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Biomedical subjects

A Lundgren

Publications and source records attributed to A Lundgren.

At least 19 recordsLinked to original sources
PubMed2003

Increased frequency of activated T-cells in the Helicobacter pylori-infected antrum and duodenum.

Helicobacter pylori colonize the human stomach and duodenum. The infection has been shown to induce a strong T-cell response in the stomach, whereas the response within the duodenum has been poorly characterized. Furthermore, it remains to be elucidated whether the T-cell response may contribute to ulcer formation in the host. In this study, the frequency of different T-cell subsets, their degree of activation and expression of co-stimulatory receptors in biopsies from the duodenum as well as the antrum were studied by immunohistochemistry and flow cytometry. It was also evaluated whether there are differences in the T-cell responses between duodenal ulcer patients and asymptomatic carriers that might explain why only 10-15% of the infected subjects develop duodenal ulcers. The frequencies of CD4+, CD8+ and CD45RO+, i.e. memory T-cells, were significantly increased in the antrum, and the number of CD25+ cells was considerably higher in both the antrum and duodenum of duodenal ulcer patients and asymptomatic carriers as compared to uninfected individuals. Interestingly, the levels of immunosuppressive CTLA-4+ cells were significantly higher in the duodenum of duodenal ulcer patients, as compared to the asymptomatic carriers. H. pylori cause activation of T-cells in the duodenum as well as in the stomach. Our observation of higher levels of CTLA-4+ cells in the duodenum of duodenal ulcer patients than in the asymptomatic carriers suggests that a suppressive T-cell response may be related to the development of duodenal ulcers.

Adult↗
PubMed2002

A novel evaluation of subcutaneous formulations by in vivo magnetic resonance imaging (MRI).

The applicability of magnetic resonance imaging (MRI) for non-invasive in vitro studies of parenteral vehicles without use of marker substances was investigated. A wide range of extended release (ER) formulations such as oils, a lipid emulsion, and water solutions of a cyclodextrin and block co-polymers were visualized in vitro and in vivo by a (1)H-MRI technique. The study included measurements in vitro in a beaker and by injections in pig flesh. In vivo studies were carried out in rats. The contrast of the vehicles vs the background material could be visualized and quantifications of vehicle dispersion and disappearance were performed on obtained in vivo data. A wide range of different vehicles suitable for s.c. ER delivery were tested, such as different oils, a lipid emulsion, and water solutions of a cyclodextrin and block co-polymers. The vehicle volume expansion in vivo was possible to follow. However, this was not generally applicable for all kinds of vehicle component. The tested co-polymers, Poloxamers, were one type of vehicle component that provides an excellent MRI signal. The in vitro tests predicted the suitability of this vehicle for in vivo MRI studies. In the in vivo study of the block co-polymer formulations the apparent vehicle volume increased to a peak value from an initial value close to the injected volume. Thereafter the volume diminished and no vehicle could be detected after 29 h after injection. MRI could be applied for measurements of the dispersion and disappearance of some vehicles at the site of injection after s.c. administration without use of contrast agents.

Animals↗
PubMed2001

A quantum adiabatic evolution algorithm applied to random instances of an NP-complete problem.

A quantum system will stay near its instantaneous ground state if the Hamiltonian that governs its evolution varies slowly enough. This quantum adiabatic behavior is the basis of a new class of algorithms for quantum computing. We tested one such algorithm by applying it to randomly generated hard instances of an NP-complete problem. For the small examples that we could simulate, the quantum adiabatic algorithm worked well, providing evidence that quantum computers (if large ones can be built) may be able to outperform ordinary computers on hard sets of instances of NP-complete problems.

Journal Article↗
PubMed2001

Proximal promoter of the murine syndecan-1 gene is not sufficient for the developmental pattern of syndecan expression in B lineage cells.

Syndecan-1 (CD138) is a cell membrane proteoglycan that binds extracellular matrix components and various growth factors. The role of syndecan-1 in the control of cell growth and morphology has been illustrated by its altered expression in hematological malignancies such as multiple myeloma as well as some solid tumors. It has been reported that the expression of syndecan-1 in cells of the B lineage is developmentally regulated such that pre-B cells and plasma cells express syndecan-1 while mature B cells do not. Thus, we investigated whether the proximal promoter region of the murine syndecan-1 promoter was able to confer the observed on-off-on expression of syndecan-1 in cells of the B lineage as they develop from pre-B cells to plasma cells. Experiments carried out using deletion mutants of the proximal promoter cloned upstream of the CAT reporter gene transfected into murine cell lines, representing the above stages of B-cell development, such as BA/F3 (pro-B cell), 70Z/3 (pre-B cell), 2PK3 (late mature B cell), and MPC-11 (plasma cell), showed detectable levels of CAT expression. The WEHI-231 (mature B cell) cell lines did not show detectable levels of CAT reporter activity. The strong levels of expression were observed with a fragment of the proximal promoter spanning the region from -365 to -95 (from the translation start point). However, Northern analysis of RNA obtained from the five murine B-cell lines, representing various stages of B-cell development, showed that the 70Z/3, MPC-11 but not BA/F3, and 2PK3 cells expressed detectable levels of syndecan-1 mRNA. By FACS analysis, using a rat anti mouse syndecan-1 antibody, syndecan-1 expression on the cell surface was found to correlate with the observed mRNA expression patterns in these cell lines. Our results indicate that the proximal promoter of the murine syndecan-1 promoter is not sufficient for the observed developmental pattern of syndecan expression in B cells.

Animals↗
PubMed2001

Immediate occlusal loading of Brånemark implants applied in various jawbone regions: a prospective, 1-year clinical study.

BACKGROUND: The original protocol for dental implant treatment ad modum Brånemark was based on submerged healing prior to loading. For patients, immediate implant function could reduce cost and increase attractiveness of implant treatment. PURPOSE: The goal of this study was to evaluate the short-term success rate of immediately loaded implants placed in various regions of the jaws. MATERIALS AND METHODS: Forty-one patients received a total of 127 immediately loaded implants (76 maxillary and 51 mandibular). Seventy-one percent of the patients received their prosthetic restoration the same day and the others within 11 days. All prosthetic constructions were in full contact in centric occlusion. Clinical follow-up examinations were performed at 1 week, 2 weeks, and at 1, 2, 3, 6, and 12 months after implant loading. The study was completed 1 year after loading. RESULTS: Twenty-two implants were lost in 13 patients (including 7 maxillary implants lost in 1 patient). The cumulative success rate of the implants was 82.7% after 1 year of prosthetic loading. All sites with implant losses were re-implanted, using a two-stage technique, with no further complications reported. Ninety-one percent of implants placed in regions other than the posterior maxilla were successful compared with 66% of implants placed in the posterior maxilla. Implants in patients with a parafunctional habit (bruxers) were lost more frequently than those placed in patients with no parafunction (41% vs. 12%). Implants subjected to guided bone regeneration were more successful compared with those not subjected to regeneration procedures (90% vs. 67%). CONCLUSIONS: The immediate loading concept is a realistic treatment alternative in various jawbone regions except for the posterior part of the maxilla. High occlusal loads should be considered a risk factor. On the other hand, implants in combination with bone defects frequently are penetrating cortical layers to a higher extent, thereby contributing to implant stability during the healing phase and consequently do not inevitably jeopardize the treatment result. However, further controlled clinical studies with larger sample sizes need to be performed to evaluate the influence of different parameters on treatment outcome.

Adult↗
PubMed2001

Antigenic variation of Anaplasma marginale: major surface protein 2 diversity during cyclic transmission between ticks and cattle.

The rickettsial pathogen Anaplasma marginale expresses a variable immunodominant outer membrane protein, major surface protein 2 (MSP2), involved in antigenic variation and long-term persistence of the organism in carrier animals. MSP2 contains a central hypervariable region of about 100 amino acids that encodes immunogenic B-cell epitopes that induce variant-specific antibodies during infection. Previously, we have shown that MSP2 is encoded on a polycistronic mRNA transcript in erythrocyte stages of A. marginale and defined the structure of the genomic expression site for this transcript. In this study, we show that the same expression site is utilized in stages of A. marginale infecting tick salivary glands. We also analyzed the variability of this genomic expression site in Oklahoma strain A. marginale transmitted from in vitro cultures to cattle and between cattle and ticks. The structure of the expression site and flanking regions was conserved except for sequence that encoded the MSP2 hypervariable region. At least three different MSP2 variants were encoded in each A. marginale population. The major sequence variants did not change on passage of A. marginale between culture, acute erythrocyte stage infections, and tick salivary glands but did change during persistent infections of cattle. The variant types found in tick salivary glands most closely resembled those present in bovine blood at the time of acquisition of infection, whether infection was acquired from an acute or from a persistent rickettsemia. These variations in structure of an expression site for a major, immunoprotective outer membrane protein have important implications for vaccine development and for obtaining an improved understanding of the mechanisms of persistence of ehrlichial infections in humans, domestic animals, and reservoir hosts.

Anaplasma↗
PubMed2000

Antigenic variation of Anaplasma marginale by expression of MSP2 mosaics.

Anaplasma marginale is a tick-borne pathogen, one of several closely related ehrlichial organisms that cause disease in animals and humans. These Ehrlichia species have complex life cycles that require, in addition to replication and development within the tick vector, evasion of the immune system in order to persist in the mammalian reservoir host. This complexity requires efficient use of the small ehrlichial genome. A. marginale and related ehrlichiae express immunoprotective, variable outer membrane proteins that have similar structures and are encoded by polymorphic multigene families. We show here that the major outer membrane protein of A. marginale, MSP2, is encoded on a polycistronic mRNA. The genomic expression site for this mRNA is polymorphic and encodes numerous amino acid sequence variants in bloodstream populations of A. marginale. A potential mechanism for persistence is segmental gene conversion of the expression site to link hypervariable msp2 sequences to the promoter and polycistron.

Amino Acid Sequence↗
PubMed1999

Genomic and phylogenetic characterization of coxsackievirus B2 prototype strain Ohio-1.

The human picornavirus coxsackievirus B2 (CVB2) is often linked to several infections, from mild respiratory diseases to more severe illnesses such as myocarditis. In this study, we report the complete genome sequence of CVB2 prototype strain Ohio-1. The genome sequence was determined from reverse transcribed viral RNA, amplified with long distance PCR and used for non-radioactive sequencing. The full length PCR amplicons were used for in vitro transcription and the obtained cRNA was lipofected onto green monkey kidney cells, in order to confirm that the PCR generated sequence reflects a viable virus RNA. The CVB2 genome sequence shows a typical enterovirus genome organization with a total length of 7411 nucleotides. Phylogenetic analysis, using the CVB2 polyprotein in comparison with other enterovirus polyproteins, clearly shows that CVB2 clusters with the coxsackievirus B-like enteroviruses and is more related to coxsackievirus B4 (CVB4) than any other published CVB serotype. The grouping of CVB2 and CVB4 as one subgroup has earlier been reported in connection with receptor usage and ability to replicate in different cell lines. The exposed viral capsid proteins of CVB2 (VP1-VP3) show high similarity to other CVB proteins, except in regions that are likely to be surface epitopes.

Amino Acid Sequence↗
PubMed1999

Effect of education on evidence-based care and handling of peripheral intravenous lines.

Deficient routines in use, care, handling and documentation of peripheral intravenous vein cannulae (PIV) have previously been reported, and complications have been noted in 50-75% of the patients. The aim of the study was to examine whether specially trained nurses change their actions to decrease complications when using cannulae. The study included 36 nurses assigned to experimental and control groups. The experimental group followed an education programme explaining how to use and take care of a PIV. To evaluate the intervention document analysis, observations and patient interviews were performed in 99 patients with 172 PIVs in situ for less than 24 h. After the education programme, fewer complications, more carefully performed care and handling, and better documentation and information were found in the experimental group. Nurses in the control group followed current routines, which resulted in a greater degree of complications. Education in evidence-based care and handling gives nurses the opportunity to improve their ability to use theoretical knowledge in clinical problems.

Adult↗
PubMed1998

Influence of barrier occlusiveness on guided bone augmentation. An experimental study in the rat.

The present study was designed to test perforated and non-perforated barriers for their ability to promote augmentation of bone tissue. More specifically, 1 totally occlusive barrier and 6 barriers with perforation sizes of about 10, 25, 50, 75, 100, and 300 microns and 1 group with no barriers placed (open test chambers) were used to test the effect of a barrier's occlusiveness on the amount and composition of augmented tissue over time. The skull of the rat was used as the experimental area. Prefabricated, flexible silicone frames with an inferior flange for peripheral sealing to the bone surface and a central vertical through hole with a diameter of 3.6 mm and a height of 2 mm were used as test chambers. The barriers were inserted to cover the superior opening of the through hole. The healing periods were 4, 8, and 12 weeks. All test chambers exhibited newly formed skull bone which was augmented over time. The placement of totally occlusive barriers resulted in the slowest rate of bone tissue augmentation but in a highly predictable manner, i.e., there were only small individual variations. Placement of barriers with perforations exceeding 10 microns, on the other hand, resulted in a faster rate of bone augmentation with larger individual variations and a totally different augmentation pattern. A pronounced augmentation of calvarial soft tissue from the sagittal suture of the skull as well as ingrowth of suprabony connective tissue through the barriers were also observed. After 12 weeks of healing, no differences in the amount of augmented mineralized bone related to perforation sizes > 10 microns were found. The open test chambers also showed bone augmentation, although most of their volume was occupied by suprabony connective tissue.

Analysis of Variance↗
PubMed1998

Handling and control of peripheral intravenous lines.

The purpose of the study was to describe nurses' routines in connection with the planning, care and handling, and documentation of a peripheral intravenous cannula (PIV) and also to examine factors that control how nurses act. Nurses and physicians in three English hospitals were interviewed. The results showed a difference between nurses' and physicians' opinions about PIV routines, except in few cases. The PIV was inserted by the physicians while the nurses took care of and documented its care and handling. In many cases the insertion of the PIV was also documented by the nurses. Although small PIVs and short insertion time had previously been recommended, many physicians preferred large cannulae and an insertion time of between 3 and 7 days. All nurses and six physicians had the opinion that the cannula should be changed more often, but this did not happen. Some physicians maintained that the nurses' care and handling varied. On the other hand some criticism had been expressed by the nurses about unclear directives from the physicians. English participants were aware that unsatisfactory routines existed and that the policy had not always been followed.

Adult↗
PubMed1996

Factors influencing nurses' handling and control of peripheral intravenous lines--an interview study.

The purpose of the study was to describe how nurses (n = 37) planned, took care of, and documented peripheral intravenous (vein) cannulae (PIV) and what controls their way of action. Knowledge, experience, and routine were said to govern the care and handling of PIV. The nurses' intention was that a PIV should be inserted for 1-3 days, but all of them were aware of PIV being inserted considerably longer, the reasons being forgetfulness, carelessness, mistake, no one to take responsibility, bad routines and stress. Patients who had received drugs or solutions daily were given less information and furthermore the same PIV-entry was used for drugs, solutions and blood. Only one nurse documented the insertion and the removal of a PIV. The nurses' personal comments were that the area was neglected and there were great variations in the care and handling of PIV. Their task is to systematically identify the patients' needs and risk factors, and to analyse, diagnose, plan, implement and evaluate the care given. Using a standardised guide could be a way to reduce the frequency of complications in the daily care of PIV.

Adult↗
PubMed1993

The care and handling of peripheral intravenous cannulae on 60 surgery and internal medicine patients: an observation study.

The purpose of this study was to analyse the actual routines surrounding the use of peripheral cannulae and the occurrence of complications. Thirty surgery patients and 30 internal medicine patients were observed daily at a medium-sized hospital. The patients were followed from the time the cannula was inserted until after withdrawal and until both the insertion site and the vein were free from pain. The results showed that most of the cannulae were placed on the upper side of the hand and sizes most frequently used were 1.0 and 1.2 mm. The fixation was unsatisfactory in 23 cases already after the second day. Twenty-three cannulae were removed after 24 hours. Thirty-seven (62%) patients were stated to have thrombophlebitis phlebitis in different degrees. Only seven cannulae fulfilled the criteria for good cannula care and handling. The frequency of complication was especially high when fructose-glucose, antibiotics or anticoagulants were given. There was no documentation in the patient record, according to current laws in Sweden. The complications observed were redness, swelling, haematoma, subcutaneous swelling and suppurating infection. The study showed that the longer the cannula had been in situ, the greater were the complications (very distinct after 24 hours). The care and handling was unsatisfactory to very unsatisfactory in 52% of the cases. Complications can last for a very long time. In this research, pain was noted up to 5 months after the cannulae were removed.

Adult↗
PubMed1992

Environmental hazard classification of chemicals.

Information on the environmentally dangerous properties of chemicals is of fundamental importance if the users of chemicals are to take account of the risks to the environment in their choice of chemical products, and to organize the use of chemicals and waste disposal in an environmentally safe manner. In order to assist suppliers of chemicals in setting out their product information and to ensure its consistency, it is important to have rules on classification and labelling. Such rules must be based on criteria for environmental hazard classification. During the 1980s specific classification criteria for the aquatic environment were developed in the Nordic countries and by the Commission of the European Communities. These criteria now form the basis for the regulations on classification and labelling of chemical substances in both the EC and EFTA countries. The regulations entered into force in the EC on 1 July 1992 and will be enforced in the EFTA countries as soon as possible. Besides labelling there are several other areas, e.g. transport regulations, where classification criteria are or will be applied on a national or international scale. International harmonization of criteria at this early stage is highly desirable as it will prevent the development of divergent systems which will require harmonization at a later stage. To this end, the OECD initiated a Clearing House activity on the feasibility of elaborating harmonized approaches to environmental hazard classification. The Clearing House recommended adoption of the current classification criteria, joint development of criteria for other sections of the environment and joint development of procedures for updating and methodologies for classification of chemical preparations. Further international work in this area will be coordinated by IPCS. Harmonization of classification is also a programme area under Chemical Forum with IPCS as coordinator as agreed at UNCED 92.

Animals↗
PubMed1978

Mandibular reconstruction with bone grafts.

A total of 23 patients with partly resected mandible were repaired with autogenous bone grafts from the iliac crest and ribs. The reasons for reconstruction are presented in Table 1. The grafts healed without complications in 21 cases. With the exception of two of the cases with gunshot wounds, all patients recovered good mobility of the jaw and satisfactory mandibular contours. The patients had been folloed up for 6 months to 11 years. Radiographic examination at the last examination showed that resorption of the graft had been only slight or moderate. Through marrow-spongious bone grafts are regarded as best from an osteogenetic point of view, our cases showed that good results can be achieved also with solid block grafts. The authors discuss the use of plate osteosynthesis without IMF instead of other types of graft fixation and IMF. In six cases where the area of the graft was loaded with a prosthesis, resorption was not more extensive than in the other cases.

Adolescent↗