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Biomedical subjects

M Burton

Publications and source records attributed to M Burton.

At least 19 recordsLinked to original sources
PubMed2026

Carrot Juice Intake Modulates Oncogenic and Inflammatory Pathways in Advanced Colorectal Adenomas: A Pilot Feasibility Study.

Carrots are a rich dietary source of carotenoids and polyacetylenes, bioactive compounds with demonstrated anti-inflammatory and anticancer properties in experimental models. Epidemiological evidence suggests that carrot consumption is associated with a reduced risk of colorectal cancer; however, clinical data linking carrot intake to molecular changes in premalignant colorectal tissue remain limited. In this pilot intervention study, 20 patients with advanced colorectal adenomas were enrolled. Fifteen participants consumed carrot juice daily for 21 days, while five served as untreated controls. Paired adenoma biopsies were collected before and after the intervention and were analyzed using gene expression microarrays to assess transcriptional responses. Carrot juice intake was well tolerated, with adherence exceeding 95% and no reported adverse events. Transcriptomic analysis revealed modulation of key pathways implicated in colorectal carcinogenesis, including downregulation of the WNT, PI3K-AKT, and MAPK signaling pathways, as well as cyclooxygenase-2-related inflammatory pathways and cytokine signaling. These changes were consistent with reduced oncogenic signaling and attenuation of inflammatory activity within adenoma tissue. In summary, short-term carrot juice consumption was associated with coordinated suppression of molecular pathways involved in colorectal adenoma progression. These findings provide preliminary clinical evidence that a whole-food dietary intervention may influence early carcinogenic processes and support the need for larger controlled studies evaluating clinical outcomes.

Journal Article↗
PubMed1995

Refinement by linkage analysis in two large families of the candidate region of the third locus (SCA3) for autosomal dominant cerebellar ataxia type I.

The autosomal dominant cerebellar ataxias (ADCA) are clinically and genetically heterogeneous. To date, several loci (SCAI-V) have been identified for ADCA type I. We have studied two large families from the northern part of The Netherlands with ADCA type I with a broad intra-familial variation of symptoms. In both families significant linkage is shown of the disease to the markers of the SCA3 locus on chromosome 14. Through recombinations, the candidate region for SCA3 could be refined to a 13-cM range between D14S256 and D14S81. No recombinations were detected with the markers D14S291 and D14S280, which suggests that the SCA3 gene lies close to these loci. This finding will benefit the individuals at risk in these two families who are seeking predictive testing or prenatal diagnosis.

Adult↗
PubMed1994

The role of lexical status on the phonetic categorization of speech in aphasia.

Recent results with normal subjects have shown that the locus of the phonetic boundary of a speech continuum may change as a function of the word/nonword status of the endpoint stimuli. This so-called lexical effect in phonetic categorization has been used as evidence for the role of top-down processing in speech perception. This study investigated whether aphasic patients show a similar influence of lexical status on phonetic categorization. Two test continua were created varying in voice-onset time: in one continuum, the two endpoint stimuli were word/nonword, i.e., "duke"--"tuke," and in the other continuum, they were nonword/word, i.e., "doot"--"toot." Twelve aphasic patients were tested including 6 Broca's aphasics and 6 Wernicke/Conduction aphasics. The subject's task was to determine whether the first sound of the stimulus was a "d" or "t." Broca's aphasics showed a large lexical effect, with the magnitude of the effect being greater than that for normals. These results suggest that the Broca's aphasics place a heavier reliance on a heuristic strategy than on the perceptual information embedded in the test stimuli in making a phonetic categorization. In contrast, Wernicke/Conduction aphasics did not show a lexical effect, suggesting that these patients are less likely than either normals or Broca's aphasics to use heuristic strategies in lexical processing. The overall results are considered in relation to current views on language-processing deficits in aphasia.

Adult↗
PubMed1994

Cathepsin B and N-acetyl-beta-D-glucosaminidase in human synovial cells in culture: effects of interleukin-1.

Human synovial cells were cultured in vitro and tested for the activities of two lysosomal enzymes, cathepsin B and N-acetyl-beta-D-glucosaminidase (NAGA) under various conditions. Unstimulated synovial cells display intracellular and extracellular activities of both enzymes. However, cathepsin B was secreted in a latent pepsin-activatable form, whereas NAGA was secreted in an active form. Most of the cell strains analysed secreted rather limited amounts of the enzymes (less than 25% of total activity); some strains, however were highly secretory, the secreted activity reaching up to 50% of total activity. Cells were then stimulated with human recombinant interleukin-1 alpha (rhIL-1 alpha) or beta. Only the levels of secreted NAGA were clearly increased. Results are to be interpreted in view of the role played by synovial cells and by the lysosomal enzymes they release in inflammatory joint diseases and it would be worthwhile in the future to check for secreted NAGA in various body fluids, such as the synovial fluid of the inflamed joint.

Acetylglucosaminidase↗
PubMed1994

The effect of subphonetic differences on lexical access.

This study investigated whether lexical access is affected by inherent acoustic variations that contribute to the identity of a phonetic feature and ultimately a phonetic segment. Two experiments were conducted to determine whether the magnitude of semantic (associative) priming in a lexical decision task is influenced when the acoustic manifestation of the initial voiceless stop consonant (specifically, voice onset time) of a prime word semantically related to a lexical decision target was systematically manipulated (e.g., prime: "king"; target: "queen"). Results showed no effect of the acoustic manipulations at the longer interstimulus interval (250 ms); however, at the shorter interstimulus interval (50 ms), the magnitude of semantic facilitation decreased as a function of the voice onset time manipulations. In addition, there was a tendency toward slower lexical decision latencies when the prime word had a real word voiced counterpart than when it did not. These results suggest that activation levels of words in the lexicon are graded, depending on the subphonetic shape of the input word. Results also suggest that words which are phonologically similar to the intended word candidate are activated to some extent, whether the input provides a relatively poor phonetic representation of the intended word or a good one.

Humans↗
PubMed1994

Induction of cyclooxygenase by interleukin 1: comparative study between human synovial cells and chondrocytes.

OBJECTIVE: To investigate the regulation of the prostaglandin (PG) synthesis by interleukin 1 (IL-1) in human synovial cells and chondrocytes. METHODS: Both cell types stimulated by human recombinant IL-1 synthesized PGE2, PGF2 alpha and 6-keto-PGF1 alpha. RESULTS: PGE2 was the major PG synthesized. When arachidonic acid was added exogenously at the end of the stimulation, an increase in the prostaglandin synthesis was observed after 6 and 24 h suggesting that cyclooxygenase is the limiting enzyme. Using actinomycin D and cycloheximide, PG synthesis was shown to be protein synthesis dependent. Inhibition of the constitutive cyclooxygenase by aspirin before the IL-1 stimulation confirmed that the increased prostaglandin synthesis was due to a de novo synthesis of cyclooxygenase. CONCLUSION: This enzyme induction by IL-1 was found to be similar in both cell types.

Arachidonic Acid↗
PubMed1993

Routine prostaglandin assay by GC-MS in multiwell tissue culture plates: application to human synoviocytes and chondrocytes.

Prostanoids can be assayed by the highly sensitive and reproducible gas chromatography-negative ion chemical ionization-mass spectrometry (GC-NICI-MS) technique. This paper describes a simplified method applied to the quantification of prostaglandins (PG) in the supernatants of limited amounts of cells, cultured in multiwell plates (30,000 cells/well). The culture medium was extracted on C2 columns and the derivatization was performed in three steps. Prostanoids were then analyzed by GC-NICI-MS within 10 min. The storage conditions at each step were tested in order to achieve maximal yields. This procedure allowed the determination and quantification of PG produced by cultured human synovial cells and chondrocytes at the basal level as well as after interleukin-1 stimulation. PGE2, PGF2 alpha, and 6-keto-PGF1 alpha, the stable form of PGI2, were the main PG detected. Derivatization and GC-MS analyses of 18 samples could easily be performed in 1 day. The simplified GC-NICI-MS method can thus be routinely applied for assaying PG in any cell line cultured in multiwells.

Calibration↗
PubMed1993

Differential effects of interleukin-1 alpha and beta on the arachidonic acid cascade in human synovial cells and chondrocytes in culture.

The effects of interleukin-1 alpha and beta were tested on the [3H]-arachidonic acid release and the prostaglandin synthesis by human cultured synovial cells and chondrocytes. Both forms of interleukin-1 stimulated the arachidonic acid release but interleukin-1 beta was more potent than IL-1 alpha. Human synovial cells and chondrocytes synthesized three types of prostaglandins upon stimulation with interleukin-1 alpha or beta: prostaglandin E2, F2 alpha and 6-keto-prostaglandin F1 alpha. Regarding the synthesis of these prostaglandins, IL-1 beta was again more potent than IL-1 alpha. A comparison between interleukin-1-stimulated synovial cells and chondrocytes revealed neither significant quantitative nor qualitative differences in both the arachidonic acid release and the prostaglandin synthesis.

Arachidonic Acid↗
PubMed1993

Effects of distinctiveness, repetition and semantic priming on the recognition of face familiarity.

Three experiments are reported which provide evidence for the independence of effects of repetition from those of distinctiveness and semantic priming in the recognition of familiar faces. In Experiment 1, repetition priming is shown to be additive with face distinctiveness in a face familiarity decision task, where subjects make speeded familiarity decisions to a sequence of famous and unfamiliar faces. Experiment 2 examines the combined effects of distinctiveness and semantic priming. The results suggest that the effect of distinctiveness is additive with that of semantic priming. Experiment 3 uses a more powerful design in which effects of distinctiveness and semantic priming were assessed while all items were repeated three times during the course of the experiment. Effects of repetition and distinctiveness were again additive, as were effects of repetition and semantic priming. Distinctiveness and semantic priming were additive at 1,000 ms SOA, though appeared to interact at 250 ms SOA. The results give further evidence for the separation of the mechanisms of semantic from repetition priming, and furthermore suggest that distinctiveness operates at a different locus from those of either of the priming mechanisms.

Adult↗
PubMed1993

Purification and characterization of Alt a-29 from Alternaria alternata.

A major protein component reactive with pooled human atopic sera was isolated from a lyophilized broth extract of Alternaria alternata 34-016. By successive chromatography on Whatman DE-52, Sephadex G-100 and Mono Q HR5/5, a low molecular weight antigen was obtained. Comparison with standard proteins on Sephadex G-100 indicated its molecular weight was 31 kD. Non-reduced samples run on SDS-PAGE showed a band at 29.2 kD which reacted strongly with human IgE. After reduction, it produced a doublet pattern on SDS-PAGE with MW 14.5 and 16.0 kD. The doublet pattern was confirmed by Western blotting with pooled human atopic sera. IEF of the protein showed a major component with a PI of 4.15 and two minor components at 4.25 and 4.40. Immunoblots of the IEF bands showed all three were reactive with human IgE. Ion exchange chromatography of the protein on Mono Q HR5/5 resulted in three resolved components, all of which are immunoreactive. Together with the IEF data, this suggests that there are several conformational or structural isoforms of this protein.

Allergens↗
PubMed1992

Acoustic and perceptual characteristics of voicing in fricatives and fricative clusters.

Several types of measurements were made to determine the acoustic characteristics that distinguish between voiced and voiceless fricatives in various phonetic environments. The selection of measurements was based on a theoretical analysis that indicated the acoustic and aerodynamic attributes at the boundaries between fricatives and vowels. As expected, glottal vibration extended over a longer time in the obstruent interval for voiced fricatives than for voiceless fricatives, and there were more extensive transitions of the first formant adjacent to voiced fricatives than for the voiceless cognates. When two fricatives with different voicing were adjacent, there were substantial modifications of these acoustic attributes, particularly for the syllable-final fricative. In some cases, these modifications leads to complete assimilation of the voicing feature. Several perceptual studies with synthetic vowel-consonant-vowel stimuli and with edited natural stimuli examined the role of consonant duration, extent and location of glottal vibration, and extent of formant transitions on the identification of the voicing characteristics of fricatives. The perceptual results were in general consistent with the acoustic observations and with expectations based on the theoretical model. The results suggest that listeners base their voicing judgments of intervocalic fricatives on an assessment of the time interval in the fricative during which there is no glottal vibration. This time interval must exceed about 60 ms if the fricative is to be judged as voiceless, except that a small correction to this threshold is applied depending on the extent to which the first-formant transitions are truncated at the consonant boundaries.

Female↗
PubMed1991

Remembering facial configurations.

Eight experiments are reported showing that subjects can remember rather subtle aspects of the configuration of facial features to which they have earlier been exposed. Subjects saw several slightly different configurations (formed by altering the relative placement of internal features of the face) of each of ten different faces, and they were asked to rate the apparent age and masculinity-femininity of each. Afterwards, subjects were asked to select from pairs of faces the configuration which was identical to one previously rated. Subjects responded strongly to the central or "prototypical" configuration of each studied face where this was included as one member of each test pair, whether or not it had been studied (Experiments 1, 2 and 4). Subjects were also quite accurate at recognizing one of the previously encountered extremes of the series of configurations that had been rated (Experiment 3), but when unseen prototypes were paired with seen exemplars subjects' performance was at chance (Experiment 5). Prototype learning of face patterns was shown to be stronger than that for house patterns, though both classes of patterns were affected equally by inversion (Experiment 6). The final two experiments demonstrated that preferences for the prototype could be affected by instructions at study and by whether different exemplars of the same face were shown consecutively or distributed through the study series. The discussion examines the implications of these results for theories of the representation of faces and for instance-based models of memory.

Adolescent↗
PubMed1991

Recognising facial surfaces.

The extent to which faces depicted as surfaces devoid of pigmentation and with minimal texture cues ('head models') could be matched with photographs (when unfamiliar) and identified (when familiar) was examined in three experiments. The head models were obtained by scanning the three-dimensional surface of the face with a laser, and by displaying the surface measured in this way by using standard computer-aided design techniques. Performance in all tasks was above chance but far from ceiling. Experiment 1 showed that matching of unfamiliar head models with photographs was affected by the resolution with which the surface was displayed, suggesting that subjects based their decisions, at least in part, on three-dimensional surface structure. Matching accuracy was also affected by other factors to do with the view-points shown in the head models and test photographs, and the type of lighting used to portray the head model. In experiment 2 further evidence for the importance of the nature of the illumination used was obtained, and it was found that the addition of a hairstyle (not that of the target face) did not facilitate matching. In experiment 3 identification of the head models by colleagues of the people shown was compared with identification of photographs where the hair was concealed and eyes were closed. Head models were identified less well than these photographs, suggesting that the difficulties in their recognition are not solely due to the lack of hair. Women's heads were disproportionately difficult to recognise from the head models. The results are discussed in terms of their implications for the use of such three-dimensional head models in forensic and surgical applications.

Adolescent↗
PubMed1991

Influence of soluble haemagglutinins on adherence of Helicobacter pylori to HEp-2 cells.

In a study of six laboratory strains of Helicobacter pylori, two different modes of bacterial adherence to HEp-2 cells were found. Electronmicroscopy revealed that strains known to possess soluble haemagglutinin adhered intimately to the cell surfaces, with cupping of the plasma membrane and coalescence of glycocalyces at sites of attachment. Strains of H. pylori without soluble haemagglutinin also attached, but did not induce membrane cupping or show glycocalyx fusion. Light microscopy did not distinguish between these patterns of adherence. Bacterial attachment was unaffected by pre-treatment of HEp-2 cells with neuraminidase. Exposure of the bacteria to trypsin or to colloidal bismuth subcitrate (CBS) before being added to HEp-2 cells markedly impaired bacterial adherence. This effect of CBS may contribute to the known efficacy of bismuth therapy in patients with H. pylori-related gastritis.

Bacterial Adhesion↗
PubMed1991

Sodium salicylate centrally augments ventilation through cholinergic mechanisms.

Several different stimuli, including hydrogen ions, may exert their effect on central ventilatory control through cholinergic mechanisms. Salicylates are known to be central respiratory stimulants. Therefore this study explored whether the ventilatory effect of sodium salicylate (SAL) is through cholinergic mechanisms. Ventriculocisternal perfusion was used in spontaneously breathing anesthetized (pentobarbital sodium, 30 mg/kg) mongrel dogs to study the effects of SAL (50 mM), atropine (ATR, 4.8 mM), and SAL-ATR on ventilation. After 15 min of perfusion with mock cerebrospinal fluid, each test agent was perfused for 15 min at a rate of 1 ml/min. Cardiovascular and ventilatory parameters were monitored. Values at 15 min of test agent perfusion were compared with values at 15 min of mock cerebrospinal fluid perfusion, with each animal used as its own control. Body temperature was kept between 37.5 and 39.0 degrees C. Perfusion with SAL increased minute ventilation (VE) by 54% (P less than 0.005) and respiratory frequency by 50% (P less than 0.005). Tidal volume was not changed, but mean inspiratory flow rate increased (P less than 0.05). Perfusion with ATR decreased VE by 22% (P less than 0.1), and perfusion with SAL-ATR decreased VE by 20% (P = 0.01). No significant cardiovascular changes were noted in any group. We conclude that SAL increases VE centrally, primarily by increasing respiratory frequency. Because ATR blocked this effect, cholinergic mechanisms are probably involved in the salicylates' central stimulation of ventilation.

Animals↗