Biomedical subjects

D M Mathews

Publications and source records attributed to D M Mathews.

6 recordsLinked to original sources

PubMed1990

Factors affecting efficient infection of tobacco with in vitro RNA transcripts from cloned cDNAs of satellite tobacco mosaic virus.

Recombinant cDNA clones of the complete satellite tobacco mosaic virus (STMV) genome (1059 ribonucleotides) were constructed with unique Xbal and HindIII or Pstl restriction sites engineered at the 5' and 3' termini, respectively. The genome-length cDNAs were positioned downstream of T7 or SP6 phage promoters. Genome-sense RNAs transcribed in vitro from the T7 promoter were biologically active, while negative-sense RNAs transcribed in vitro from the SP6 promoter were not. Constructs that were identical to STMV and two other constructs in which there were two or six specific nucleotide differences in the 3' noncoding region yielded RNAs that were infectious. Sequence analysis of the progeny RNA derived from infections with transcripts containing nucleotide differences between nucleotides 682 and 753 revealed that these changes in sequence were maintained. In contrast, differences in the nucleotide sequence between nucleotides 989 and 1059 were not maintained in progeny RNA; one mutant reverted to the wild-type sequence, and the other generated a new sequence during infection.

Base Sequence↗

PubMed1990

Diaphragmatic breathing maneuvers and movement of the diaphragm after cholecystectomy.

Coached efforts at diaphragmatic breathing were assessed as a means of increasing diaphragmatic movement in postoperative patients. Inductive plethysmography was used to measure compartmental tidal volumes of the abdomen (Vab) and the chest (Vc) in eight women (aged 41 +/- 16 years) who had no history of cardiovascular or pulmonary disease. These patients were studied before and after (POD1,3) elective cholecystectomy. In preoperative studies, DB increased the supine value of Vab. The corresponding increase on POD1 represents a similar proportion of the resting value. The postoperative fall in resting and stimulated values of Vab is attributed to the known effects of abdominal surgery on diaphragmatic movement. Hence, DB warrants investigation as a method of prophylaxis against the pulmonary complications of surgery, because diaphragmatic movement is largely responsible for ventilation of the lower lung fields, where atelectasis and infection occur most often.

Adult↗

PubMed1989

Nucleotide sequence and translation of satellite tobacco mosaic virus RNA.

Satellite tobacco mosaic virus (STMV) is a plant virus with a 17-nm icosahedral particle encapsidating a 0.3 X 10(6) Mr ssRNA genome that depends on tobamoviruses for its replication. The complete nucleotide sequence of STMV RNA deduced in the experiments described here was 1059 nucleotides in length. The efficiency of labeling viral RNA with [gamma-32P]ATP using T4 polynucleotide kinase was not affected by treatment with tobacco acid pyrophosphatase and/or bacterial alkaline phosphatase, indicating that the majority of the 5' termini of encapsidated STMV RNAs were not phosphorylated. The 240 3'-terminal nucleotides of STMV RNA and either tobacco mosaic virus (TMV) U1 RNA or TMV U2/U5 RNA had greater than 65% overall sequence similarity, with two nearly identical regions of 40 and 50 bases, respectively. There were no other regions of sequence relatedness to TMV RNA. The 19 5'-terminal nucleotides of STMV RNA had greater than 65% sequence similarity with the 16 5'-terminal nucleotides of brome mosaic virus (RNA 3 and 50% sequence similarity with the 12 5'-terminal nucleotides of the Q strain of cucumber mosaic virus RNA 3. The first open reading frame (ORF) beginning at base 53 encoded a 6800 Mr protein that corresponded in size to a major in vitro translation product directed by STMV RNA. A second ORF, beginning at nucleotide 163, had the capacity to code for a protein that corresponded in size (17,500 Mr) to the other major in vitro translation product. The first 12 codons of this ORF corresponded to the sequence of the N-terminal amino acids of the capsid protein. Western-blot analysis of the in vitro translation products revealed that the 17,500 Mr protein had the same electrophoretic mobility as the authentic capsid protein; it was also antigenically related to the capsid protein, but the 6800 Mr protein was not. Time course analysis of in vitro translation demonstrated that the 6800 Mr protein was synthesized at the same time as the capsid protein and did not arise by the proteolytic cleavage of a larger precursor polypeptide. These results suggest that the genome of STMV functioned as a polycistronic messenger RNA. It has not been determined if the 6800 Mr protein is synthesized in vivo. STMV RNA had untranslated regions of 52 and 418 nucleotides at its 5' and 3' termini, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗

PubMed1989

A technique for liver biopsy in Pekin ducks.

The duck hepatitis B virus (DHBV), a member of the hepadna-virus group, has become a useful animal model for exploring important aspects in this family of viruses such as viral replication, course of infection, and the response to antiviral therapy. In chronically DHBV infected ducks, repeated analyses of liver tissue are important in defining the degree of viral replication and liver injury. We describe a technique for repeated liver biopsy using a Keyes skin punch biopsy. This technique provided sufficient quantities of liver tissue for serial analyses with minimal hemorrhage in 18 Pekin ducks. This procedure offers a safe and reliable method of obtaining serial liver biopsies.

Animals↗

PubMed1976

Evidence for a single common carrier for uptake of a dipeptide and a tripeptide by hamster jejunum in vitro.

This paper describes an investigation of whether a dipeptide and a tripeptide were taken up by hamster jejunum by the same transport system, or whether there was evidence of uptake by more than one transport system. The work was carried out with rings of everted hamster jejunum in vitro, under conditions of influx, using the "model" peptides glycylsarcosine, glycylsarcosylsarcosine, and glycylsarcosylsarcosylsarcosine. These peptides are all exceptionally resistant to hydrolysis, appearing intact in the rings, and the di- and tripeptide have previously been shown to be concentrated in the rings by active transport. The results showed that influx of glycylsarcosine was inhibited by glycylsarcosylsarcosine in a competitive way, and that each of the peptides was capable of causing virtually complete inhibition of influx of the other. Glycylsarcosylsarcosylsarcosine had no effect on influx of glycylsarcosine or of glycylsarcosylsarcosine. It was concluded that although the existence of multiple transport systems shared by both glycylsarcosine and glycylsarcosylsarcosine could not be ruled out, the simplest hypothesis was that both the dipeptide and the tripeptide shared a single common carrier for uptake. The tetrapeptide glycylsarcosylsarcosylsarcosine was apparently not transported by this carrier, in agreement with previous results. The possible effects of the "unstirred layer" were taken into account in considering the results and are discussed. They do not alter the conclusions reached.

Animals↗

PubMed1976

Peptide absorption.

Explore the source record for details and available documents.

Amino Acid Sequence↗