. These results suggest that UL28 and the 81-kDa form of UL15 are transiently associated with capsid intermediates during the packaging process. Surprisingly, however, a previously unidentified 87-kDa form of UL15 was found in the B and C capsids and in virions. Analysis of cells infected with mutants individually lacking UL6, UL15, UL25, UL28, or UL32 demonstrates that the lack of one cleavage and packaging protein does not affect the expression of the others. Furthermore, this analysis, together with guanidine HCl extraction analysis of purified capsids, indicates that UL6, UL25, and UL28 are able to associate with B capsids in the absence of other DNA cleavage and packaging proteins. On the other hand, the two UL15-related proteins (81 and 87 kDa) do not associate efficiently with B capsids in cells infected with UL6 and UL28 mutants. These results suggest that the ability of the UL15-related proteins to bind to B capsids may be mediated through interactions with UL6 and UL28.

Animals↗

PubMed1998

GFP:HIV-1 protease production and packaging with a T4 phage expression-packaging processing system.

A bacteriophage T4-derived protein expression, packaging and processing system was used to create recombinant phage that encode, produce and package a protein composed of human HIV-1 protease fused to green fluorescent protein (GFP). The fusion protein is targeted within the phage capsid by an N-terminal capsid targeting sequence (CTS), which is cleaved through proteolysis by the viral scaffold protease P21. The fusion protein is designated CTS [symbol see text] GFP:PR. The [symbol see text] symbol indicates the linkage peptide sequence leu(ile)-N-glu that is cleaved by the T4 head morphogenetic proteinase gp21 during head maturation. The fusion protein is fluorescent and has protease activity as detected by the appearance of the expected substrate cleavage product on a Western blot. CTS [symbol see text] GFP:PR packaging occurs at about 200 molecules per phage particle. The CTS [symbol see text] GFP:PR fusion protein, when protected within the phage capsid, has been maintained stably for over 16 months at 4 degrees C. Production and storage of fusion protein within the phage circumvents problems of toxicity and solubility encountered with E. coli expression systems. Because recombinant phage inhibit host proteolytic enzymes, foreign proteins are stabilized. This phage system packages and processes the fusion protein by means of the CTS. Proteins can be purified from the phage to give high yields of soluble, proteolytically processed protein. The T4 phage packaging system provides a novel means of identification, purification and long-term storage of toxic proteins whose folding and DNA-directed activities can be studied readily in vivo.

Bacteriophage T4↗

PubMed2004

The evaluation of multimedia learning packages in the education of health professionals: experience of a musculoskeletal examination package.

The last 20 years have seen rapid technological developments within the field of information technology. The internet, sophisticated software packages and increased accessibility to computers have all opened opportunities for educators. Against this background, increasing numbers of multimedia learning packages are available to the health professional. In this paper, Pirashanthie Vivekananda-Schmidt, Andrew Hassell and Monica McLean discuss the methodological issues relating to the evaluation of such multimedia based learning tools, using the example of a specific package, Virtual Rheumatology. They discuss the reasons for the increasing interest in the area of computer-based learning, the available evidence supporting the use of such tools in education, and issues about the design and production of this CD. They then discuss the evaluation of the package to illustrate the considerable methodological difficulties in the research and evaluation of Computer Assisted Learning (CAL) packages generally.

Attitude of Health Personnel↗

PubMed2003

The role of packaging film permselectivity in modified atmosphere packaging.

Modified atmosphere packaging (MAP) is commercially used to increase the shelf life of packaged produce by reducing the produce respiration rate, delaying senescence, and inhibiting the growth of many spoilage organisms, ultimately increasing product shelf life. MAP systems typically optimize O(2) levels to achieve these effects while preventing anaerobic fermentation but fail to optimize CO(2) concentrations. Altering film permselectivity (i.e., beta, which is the ratio of CO(2)/O(2) permeation coefficients) could be utilized to concurrently optimize levels of both CO(2) and O(2) in MAP systems. We investigated the effect of modifying film permselectivity on the equilibrium gas composition of a model MAP produce system packaged in containers incorporating modified poly(ethylene) ionomer films with CO(2)/O(2) permselectivites between 4-5 and 0.8-1.3. To compare empirical to calculated data of the effect of permselectivity on the equilibrium gas composition of the MAP produce system, a mathematical model commonly used to optimize MAP of respiring produce was applied. The calculated gas composition agreed with observed values, using empirical respiration data from fresh cut apples as a test system and permeability data from tested and theoretical films. The results suggest that packaging films with CO(2)/O(2) permselectivities lower than those commercially available (<3) would further optimize O(2) and CO(2) concentration in MAP of respiring produce, particularly highly respiring and minimally processed produce.

Carbon Dioxide↗

PubMed1993

Polycos vectors: a system for packaging filamentous phage and phagemid vectors using lambda phage packaging extracts.

A new class of hybrid vectors, 'polycos' vectors, incorporate a phage lambda cos site and filamentous phage origin to allow high-efficiency cloning via in vitro lambda packaging extracts. The head-filling mechanism of cos site recognition by lambda packaging proteins permits concatemers of several of these small cos-containing vectors to be packaged per phage particle. Excision of vector monomers after infection is accomplished via a lambda ZAP-like M13 excision process. This system has the advantage of adapting high-efficiency lambda packaging extracts to M13 and phagemid cloning vectors.

Bacteriophage M13↗

PubMed2003

Only one pRNA hexamer but multiple copies of the DNA-packaging protein gp16 are needed for the motor to package bacterial virus phi29 genomic DNA.

A common feature in the maturation of linear dsDNA viruses is that the lengthy viral genome is translocated with remarkable velocity into a limited space within a preformed protein shell using ATP as motor energy. Most biomotors, such as myosin, kinesin, DNA-helicase, and RNA polymerase, contain one ATP-binding component that acts processively. An examination of the well-studied dsDNA viruses reveals that DNA packaging motors involve two nonstructural components. Which component of the motor is the integrated processive factor to turn the motor has not been identified. In bacterial virus phi 29, these two components consist of a gp16 protein and an RNA molecule called pRNA. We have previously predicted and recently confirmed that gp16 binds ATP. It is generally believed that gp16 serves as an ATP-binding and processive component to drive the motor. In this article, phi 29 DNA-packaging intermediates were purified in quantity and examined to differentiate the role between gp16 and pRNA. It was found that the pRNA hexamer is an integral motor component, while gp16 is not stably bound. Only one pRNA hexamer, but multiple copies of gp16, were needed to accomplish DNA packaging. pRNA functions continuously during the entire DNA translocation process, suggesting that pRNA is a vital part of the DNA packaging motor.

Bacillus Phages↗

PubMed1990

Efficient replication, integration, and packaging of retroviral vectors with modified long terminal repeats containing the packaging signal.

Retroviral vectors were modified to contain packaging (psi) signals of varying lengths (nucleotides 211-355, 211-565, or 211-1039 of MoMuLV RNA) between the U3-r and U5 sequences of their 5' long terminal repeat (LTR). For the vector MoTN-PR3, containing the full length 211-1039 nucleotide-long psi signal within the 5' LTR, replication, integration, and packaging were almost as efficient as for the original unmodified vector. This result confirmed that the 211-1039 nucleotide-long sequence from the MoMuLV RNA is sufficient and necessary to allow efficient packaging of RNAs. In addition, an important site was revealed where insertion of foreign DNA sequences of up to 829 nucleotides can be made within the 5' LTR, between U3-r and U5 sequences, without affecting viral replication, integration, or packaging.

Animals↗

PubMed2004

2000-2001 food label and package survey: an update on prevalence of nutrition labeling and claims on processed, packaged foods.

The food label is an important tool for improving the public's understanding of the health benefits of following a nutritious diet. The Center for Food Safety and Applied Nutrition (CFSAN) of the Food and Drug Administration (FDA) has continued to study food labels with its Food Label and Package Survey (FLAPS). Data from the 2000-2001 FLAPS characterize various aspects of the labeling of processed, packaged foods, including nutrition labeling and various types of label claims. The FDA used a multistage, representative sample of food products from the Information Resources Inc (IRI) 1999 supermarket database as the basis for the FLAPS sample. The final FLAPS database consists of 1281 foods. An estimated 98.3% of FDA-regulated processed, packaged foods sold annually have nutrition labels, with an additional 1.7% of products exempt from nutrition labeling requirements. Health claims (4.4%), structure/function claims (6.2%), and nutrient content claims (49.7%) were identified on food labels. In addition to the resource this survey provides to CFSAN in assessing health and nutrition information on the food label, registered dietitians and other health professionals can use FLAPS data to assist consumers in choosing a more nutritious diet to improve their health and well-being.

Data Collection↗

PubMed2001

Development and validation of growth model for Yersinia enterocolitica in cooked chicken meats packaged under various atmosphere packaging and stored at different temperatures.

Mathematical models that can predict the growth of Yersinia enterocolitica in chicken meats were evaluated in this study. The growth curves for Y. enterocolitica in chicken meats variously packaged (air, vacuum, and modified atmosphere packaging [MAP]) and stored at various temperatures (4, 10, 16, 22, 28, and 34 degrees C) were constructed. The Gompertz model was applied to fit each of the experimental curves for the conditions mentioned above. The variations in the parameters, including lag time (lambda) and specific growth rate (mu), at various temperatures were then described by the following models: the variations in lag time were described by the Adair and Smith models and the variations in the specific growth rate were described by the Ratkowsky and Zwietering models. The various models were then compared using graphical and mathematical analyses such as mean square error (MSE), regression coefficient (r2), bias factor, and accuracy factor. The results indicate that the mean r values in the Gompertz model for chicken meats packaged in air, vacuum, and MAP were 0.99, 0.99, and 0.95, respectively. The lag time modeled with the Adair and Smith functions exhibited a greater variance and demonstrated larger errors. The MSEs were 0.0015 and 0.0017 for Ratkowsky and Zwietering models, respectively. The r2 values in the Ratkowsky and Zwietering models were both 0.99. The bias factor was 1.017 for the Ratkowsky model and 1.096 for the Zwietering model. The accuracy factor of the Zwietering model was 1.174, which was lower than that in the Ratkowsky model (1.275), indicating that the former model was more accurate than the latter in predicting the specific growth rate of Y. enterocolitica in chicken meats.

Animals↗

PubMed2003

Iron-containing supplements and drugs; label warning statements and unit-dose packaging requirements; removal of regulations for unit-dose packaging requirements for dietary supplements and drugs. Final rule; removal of regulatory provisions in response to court order.

The Food and Drug Administration (FDA) is removing, in part, a final rule that required unit-dose packaging for iron-containing dietary supplement and drug products that contain 30 milligrams (mg) or more of iron per dosage unit. FDA is taking this action in response to the Court's ruling in Nutritional Health Alliance v. FDA, in which the Court concluded that the Federal Food, Drug, and Cosmetic Act (the act) does not provide FDA with authority to require manufacturers of iron-containing dietary supplement and drug products to use unit-dose packaging for poison prevention purposes. Today's action takes the ministerial step of removing the unit-dose packaging provisions from title 21 of the Code of Federal Regulations.

Dietary Supplements↗

PubMed1996

Identification and deletion of sequences required for feline leukemia virus RNA packaging and construction of a high-titer feline leukemia virus packaging cell line.

Sequences required for specific encapsidation of feline leukemia virus (FeLV) genomic RNA have not yet been defined. Deletion of 107 nucleotides between the splice donor (SD) and the gag coding region of a prototypic subgroup A FeLV, 61E, resulted in an approximately 200-fold reduction of packaged viral RNA. Virus particle production was not disrupted by the deletion, although viral infectivity was dramatically reduced. These data indicate that the 107-nucleotide sequence comprises a portion of the FeLV packaging signal. FeLV particles expressed from the deleted genome were able to efficiently package murine leukemia virus vectors, resulting in high-titer G418R virus production. This system can be easily adapted to produce FeLV particles that contain envelope proteins from other feline leukemia virus subgroups and will be broadly useful for studies of FeLV envelope/receptor interactions.

Animals↗

PubMed1993

Problem-based learning packages: considerations for neophyte package writers.

Adopting problem-based learning (PBL) as the major educational approach in the implementation of a nursing curriculum requires the development of numerous learning stimulus packages. When reviewing the experience of the Division of Nursing within the Faculty of Health at the University of Western Sydney, Macarthur in Australia, several considerations for package writers were identified and are discussed. These include needs assessment, integration of the curricula content strands, multi-media learning stimuli, context, role and the incorporation of ongoing client management. The need for nurturance of writers and peer review of the developed packages is also addressed, as is a review of the impact of different learning stimuli.

Education, Nursing, Baccalaureate↗

PubMed2005

The procapsid binding domain of phi29 packaging RNA has a modular architecture and requires 2'-hydroxyl groups in packaging RNA interaction.

The phi29 packaging RNA (pRNA) is an essential component in the phi29 bacteriophage DNA packaging motor, the strongest biomolecular motor known today. Utilizing Mg2+-dependent intermolecular base pairing interactions between two 4-nucleotide loops within the pRNA procapsid binding domain, multiple copies of pRNA form a ring-shaped complex that is indispensable for packaging motor function. To understand pRNA structural organization and pRNA/pRNA interaction, studies were carried out on pRNA closed dimers, the simplest functional pRNA complex believed to be the building blocks for assembling the oligomeric ring. Tertiary folding and interactions in various pRNA mutants were evaluated based on measured closed dimer affinity that is directly linked to the proper positioning of the interacting loops. The data revealed that the procapsid binding domain contains two autonomous modules that are capable of interacting noncovalently to form a fully active species in pRNA/pRNA interaction. Deleting the 2'-hydroxyl groups in one of the interacting loops weakens the dimer affinity by 125-fold, suggesting potential tertiary interactions involving these 2'-hydroxyl groups. The results provide evidence that nonbase functional groups are involved in pRNA folding and interaction and lead to a simple model that describes the pRNA monomer configuration in terms of three arms spanning a hinge. The functional constructs developed here will aid biophysical and biochemical investigations of pRNA structure and function, as well as developments of pRNA-based technology for nanoscience and gene therapy.

Bacillus Phages↗

PubMed1998

A replication-competent retrovirus arising from a split-function packaging cell line was generated by recombination events between the vector, one of the packaging constructs, and endogenous retroviral sequences.

Previously we reported the presence of a replication-competent retrovirus in supernatant from a vector-producing line derived from a widely used split-function amphotropic packaging cell line. Rigorous routine screening of all retroviral stocks produced in our laboratory has not, previously or since, indicated the presence of such a virus. Replication-competent retroviruses have never previously been used in our laboratory, and stringent screening of all routinely used cell lines has not revealed the presence of any helper viruses. Therefore, it is highly unlikely that this virus represents an adventitious cross-contaminant or had been imported unknowingly with our cell line stocks. PCR studies with DNA from infected cell lines and Northern blot analysis and reverse transcriptase PCR with RNA from infected cells suggest that the helper virus arose by recombination events, at sites of partial homology, between sequences in the vector, one of the packaging constructs, and endogenous retroviral elements. These recombinations were not present in stocks of the packaging cell line or in an initial stock of the vector-producing line, indicating that these events occurred while the vector-producing line was being passaged for harvest of supernatant stocks.

Animals↗

PubMed1982

Prescription drugs; revocation of final guideline patient package inserts and withdrawal of draft guideline patient package inserts--Food and Drug Administration. Notice.

The Food and Drug Administration (FDA) is revoking the final guideline patient package inserts for 5 classes of drugs and is withdrawing the draft guideline patient package inserts for 5 other classes of drugs. Elsewhere in this issue of the Federal Register, the agency is revoking the regulations that established general requirements for the preparation and distribution of patient package inserts for prescription drug products. Those regulations had established a pilot program that would have been applied to 10 classes of drugs for 3 years. This notice revokes the draft and final guidelines which described how manufactures might comply with the regulations with respect to affected classes of drug.

Drug Labeling↗

PubMed2002

The primary nucleotide sequence of the bovine leukemia virus RNA packaging signal can influence efficient RNA packaging and virus replication.

Two RNA stem-loop structures in the gag gene have been implicated as representing the primary encapsidation (packaging) signal for bovine leukemia virus (BLV), a member of the Delta retrovirus of the Retroviridae. In this study, we conducted an analysis of these RNA structures, stem loop 1 (SL1) and stem loop 2 (SL2), to determine if both the loop and the stem nucleotide bases are important for RNA encapsidation. We have found that the primary sequence of the unpaired bases located in the loop regions of both SL1 and SL2 are important for efficient RNA encapsidation and virus replication. The primary sequence of the bases that form the stems for both SL1 and SL2 was observed to aid in efficient encapsidation and replication. We also observed that the order of SL1 and SL2 is important for RNA encapsidation and virus replication efficiency. A viral RNA with two copies of either SL1 or SL2 was found to replicate and package RNA as efficiently as a viral RNA with only one copy of SL1 or SL2. This provides evidence that SL1 and SL2 are not functionally equivalent. Sequences from human T cell leukemia virus type 1 (HTLV-1) that are located in the same region of HTLV-1 as the SL1 and SL2 of BLV were used to replace the BLV SL1, SL2, or both in a BLV RNA. These BLV RNAs were still encapsidated and replicated, suggesting that these sequences may function as an encapsidation signal in HTLV-1. The chimeric RNAs did not replicate as well as the parental, indicating that the primary nucleotide sequence along with the secondary and tertiary structure of the RNA plays a role in efficient RNA encapsidation and replication.

Animals↗

PubMed1982

The packaging initiation site of phage P22. Analysis of packaging events by transduction.

P22 lysates were grown on Salmonella strains carrying P22 prophages deleted to various extents. Transducing bacterial markers at both sides of the prophage insertion site it could be shown that: (i) transduction of markers can be enhanced by the prophage pac site; (ii) the recognition signal pac is in the area of gene 3 on the phage genome and thus close to the cutting site(s); (iii) transposon Tn10 may also act as a signal for packaging initiation; (iv) (at least) Tn10 initiates packaging sequences in both directions.

Genes, Viral↗