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Biomedical subjects

J Armstrong

Publications and source records attributed to J Armstrong.

At least 181 records · Page 10Linked to original sources
PubMed1985

The effect of capping and polyadenylation on the stability, movement and translation of synthetic messenger RNAs in Xenopus oocytes.

Synthetic RNAs coding for chicken lysozyme, calf preprochymosin and Xenopus globin were transcribed in vitro using Sp6 RNA polymerase. The effects of capping and adding a poly(A) tail on the stability, movement and translation of these RNAs in Xenopus oocytes was examined. Capping and polyadenylation increased stability of the transcripts, with at least 40% remaining intact 48 h after injection into oocytes. Capped poly(A)- transcripts moved more rapidly in oocytes than either capped poly(A)+ transcripts or naturally occurring mRNAs. The translational efficiency of most of the synthetic RNAs in oocytes increased with both capping and polyadenylation. The exception was one Xenopus globin transcript which had an unusual 3' end of 20As and 30Cs, where further polyadenylation decreased translational efficiency. Polyadenylation was essential for detectable expression of the synthetic RNAs in cultured cells, but decreased translation of the synthetic RNAs in vitro.

Animals↗
PubMed1985

Intranasal aerosolized insulin. Mixed-meal studies and long-term use in type I diabetes.

We assessed the efficacy of intranasal aerosolized insulin containing laureth-9 as a surfactant in patients with Type I diabetes by fasting studies in 8 patients, mixed-meal studies in 15, and long-term home use in 8. The intranasal insulin (1 U per kilogram of body weight in 1 per cent laureth-9) was rapidly absorbed (in 15 minutes); it lowered the plasma glucose level by 50 per cent in 45 minutes in fasting normal controls and by 50 per cent in 120 minutes in fasting diabetics. The glucose-lowering potency depended on the insulin dose and surfactant concentration. Nasal irritation was proportional to surfactant concentration, with great variability among subjects. After intranasal insulin used before meals (1 U per kilogram in 1 per cent laureth-9), the two-hour postprandial glucose level increased above before-meal levels by 38 mg per deciliter, as compared with 191 mg per deciliter after intranasal placebo in patients with Type I diabetes (P less than 0.05). An outpatient feasibility study examining three months of use of intranasal aerosolized insulin before meals as a supplement to Ultralente insulin revealed that the aerosol was well tolerated, with glycemic control (as indicated by the percentage of glycohemoglobin, home glucose measurements, and hypoglycemic reactions) comparable to that during a subsequent three-month period of conventional subcutaneous insulin treatment. The results suggest that intranasal insulin has potential as an adjunct to subcutaneous insulin in the therapy of Type I diabetes.

Absorption↗
PubMed1985

Signal recognition particle-dependent insertion of coronavirus E1, an intracellular membrane glycoprotein.

The membrane insertion of the E1 protein of a coronavirus, mouse hepatitis virus A59, was studied in a wheat germ cell-free translation system. E1 is a transmembrane protein spanning the lipid bilayer several times. It is synthesized without a cleavable signal sequence, localized intracellularly, and not transported to the cell surface. It thus represents a model intracellular protein. We found that the synthesis of E1 is specifically and stably blocked by the addition of signal recognition particle to the wheat germ system. Subsequent addition of salt-extracted pancreatic microsomes resulted in the full release of this arrest as well as the completion and the correct membrane integration of E1. Such signal recognition particle-induced arrests failed to produce shorter peptides of a defined length. Addition of signal recognition particle to a synchronized translation at any time during the synthesis of about the first two thirds of E1 (150 amino acids) blocked further translation, suggesting that the most C-terminal of the three internal hydrophobic domains of E1 could function as its signal sequence.

Animals↗
PubMed1984

Transcription strategy of coronaviruses: fusion of non-contiguous sequences during mRNA synthesis.

MHV replicates in the cell cytoplasm and viral genetic information is expressed in infected cells as one genomic sized RNA ( mRNA1 ) and six subgenomic mRNAs. The seven RNAs were assumed to have common 3' ends of the size of RNA7 , the smallest RNA. The data reported here, show that this model is too simple and that the mRNAs are composed of a leader and body sequence. Electron microscopic analysis of hybrids formed between single stranded cDNA copied from mRNA7 and genomic RNA or mRNA6 shows that genomic RNA, mRNA6 and mRNA7 have common 5' terminal sequences. Furthermore, nucleotide sequence analysis shows that the nucleotide sequence of the 5' end of mRNA7 diverges from the corresponding region of the genome just upstream from the initiation codon of the nucleocapsid gene. Because the synthesis of each mRNA is inactivated by UV irradiation in proportion to its own length, the subgenomic mRNAs are apparently not produced by the processing of larger RNAs. The available data have to be explained by translocation of the polymerase/leader complex to specific internal positions on the negative strand. In this way the leader and body sequences are joined together by a mechanism completely different from conventional RNA splicing but nevertheless giving the same end result.

Animals↗
PubMed1984

Assembly in vitro of a spanning membrane protein of the endoplasmic reticulum: the E1 glycoprotein of coronavirus mouse hepatitis virus A59.

The E1 glycoprotein of coronavirus mouse hepatitis virus A59 was synthesized in vitro by translation of viral mRNA in the presence of dog pancreatic microsomes. Its disposition in the membrane was investigated by digestion with proteases and by selective NH2-terminal labeling. The protein spans the membrane, but only small portions from the NH2 and COOH terminus are exposed respectively in the lumenal and cytoplasmic domains; the bulk of the molecule is apparently buried in the membrane. The protein lacks a cleavable leader sequence and does not acquire its characteristic O-linked oligosaccharides in rough microsomes. It may enter the membrane at any stage during synthesis of the first 150 amino acid residues. These unusual features of the protein might help to explain why it is not transported to the cell surface in vivo but remains in intracellular membranes, causing the virus to bud there.

Animals↗
PubMed1984

Nutrition and catering: 1. Some options in the delivery of meals on wheels.

Various options in the delivery of food to the elderly housebound are reviewed. These include precooked warm-held meals; precooked frozen meals reheated in a microwave oven en route, frozen meals or sterilised pouched meals for reheating at home, and packs of prepared raw ingredients for home cooking.

Aged↗
PubMed1983

Primary structure and genetic organization of phage T4 DNA ligase.

The primary structure of phage T4 DNA ligase has been determined by DNA sequencing of a cloned restriction fragment containing its gene, and partial amino acid sequence analysis of the protein. The molecule has a Mr of 55,230, and contains 487 amino acids. The DNA sequence may also encode all of one and parts of two other, hitherto unidentified, T4 proteins. The four genes are closely packed, with overlaps between terminator and initiator codons of adjacent genes. Potential terminator and promoter sites for transcription are located within the coding sequence of one of the genes.

Amino Acid Sequence↗
PubMed1983

Sequence of the nucleocapsid gene from murine coronavirus MHV-A59.

The nucleotide sequence of the RNA encoding the nucleocapsid protein of coronavirus MHV-A59 has been determined. Copy DNA was prepared from mRNA isolated from virally infected cells, fragmented and cloned in the phage vector M13 mp8 for direct sequence determination. A sequence of 1817 nucleotides, adjacent to the viral poly-A tail, was obtained. It contains a single long open reading frame encoding a protein of mol. wt. 49660, which is enriched in basic residues.

Base Sequence↗
PubMed1983

Chemical modification of the coat protein in bacteriophage fd and orientation of the virion during assembly and disassembly.

The major (gene VIII) coat protein of bacteriophage fd was radiolabelled by treating the virus with methyl[3H]acetimidate without causing any loss of infectivity. Complete amidination of lysine-8 in the amino acid sequence of the protein was achieved but little or no modification of the lysine residues near the C terminus was observed. This supports the assumption that the coat protein is oriented in the viral filament with its N terminus on the outside and its C-terminal region abutting the DNA. Escherichia coli was co-infected with radiolabelled bacteriophage and with unlabelled miniphage, a shorter defective form of phage fd. Radiolabel was detected in the progeny miniphage, proving that individual coat protein subunits can be recycled and assembled onto progeny miniphage DNA. About 35% of the coat protein subunits of phage particles infecting E. coli were recycled in 1 h. These facts support a model of the assembly and disassembly of the virion at the bacterial membrane in which the end of the particle containing the minor adsorption (gene III) protein, which is presumably the first to disassemble during infection, is the last to assemble during morphogenesis.

Amino Acids↗
PubMed1983

Coronavirus mRNA synthesis involves fusion of non-contiguous sequences.

Positive-stranded genomic RNA of coronavirus MHV and its six subgenomic mRNAs are synthesized in the cytoplasm of the host cell. The mRNAs are composed of leader and body sequences which are non-contiguous on the genome and are fused together in the cytoplasm by a mechanism which appears to involve an unusual and specific 'polymerase jumping' event.

Base Sequence↗