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Biomedical subjects

B A Phillips

Publications and source records attributed to B A Phillips.

At least 73 records · Page 4Linked to original sources
PubMed1983

Use of temperature-sensitive mutants to study the morphogenesis of poliovirus.

Three temperature-sensitive (ts) mutants of poliovirus (type 1 Mahoney) were isolated after nitrous acid treatment and characterized as phenotypically RNA+. When cells were infected at 37 degrees with two of the three RNA+ ts mutants (ts109 and ts739), reduced levels of 14 S particles were synthesized. One RNA+ mutant (ts520) synthesized significant amounts of viral 14 S particle subunits. All of the mutants synthesized reduced amounts of procapsids and virions at 37 degrees. At 39.5 degrees, with all three ts mutants, the production of all virus-related particles in infected cells was markedly suppressed. Isoelectric focusing of the viral-related particles produced at 37 degrees by the ts mutants and electrophoretic analysis of their structural polypeptides revealed the following: (i) ts739 synthesized an altered VP0 polypeptide and produced 14 S particles with an altered isoelectric point; (ii) ts109 produced 14 S particles with a normal pI but containing what appeared to be an altered VP1; (iii) ts520 produced normal 14 S particles as demonstrated by their pI, the electrophoretic behavior of their constituent structural polypeptides in SDS-PAGE, their ability to self-assemble, and their ability to form procapsid-like structures when incubated in extracts from wild-type (wt) virus-infected cells. However, ts520-infected cells contained few, if any, procapsids and extracts made therefrom were unable to assemble ts520 or wt 14 S particles into detectable amounts of pI 6.8 empty capsids. These and other findings are consistent with ts739 (and probably ts109) possessing an altered structural protein and ts520 being mutant in its morphopoietic factor.

Capsid↗
PubMed1983

Streptococcus garvieae sp. nov. and Streptococcus plantarum sp. nov.

Biochemical and chemotaxonomical studies were performed on some streptococci from frozen peas and bovine mastitis in an attempt to clarify their taxonomy. The results of the present and earlier studies indicate the pea and mastitis isolates represent two new species of the genus Streptococcus. The isolates from frozen peas are named Streptococcus plantarum sp. nov. and those from mastitis, Streptococcus garvieae sp. nov. The type strains are NCDO 1869 and NCDO 2155, respectively.

Animals↗
PubMed1983

Taxonomic studies on some group D streptococci.

Biochemical, menaquinone, fatty acid and DNA analyses were conducted on a number of streptococci of serological group D. The results indicate that S. faecalis, S. faeclum, S. casseliflavus and taxa previously designated 'S. avium', 'S. durans' and "S. faecalis var. malodoratus' are distinct species. Strains previously labelled 'S. faecium var. mobilis' were shown to be identical with S. casseliflavus. The results also indicate that some group D streptococci recently isolated from chickens constitute a new species.

Base Composition↗
PubMed1983

Effect of bronchoscopy on localization of gallium-67 citrate.

Bronchoscopy, bronchoalveolar lavage (BAL), and 67Ga lung scans are frequently performed for diagnosis or follow-up of patients with sarcoidosis, interstitial pneumonitis, lymphoma, infections, and bronchogenic carcinoma. Because many patients undergo all 3 of these procedures, it is important to determine what effects bronchoscopy and/or BAL may have on gallium imaging. Because 67Ga accumulates in neutrophils at the site of an inflammatory lesion as well as in those circulating in the vascular compartment, it seems reasonable to postulate that bronchoscopy could cause migration of labeled neutrophils into the lung, resulting in false positive gallium scans. To test this hypothesis, we studied 5 patients with varying chronologic relationships of 67Ga injection, gallium scanning, and bronchoscopy with BAL. In all patients, the repeat 67Ga lung scans remained normal or showed no change after bronchoscopy and BAL. We conclude that bronchoscopy with or without BAL does not cause increased 67Ga uptake by the lung.

Adult↗
PubMed1982

Poliovirus empty capsid morphogenesis: evidence for conformational differences between self- and extract-assembled empty capsids.

In this paper we describe the use of specific proteinases, surface-specific radioiodination, and antigenic reactivity in conjunction with isoelectric focusing for probing the conformations of different polioviral empty capsid species. Naturally occurring empty capsids (called procapsids) with an isoelectric point of 6.8 were resistant to proteolytic digestion by trypsin or chymotrypsin, as were empty capsids assembled in vitro in the presence of a cytoplasmic extract prepared from poliovirus-infected HeLa cells. In contrast, self-assembled empty capsids (isoelectric point, 5.0) were sensitive to both proteinases. Capsid proteins VP0 and VP1 were attacked predominantly, whereas VP3 was resistant to cleavage. Unpolymerized 14S particles possessed a trypsin sensitivity which was qualitatively similar to that of self-assembled empty shells. Surface-specific iodination of virions and procapsids labeled VP1 exclusively. In contrast, radioiodination of self-assembled empty capsids labeled predominantly VP0. After radioiodination the sedimentation coefficient corrected to water at 20 degrees C, the isoelectric point, and the trypsin resistance of the procapsids remained unchanged. Procapsids and extract-assembled empty capsids were N antigenic, whereas self-assembled empty capsids were H antigenic. Self-assembled empty capsids were not converted to pH 6.8 trypsin-resistant structures by incubation with a virus-infected cytoplasmic extract. However, 14S particles assembled in the presence of a mock-infected extract formed empty capsids, 20% of which resembled extract-assembled empty shells as determined by the above-described criteria. These and related findings are discussed in terms of empty capsid structure and morphogenesis.

Capsid↗
PubMed1982

Effect of short-term sleep loss on breathing.

Loss of sleep is common among patients with respiratory disorders. We studied ventilatory performance in 15 normal subjects to determine whether a single night of sleep loss would have any detectable effect on breathing. Spirometry and hypercapnic ventilatory response testing were performed daily for 3 consecutive days with no sleep permitted between testing on days 1 and 2. We found a small but significant decline in forced vital capacity and maximal voluntary ventilation and a 20% decrease in hypercapnic ventilatory response slope after sleep loss (P less than 0.05). We conclude that sleep loss results in a significant deterioration in ventilatory performance, which may be clinically important to patients with respiratory diseases.

Adult↗
PubMed1981

Differences between poliovirus empty capsids formed in vivo and those formed in vitro: a role for the morphopoietic factor.

Empty capsid species formed from the self- and extract-mediated assembly of poliovirus type 1 14S particles in vitro and procapsids isolated from virus-infected cells were subjected to isoelectric focusing in charge-free agarose gels. The empty capsid formed in the self-assembly reaction had an isoelectric point (pI) of 5.0, whereas procapsids and extract-assembled empty capsids focused at pH 6.8. Unreacted 14S particles focused at pH 4.8 to 5.0. The sedimentation coefficient (s20,w) and density of the empty capsid species were also determined. Procapsids had a density in CsCl of 1.31 g/cm3, whereas empty capsids formed by self- or extract-mediated assembly had a density of 1.29 g/cm3. Both extract-assembled empty capsids and procapsids had an s20,w of 75S, whereas self-assembled empty capsids had an s20,w of 71S. Self-assembled empty capsids were not converted to pI 6.8 empty capsids by incubation with poliovirus-infected HeLa cell extracts. The dissociated polypeptides of self-assembled empty capsids (pI 5.0) and procapsids (pI 6.8) behaved identically when analyzed by isoelectric focusing in the presence of 9 M urea and by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. These results suggest that infected cell extracts possess a factor that influences the final conformation of the empty shell (pI 6.8, 75S) formed from 14S particles and that this influences is exerted at the initiation step or during the polymerization reaction. A small amount of this activity (less than or equal to 20% of infected extracts) was detected in uninfected cells; the significance of this remains unknown.

Capsid↗
PubMed1975

Glycerol teichoic acid as an antigenic determinant in a Gram-negative bacterium Butyrivibrio fibrisolvens.

An antigenic determinant isolated from a strain of the Gram-negative bacterium Butyrivibrio fibrisolvens reacted with specific antisera to the polyglycerophosphate backbone of membrane teichoic acids of lactobacilli. It gave a reaction of identity with membrane glycerol lipoteichoic acid and glycerol teichoic acid preparations from lactobacilli, and with phenol extracts of other Gram-positive bacteria. The antigen-antibody reactions was strongly inhibited by glycerol-phosphoryl-glycerol-phosphoryl-glycerol and the chemical composition was consistent with glycerol teichoic acid. It was concluded that this Gram-negative bacterium contained a glycerol teichoic acid whose polyglycerophospate backbone was acting as antigenic determinant. Extracts of 33 out of 52 other strains of butyrivibrios examined gave similar reactions.

Antibodies, Bacterial↗
PubMed1974

Polypeptide composition of urea- and heat-resistant mutants of poliovirus types 1 and 2.

Five urea-resistant and two heat-resistant mutants of poliovirus types 1 and 2 were isolated and their structural and nonstructural polypeptides compared to those of their wild-type, parental strains in an attempt to correlate mutant phenotypes with alterations in specific capsid polypeptides. Four of the seven mutants were found to contain polypeptides which differed in molecular weight from their respective parental viruses. However, resistance of virions to heat- or urea-inactivation could not be attributed to changes in particular capsid polypeptides because alterations were detected in all but one of the capsid components. For two of the urea-resistant mutants and one heat-resistant mutant, no differences were found in the molecular weights of the capsid and noncapsid polypeptides. These results, and the fact that at least 12 selective treatments were required to obtain stable mutants, indicate that: (i) such phenotypes probably can be expressed by mutations affecting one or more of the larger capsid polypeptides, and (ii) such phenotypes reflect multiple mutational steps.

Amino Acids↗