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Biomedical subjects

A Thompson

Publications and source records attributed to A Thompson.

At least 127 records · Page 7Linked to original sources
PubMed1999

Low-bandwidth tele-ultrasound.

We examined the acceptability and diagnostic accuracy of dynamic ultrasound images transmitted at 128 kbit/s and 384 kbit/s. The gold standard was the direct recording of 200 ultrasound examinations on video-tape. The taped images were later transmitted at both 128 kbit/s and 384 kbit/s and recorded, resulting in three tapes for each case. Four observers viewed each tape individually. Ninety per cent of images transmitted at 384 kbit/s were rated as diagnostically acceptable compared with 32% of images transmitted at 128 kbit/s. Diagnostic agreement between tapes transmitted at 384 kbit/s and the gold standard was 85%, compared with 78% for 128 kbit/s transmissions. Observers were not satisfied with low-bandwidth transmission of ultrasound images despite adequate diagnostic accuracy. Dynamic ultrasound images transmitted at 384 kbit/s were viewed as both diagnostically acceptable and accurate.

Electronics↗
PubMed1999

Domiciliary midwifery support in high-risk pregnancy incorporating telephonic fetal heart rate monitoring: a health technology randomized assessment.

We conducted a health technology assessment of the care of women with high-risk pregnancies in the South Wales valleys. Women in the control arm were intended to receive conventional care with standard midwifery visits. Women in the intervention arm received additional or longer visits and domiciliary fetal heart rate telemonitoring. Eighty-one mothers were randomized. There were significant differences in midwifery intervention resources between domiciliary and control groups, with the former receiving a mean of 3.7 visits lasting 33.5 min, compared with 1.4 visits lasting 12.8 min for the latter. There were slightly more spontaneous labours and fewer Caesarean sections in the domiciliary group. Maternal satisfaction and anxiety were high in both groups. Domiciliary care increased the service costs by 21.02 Pounds per woman in terms of extra midwife travel and visiting time, and by a further 18.38 Pounds per woman in home monitoring equipment costs. This, however, was more than offset by health service savings from fewer clinic visits (35.60 Pounds) and fewer clinic ultrasound scans (9.01 Pounds). Adding the reductions in lost productivity to women and their partners (34.51 Pounds) suggests that domiciliary care was cheaper than conventional care, even if it did not greatly reduce inpatient days (a reduction nonetheless saving 184.24 Pounds). While clinical processes were similar in both groups, there were useful practical advantages and savings for patients and the health service from the domiciliary intervention.

Anxiety↗
PubMed1999

Using the Short Form-36 with multiple sclerosis patients in five countries: a cross-cultural comparison.

Questionnaires measuring health-related quality of life are increasingly used in international studies of medical effectiveness. It is important to know if data from these instruments are comparable across countries. We initiated a collaboration among five research groups--from the USA, The Netherlands, Belgium, France, and the UK--in the field of health-related quality of life in multiple sclerosis. All groups used the 36-item Short Form Health Survey. The goal of our study was to make a cross-cultural comparison. In the five countries under study the sample size varied from 50 to 134 patients with multiple sclerosis. The survey was completed by a total of 457 patients, who were heterogeneous in relation to age, duration of illness, severity and type of multiple sclerosis. There appeared to be major differences among the samples in scores on each of the eight scales. These findings may be influenced by differences in method of recruitment, demographic and disease-related characteristics, administration, and cultural factors. After having performed a number of analyses, it appeared that the differences were mainly attributable to sampling effects; however, cultural influences could not be excluded.

Adult↗
PubMed1999

The benefits of support group participation to lung cancer survivors--an evaluation.

It has been known for some time that participation in support groups is beneficial for most cancer survivors. Despite this, and even though lung cancer causes more deaths than breast, prostate, and colorectal cancers combined, the number of support groups formed for lung cancer survivors is surprisingly very small. In an effort to understand the lack of lung cancer specific support groups, the Alliance for Lung Cancer Advocacy, Support, and Education (ALCASE) conducted a survey of the facilitators of the lung cancer support groups then known to be in existence in the United States, in addition to a follow-up focus group with the facilitators via teleconference. The results of the survey and the focus group provide a very preliminary look at the value to lung cancer survivors of participating in support groups organized specifically for them. However, much more research is required, not only with the participants of these groups, but also with lung cancer survivors who do not participate, to fully gauge the effects of support group participation on the progress of their disease and on their quality of life.

Journal Article↗
PubMed1999

Caries inhibition in rats by a remineralizing toothpaste.

We tested the anti-caries properties of a prototype remineralizing toothpaste containing sodium fluoride, soluble phosphate and soluble calcium, similar but not identical to Enamelon Toothpaste in specific pathogen-free Osborne-Mendel rats. A fluoride-free placebo and sodium fluoride-containing Crest Regular were used as negative and positive control toothpastes, respectively. Sixty weanling rats were randomly distributed into groups of 20, all were inoculated with S. mutans 10449S, ate diet 2000, and drank demineralized water. Each toothpaste, contained in coded tubes, was applied to the rats' teeth, once for one minute/day, five days/week. There was no difference in bacterial recoveries from tooth swabs among the groups at either the 22- or 37-day post-inoculation recovery date. After rat sacrifice and defleshing, heads were randomly coded and scored blindly for carious lesions according to Keyes/Larson methods. Only after scoring was completed were the random codes broken and the treatment groups identified. Both the Enamelon-like product and Crest Regular treatments resulted in lower total enamel caries scores than the placebo (p < 0.001). The sum of smooth surface scores was also lower for the fluoride-containing toothpastes than for the placebo (p < 0.001). However, the Enamelon-like product had greater caries inhibitory properties than Crest Regular on sulcal and approximal tooth surface categories (p = 0.004 and p = 0.045, respectively). Therefore, the Enamelon-like product had superior caries inhibiting properties compared to Crest Regular at these tooth areas.

Administration, Topical↗
PubMed1999

Model for assessment of carious lesion remineralization, and remineralization by a novel toothpaste.

This study is of a novel toothpaste which induced remineralization of carious lesions in specific pathogen-free Osborne-Mendel rats. Randomly distributed weanlings in 7 groups (n = 10) each were initially induced to develop carious lesions as a result of a severe dietary and bacteriological challenge. Thus, all were inoculated with S. mutans 10449S, ate diet 2000CS (containing 56% cornstarch) ad libitum, and, upon weaning and for 10 additional days, drank demineralized water supplemented to 10% (w/v) with sucrose (SW) ad libitum. During these 10 days, 6 of the 7 groups of rats were topically treated with a slurried F(-)-free placebo toothpaste. On the 10th day after initial inoculation, two groups were sacrificed, one which had been treated with the placebo and the one which had been untreated. The remaining groups were then provided unsupplemented demineralized water (DW), fed diet 2000CS, and topically treated with either of 5 coded toothpastes: a slurry of the F(-)-free placebo, a similar slurry of a conventional sodium fluoride toothpaste (Crest Regular) containing about 383 ppm F-, or one of three prototype toothpastes formulated by Enamelon, Inc. containing soluble calcium and phosphate salts. Two of these contained 377 ppm F- after mixing their components, either as sodium monofluorophosphate (E-MFP) or as NaF (E-NaF). The third prototype contained 0 ppm F- (E-w/o F). Test items were applied to the dentition for one minute/day, five days/week. These 5 remaining groups were sacrificed 13 days after the DW provision. After defleshing, heads were coded randomly and scored blindly for carious lesions. The exchange of DW for SW was associated with highly significant reductions of 10449S recoveries (p < 0.001), but there were no differences in recoveries among the groups as a function of toothpaste type. Total mandibular and maxillary sulcal and smooth surface caries scores were statistically significantly lower for the E-NaF-treated group at 23 days than for the 23-day placebo-, E-w/o F(-)-, and conventional NaF toothpaste-treated group. Reductions were most impressive quantitatively on approximal tooth surfaces, where both the E-MFP and E-NaF groups had the lowest scores, but were also statistically significant at sulcal surfaces for the E-NaF group. Thus, this study model can be used to detect significant remineralization effects, as occurred with the prototype toothpaste E-NaF.

Administration, Topical↗
PubMed1998

Reported alcohol consumption and the serum carbohydrate-deficient transferrin test in third-year medical students.

The serum carbohydrate-deficient transferrin (CDT) test was performed on 143 third-year medical students along with questionnaires for the self-reporting of alcohol consumption during the last 2 weeks, the last 6 months, and questions on any alcohol-related untoward events. We found that the CDT test has poor sensitivity for detecting binge drinking in our population of students, despite some likely under-reporting of drinking. Self-reporting of drinking is commonly unreliable, and we found no significant correlation between the CDT concentrations in serum and the magnitude of self-reported alcohol use during 2-week and 6-month periods. Hangover was by far the commonest self-reported untoward event, and there was a highly significant relationship (P < 0.001) between drinking and untoward events. From a small population of non-drinkers, we estimated the reference ranges for CDT to be <27 U/l for men and <35 U/l for women.

Accidents↗
PubMed1998

Structure of a cephalosporin synthase.

Penicillins and cephalosporins are among the most widely used therapeutic agents. These antibiotics are produced from fermentation-derived materials as their chemical synthesis is not commercially viable. Unconventional steps in their biosynthesis are catalysed by Fe(II)-dependent oxidases/oxygenases; isopenicillin N synthase (IPNS) creates in one step the bicyclic nucleus of penicillins, and deacetoxycephalosporin C synthase (DAOCS) catalyses the expansion of the penicillin nucleus into the nucleus of cephalosporins. Both enzymes use dioxygen-derived ferryl intermediates in catalysis but, in contrast to IPNS, the ferryl form of DAOCS is produced by the oxidative splitting of a co-substrate, 2-oxoglutarate (alpha-ketoglutarate). This route of controlled ferryl formation and reaction is common to many mononuclear ferrous enzymes, which participate in a broader range of reactions than their well-characterized counterparts, the haem enzymes. Here we report the first crystal structure of a 2-oxoacid-dependent oxygenase. High-resolution structures for apo-DAOCS, the enzyme complexed with Fe(II), and with Fe(II) and 2-oxoglutarate, were obtained from merohedrally twinned crystals. Using a model based on these structures, we propose a mechanism for ferryl formation.

Cloning, Molecular↗
PubMed1998

The reverse transcriptase activity in cell-free medium of chicken embryo fibroblast cultures is not associated with a replication-competent retrovirus.

BACKGROUND: Reverse transcriptase (RT) activity has previously been reported in concentrated medium of primary chicken embryo cell cultures using the traditional RT assay. Recently, using the newly-developed and highly-sensitive product-enhanced reverse transcriptase (PERT) assay, RT activity has been detected in live, attenuated vaccines grown in chicken cell substrates. Furthermore, this activity has been associated with particles that contain RNA related to an ancient, endogenous avian retrovirus family designated as EAV-0. OBJECTIVE: To investigate whether the RT activity present in vaccines produced in specific pathogen-free chicken cell substrates is associated with an infectious retrovirus that can replicate in human cells. STUDY DESIGN: The kinetics of RT activity produced by 10-day-old chicken embryo fibroblast (CEF) cultures was determined by analyzing cell-free medium in a PCR-based RT (PBRT) assay. Material containing the peak PBRT activity was used as the inoculum to infect various human cell lines and peripheral blood mononuclear cells. Filtered supernatants from control and test cultures were analyzed for the presence of replication-competent retroviruses by the PBRT assay. The cells were monitored for other adventitious agents by routine observation for cytopathic effect (CPE) and by transmission electron microscopy (TEM) at culture termination. RESULTS: The PBRT activity did not increase above the background level in the human target cells through at least five cell passages, thus indicating the absence of a replicating retrovirus. No other adventitious agents were detected based upon TEM analysis and the absence of CPE. CONCLUSION: The RT activity produced by chicken primary cell cultures is not associated with a retrovirus that can replicate in human cells.

Animals↗
PubMed1998

Structure of the complex of Maclura pomifera agglutinin and the T-antigen disaccharide, Galbeta1,3GalNAc.

Maclura pomifera agglutinin is a tetrameric plant seed lectin with high affinity for the tumor-associated T-antigen disaccharide, Galbeta1,3GalNAcalpha, and hence for many O-linked glycopeptide structures. Unlike members of most lectin families, it lacks both metal ions and Cys residues. The structure of its complex with Galbeta1,3GalNAc was determined to 2.2 by first using multiwavelength anomalous diffraction with a lead derivative of the native protein, and then using molecular replacement with the unrefined structure as a model to solve the structure of the complex. The subunits share the beta-prism architecture and three-fold pseudo-symmetry of the related lectin jacalin, with the 21-residue beta-chains in the center of the tetramer. Interactions with the GalNAc predominate in the binding of the disaccharide. It forms a network of H-bonds with only one side chain, from an Asp residue, the amino group of the N-terminal Gly of the alpha-chain, and peptide backbone atoms of two aromatic residues. The Gal moiety does not H-bond directly with residues in the same monomer, i.e. there is no true subsite for it, but there are interactions through two water molecules. In the crystal, it interacts with residues in the binding site of an adjacent tetramer. The minimum energy conformation expected for the disaccharide is retained, despite its mediating the tetramer-tetramer interactions in the crystal packing. The resulting lattice is comparable to those seen for complexes of other lectins with branched glycopeptides.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1998

MRI of hyperpolarized 3He gas in human paranasal sinuses.

In this study, MRI of hyperpolarized 3He gas in human paranasal sinuses is presented. Helium images were obtained at 1.5 T, using a surface coil and a 2D, fast gradient-echo sequence with a nominal constant flip angle of 12 degrees. Coronal images of 20-mm thick slices were generated and compared with proton images of the corresponding sections. The images enable visualization of the paranasal sinuses and the nasal cavity, suggesting a potential use of this method not only in identifying the anatomical configuration of these pneumatic spaces, but also in assessing sinus ventilation.

Adult↗
PubMed1998

A pro-B-cell stage characterized by germline Ig transcription without surrogate light chain expression.

B-cell commitment is characterized by the expression of specific membrane proteins and the rearrangement and expression of immunoglobulin (Ig) heavy (H) and light (L) chain genes. At early stages of B-cell development, unrearranged Ig loci are transcribed, which correlates with these regions becoming accessible for Ig gene rearrangement. Some germline transcripts can be translated into protein and potentially play a role in cell signaling during B-cell development. In this report an early stage in human B-cell development is characterized using Epstein-Barr virus (EBV)-transformed cell lines from patients with a severe combined immunodeficiency (SCID). These lines were shown to produce germline constant (C) gene transcripts from the IGH and IGK loci. We demonstrate here that these cells are committed to the B-cell lineage as substantiated by expression of CD79a and CD79b. No surrogate light chain (SLC) gene transcription was detected, indicative of a very early differentiation stage. From these cell lines two types of germline IgV gene transcripts were isolated: a transcript containing the IGKV4-1 gene and a germline IGHV-1 transcript nearly identical to IGHV1/OR15-1 (HC15-1, DP-1), an orphon VH gene on chromosome 15. Germline VH transcripts originating from the VH locus on chromosome 14 could not be detected. It is of interest that, apart from Ig V and C genes (non-functional), V genes that reside outside the Ig locus are a target for the transcription factors that are postulated to initiate Ig gene rearrangement early in B-cell development.

Antigens, CD↗
PubMed1998

Sulphur isotopic investigation of a polluted raised bog and the uptake of pollutant sulphur by Sphagnum.

The sulphur content and sulphur isotopic composition of Sphagnum as well as anionic compositions and sulphur isotope ratios of rainwater inputs and bog waters have been measured at Thorne Moors, a raised bog in eastern England. Rainwater sulphate isotopic composition shows the sulphur input at this site to be dominated by anthropogenic pollution from fossil fuel burning. Strong depletion of sulphate (low SO4(2-)/Cl-) and enrichment in 34S in sulphate occurs at depth in the bog porewaters due to bacterial sulphate reduction. Some surface waters have low SO4(2-)/Cl-) and are 34S enriched due to removal of sulphate by downward diffusion into a sulphate-reducing zone. Other sites have high SO4(2-)/Cl-) which appears to result from oxidation of organically bound sulphur in the peat. Sulphur is present in Sphagnum at around 0.2% by weight and is depleted by 0 to -9 per thousand in the heavier 34S isotope compared to sulphate. Comparison with similar data from pristine coastal sites shows that sulphur incorporation into Sphagnum is enhanced in the polluted site (as Sphagnum sulphur concentrations are higher at lower total sulphur inputs) and that sulphur incorporation is accompanied by a smaller isotopic shift than in the pristine sites. The data support a model of preferential incorporation of partially reduced sulphur species (probably HSO3-) into Sphagnum. In pristine sites these are only available as oxidation products of sulphide formed by sulphate reduction and are 32S depleted. In polluted sites this source is augmented by sulphur(IV) species in atmospheric inputs and the resultant mixture is less depleted in 32S. Thus, in the polluted sites more HSO3- is available for uptake and the isotopic shift between Sphagnum and aqueous sulphur species is smaller.

Journal Article↗
PubMed1998

Comparison of ultrasound measurements at the heel between adults with mental retardation and control subjects.

Little is known about the prevalence of metabolic bone disease among adults with mental retardation (now known as learning disability), although they may be at increased risk of fractures. Broadband-ultrasound attenuation (BUA) and velocity-of-sound (VOS) measurements were performed on the left heel of 170 patients in a large hospital for adults with mental retardation. For 108 of these patients, age- and gender-matched control subjects were recruited from the local community, who also underwent BUA and VOS measurements. The mean age of matched pairs of patients and control subjects was 54 (range 32-83) years for men and 53 (range 27-82) years for women. Mean +/- SEM BUA for male patients was 52 +/- 4 dB/MHz and 89 +/- 2 for control subjects, whereas for female patients it was 34 +/- 3 dB/MHz and 68 +/- 2 for control subjects. VOS was 1603 +/- 7 m/sec for male patients and 1649 +/- 5 for control subjects, and 1573 +/- 7 m/sec for female patients and 1623 +/- 5 for control subjects. All differences between patients and control subjects were significant (p < 0.005). Dual-energy X-ray absorptiometry bone mineral density (BMD) measurements were also performed in seven patients with BUA less than 50 dB/MHz, four of whom were found to have a lumbar spine or femoral neck BMD more than 2.5 SD below the mean value for young adults. This study shows that patients with mental retardation have a marked reduction in BUA and VOS measurements at the heel, compared with age-matched control subjects. There is a need to identify the major causes of low bone mass in this group, as there may be potentially avoidable risk factors for osteoporosis, such as vitamin D deficiency and hypogonadism.

Absorptiometry, Photon↗
PubMed1998

31P-nuclear magnetic resonance studies of bioenergetic changes in skeletal muscle in malnourished human adults.

In previous studies, both animals and malnourished children receiving 25% of the protein-energy intake of a control group, resulting in a 25% weight loss, had lower ratios of phosphocreatine to beta-ATP and of phosphocreatine to inorganic phosphorus, higher free ADP concentrations, and lower free energy of ATP hydrolysis than the control group. Therefore, the effect of malnutrition on muscle energetics in adult humans was examined by using 31P-nuclear magnetic resonance spectroscopy in malnourished patients with a mean body mass index (BMI; in kg/m2) of 16.4 compared with healthy control subjects with a significantly higher body mass index of 24.5 (P < 0.005). The mean (+/- SEM) ratio of phosphocreatine (PCr) to ATP in the malnourished patients was 2.28 +/- 0.27, which was significantly lower than the ratio of 3.1 +/- 0.15 in control subjects (P < 0.02). The ratio of inorganic phosphorus (Pi) to ATP in malnourished patients was 0.33 +/- 0.04, which was significantly lower than the ratio of 0.48 +/- 0.03 in control subjects (P < 0.02), but the ratio of PCr to Pi was not significantly different from that in control subjects. There was a significant correlation between BMI and the ratio of PCr to ATP (P < 0.01) and of Pi to ATP (P < 0.01). These data suggest that progressive loss of BMI is associated with a relative loss of muscle creatine and phosphorus in relation to ATP. The findings were unlikely to have been due only to atrophy of fast-twitch fibers because such atrophy would have altered the ratio of PCr to Pi.

Adult↗
PubMed1998

Investigation of acidic fibroblast growth factor delivered through a collagen scaffold for the treatment of full-thickness skin defects in a rabbit model.

In this study the wound healing response of full-thickness skin defects was enhanced through the use of acidic fibroblast growth factor using a collagen scaffold. The objectives of this study were (1) to compare the facilitatory effects of acidic fibroblast growth factor on the cellular response (fibroblast, neutrophil, macrophage, epithelial), tissue response (angiogenesis, collagen) and mechanical properties in a healing wound; and (2) to determine the effect of a collagen scaffold on wound healing when compared with the control. Three 3 x 3 cm full-thickness defects were created on the dorsi of 15 New Zealand White rabbits. Each rabbit had a control (no treatment), collagen scaffold, and collagen scaffold with FGF-1 (100 microg/cm2). All the wounds were covered with a transparent polyurethane dressing. There were three periods of study (1, 2, and 3 weeks) with five rabbits in each period. The volume fraction of the tissue and cells was histomorphometrically determined for each wound. The acidic fibroblast growth factor/collagen system showed promise in enhancing the healing process. Acidic fibroblast growth factor/collagen treatment increased angiogenesis, enhanced epithelialization, and reduced contraction rate over the control. A higher inflammatory response was indicated in the collagen scaffold treated group. Hence acidic fibroblast growth factor delivered through a collagen scaffold shows promise in future clinical applications.

Analysis of Variance↗