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Biomedical subjects

J Taylor

Publications and source records attributed to J Taylor.

At least 523 records · Page 29Linked to original sources
PubMed1988

Long-term evaluation of human teeth after Le Fort I osteotomy: a histologic and developmental study.

Transient pulpal vascular ischemia and direct injury to the apices of the teeth have been implicated as the causes of degenerative and atrophic pulpal changes in experimental animals after Le Fort I osteotomy despite the presence of collateral circulation. The long-term clinical effect of these pathologic changes in human teeth has not been studied. Seventeen maxillary third molar teeth from 10 patients whose postsurgical follow-up ranged from 6 months to 78 months (mean, 40 months) were extracted. The long-term biologic effects of Le Fort I osteotomy on the pulp and on the development of teeth were retrospectively evaluated with clinical and standard histologic techniques. Normal teeth from patients who were not operated on were used as controls. Histologic examination revealed an intact pulpal circulation and minimal pathologic changes in the pulpal tissue. Clinical and radiographic studies showed that the growing teeth developed normally after surgery. The Le Fort I downfracture procedure had little discernible long-term effect on the pulp and on the development of human third molar teeth.

Adolescent↗
PubMed1988

Fowlpox virus as a vector in non-avian species.

Examination of the members of the Poxvirus family reveals a large and diverse group with members infecting almost every animal species. To a large extent, members of the individual genera have a broad host range and infect a number of animal species, although, as Baxby has pointed out, successful experimental inoculation of a species does not necessarily mean that this species provides a natural host for that virus. Avipox viruses, together with swinepox virus occupy a somewhat unique position in possessing a restricted host range. We have taken advantage of this restricted host range in fowlpox virus to engineer recombinant vector viruses for use in the poultry industry and in vaccination of non-avian species.

Animals↗
PubMed1988

Recombinant fowlpox virus inducing protective immunity in non-avian species.

The natural host of fowlpox virus is limited to avian species. When inoculated into non-avian tissue culture cells, however, fowlpox virus can initiate an abortive infection. A fowlpox virus was engineered to express rabies virus glycoprotein. On inoculation of the recombinant virus into either avian (permissive) or non-avian (non-permissive) cells, the rabies glycoprotein was expressed as a membrane-associated antigen. Inoculation of the fowlpox virus recombinant into six different species of mammal resulted in specific immune responses to both fowlpox antigens and to rabies glycoprotein. In mice, cats and dogs the immune response was sufficient to protect against a live rabies virus challenge. The results demonstrate the utility of a fowlpox virus vector in immunizing non-avian species against rabies in the absence of productive viral replication of the fowlpox vector.

Animals↗
PubMed1988

Protective immunity against avian influenza induced by a fowlpox virus recombinant.

Fowlpox virus, the prototypic virus of the genus Avipoxvirus has a natural host range limited to avian species. As such, fowlpox virus provides a suitable candidate for the development of a species-specific recombinant viral vector. This paper reports the development of a fowlpox virus recombinant expressing the haemagglutinin molecule from a highly virulent avian influenza virus. On immunization of chickens and turkeys with the recombinant, protection is afforded against a lethal challenge with either the homologous or a heterologous influenza virus strain.

Animals↗
PubMed1988

19F-nuclear magnetic resonance: measurements of [O2] and pH in biological systems.

19F-nuclear magnetic resonance (NMR) has been used to determine both intracellular pH and oxygen concentrations in cell suspensions. Oxygen concentrations in Paracoccus denitrificans and insulinoma cells, RINm5F, in the NMR probe can be monitored directly by 1/T1 measurements of perfluorotripropylamine (FTPA)/lecithin emulsion added to the suspensions. With FTPA oxygen monitoring, we investigated the relative aeration capabilities of two types of NMR chambers. Both normal and transformed eucaryotic cells can be maintained in either chamber for at least 1-2 h at cytocrits of up to 20-25%, with 30% oxygen saturation and cell viabilities of 90-95%. Similar concentrations of procaryotes were maintained aerobic with high FTPA concentrations in the more efficient of the two NMR chambers. A new precursor molecule for the 19F-NMR pH indicator difluoromethylalanine, the para-chlorophenyl ester, has been tested and used in RINm5F cells and P. denitrificans, neither of which hydrolyzes methyl esters.

Animals↗
PubMed1988

Age changes in the lumbar spinal and intervertebral canals.

A variety of measurements of the lumbar spinal canal (SC) and intervertebral foramina (IVF) are presented and compared in two adult age groups (48 individuals aged 20-35 and 48 individuals over 60 years) in both males and females. The dimensions measured in fresh post-mortem material include: mid-sagittal (AP) and transverse diameters (TD) of the SC; height, length and greater antero-posterior (AP) width of the IVF and ligamentum flavum (LF) thickness at the lumbo-sacral level. The data show a significant decline in the SC APD in both sexes, but the SC TD increases with ageing in males while it declines with ageing in females. The IVF height decreases with ageing but its AP width increases and its length increases. The LF shows a 50% increase in thickness with ageing. These ageing changes in a 'normal' population provide the neurovascular bundle in the IVF with less 'room for manoeuvre' and support the view that minor additional pathology is more likely to lead to entrapment syndromes in the elderly than in the young.

Adult↗
PubMed1988

Mammalian cerebral cortical tissue responds to low-intensity visible light.

Low levels of visible light directed onto slices of rat cerebral cortical tissue enhanced net potassium-induced release of the neurotransmitter gamma-aminobutyric acid (GABA) from these brain slices. At higher light intensity, net potassium-induced release was suppressed. These effects were apparently not from increased temperature. The amount of light enhancing this neurotransmitter release is approximately equal to the amount of light that can penetrate the head and reach the brain at the intensities of sunlight; this was determined by measuring the light entering the rat head through fur, scalp, skull, and dura mater and considering several natural lighting conditions. These results suggest that ambient light may be sufficient to alter the release of transmitters from mammalian cerebral cortex in vivo.

Animals↗
PubMed1988

Synthesis and biological evaluation of pNPY fragments.

Peptide fragments of pNPY corresponding to the C-terminal segments (13-36) and (25-36), the N-terminal segments (1-12) and (1-24), the segments (6-14) and (7-20), which contain a putative beta-turn, and the internal segments (13-24) and (20-30) were synthesized using solid phase methodology. These fragments were assayed for NPY receptor binding activity in the rat hypothalamus membrane preparation, enhancement of food intake in the rat following ivt administration and inhibition of electrically stimulated muscle contraction in the rat vas deferens. Only the C-terminal fragment (13-36) retained some of the activities of pNPY, appearing to act as a weak agonist, having an additive effect with pNPY on the inhibition of muscle contraction and prolonging the duration of action of pNPY in the feeding assay. It also had considerable alpha-helical character, as did pNPY. None of the other peptide fragments had any agonist or antagonist activity. These results suggest that the expression of full biological NPY activity requires both the C- and the N-terminal segments as well as a putative amphiphilic alpha-helical segment (14-31).

Amino Acid Sequence↗
PubMed1988

Characterization of self-cleaving RNA sequences on the genome and antigenome of human hepatitis delta virus.

Recently we reported that in vitro RNA transcripts complementary to the genome of hepatitis delta virus (HDV) contain a unique site at which self-cleavage can occur. Subsequent studies showed that a similar self-cleavage site was present on in vitro RNA transcripts of genomic HDV RNA. The same self-cleavage reactions were also found to occur on HDV RNAs from the livers of infected chimpanzees. Using the in vitro RNA it was also possible to determine that the minimum length of contiguous sequence needed for self-cleavage of genomic RNA was 30 bases 5' and 74 bases 3' of the cleavage site. This sequence was not compatible with the "hammerhead" structure hypothesized to be important in the self-cleavage reactions of other RNAs.

Animals↗
PubMed1988

Molecular cloning of hepatitis delta virus RNA from an infected woodchuck liver: sequence, structure, and applications.

cDNA prepared from the single-stranded circular RNA genome of hepatitis delta virus was cloned in lambda gt11 by using RNA from the liver of an infected woodchuck. From the sequence of overlapping clones, we assembled the full sequence of 1,679 nucleotides. The sequence indicated an exceptional ability for intramolecular base pairing, yielding a rod structure with at least 70% of the bases paired and a predicted free energy of -805 kcal (-3,368 kJ)/mol. Three of the lambda clones contained sequences that were not only expressed as fusion proteins with beta-galactosidase but were recognized by human hepatitis delta virus-specific antibody. These clones were sequenced so as to establish the reading frame of the delta antigen on the antigenomic strand. The fusion protein produced by one clone was purified by immunoaffinity chromatography and then was used to raise rabbit antibodies specific for the delta antigen.

Animals↗
PubMed1988

Antigenomic RNA of human hepatitis delta virus can undergo self-cleavage.

The structure and replication of the single-stranded circular RNA genome of hepatitis delta virus (HDV) are unique relative to those of known animal viruses, and yet there are real similarities between HDV and certain infectious RNAs of plants. Therefore, since some of the latter RNAs have been shown to undergo in vitro site-specific cleavage and even ligation, we tested the hypothesis that similar events might also occur for HDV RNA. In partial confirmation of this hypothesis, we found that in vitro the RNA complementary to the HDV genome, the antigenomic RNA, could undergo a self-cleavage that was not only more than 90% efficient but also occurred only at a single location. This cleavage was found to produce junction fragments consistent with a 5'-hydroxyl and a cyclic 2',3'-monophosphate. Since the observed cleavage was both site-specific and occurred only once per genome length, we propose that the site may be relevant to the normal intracellular replication of the HDV genome. Because the site is located almost adjacent to the 3' end of the delta antigen-coding region, the only known functional open reading frame of HDV, we suggest that the cleavage may have a role not only in genome replication but also in RNA processing, helping to produce a functional mRNA for the translation of delta antigen.

Antigens, Viral↗
PubMed1988

Endogenous digoxin-like substance(s) associated with uneventful and high-risk pregnancies.

We assessed the existence of endogenous digoxin-like substance(s) (EDLS) in mother-neonate pairs using a routine radioimmunoassay for digoxin. None of those studied had been treated with cardiac glycosides during or before pregnancy. In uneventful pregnancies, cord EDLS levels (0.31 +/- 0.02 ng/ml mean +/- SEM) were significantly higher (p less than 0.001) than both antepartum and postpartum maternal levels (0.14 +/- 0.02 and 0.17 +/- 0.02 mg/ml, respectively). This observation was in contrast with findings in high-risk pregnancies. In general, EDLS levels in the high-risk group were significantly higher than in normal pregnancies (cord 0.94 +/- 0.38 ng/ml; antepartum 1.63 +/- 0.54 ng/ml; postpartum 0.89 +/- 0.73 ng/ml). In the high-risk group there was a remarkably wide range of maternal and cord EDLS concentrations. The present studies suggest that following pregnancies of high risk for a variety of reasons, EDLS determination may be commonly high in the perinatal period and may affect the determination of 'true' digoxin. Consequently, digoxin dosing based on monitoring drug concentration may be futile.

Blood Proteins↗
PubMed1988

Myeloperoxidase secretion during phagocytosis: a case of a patient with impaired bactericidal activity.

We describe a case of a 5-year-old male patient with prolonged and extensive osteomyelitis of the left femur. Staphylococcus aureus was grown from blood cultures taken upon admission and also from pus drained from an incised hip joint. A defect in immune function was suspected and neutrophil function was assessed. Chemotaxis and phagocytosis were normal, but phagocytosed S. aureus were not killed as efficiently as in control neutrophils. No inherent defect in the ability of these neutrophils to generate reactive oxidants was observed, but an unusual luminol-dependent chemiluminescence response was obtained during phagocytosis of latex beads or opsonized S. aureus: This was characterized by an initial rapid, but transient increase occurring within 1 min of addition of phagocytic stimulus. Whereas during phagocytosis of latex beads by control neutrophils less than 1% of the total myeloperoxidase activity was detected extracellularly, up to 15% was released from the patient's neutrophils. We propose that release of myeloperoxidase from the patient's neutrophils during phagocytosis reduces the intraphagosomal concentration of this enzyme and thus impairs the efficiency of intracellular killing of S. aureus.

Chemotaxis, Leukocyte↗