Search PubMed⌕ Search

Biomedical subjects

T Peters

Publications and source records attributed to T Peters.

At least 73 records · Page 4Linked to original sources
PubMed1999

Anxiety among women with mild dyskaryosis: a randomized trial of an educational intervention.

BACKGROUND: Women with mild dyskaryosis are currently managed by six-month cytological surveillance. While there is good evidence that women suffer psychological distress on receipt of an abnormal test, and that this is amenable to educational intervention, it remains uncertain whether this distress is prolonged and, if so, how it should best be managed. AIM: To investigate whether a structured educational intervention containing a risk communication package impacts upon psychological sequelae associated with this surveillance. METHOD: A pragmatic cluster-randomized controlled trial during 14 months in 1995 and 1996, based in general practices in Avon and South Glamorgan, that compared the intervention with standard care. Follow-up was by postal questionnaire at six weeks and four months after the screening laboratory had reported the test result. The intervention was an invitation to attend the general practice to consult with a practice nurse trained to deliver the package. The main outcome measures were Spielberger state-anxiety, SF-36 Mental Health dimension, four condition-specific questions regarding concerns about gynaecological health and timing of the repeat smear test, and attendance for the repeat test. RESULTS: Of 514 eligible women, 270 were recruited, of whom 240 returned the six-week questionnaire and 181 returned the four-month questionnaire. On all but one outcome measure, the differences between the groups were not statistically significant. At six-week follow-up, the proportion who preferred the repeat test to be sooner than six months was statistically significantly higher among controls (74% versus 53%; 95% CI = 9% to 33%). At the four-month follow-up, the difference was 7% (95% CI = -7% to 21%). CONCLUSION: There appear to be high levels of anxiety during surveillance for mild dyskaryosis that were not reduced by the intervention. Given that a personally delivered educational intervention designed to reduce anxiety could be viewed as the best available practice, it is of concern that women in the intervention group demonstrated sustained anxiety over a four-month period. The research agenda therefore seems to return to the fundamental question of whether surveillance should be the management of choice.

Adult↗
PubMed1998

A clinical and virological study of hepatitis C virus-related cryoglobulinemia in Germany.

BACKGROUND/AIMS: Several reports, especially from Southern Europe, have demonstrated a close association between hepatitis C virus (HCV) infection and mixed cryoglobulinemia. In this study we have analyzed the significance of HCV-related cryoglobulinemia in Germany. METHODS: Sera from 79 patients with cryoglobulinemia of type I (n=21), II (n=28) or III (n=30) were investigated for HCV markers. Furthermore, 132 consecutive patients with chronic hepatitis C were studied for the presence of cryoglobulins. Genotypes of HCV were determined according to Simmonds, and HCV-RNA concentrations were measured in patients with and without cryoglobulinemia. RESULTS: In 79 patients with cryoglobulinemia we found anti-HCV antibodies in 17 (22%) and HCV-RNA in 11 patients (14%). HCV antibodies were more frequent in essential (44%) compared to secondary mixed cryoglobulinemia (15%). In 132 patients with chronic HCV infection cryoglobulins were detected in 37 patients (28%), in 21 of them at low levels. Clinical symptoms due to cryoglobulinemia were observed in eight of the 37 patients, severe vasculitis in three patients with high cryocrit-levels and cryoprecipitation at room temperature. HCV genotype 1 and subtype 1b were most prevalent, both in patients with and without cryoglobulinemia, and mean HCV-RNA levels were not different between the two groups. Comparison of HCV-RNA levels in cryoprecipitates, supernatant and native serum suggests binding of HCV-RNA to the cryoprecipitate with different affinity in individual patients. CONCLUSIONS: The lower prevalence of HCV-related cryoglobulinemia in our study compared with data from Italy and France suggests a south-north gradient in the prevalence of HCV-associated cryoglobulinemia in Europe.

Adult↗
PubMed1998

Natural defenses and autoprotection: naturotherapy, an old concept of healing in a new perspective.

Recent molecular-biological and molecular-genetic research has shown that important cellular-based autoprotective mechanisms are mediated by heat-shock proteins (HSPs) or stress-response proteins, also called 'chaperones'. This can happen because cells react to extracellular stimuli by activating signal transduction pathways which result in activating the genetic program. Molecular biologists and cardiologists are tempted to evaluate these phenomena in respect to their potential meaning for a better understanding of the complex notions of health and disease. When molecular geneticists or cardiologists talk about autoprotective or natural defense mechanisms, and physicians talk about salutogenesis, they all mean something very specific. The phenomenon seen here belongs to the body's own defense mechanisms which make it capable of reacting to harmful influences and allow it to stabilize a structure and/or function of the body for a certain period. Here we see a connecting link to the historically grounded term self-healing forces, which has challenged medical doctors in the different historical periods of medical science. They tried to explain these effects based on the current model of the organism. Their understanding of this phenomenon played a role in defining the concept of health and disease. Thus, it seems very fitting to look back into history, since the phenomena discussed here as well as the insights into autoprotective mechanisms will continue to influence medical understanding of health and disease.

Animals↗
PubMed1998

Mechanisms of autoprotection and the role of stress-proteins in natural defenses, autoprotection, and salutogenesis.

We hypothesize that in all physiotherapeutically oriented procedures of naturotherapy -- such as helio-, climate-, thalasso- or hydrotherapy or certain forms of physical exercise -- the transient expression of stress-proteins (heat-shock proteins, HSPs) is an important element of salutogenesis. These therapeutical procedures all cause a transitory 'disturbance' by an unspecific stressor that leads to functional responses. These functional responses can be trained and thus increase the forces and the capacity for resistance of the organism. The autoprotective mechanisms which we want to deal with in more detail are based on the functions of the heat-shock proteins (HSPs, stress-response proteins, 'chaperones') and represent archaic autoprotective responses. In addition, more complex mechanisms of autoprotection seem to have evolved that may play a role in the natural defenses against disease and which show a hierarchy of various genomically conserved strategies with different time-constants and time windows. This becomes apparent by studying autoprotective responses of the cardiovascular system of warm-blooded animals under ischemic stress. Recent extensive experimental protocols and clinical observations in elucidating the molecular basis of cardiac ischemia show that powerful autoprotective mechanisms are involved in the phenomena of 'hibernation', 'stunning', and 'ischemic preconditioning'. The system of the heat-shock proteins may therefore be regarded as a basic model for the principle of autoprotection and salutogenesis.

Animals↗
PubMed1998

Conformational analysis of a Chlamydia-specific disaccharide alpha-Kdo-(2-->8)-alpha-Kdo-(2-->O)-allyl in aqueous solution and bound to a monoclonal antibody: observation of intermolecular transfer NOEs.

The disaccharide alpha-Kdo-(2-->8)-alpha-Kdo (Kdo: 3-deoxy-D-manno-oct-2-ulosonic acid) represents a genus-specific epitope of the lipopolysaccharide of the obligate intracellular human pathogen Chlamydia. The conformation of the synthetically derived disaccharide alpha-Kdo-(2-->8)-alpha-Kdo-(2-->O)-allyl was studied in aqueous solution, and complexed to a monoclonal antibody S25-2. Various NMR experiments based on the detection of NOEs (or transfer NOEs) and ROEs (or transfer ROEs) were performed. A major problem was the extensive overlap of almost all 1H NMR signals of alpha-Kdo-(2-->8)-alpha-Kdo-(2-->O)-allyl. To overcome this difficulty, HMQC-NOESY and HMQC-trNOESY experiments were employed. Spin diffusion effects were identified using trROESY experiments, QUIET-trNOESY experiments and MINSY experiments. It was found that protein protons contribute to the observed spin diffusion effects. At 800 MHz, intermolecular trNOEs were observed between ligand protons and aromatic protons in the antibody binding site. From NMR experiments and Metropolis Monte Carlo simulations, it was concluded that alpha-Kdo-(2-->8)-alpha-Kdo-(2-->O)-allyl in aqueous solution exists as a complex conformational mixture. Upon binding to the monoclonal antibody S25-2, only a limited range of conformations is available to alpha-Kdo-(2-->8)-alpha-Kdo-(2-->O)-allyl. These possible bound conformations were derived from a distance geometry analysis using transfer NOEs as experimental constraints. It is clear that a conformation is selected which lies within a part of the conformational space that is highly populated in solution. This conformational space also includes the conformation found in the crystal structure. Our results provide a basis for modeling studies of the antibody-disaccharide complex.

Antibodies, Monoclonal↗
PubMed1998

Dose-dependent reduction of cerebral blood flow during rapid-rate transcranial magnetic stimulation of the human sensorimotor cortex.

Rapid-rate transcranial magnetic stimulation (rTMS) was used to stimulate the primary sensorimotor cortex in six healthy volunteers while regional changes in cerebral blood flow (CBF) were simultaneously measured by means of positron emission tomography. A figure-eight TMS coil (Cadwell Corticoil) was positioned, using frameless stereotaxy, over the probabilistic location of the left primary sensorimotor cortex, and a series of brief 10-Hz trains of TMS was delivered at subthreshold intensity during each of six 60-s scans. The scans differed in the number of trains delivered, namely 5, 10, 15, 20, 25, and 30 trains/scan, respectively. In the left primary sensorimotor cortex, CBF covaried significantly and negatively with the number of stimulus trains. These CBF decreases may reflect TMS-induced activation of local inhibitory mechanisms known to play a role in TMS-related phenomena, such as the electromyographic silent period.

Adult↗
PubMed1998

Can we trust the quality of routine hospital outpatient information in the UK? Validating outpatient data from the patient administration system (PAS).

BACKGROUND: A validation study of routine hospital outpatient data was carried out as part of a broader project focusing on outpatient re-attendance. The aim was to compare two patient administration system (PAS) data items with the same information collected directly from hospital clinicians. METHODS: A total of 140 cases from four specialties at four National Health Service hospitals was randomly selected for comparison. The specific data items compared were the grade of doctor seen and the management decision taken following an outpatient appointment. The proportion of cases in which there was agreement was calculated, together with kappa values and relevant statistics indicating the accuracy of the PAS data when compared with information compiled immediately after the consultation by the relevant clinician. RESULTS: There was agreement between the clinician's data and the PAS data in 118/140 (84.3%) cases for grade of doctor seen and in 105/139 (76.7%) cases for the management decision. There was complete agreement for both items in 88/139 (62.6%) cases. Kappa values indicated good agreement between the two data sources. However, 'sensitivity' statistics suggested that the likely accuracy of each data item varied. CONCLUSION: Although there was good agreement within individual categories between the two sources, 37% of patient computerised records held at least one inconsistency in this small study focusing on only two data items. Further systematic evaluation is needed to test the extent to which other items are similarly discrepant.

Data Collection↗
PubMed1998

Occurrence and management of hepatitis B virus reactivation following kidney transplantation.

A 28-year-old woman was kidney transplanted. She had an inapparent hepatitis B virus (HBV) infection 2 years previously. At the time of transplantation she was hepatitis B surface antigen (HBsAg) negative, anti-HBs, anti-HBc, anti-HBe and anti-HCV antibody positive and her transaminase activities were within the normal range. The donor of the kidney allograft was HBV negative. Twelve weeks after transplantation a life-threatening liver failure occurred with a rapid rise of alanine aminotransferase (ALT) to 1427 U/l and a decrease of the prothrombin time to 25% of normal value. Anti-HBs had become negative, anti-HBc and anti-HBe titers had decreased. HBsAg became positive, associated with a HBV DNA of 3 x 10(8) genome equivalents/ml. Azathioprine and prednisone were withdrawn and foscarnet therapy was started. This therapy led to a decrease of ALT activity associated with an elimination of HBsAg and HBV DNA. Eight months after transplantation liver function tests were within the normal range. Graft rejection did not occur despite low or intermittent cessation of immunosuppressive therapy.

Adult↗
PubMed1997

Mass spectrometric determination of HCO3- permeability and carbonic anhydrase activity in intact guinea-pig colon epithelium.

1. A mass spectrometric method originally used in red blood cells was applied to suspensions of isolated colonocytes and intact colonic epithelium to measure the exchange of 18O between HCO3-, CO2 and H2O to determine intracellular carbonic anhydrase activity (Ai) and membrane bicarbonate permeability (P). 2. In suspensions of isolated guinea-pig colon epithelial cells, colonocytes, we found significantly higher values of Ai and P for cells derived from the proximal colon than for cells from the distal colon. In the case of Ai, this confirms earlier reports. 3. When the 18O exchange process was observed across the mucosal (apical) side of intact colon mucosa, the estimated values of Ai were identical to those obtained for isolated colonocytes, for both the proximal and the distal part of the colon. This is considered to be strong evidence that this method can be applied to a layer of intact epithelium as well as to cell suspensions. 4. The values of P obtained from the apical side of intact colon mucosa were 6 times higher than those estimated from measurements with isolated colonocytes. This indicates that the basolateral membrane of colon epithelium, which participates in the 18O exchange process in isolated colonocytes but not in the 18O exchange process across the apical side of intact mucosa, has a markedly lower bicarbonate permeability than the apical membrane. 5. When the 18O exchange process was observed across the serosal (basolateral) side of intact colon mucosa, the P values, as expected, were low compared with the apical side of intact mucosa. However, rather unexpectedly, the Ai values derived from these measurements were 2-3 times lower than those obtained with isolated colonocytes. It appears possible that the latter finding is an artifact due to the submucosal tissue markedly slowing down CO2 diffusion from the bathing medium into the epithelial cells, thus causing an apparent fall in Ai. 6. Ai decreased and P increased with increasing temperature, as expected, when studied on the mucosal side of intact colon. This provides additional support for the validity of the method.

Animals↗
PubMed1997

Screening mixtures for biological activity by NMR.

Development of the new drugs often involves the screening of compound libraries for biological activity. Currently, the biologically active component can only be identified if either a pure compound is being tested or if the components of a mixture are spatially separated, for example, on beads. Here, we present an NMR technique based on the transferred nuclear Overhauser effect (transfer NOE) that allows identification and structural characterization of biologically active molecules from a mixture. As an example we demonstrate that from mixtures of oligosaccharides only alpha-L-Fuc-(1-->6)-beta-D-GlcNAc-OMe binds to Aleuria aurantia agglutinin. The sign of transferred NOEs is opposite to NOEs of small molecules that do not bind to the protein and, thus, an unequivocal identification of molecules with binding activity is possible. Normally, the selection of bound ligands is further facilitated in that the absolute intensity of transfer NOEs is much greater than that of NOEs of non-binding molecules. In addition, transfer NOEs provide information on the three-dimensional structure of the ligands in the bound state. Therefore, measuring transfer NOEs of mixtures of small molecules in the presence of large molecules, like proteins, should significantly enhance the options for screening mixtures of compounds for biological activity.

Basidiomycota↗
PubMed1997

Transcranial magnetic stimulation during positron emission tomography: a new method for studying connectivity of the human cerebral cortex.

We describe a new technique permitting the mapping of neural connections in the living human brain. The method combines two well established tools of brain research: transcranial magnetic stimulation (TMS) and positron emission tomography (PET). We use TMS to stimulate directly a selected cortical area while simultaneously measuring changes in brain activity, indexed by cerebral blood flow (CBF), with PET. The exact location of the stimulation site is achieved by means of frameless stereotaxy. In the first study using this technique, we found significant positive correlations between CBF and the number of TMS pulse trains at the stimulation site, namely the left frontal eye field (FEF) and, most importantly, in the visual cortex of the superior parietal and medial parieto-occipital regions. The pattern of these distal effects was consistent with the known anatomic connectivity of the monkey FEF. We suggest that the combined TMS/PET technique offers an objective tool for assessing the state of functional connectivity without requiring the subject to engage in any specific behavior.

Adult↗
PubMed1997

Transferred nuclear Overhauser enhancement (NOE) and rotating-frame NOE experiments reflect the size of the bound segment of the Forssman pentasaccharide in the binding site of Dolichos biflorus lectin.

A complex between the Forssman pentasaccharide alpha-D-GalNAc-(1-->3)-beta-D-GalNAc-(1-->3)-alpha-D-Gal-(1-->4)-beta-D- Gal-(1-->4)-D-Glc and the seed lectin from Dolichos biflorus was studied using transfer-NOESY and transfer rotating frame NOE spectroscopy (ROESY) experiments. The evolution of transferred NOEs and ROEs as a function of the pentasaccharide/lectin ratio was different for the non-reducing disaccharide moiety alpha-D-GalNAc-(1-->3)-beta-D-GalNac compared to the rest of the molecule, which reflects distinct relaxation properties and effects of exchange broadening of the corresponding ligand resonances. Significantly, several intermolecular transferred NOEs were observed between protons of the nonreducing disaccharide moiety alpha-D-GalNAc-(1-->3)-beta-D-GalNAc and aliphatic as well as aromatic amino acid side chain protons in the binding pocket of the lectin. It is concluded that the non-reducing disaccharide fragment is buried in the lectin-binding pocket, whereas the reducing trisaccharide portion alpha-D-Gal-(1-->4)-beta-D-Gal-(1-->4)-D-Glc has no immediate contacts with the protein. The experimental transfer NOE data were qualitatively compared to theoretical proton-proton distances from a model that was based on a previous homology modeling study of a complex between the disaccharide fragment alpha-D-GalNAc-(1-->3)-beta-D-GalNAc and D. biflorus lectin. It was found that all intermolecular transferred NOEs matched short interatomic distances between ligand protons and aliphatic or aromatic amino acid side chain protons predicted by the theoretical model.

Binding Sites↗
PubMed1997

Serum and urine albumin: a progress report on their measurement and clinical significance.

For about 25 years, bromcresol green and bromcresol purple have been the basis for most of the measurements of serum albumin in the US and perhaps in the world. The longevity of the methods is due to their being simple, sensitive, specific, inexpensive and relatively free from interferences. The lack of change in the serum albumin methodology is balanced by two important developments. First, the recognition of the importance of serum albumin in the maintenance of good health, and the association of decreased concentrations with increased risk of morbidity and mortality. Second, the association of albuminuria with diabetic nephropathy, which without medical intervention could lead to end-stage renal disease. The development of accurate and precise methods for urinary albumin has provided a tool to physicians to extend the length and improve the quality of life of many diabetic individuals.

Albuminuria↗
PubMed1997

Coronary artery and saphenous vein graft remodeling: a review of histologic findings after various interventional procedures--Part V.

Catheter balloon angioplasty is a well accepted form of nonsurgical treatment of acutely and chronically obstructed coronary artery vessels. It is also the centerpiece for various new intervention techniques. Their morphologic effect on the site of obstruction has been termed "remodeling." Part V of this six-part series focuses on remodeling effects of balloon angioplasty on obstructed young (< or = 1 year) and old (> 1 year) saphenous vein bypass grafts.

Angioplasty, Balloon, Coronary↗