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Biomedical subjects

D Perry

Publications and source records attributed to D Perry.

At least 91 records · Page 5Linked to original sources
PubMed1983

Genetic transformation of putative cariogenic properties in Streptococcus mutans.

Rough colonial morphology and bacteriocin production, two properties which may be associated with the cariogenicity of Streptococcus mutans, were transformed into several strain GS-5 mutants defective in each respective property. Transformation was determined by observing the frequency of cotransfer of these properties with different reference markers. The rough colonial transformants were identical to the parental GS-5 strain with respect to ability to synthesize water-insoluble glucans and undergo in vitro sucrose-dependent colonization of glass surfaces. Alterations in the growth medium and the concentration of the initial cell inoculum resulted in an approximate 10-fold increase in the frequency of transformation of strain GS-5 compared to previous observations.

Bacteriocins↗
PubMed1981

Human and animal togavirus antibodies in congenitally deformed infants.

The cord bloods of 30 congenitally malformed infants, born consecutively at the Worcester Royal Infirmary, were screened for serological evidence of infection with Border disease and bovine virus diarrhoea viruses as well as for the presence of rubella-, cytomegalovirus-, and measles-specific IgM. Despite Border disease and bovine virus diarrhoea being endemic among sheep and cattle in counties bordering Wales, none of the cord blood samples contained antibodies to Border disease or bovine virus diarrhoea viruses. No rubella-, measles-, or cytomegalovirus-specific IgM was detected. When the total immunoglobulins were estimated, 15 of the malformed infants and elevated levels, but in a control group of 35 infants born in the same unit, none showed significantly elevated immunoglobulin levels.

Antibodies, Viral↗
PubMed1981

Peptide transport in Staphylococcus aureus.

Using the agar diffusion test of Zähner et al. (1960), it was demonstrated that bacilysin and a variety of di- and tri-L-peptides compete with each other for uptake into Staphylococcus aureus. Several di- and tripeptides containing L-phenylalanine produced transient growth inhibition of S. aureus NCTC 6571, but not of bacilysin-resistant mutants. The results confirm that the major peptide transport system in S. aureus recognizes both di- and tripeptides as substrates.

Agar↗
PubMed1981

Genetic transformation of Streptococcus mutans.

Three strains of Streptococcus mutans belonging to serotypes a, c, and f were transformed to streptomycin resistance by deoxyribonucleic acids derived from homologous and heterologous streptomycin-resistant strains of S. mutans and Streptococcus sanguis strain Challis. Homologous transformation of S. mutans was less efficient than heterologous transformation by deoxyribonucleic acids from other strains of S. mutans.

DNA, Bacterial↗
PubMed1980

In vivo and in vitro models of demyelinating diseases. III. JHM virus infection of rats.

Suckling rats of three inbred and three outbred strains were inoculated intraperitoneally (P) or intracerebrally (IC) with the JHM strain of mouse hepatitis virus (JHMV) and were monitored for evidence of neurologic diseases. Consequences of varying age at inoculation, route of injection, and virus dose were ascertained. No disease was evident after IP injection but IC inoculation with at least 10(4) plaque-forming units at 2 days of age resulted in either a rapidly fatal encephalitis or a chronic, progressive, fatal neurologic disease in most rats, regardless of strain. Inoculation at 5 or 10 days of age predominantly caused the chronic neurologic disease, characterized by demyelinating lesions in the brain, spinal cord, or optic nerve, which sometimes were evident as late as several months postinoculation. Demyelination in the optic nerve proved to be concurrent with demyelinating lesions elsewhere in the CNS. Occasionally, clinical remissions were observed in rats in which posterior paralysis developed, suggesting that remyelination in the rat can occur. Demonstration of virus replication, by infectivity, in rats exhibiting neurologic disease and in rats without clinical symptoms was substantiated by electron microscopic observations of virus development and assembly in oligodendroglia of the optic nerve and spinal cord. In view of the protracted course of the disease in some rats, presence of demyelinating lesions confirmed by light and electron microscopy, and remissions of clinical symptoms, the JHMV-infected rat seems to be an appropriate animal model to study virus-mediated progressive demyelinating disease.

Animals↗
PubMed1979

Transport and metabolism of bacilysin and other peptides by suspensions of Staphylococcus aureus.

L-Alanyl-L-tyrosine and glycyl-L-phenylalanine labelled with 14C competed with each other and with the dipeptide antibiotic bacilysin for transport into Staphylococcus aureus NCTC 6571 in a medium which did not support growth. They also competed with other dipeptides and several tripeptides. The fast initial transport ofthe two labelled peptides appeared to show Michaelis-Menten kinetics. Neither was transported into a bacilysin-resistant mutant of S. aureus NCTC 6571, although tyrosine was taken up by the mutant as readily as it was by the parent strain. Uptake of alanyltyrosine or glycylphenylalanine was followed by rapid hydrolysis of the peptide and the excretion of tyrosine or phenylalanine. Glycine liberated from glycylphenylalanine was partly degraded and partly incorporated into the bacterial wall. The behaviour of these dipeptides paralleled the inactivation of bacilysin by suspensions of S. aureus and the appearance of its C-terminal amino acid, anticapsin, in the extracellular fluid.

Amino Acids↗
PubMed1978

Isolation and characterization of a Streptococcus mutans bacteriocin inhibitor from Streptococcus pyogenes.

An inhibitor of Streptococcus mutans strain GS5 bacteriocin was released from a bacteriocin-sensitive strain of S. pyogenes by sonic treatment and partly purified by gel filtration on a Sepharose 6B column. The inhibitory factor was sensitive to heat, trypsin, and periodate and possessed a molecular weight of approximately 93,000. This factor may be the receptor for the S. mutans bacteriocin.

Bacterial Proteins↗
PubMed1977

Abnormalities of immunglobulins in infants with congenital heart disease.

Twenty-eight infants had their serum immunoglobulins estimated (by radial immunodiffusion) in early infancy. The IgG level was abnormal in twelve infants. Elevated levels of IgA were found in ten and IgM in fourteen. These variations, mostly obvious in the first ten days of life, were detected in the absence of clinical or immunological evidence of congenital rubella infection.

Heart Defects, Congenital↗
PubMed1975

Kanner's syndrome or early-onset psychosis: a taxonomic analysis of 142 cases.

Case history data on 142 psychotic children were obtained using the Rimland Diagnostic Check List. A particular variety of the method known as numerical taxonomy was used to classify the children into subgroups on the basis of responses on the Check List. A comparison was made between a classification of Kanner's syndrome vs. "no Kanner's syndrome" and a classification using random classes as starting points. The "best" classification of the data was one in which 2 classes were obtained, one containing all the Kanner's syndrome children plus other early-onset, nonrelating psychotic children and the other containing children with later onset and more varied symptoms. Those attributes which significantly differentiated between the classes both in the "best" classification and in the Kanner's syndrome classification were extracted. A distinction between Kanner children and other similar children was found only for 3 specific behaviors: obsessive desire for sameness, islets of special ability, and skillful manipulation of small objects.

Adolescent↗
PubMed1975

Relationship of macromolecular synthesis to competence induction in a group H streptococcus.

Group H streptococcus strain Wicky, which was induced to competence for genetic transformation with competence factor (CF) derived from a related strain, displayed reduced rates of ribonucleic acid (RNA) and peptidoglycan synthesis. Pulse-labeling studies revealed that the inhibition of both RNA and peptidoglycan synthesis was maximal at the peak of competence and decreased as competence declined. These studies indicated that competence induction had only a slight effect on the rate of protein synthesis. Trypsin inactivation of CF prevented the reductions in synthesis normally elicited by CF preparations. If the addition of trypsin was delayed until 5 min after the addition of CF, competence induction and decreased synthesis of RNA and peptidoglycan were again apparent. Thus, the alterations in the synthesis of these macromolecules appeared to be related to the induction of competence. Further studies indicated that the apparent reductions in biosynthesis were not caused by decreased uptake of the labeled precursors by intact Wicky cells. In addition, these effects were probably not the result of turnover of macromolecules induced by CF. The lack of turnover of labeled peptidoglycan suggested that competence induction may not involve an autolysin.

Amino Acids↗
PubMed1974

Binding of streptococcal competence factor by the spheroplast membrane of a group H streptococcus.

The binding of streptococcal competence factor (CF) was found to be specific for a strain of streptococcus which was capable of undergoing competence induction. Three other streptococcal strains which could not be induced to competence, did not bind CF. CF binding was independent of time, temperature, age of the culture, and type of growth media employed. Several observations indicated that the receptor sites for CF are located in the bacterial membrane: (i) the retention of CF by spheroplasts, (ii) the binding of CF by isolated membrane fractions, and (iii), the degradation of CF binding capacity of membranes by different chemicals and enzymes.

Bacterial Proteins↗
PubMed1974

Effect of competence induction on macromolecular synthesis in a group H streptococcus.

The effects of competence induction by competence factor (CF) on macromolecular synthesis in group H streptococcus strain Wicky were investigated. CF preparations (culture filtrates from competent group H streptococcus strain Challis) were either heated or partially purified to remove a bacteriocin. These preparations did not inhibit growth, although they induced high levels of competence in strain Wicky. The action of the CF preparations did not affect the overall rates of deoxyribonucleic acid and protein synthesis, but caused a reduction in the rates of ribonucleic acid (RNA) and peptidoglycan synthesis. When competence induction by CF was prevented, no alterations in RNA or peptidoglycan synthesis were observed, indicating that these changes are in fact related to the development of competence.

Bacterial Proteins↗
PubMed1973

Isolation of group H streptococcal competence factor.

Competence factor (CF) was purified 600-fold from culture filtrates of competent group H streptococcus, strain Challis, by fractionation on a carboxymethyl-Sephadex column. The preparation did not contain orcinol- or diphenylamine-positive material, and CF activity was destroyed by trypsin. An examination of its chemical composition revealed 10 amino acids, muramic acid, glucosamine, and glucose.

Amino Acids↗
PubMed1972

Effect of D-cycloserine on transformation in group H streptococcus, strain Challis.

d-Cycloserine (d-CS), a selective inhibitor of bacterial cell wall biosynthesis, inhibited transformation in group H streptococcus, strain Challis, by preventing the development of the competent state. The incubation of strain Challis cells with d-CS resulted in the production of a substance which inhibited the action of competence factor on these cells. d-CS had an enhancing effect on transformation when deoxyribonucleic acid uptake or phenotypic expression was allowed to occur in its presence.

Cell Wall↗