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Biomedical subjects

D Taylor

Publications and source records attributed to D Taylor.

At least 271 records · Page 15Linked to original sources
PubMed1994

Conservation of immune responses to proteins isolated by preparative polyacrylamide gel electrophoresis from the outer membrane of nontypeable Haemophilus influenzae.

Outer membrane proteins P2, P4, and P6 and two with molecular masses of 26 and 28 kDa have been purified from a strain of nontypeable Haemophilus influenzae by a preparative form of polyacrylamide gel electrophoresis (PAGE). Outer membrane protein P6, with a molecular mass of 16 kDa (determined by sodium dodecyl sulfate [SDS]-PAGE) was purified by both native PAGE and SDS-PAGE from three strains of nontypeable H. influenzae and one strain of type b H. influenzae. The same conditions were required for purification from each strain. The suitability of proteins isolated by these methods was assessed by studying the immune response of rats immunized with P6 in incomplete Freund's adjuvant into the Peyer's patches. P6 purified by either native PAGE or SDS-PAGE did not differ significantly from P6 purified by gel filtration and anion-exchange chromatography in the ability to enhance pulmonary clearance of live bacteria. This study also investigated the effects of SDS on P2 immunological responses in vivo and the effects of the reagents Zwittergent and sodium lauryl sarcosinate on outer membrane protein lymphocyte-proliferative responses in vitro. It was found that the presence of SDS in the immunization emulsion enhanced the antigen-specific cell-mediated response but suppressed the antigen-specific antibody responses. The presence of residual traces of Zwittergent in an outer membrane protein preparation inhibited antigen-specific cell-mediated proliferation, whereas extraction of outer membrane proteins with sodium lauryl sarcosinate did not inhibit antigen-specific proliferation. These results demonstrate that preparative PAGE is a suitable method for the purification of proteins from the outer membrane of H. influenzae required for investigation of their immunological significance as vaccine candidates and that traces of reagents used during protein purification may play an important role in determining the success of in vivo and in vitro studies.

Animals↗
PubMed1994

An electrophysiological study on children and young adults with Alport's syndrome.

Alport's syndrome is characterised by progressive haematuric nephritis and high tone sensorineural hearing loss. Ocular signs are variable, the most consistent findings being anterior lenticonus and retinal flecks in the macula and mid peripheral areas. Previous electrophysiological studies on patients with Alport's syndrome have mostly been on adult patients undergoing haemodialysis, or after renal transplantation. A group of young patients with Alport's syndrome were studied to assess if early electrophysiological changes were detectable. A total of 20 patients (15 males and five females) between the ages of 3.5 and 22 years (mean 12.7 (years) were examined and compared with control subjects. Visual evoked potentials and electroretinograms were obtained following flash and pattern reversal stimulation. Electro-oculograms were also recorded. No significant electrophysiological changes were found in any of the 20 patients, including four who had visible fundus changes.

Adolescent↗
PubMed1994

University of Alberta norms of relative meaning frequency for 566 homographs.

For many models of lexical ambiguity resolution, relative frequency of the different meanings of homographs (words with more than one meaning) is crucial. Although several homograph association norms have been published in the past, none has involved a large number of subjects responding to a large number of homographs, and most homograph norming studies are now at least a decade old. In Experiment 1, associations to 566 homographs were collected from an average of 192 subjects per homograph. Frequency of occurrence for the three most common meanings is reported, along with the corresponding associates, and a measure of the overall ambiguity of each homograph. Homographs whose meanings differed in part of speech were more ambiguous overall than homographs whose different meanings belonged to a single grammatical class. Homographs whose pronunciation depended on meaning (heterophones) were no more ambiguous than nonheterophones, and word frequency was unrelated to overall ambiguity. Estimates of homograph balance across different norming studies were compared, and homographs with two meanings of approximately equal relative meaning frequency (balanced homographs) and homographs with one clearly dominant meaning (polarized homographs) were identified. In Experiment 2, reliability of meaning categorizations was measured for a subset of the homographs in the first experiment. Meaning categorizations were shown to be highly reliable across raters.

Humans↗
PubMed1994

Mutants of Streptomyces cattleya defective in the synthesis of a factor required for thienamycin production.

Thienamycin non-producing mutants of Streptomydes cattleya were identified that displayed a cross-feeding relationship. A diffusible product from one of these mutants (RK-11) resulted in restoration of thienamycin production when fed to cultures of another mutant (RK-4). In vivo radiolabeling experiments were conducted to test whether the RK-11 mutant produced a late biosynthetic intermediate which contained a carbapenem ring and a cysteaminyl and/or a hydroxyethyl side chain. Both [35S]cystine and [methyl-3H]methionine were used to label the RK-11 product which was then fed to RK-4 cultures. None of the thienamycin subsequently produced by RK-4 converter cells was labeled, implying the lack of either side chain of the thienamycin molecule in the RK-11 product. Further stability studies suggested that the RK-11 product does not contain a carbapenem ring. Additional feeding experiments with RK-4 cells also ruled out the possibility that the RK-11 product is a co-factor necessary for thienamycin production. It is concluded that the RK-11 product may regulate expression of the thienamycin gene cluster.

Chromatography, High Pressure Liquid↗
PubMed1994

Megalocornea, developmental retardation and dysmorphic features: two further patients.

Two unrelated children are described with megalocornea, mild-moderate developmental delay, mild joint laxity and a similar dysmorphic appearance, comprising a bossed forehead, hypertelorism, a saddle-shaped nose and a carp-shaped mouth with prominent lips. Similar abnormalities have been observed in previously reported cases of megalocornea/mental retardation and may help to define one subtype of this heterogeneous group of conditions.

Abnormalities, Multiple↗
PubMed1994

Frontofacionasal dysplasia: a new case and review of the phenotype.

A boy is presented with frontofacionasal dysplasia. The severity of his malformations exceeds that encountered in the cases described previously. The range of clinical abnormality seen in this disorder is reviewed and the delineation of the condition as a separate entity is explored.

Abnormalities, Multiple↗
PubMed1993

Concordance and recessive inheritance of Leber congenital amaurosis.

Pedigrees were obtained on 43 patients with confirmed Leber congenital amaurosis, a rare form of blindness caused by congenital dysfunction of the retina. All of the pedigrees were consistent with autosomal recessive inheritance and the segregation frequency using classical segregation analysis was 0.24 +/- 0.07. Six of the 7 affected sib pairs were concordant in regards to systemic abnormalities. Despite previous reports that Leber congenital amaurosis can be inherited either as an autosomal dominant or recessive condition, our findings support only an autosomal recessive inheritance of this disorder.

Adolescent↗
PubMed1993

Structural influences on pyrrolizidine alkaloid-induced cytopathology.

Pyrrolizidine alkaloids (PAs), which are common constituents of hundreds of plant species around the world, have been reported to have cytotoxic, carcinogenic, antineoplastic, and genotoxic activity in vivo and in vitro. The exact mechanism of these biological toxicities is not yet clear. The ability of eight PA congeners to inhibit mitosis and induce megalocyte formation in cultured bovine kidney epithelial cells was studied to examine possible structural influences on these endpoints. Representatives of the three PA structural groups, the macrocycles (seneciphylline, senecionine, riddelliine, retrorsine, monocrotaline), open diesters (heliosupine, latifoline), and a necine base (retronecine), were cocultured for 2 hr with a NADPH-generating system and rat liver S9. Macrocyclic PAs with alpha,beta-unsaturation (seneciphylline, senecionine, riddelliine, retrorsine) showed a dose-dependent inhibition of colony formation at 50, 100, and 300 microM and induction of megalocytosis at 500 microM. Colony growth resumed 3 weeks after removal of PAs at 50 and 100 microM, and normal cellular morphology returned 5 or 6 weeks after removal of PAs at 500 microM. The saturated macrocyclic (monocrotaline) and open diesters (heliosupine, latifoline), elicited only a slight inhibition of colony formation and had no effect on cellular morphology at 500 microM. The necine base (retronecine) had no effect on either colony formation or cell morphology. Pyrrolic PAs (dehydrosenecionine, dehydromonocrotaline, dehydroretronecine) were more active in inhibition of colony formation than their parent compounds and were potent inducers of abnormal cellular morphology at 500 microM. An N-oxide metabolite, indicine N-oxide, was completely inactive. The results support previous studies showing that there are structural influences on PA-induced cytopathological effects.

Animals↗
PubMed1993

Indomethacin-induced maternal convulsion in the treatment of preterm labour.

A caucasian 28-year-old woman at 25 weeks gestation with a diagnosis of preterm labour suffered a convulsion after the administration of indomethacin. Convulsions are described as an infrequent complication with this therapy in the non-pregnant population. No such convulsion has been described to date in pregnancy.

Adult↗
PubMed1993

Fatigue failure in the cement mantle of an artificial hip joint.

The cement mantle of an artificial hip joint was retrieved, largely intact, during a revision operation, and subjected to detailed failure analysis. The results reveal a number of features which are important to our understanding of the failure of bone cement in situ and its consequences for prosthesis loosening. Microscopic examination showed clear evidence of fatigue cracking in the mantle prior to removal. This took the form of worn areas in certain regions of the fracture surfaces, which elsewhere showed evidence of rapid, brittle fracture. The mantle contained two large defects which had been introduced during insertion; fatigue was shown to have originated both from these defects and from the proximal surface. Results from a finite element analysis were used, together with the techniques of fracture mechanics, in an attempt to explain the magnitude and direction of fatigue cracking. Fracture mechanics calculations, though subject to some uncertainty in this case, indicate that the local stress intensity in the region of the principal defect would have been sufficient to exceed the threshold for fatigue crack propagation in this material. This approach demonstrates the advantages of this 'defect-tolerance' analysis.

Bone Cements↗
PubMed1993

Effects of sentence form on the construction of mental plans from procedural discourse.

Memory for procedural discourse was examined in two experiments. In Experiment 1, memory was assessed using recall; in Experiment 2, a recognition test was used. In both experiments, the memorability of three types of action statements were compared: a transitive verb form, in which the action was described by a main clause; a verbal adjective form, in which the action was indicated by an adjective derived from a verb; and an implicit action form, in which the action was only implied. Information associated with transitive verbs and verbal adjectives was more likely to be recalled than information associated with implicit actions. Although a manipulation of prior knowledge affected overall recall performance, it did not interact with sentence form. In addition, recognition accuracy was affected by neither sentence form nor prior knowledge. To account for these results, it was proposed that transitive verbs and verbal adjectives generate a semantic representation that includes features of the action, whereas implicit actions do not. This difference in semantic representation leads to structural differences in a mental plan for the task. The obtained effects on recall reflect these differences in plan structure.

Adult↗
PubMed1993

Dose-response effects of adrenergic and cholinergic stimulation on atrial natriuretic peptide secretion from beating isolated guinea-pig atria.

1. The possible role of autonomic neurotransmitters in atrial natriuretic peptide secretion was investigated using spontaneously beating guinea-pig atria in vitro. Dose responses were determined for adrenaline, noradrenaline and acetylcholine and the selective alpha- and beta-adrenoceptor agonists phenylephrine and isoprenaline, respectively. Adrenoceptor effects were further studied using the selective alpha- and beta-adrenoceptor antagonists prazosin and propranolol, respectively, in conjunction with maximal adrenaline challenge. Results for rate and force of contraction and atrial natriuretic peptide secretion are expressed as a ratio (mean +/- SEM) of a 15 min treatment period (stage 2) to a corresponding pretreatment period (stage 1). 2. Adrenaline and noradrenaline caused dose-dependent increases in the rate and force of contraction and in atrial natriuretic peptide secretion with a peak secretory response at 2 x 10(-6) mol/l of 1.54 +/- 0.08 (P < 0.01) and 1.34 +/- 0.08 (P < 0.01) for adrenaline and noradrenaline, respectively. Acetylcholine decreased the rate and force of contraction, and ANP secretion was reduced to 0.47 +/- 0.06 at 3 x 10(-5) mol/l (P < 0.01). Isoprenaline increased the rate and force of contraction and atrial natriuretic peptide secretion with a peak secretory response of 1.52 +/- 0.22 at 2 x 10(-6) mol/l (P < 0.01). Phenylephrine increased the force but had no effect on the rate of contraction, and stimulated atrial natriuretic peptide secretion to 1.13 +/- 0.09 at 2 x 10(-5) mol/l (P < 0.05). After both alpha- and beta-adrenoceptor blockade, adrenaline was still able to significantly stimulate atrial natriuretic peptide secretion and positive inotropy.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1993

Differences between genetic stocks of chickens in response to acute and delayed effects of an organophosphorus compound.

The influence of genotypes of the major histocompatibility complex (MHC) on susceptibility to acute and delayed effects of an organophosphorus ester was measured in adult White Leghorn chickens from lines differing in response to sheep red blood cell (SRBC) antigen. Chickens from lines selected for high (HA) or low (LA) antibody response to SRBC and homozygous for B13B13 or B21B21 genotypes at the MHC were administered a single subcutaneous injection of diisopropyl phosphorofluoridate (DFP) at dosages of 0, 0.25, 0.50, or 1.0 mg/kg body weight using corn oil as the carrier. Criteria for toxicological responses included clinical, biochemical, and pathological measures. Clinical signs of acute cholinergic poisoning and delayed neuropathy were dose related. Brain and blood cholinesterase and carboxylesterase activities were more sensitive to inhibition by DFP than were liver cholinesterase and carboxylesterase activities. Cholinergic signs 3 h after administration of DFP were more pronounced in line HA than in line LA chickens. Pathological evidence of delayed neuropathy 2 wk after DFP administration was also more evident in HA than LA chickens. Although less pronounced than that for lines, differences in neurotoxic manifestations following DFP administration were greater for chickens of B21B21 than B13B13 genotypes. Activity of A-esterases, which hydrolyze organophosphorus esters without being inhibited by them, was lower in plasma of line HA than line LA chickens. Differences among the genotypes in activity of other esterases were not found in chickens not receiving DFP. These results indicated that responses of chickens to the neurotoxicant DFP were influenced by the background genome of the chickens.

Animals↗
PubMed1993

Vaginography: the investigation of choice for vaginal fistulae?

Adequate demonstration of the pathology and site of vaginal fistulae is preferable before surgical intervention is planned. Vaginal fistulae have traditionally been investigated by upper and lower gastrointestinal contrast radiology, often with a failure to demonstrate the fistula. The authors' recent experience confirms that vaginography is a simple and accurate method of assessing many types of vaginal fistulae.

Aged↗