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Biomedical subjects

M Persson

Publications and source records attributed to M Persson.

At least 37 records · Page 2Linked to original sources
PubMed2003

Antiseptic wound ventilation with a gas diffuser: a new intraoperative method to prevent surgical wound infection?

Postoperative wound infections are often a result of peri-operative contamination by Staphylococcus aureus. With a new insufflation device, a gas diffuser, it has become possible to establish a local micro-environment of almost 100% carbon dioxide in an open surgical wound. The device enables ventilation of the wound with an antiseptic agent, which in gaseous form can be delivered as a low uniform dose to all parts of the wound. The use of carbon dioxide (CO2) as a carrier gas eliminates possible inflammability of an antiseptic agent and helps to concentrate it to the site of interest by gravity. Using the above delivery system we have demonstrated the antibacterial effect of gaseous ethanol on S. aureus inoculated on sterile filter disks and blood agar plates, respectively. Ethanol is a very potent antiseptic agent with known properties, which makes it suitable for testing the maximal decontamination level. On filter disks, CO2 carrying vapour from a 95% ethanol solution decreased the number of colony-forming units after 5 min of exposure (P=0.04), and killed all bacteria within 10-15 min (P<0.001). In the presence of organic material, i.e. on exposed blood agar plates, the colony size decreased with exposure time, and no colonies were detected after 60 min of exposure (P<0.001). Antiseptic gas derived from 70% ethanol solution was less effective than that from 95% ethanol (P<0.001). CO2 humidified with water did not have a significant effect on number or size of the colonies. Our findings suggest that intraoperative wound antisepsis with a gas mixture of CO2 and an antiseptic agent delivered with a gas diffuser, may be a simple method to reduce the risk of postoperative wound infection.

Administration, Cutaneous↗
PubMed2003

Actinobacillus pleuropneumoniae in Thai pig herds. Prevalence of serum antibodies and relation to performance.

The aim of the study was to investigate the prevalence of Actinobacillus pleuropneumoniae infections in market weight pigs in Thailand. ELISA systems employing purified lipopolysaccharide antigens were used to detect antibodies in 549 serum samples collected from pigs of 22 herds. Relevant cut-off values were established from three herds defined seronegative. Serum antibodies were detected to all serotypes except serotype 10. Almost 60% of the samples were seropositive to at least one serotype and 45% of the pigs were seropositive to more than one serotype. Antibodies to the cross-reacting serotypes 1, 9 or 11 were found in 29% of the pigs. Other common serotypes included the cross-reacting serotypes 3, 6 or 8 (26% seropositive pigs) and serotype 5a (also 26%). Antibodies to serotypes 2, 5b and 12 were low in prevalence (<10%). Three herds were regarded to be seronegative and six to have a low pathogen load with respect to the prevalence of seropositive pigs. The remaining 13 herds had a high incidence of pigs with antibodies to A. pleuropneumoniae, dominated by serotypes 1-9-11 and 5a (n = 6), serotypes 3-6-8, and 5a (n = 4) or 1-9-11, 3-6-8, 5a and 4-7 (n = 3). A low pathogen load with respect to A. pleuropneumoniae, as well as small herd size and age-segregated rearing, tended to improve the performance of growers.

Actinobacillus Infections↗
PubMed2002

Energy loss of atoms at metal surfaces due to electron-hole pair excitations: first-principles theory of "chemicurrents".

A method is presented for calculating electron-hole pair excitation due to an incident atom or molecule interacting with a metal surface. Energy loss is described using an ab initio approach that obtains a position-dependent friction coefficient for an adsorbate moving near a metal surface from a total energy pseudopotential calculation. A semiclassical forced oscillator model is constructed to describe excitation of the electron gas due to the incident molecule. This approach is applied to H and D atoms incident on a Cu(111) surface, and we obtain theoretical estimates of the "chemicurrents" measured by Nienhaus et al. [Phys. Rev. Lett. 82, 446 (1999)] for these atoms incident on the surface of a Schottky diode.

Journal Article↗
PubMed2002

Arterial pulse wave velocity with tissue Doppler imaging.

This paper describes a new noninvasive ultrasonic method for estimating pulse wave velocity (PWV), an important physical parameter for characterizing the elastic properties of the arterial walls. The method utilizes a relatively new color Doppler modality for measuring tissue motion (tissue Doppler imaging or TDI). In contrast to previously proposed methods, the TDI modality offers multiple recording sites along the artery that improve the PWV estimation considerably. The new PWV estimation method was evaluated through an in vitro setup consisting of an elastic vessel supplied with a pulsatile pump. The study concentrated on the effect of different system parameters controlling resolution, sensitivity and the amount of acquired data. It was shown that the system parameters have a significant effect on the PWV variance, whereas the PWV mean remains unchanged. It was also established that high temporal resolution is the most vital parameter for minimizing PWV variance. Finally, the new PWV estimation method was applied to a limited set of human carotid artery data sets, with good results.

Arteries↗
PubMed2002

The reproducibility of a new dietary record routine in geriatric patients.

BACKGROUND AND AIM: Malnutrition in nursing home residents is an important clinical and public health problem. Knowledge is lacking about the reproducibility of dietary recording in geriatric patients. Few studies have described water intake in this age group. The aim of this study was to test the reproducibility of a 7-day dietary record routine in a clinical setting. METHODS: The dietary intake of 81 geriatric patients was recorded for two discrete periods of 7 consecutive days by the ward staff. The dietary record routine, which assessed both food and fluid intake, was based on standardized portion sizes and household measurements. RESULTS: The mean daily energy intake during the first period was 7.07 MJ and 6.84 MJ during the second period, with a mean difference of 4%. Corresponding values and the mean difference for water intake from food and beverages were 1781 g, 1702 g and 4% respectively. Age, gender, diagnosis, length of stay, diets or ADL function did not influence the results. The correlation coefficient for fluid intake between the periods was 0.84 for women and 0.72 for men. CONCLUSION: The 7-day dietary record routine seems to have a good reproducibility in assessing the intake of energy and fluids in geriatric patients.

Aged↗
PubMed2001

[Toxicologic information center's hotline--well-received and cost-effective for the society].

Our evaluation using postal and interview surveys suggests that the telephone hotline service at the Swedish Poisons Information Centre ('Giftinformationscentralen') may be cost-effective for society. Advice to physicians--which was highly regarded for its speed, competence and applicability--was time-saving and facilitated better treatment. Similarly, advice direct to households eliminated many unnecessary emergency visits. Indeed, we found that the annual costs of running the centre can be completely offset by savings in health care resources. Improved outcomes, time savings for individual households, and reduced uncertainty for both households and health care staff provide additional benefits.

Attitude of Health Personnel↗
PubMed2001

Groucho-mediated transcriptional repression establishes progenitor cell pattern and neuronal fate in the ventral neural tube.

The pattern of neuronal specification in the ventral neural tube is controlled by homeodomain transcription factors expressed by neural progenitor cells, but no general logic has emerged to explain how these proteins determine neuronal fate. We show that most of these homeodomain proteins possess a conserved eh1 motif that mediates the recruitment of Gro/TLE corepressors. The eh1 motif underlies the function of these proteins as repressors during neural patterning in vivo. Inhibition of Gro/TLE-mediated repression in vivo results in a deregulation of cell pattern in the neural tube. These results imply that the pattern of neurogenesis in the neural tube is achieved through the spatially controlled repression of transcriptional repressors-a derepression strategy of neuronal fate specification.

Amino Acid Sequence↗
PubMed2001

Symmetry selection rules for vibrationally inelastic tunneling.

A combined experimental and theoretical study is presented for the C-D stretch mode excitation of acetylene isotopes, C2HD and C2D2, on Cu(100) via inelastic electron tunneling (IET) in a scanning tunneling microscope junction. The calculated IET images using density functional theory show that the measured signal from C2D2 derives from the antisymmetric stretch mode. Selection rules are derived and involve the constraint imposed by the IET image on the symmetry characters of the vibrational mode and the adsorbate-induced electron states at the Fermi level.

Journal Article↗
PubMed2001

Protein compactness measured by fluorescence resonance energy transfer. Human carbonic anhydrase ii is considerably expanded by the interaction of GroEL.

Nine single-cysteine mutants were labeled with 5-(2-iodoacetylaminoethylamino)naphthalene-1-sulfonic acid, an efficient acceptor of Trp fluorescence in fluorescence resonance energy transfer. The ratio between the fluorescence intensity of the 5-(2-acetylaminoethylamino)naphthalene-1-sulfonic acid (AEDANS) moiety excited at 295 nm (Trp absorption) and 350 nm (direct AEDANS absorption) was used to estimate the average distances between the seven Trp residues in human carbonic anhydrase II (HCA II) and the AEDANS label. Guanidine HCl denaturation of the HCA II variants was also performed to obtain a curve that reflected the compactness of the protein at various stages of the unfolding, which could serve as a scale of the expansion of the protein. This approach was developed in this study and was used to estimate the compactness of HCA II during heat denaturation and interaction with GroEL. It was shown that thermally induced unfolding of HCA II proceeded only to the molten globule state. Reaching this state was sufficient to allow HCA II to bind to GroEL, and the volume of the molten globule intermediate increased approximately 2.2-fold compared with that of the native state. GroEL-bound HCA II expands to a volume three to four times that of the native state (to approximately 117,000 A(3)), which correlates well with a stretched and loosened-up HCA II molecule in an enlarged GroEL cavity. Recently, we found that HCA II binding causes such an inflation of the GroEL molecule, and this probably represents the mechanism by which GroEL actively stretches its protein substrates apart (Hammarström, P., Persson, M., Owenius, R., Lindgren, M., and Carlsson, U. (2000) J. Biol. Chem. 275, 22832-22838), thereby facilitating rearrangement of misfolded structure.

Amino Acid Sequence↗
PubMed2001

Comparison of electron paramagnetic resonance methods to determine distances between spin labels on human carbonic anhydrase II.

Four doubly spin-labeled variants of human carbonic anhydrase II and corresponding singly labeled variants were prepared by site-directed spin labeling. The distances between the spin labels were obtained from continuous-wave electron paramagnetic resonance spectra by analysis of the relative intensity of the half-field transition, Fourier deconvolution of line-shape broadening, and computer simulation of line-shape changes. Distances also were determined by four-pulse double electron-electron resonance. For each variant, at least two methods were applicable and reasonable agreement between methods was obtained. Distances ranged from 7 to 24 A. The doubly spin-labeled samples contained some singly labeled protein due to incomplete labeling. The sensitivity of each of the distance determination methods to the non-interacting component was compared.

Carbonic Anhydrases↗
PubMed2001

Total variation norm for three-dimensional iterative reconstruction in limited view angle tomography.

An iterative Bayesian reconstruction algorithm for limited view angle tomography, or ectomography, based on the three-dimensional total variation (TV) norm has been developed. The TV norm has been described in the literature as a method for reducing noise in two-dimensional images while preserving edges, without introducing ringing or edge artefacts. It has also been proposed as a 2D regularization function in Bayesian reconstruction, implemented in an expectation maximization algorithm (TV-EM). The TV-EM was developed for 2D single photon emission computed tomography imaging, and the algorithm is capable of smoothing noise while maintaining edges without introducing artefacts. The TV norm was extended from 2D to 3D and incorporated into an ordered subsets expectation maximization algorithm for limited view angle geometry. The algorithm, called TV3D-EM, was evaluated using a modelled point spread function and digital phantoms. Reconstructed images were compared with those reconstructed with the 2D filtered backprojection algorithm currently used in ectomography. Results show a substantial reduction in artefacts related to the limited view angle geometry, and noise levels were also improved. Perhaps most important, depth resolution was improved by at least 45%. In conclusion, the proposed algorithm has been shown to improve the perceived image quality.

Algorithms↗
PubMed2001

Long-term stability of dental arch form in normal occlusion from 13 to 31 years of age.

Based on observations of longitudinal changes in dental arch dimensions, it has been stated that an individuality of arch form and an integrity of this form exists. However, longitudinal studies evaluating arch form changes have rarely been reported in the literature. The purpose of this investigation was to use a computer-assisted method for the description and analysis of maxillary and mandibular arch form in a sample of normal occlusion subjects, and to evaluate the long-term stability in dental arch form from the age of 13-31 years. The study was carried out on 30 subjects of Scandinavian origin with normal occlusion, recorded at a mean age of 13.6 years and at follow-up at 31.1 years. Arch form analysis was based on a standardized photographic procedure, digitization of morphological landmarks, and a computerized form analysis in which arch form was described using eccentricity values of conics. No specific arch form could be found to represent the sample. Age changes occurred in arch form, although with large individual variations. For the mandible, a significant change to a more rounded arch form with age was found, which in males was accompanied by a significant increase in inter-molar distance and reduction in arch depth. There was also a significant correlation between change in mandibular arch form and increased irregularity of the lower incisors. These findings of lack of stability in arch form in normal occlusion subjects, when passing from adolescence into adulthood, further question the possibility of achieving stability post-orthodontically.

Adolescent↗
PubMed2001

Orthodontic side-effects of mandibular advancement devices during treatment of snoring and sleep apnoea.

The aims of this study were to investigate possible orthodontic side-effects following the use of mandibular advancement devices (MAD) in adults with snoring and sleep apnoea. A second objective was to analyse the effect of the appliance design. Seventy-five patients treated with MAD and 17 reference patients were studied at follow-up after 2.5 +/- 0.5 years. In the test group, 47 patients were provided with soft elastomeric devices, while the remaining 28 patients received hard acrylic devices. The treatment induced a change in overjet of -0.4 +/- 0.8 mm (mean +/- SD) and a change in overbite of -0.4 +/- 0.7 mm (mean +/- SD). These changes were larger than those found in the reference group (P < 0.01). The odds ratio (OR) for the largest quartile of reduction in overjet was 3.8 in patients using hard acrylic devices compared with those using soft elastomeric devices (P < 0.05). A large reduction in overjet in patients using the hard acrylic devices was unrelated to the degree of mandibular protrusion by the device. The OR for a large reduction in overjet in patients using the soft elastomeric devices with a protrusion of 6 mm or above was 6.8 compared with smaller mandibular protrusions (P < 0.05). The results indicate that the orthodontic side-effects are small during the treatment of adult subjects with MAD for snoring and sleep apnoea, especially in patients using soft elastomeric devices with mandibular protrusions of less than 6 mm. The follow-up of patients treated with MAD is recommended, as individual patients may experience marked orthodontic side-effects.

Acrylic Resins↗
PubMed2001

Mandibular advancement device in patients with obstructive sleep apnea : long-term effects on apnea and sleep.

STUDY OBJECTIVES: To evaluate the long-term effects on apneas and sleep and the tolerability of a mandibular advancement device in patients with obstructive sleep apnea. DESIGN: Prospective study. SETTING: Department of Respiratory Medicine, University Hospital, Umeå, Sweden. PATIENTS: Thirty-three consecutively treated patients. INTERVENTIONS: Individually adjusted mandibular advancement devices. MEASUREMENTS AND RESULTS: Polysomnographic sleep recordings on 1 night without the device and 1 night with the device were performed after 0.7 +/- 0.5 years (mean +/- SD) and after 5.2 +/- 0.4 years from the start of treatment. Nineteen of the 33 patients experienced a short-term satisfactory treatment result with an apnea-hypopnea index of < 10 events per hour and a satisfactory reduction in snoring. Fourteen patients were regarded as being insufficiently treated with the device. Seventeen of the short-term satisfactorily treated patients (90%) and 2 of the remaining patients continued treatment on a long-term basis. The apnea-hypopnea index was reduced by the device from 22 +/- 17 to 4.9 +/- 5.1 events per hour (p < 0.001) in these 19 long-term treatment patients, which did not differ from what was found at the short-term follow-up visits in these patients. Patients with their devices replaced or adjusted experienced a better long-term effect than patients still using their original devices (p < 0.05). CONCLUSIONS: The long-term effect and tolerability of a mandibular advancement device are good in patients who are recommended the treatment on the basis of a short-term sleep recording, provided that the device is continuously adjusted or replaced with a new one when needed. A short-term follow-up is valuable in the selection of patients who will benefit from long-term treatment with a mandibular advancement device.

Activator Appliances↗
PubMed2000

Substrate mediated long-range oscillatory interaction between adatoms: Cu /Cu(111).

A quantitative study of the long-range interaction between single copper adatoms on Cu(111) mediated by the electrons in the two-dimensional surface-state band is presented. The interaction potential was determined by evaluating the distance distribution of two adatoms from a series of scanning tunneling microscopy images taken at temperatures of 9-21 K. The long-range interaction is oscillatory with a period of half the Fermi wavelength and decays for larger distances d as 1/d(2). Five potential minima were identified for separations of up to 70 A. The interaction significantly changes the growth of Cu/Cu(111) at low temperatures.

Journal Article↗
PubMed2000

Theory of single molecule vibrational spectroscopy and microscopy.

We have carried out a density functional study of vibrationally inelastic tunneling in the scanning tunneling microscope of acetylene on copper. Our approach is based on a many-body generalization of the Tersoff-Hamann theory. We explain why only the carbon-hydrogen stretch modes are observed in terms of inelastic and elastic contributions to the tunneling conductance. The inelastic tunneling is found to be efficient and highly localized in space without any resonant interaction and to be governed by a vibration-induced change in tunneling amplitude.

Journal Article↗