Uses of fluoride in dentistry.
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Adolescent↗
Biomedical subjects
D Perry
Publications and source records attributed to D Perry.
Portage of various compounds into bacteria by attachment to glycine residues in peptides.
Synthetic di- and oligopeptides are described that contain nucleophilic moieties attached to the alpha carbon of a glycine residue. These peptides are accepted by the peptide transport systems of Escherichia coli (and other microorganisms) and are capable of being hydrolyzed by intracellular peptidases. After liberation of its amino group the alpha-substituted glycine is chemically unstable (although it is stable in peptide form) and decomposes, releasing the nucleophilic moiety. Thus, the combined result of peptide transport and peptidase action is the intracellular release of the nucleophile. Peptides containing glycine residues alpha-substituted with thiophenol, aniline, or phenol are used as models for this type of peptide-assisted entry and their metabolism by E. coli is described. Peptides of this type have broad applicability to the study of microbial physiology and the development of an additional class of antimicrobial agents.
Journal Article↗
Anorexia and progressive weight loss in long-term feeding experiments with sheep.
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Animal Feed↗
Spectrophotometric determination of affinities of peptides for their transport systems in Escherichia coli.
The use of novel synthetic peptides to measure peptide transport by spectrophotometric means is described. These peptides contain glycine residues alpha-substituted with thiophenol and are recognized as substrates by both peptide transport systems and intracellular peptidases of Escherichia coli (Kingsbury et al., Gilvarg, C., Proc. Natl. Acad. Sci. U.S.A. 81:4573-4576, 1984). Transport and peptidase cleavage results in the intracellular release of thiophenol, which exits rapidly from the cell. The release of thiophenol from these peptides by cell suspensions can be measured with Ellman sulfhydryl reagent [5,5'-dithiobis(2-nitrobenzoic acid)] and provides a direct determination of the rate of peptide transport. The reductions in thiophenol release from these peptides resulting from the addition of peptide competitors enable the affinities of the competitors for their transport systems to be determined. By this method, it is shown that the dipeptide transport system is more restrictive with respect to changes in the amino acid sidechains of its substrates than those of the oligopeptide transport system.
Biological Transport↗
Increased serum IgE concentrations during infection and graft versus host disease after bone marrow transplantation.
Serum IgE concentrations estimated in 25 bone marrow transplant recipients during episodes of infection or graft versus host disease, or both, were raised not only in some patients with acute graft versus host disease but also in many patients with infection. Raised values were not seen in chronic graft versus host disease. The routine estimation of serum IgE in bone marrow transplant recipients had minimal value because of the lack of specificity of the IgE response.
Acute Disease↗
The use of cysteinyl peptides to effect portage transport of sulfhydryl-containing compounds in Escherichia coli.
We describe a method by which sulfhydryl compounds may be transported into Escherichia coli as the mixed disulfides with a cysteine residue of a di- or tripeptide. Transport occurs through the di- or oligopeptide transport systems, and it is suggested that subsequent release of the sulfhydryl compound occurs as a result of a disulfide exchange reaction with components of the sulfhydryl-rich cytoplasm. The free sulfhydryl compounds used here (2-mercaptopyridine and 4-[N-(2-mercaptoethyl)]aminopyridine-2,6-dicarboxylic acid) show weak growth-inhibitory properties in their own right, but disulfide linkage to a cysteinyl peptide results in a considerable enhancement (up to 2 orders of magnitude). This is the first example of the use of the peptide transport systems of E. coli to effect portage transport of a poorly permeant molecule by using attachment to the side chain of one of the amino acid residues of a peptide; all previous examples have involved the incorporation of amino acid analogues into the peptide backbone. The synthesis of cysteinyl peptides containing disulfide-linked 2-mercaptopyridine is described. Displacement of the 2-mercaptopyridine by sulfhydryl compounds of interest proceeds rapidly and quantitatively in aqueous alkaline solution to provide the required peptide disulfides.
Aminopyridines↗
Metabolism of alanylalanyl-S-[N-(2-thioethyl)]aminopyridine-2, 6-dicarboxylic acid]cysteine by suspensions of Escherichia coli.
The attachment of 4-[N-2-(mercaptoethyl)]aminopyridine-2,6-dicarboxylic acid (MEPDA) to AlaAlaCys through a disulfide bond to the cysteine residue has been described (Boehm, J. C., Kingsbury, W. D., Perry, D., and Gilvarg, C. (1983) J. Biol. Chem. 258, 14850-14855). The peptide disulfide showed enhanced growth inhibitory properties in Escherichia coli compared to the free sulfhydryl compound. Genetic evidence was presented to show that this side chain-modified peptide utilizes the oligopeptide transport system to gain entry to the cell. Following transport of the peptide, MEPDA is liberated by disulfide exchange reactions with sulfhydryl-containing components of the cell pool. In this paper, we examine in more detail the metabolism of this peptide. Using gel filtration chromatography to examine filtrates from cell suspensions incubated with the peptide, it was shown that loss of the peptide from the medium is accompanied by a corresponding increase in a component having the properties of MEPDA. The release of sulfhydryl groups from the peptide by cell suspensions could be monitored by Ellman's reagent and was found to be dependent upon peptide transport. Following cleavage of the disulfide bond, MEPDA is able to cross the cytoplasmic membrane and exit from the cell as a relatively lipophilic uncharged metal chelate.
Biological Transport, Active↗
Ambulatory ventricular tachycardia: characteristics of the initiating beat.
One hundred ten 24-hour Holter ECG recordings from 82 ambulatory patients with 341 episodes of ventricular tachycardia (VT) were analyzed. Most VT was precipitated by ventricular premature beats (VPBs) with prematurity indices (coupling interval/QT) between 1.0 and 2.0. However, a disproportionate number of VPBs initiating VT occurred early and late in the cardiac cycle compared with isolated VPBs. VT rate was not related to preceding heart rate, but faster basic rates appeared to protect against VT of extended duration. Approximately 80% of episodes of VT were initiated by VPB forms also seen in isolation. Of the 20% of VT initiated by a VPB of new morphology, one third occurred late in the cardiac cycle; almost none were early cycle.
Adult↗
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↗
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↗
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↗
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↗
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↗
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↗
Mutagenic effect of 7, 12-dimethylbenz[a]anthracene-epidioxide on Salmonella typhimurium.
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9,10-Dimethyl-1,2-benzanthracene↗
Paraspinal mass associated with intervertebral disk infection secondary to Moraxella kingii.
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Abscess↗
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↗
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↗