Biomedical subjects

A Gustafsson

Publications and source records attributed to A Gustafsson.

At least 37 records · Page 2Linked to original sources

PubMed2001

Tobacco smoking and neutrophil activity in patients with periodontal disease.

BACKGROUND: Tobacco smoking has considerable negative effects on periodontal health. The mechanisms behind these effects are incompletely understood but may be related to the host response. The aim of the present study was to investigate the influence of tobacco smoking on the gingival crevicular fluid (GCF) levels of elastase, lactoferrin (LF), alpha-1-antitrypsin (alpha-1-AT), and alpha-2-macroglobulin (alpha-2-MG) under periodontally diseased conditions. METHODS: The study population included 15 smokers (5 women and 10 men) aged 34 to 69 years and 17 non-smokers (5 women and 12 men) aged 31 to 81 years. Clinical registration of gingival index (GI), plaque index (PI), probing depth, as well as sampling of GCF were made at 3 sites with severe lesions and 3 sites with moderate lesions in each individual. The elastase activity was measured with a chromogenic low molecular substrate and the LF, alpha-1-AT, and alpha-2-MG concentrations with ELISA. RESULTS: The results showed that, with regard to severe lesions, smokers had a significantly lower concentration of alpha-2-MG as well as significantly lower total amounts of alpha-2-MG and alpha-1-AT than non-smokers. With regard to moderate lesions, smokers tended to exhibit a lower concentration of alpha-2-MG, but the difference was not statistically significant. Comparing moderate and severe lesions, smokers exhibited no gradual increase with disease severity in contrast to non-smokers, who showed significantly or almost significantly increased levels of LF and alpha-2-MG in severe as compared to moderate lesions. CONCLUSIONS: The present results indicate that the levels of alpha-2-MG and alpha-1-AT are suppressed in smokers with periodontitis, suggesting that smoking interferes with these protease inhibitors. This may be one mechanism by which smoking affects the inflammatory response.

Adult↗

PubMed2000

Redesign of substrate-selectivity determining modules of glutathione transferase A1-1 installs high catalytic efficiency with toxic alkenal products of lipid peroxidation.

The evolution of proteins for novel functions involves point mutations and recombinations of domains or structural segments. Mimicking this process by rational design in vitro is still a major challenge. The present report demonstrates that the active site of the enzyme glutathione transferase (GST) A1-1 can be tailored for high catalytic efficiency with alkenals. The result is a >3,000-fold change in substrate selectivity involving a noteworthy change in preferred catalyzed reaction from aromatic nucleophilic substitution to Michael addition. The hydrophobic substrate binding pocket of GST A1-1 is formed by three structural modules, which were redesigned sequentially with four point mutations and the exchange of a helical segment. The substitutions were made to mimic first-sphere interactions with a substrate in GST A4-4, which naturally has high activity with alkenals. These substrates are toxic lipid peroxidation products of pathophysiological significance, and glutathione conjugation is a route of their inactivation. The final product of the sequential redesign of GST A1-1, mutant GIMFhelix, had a 300-fold increase in catalytic efficiency with nonenal and a >10 times decreased activity with 1-chloro-2,4-dinitrobenzene. In absolute values, GIMFhelix is more efficient than wild-type GST A4-4 with some alkenal substrates, with a k(cat)/K(m) value of 1.5 +/- 0. 1 10(6) M(-1) small middle dots(-1) for nonenal. The pKa value of the active-site Tyr-9 of GIMFhelix is 7.3 +/- 0.1, approaching the unusually low value of GST A4-4. Thus, rational redesign of the active-site region of an enzyme may be sufficient for the generation of efficient catalysts with altered chemical mechanism and novel selectivity.

Alkenes↗

PubMed2000

Epstein-Barr virus (EBV) load in bone marrow transplant recipients at risk to develop posttransplant lymphoproliferative disease: prophylactic infusion of EBV-specific cytotoxic T cells.

A semiquantitative polymerase chain reaction assay was used to monitor the blood levels of Epstein-Barr virus (EBV)-DNA in 9 patients receiving allogeneic bone marrow transplants (BMT). Four of 5 recipients of HLA-mismatched T-cell-depleted grafts showed a 4- to 5-log increase of EBV-DNA within 1 to 3 months after BMT. Administration of 2 to 4 infusions of 10(7) EBV-specific cytotoxic T-lymphocytes (CTLs)/m(2) starting from the time of maximal virus load resulted in a 2- to 3-log decrease of virus titers in 3 patients. One patient, who received a T-cell culture lacking a major EBV-specific component, progressed to fatal EBV-positive lymphoma. Administration of EBV-CTLs before the onset of the EBV-DNA peak resulted in stabilization of the virus titers within 2 to 3 logs above the normal levels in the fifth patient. A moderate increase of virus titers was also detected in 3 of 4 patients receiving unmanipulated HLA-matched grafts, whereas 1 patient with Wiskott-Aldrich syndrome reached a 5-log increase of EBV-DNA load within 70 days after BMT. Our results suggest that a rapid increase of circulating EBV-DNA occurs in the absence of EBV-specific T-cell precursors or in the presence of congenital immune defects that prevent the reestablishment of virus-specific immunity. Prophylactic administration of EBV-CTLs early after BMT appears to provide the most effective protection against the development of EBV-associated lymphoproliferative disease.

Adolescent↗

PubMed2000

A new device for 100 per cent humidification of inspired air.

STATEMENT OF FINDINGS: A new humidifier for use during mechanical ventilation in endotracheally intubated patients is described and tested. The humidifier is based on a heat-moisture exchanger, which absorbs the expired heat and moisture and releases it into the inspired air. External heat and water are then added at the patient side of the heat-moisture exchanger, so that the inspired gas should reach 100% humidity (44 mg/l) at 37 degrees C. In bench tests using constant and decelerating inspiratory flow and minute volumes of 3-25 l the device gave an absolute humidity of 41-44 mg/l, and it reduced the amount of water consumed in eight mechanically ventilated patients compared with a conventional active humidifier. During a 24-h test period there was no water condensation in the ventilator tubing with the new device.

Critical Care↗

PubMed2000

Cigarette smoking as an aggravating factor in inflammatory tissue-destructive diseases. Increase in tumor necrosis Factor-alpha priming of peripheral neutrophils measured as generation of oxygen radicals.

Stimulated neutrophils from subjects with various inflammatory tissue-destructive conditions, such as periodontal, pulmonary, gastrointestinal, and cardiovascular diseases, generate more oxygen radicals and proteases, implicated in tissue destruction, than neutrophils from healthy persons. Cigarette smoking aggravates these diseases. The aim of our study was to investigate the effect of cigarette smoking on the priming capacity of tumor necrosis factor-alpha, measured as generation of radicals from stimulated neutrophils, in smoking and non-smoking subjects with or without periodontitis. The priming effect was higher in neutrophils from smokers. In the group with periodontitis, smoking caused an even greater increase in the generation of radicals, indicating an additive effect of this local disease. The membrane expression of CD11b, CD15, and CD63 was significantly higher on neutrophils from smokers, indicating upregulated neutrophil functions. This increased priming effect of tumor necrosis factor-alpha in smokers subjects could be of importance in the aggravation of tissue-destructive inflammatory diseases.

Adult↗

PubMed2000

Follow-up of chimerism, including T- and B-lymphocytes and granulocytes in children more than one year after allogeneic bone marrow transplantation.

In bone-marrow-transplanted children, early detection of graft failure, relapse, and other potentially treatable problems is facilitated by the use of polymerase chain reaction (PCR) assays that monitor whether blood and marrow cells are of recipient or donor origin. Presence of mixed donor-recipient chimerism (MC) within the first year after BMT frequently correlates with clinical problems. To study if MC detected one year or more post-BMT was also often associated with clinical problems, the chimeric status in 33 children surviving 1-11 yr (median: 2 yr) after BMT was investigated. A PCR with a sensitivity of 1-2%, using fluorescent primers analyzing DNA fragment length polymorphisms, was applied. T- and B-cells and granulocytes were immunomagnetically isolated and tested separately for all patients. Of the 33 patients, of whom 21 had received pretreatment including total body irradiation (TBI), 27 (82%) exhibited full donor chimerism. Six children (18%), four of whom had received pretreatment without TBI, had MC. In three of these children, all with aplastic anemia, isolated T-cell MC had not posed apparent clinical problems. In two patients, both with MC including B-cells, immune hemolytic anemia was observed. A sixth patient with AML presented with MC and relapse. In two of the six children MC was detected only by cell subset analysis. In conclusion, analysis of MC in leukocyte subsets is more informative than analysis of whole blood only and may reveal clinically important variations in the origin of different cell populations. The prevalence of MC is lower after the first year post-BMT, and when present is less often associated with clinical problems.

Adolescent↗

PubMed2000

Long-term evaluation of osseointegrated dental implants in the treatment of partly edentulous patients.

AIM: The aim of this study was to evaluate the clinical, radiographic and microbiological status of implants after 10 years of functional load in patients treated for partial edentulism. METHOD: 15 patients, each successfully treated with 2-6 implants ad modum Brånemark placed in free-standing fixed prostheses, were included in the study. RESULTS: Clinical evaluation revealed similar degrees of inflammation around teeth and implants. The probing pocket depth (PPD) was significantly greater around implants than around teeth. The mean marginal bone loss during 10 years of functional load was comparable to that found at the time of the 5-year follow-up. 74% of the implants remained free of marginal bone loss exceeding 1 mm. Marginal bone loss exceeding 2 mm, was found at only 5 sites. No marked differences in bacteria were present between teeth and implants. T. denticola, S. intermedia and P. micros were the commonest organisms detected around teeth and implants. The periodontal pathogens A. actinomycetemcomitans, P. gingivalis, P. intermedia, B. forsythus, and T. denticola, were found at implants with a marginal bone loss of more than 2 mm. CONCLUSION: Our study shows that the long-term results with implants in partially dentate patients are similar to those seen in edentulous patients and that no significant change occurred after 5-year follow-up over an additional period of 5 years.

Adult↗

PubMed2000

Increased amounts of laminin in GCF from untreated patients with periodontitis.

BACKGROUND/AIMS: Our aim was to compare the levels of laminin and interleukin-8 (IL-8) in GCF from inflamed shallow (GP) and deep pockets (PP) in patients with periodontitis to these levels in GCF from inflamed shallow pockets (GG) in subjects with gingivitis alone. METHOD: Lactoferrin was used as a marker for the number of neutrophils in the sites sampled. The periodontitis group consisted of 13 subjects, having at least 6 sites with a pocket depth > or = 5 mm. The healthy control group consisted of 12 subjects with no clinical signs of periodontal destruction. GCF was collected with paper strips and the volume was measured immediately after sampling. Laminin, lactoferrin and IL-8 were measured using specific antibodies with an ELISA. RESULTS: The total amount of laminin was significantly higher in PP than in GG, but no significant difference was seen between GP and PP. The concentration and the total amounts of lactoferrin were similar in the three groups. The ratio between laminin and lactoferrin was higher in the samples from the patient, suggesting that neutrophils in patients are more activated and degrades more of the membrane per cell. The total amounts of IL-8 were very similar in the 3 groups, while the concentration also tended to be higher in the GP. CONCLUSIONS: Our study showed higher amounts of laminin in GCF from patients with periodontitis suggesting the presence of hyperactive neutrophils during the transmigration process through the endothelium/epithelium.

Adult↗

PubMed2000

Expression of intracellular elastase activity in peripheral neutrophils from patients with adult periodontitis.

This study aimed to investigate whether circulating neutrophils from patients with periodontitis contain more catalytically active elastase than neutrophils from healthy controls. The amount of IL-1beta in these cells was also analyzed and the correlation with elastase activity was tested. The periodontitis group consisted of 15 subjects with marked periodontal destruction. The healthy control group consisted of 15 subjects with no clinical signs of periodontal destruction. The elastase activity and the IL-1beta content in the cells were measured with flow cytometry using a specific substrate and antibodies, respectively. The plasma concentration of IL-1beta and the total content of antigenic elastase in the crushed cells were measured with an ELISA. The elastase activity per neutrophil was significantly higher in the patients than in the controls, while the total antigenic elastase content did not differ. The % of cells positively stained for IL- 1beta was somewhat higher in the patient group. Significantly higher amounts of IL-1beta per sample, estimated by multiplying the % of stained cell with the amount of staining per cell, were found in the patient group. A significant correlation between IL-Ibeta and elastase activity was noted in the patient group (R=0.6, p=0.001), but not in the control group. In conclusion, peripheral neutrophils from patients with adult periodontitis express more active elastase and total amounts of IL-1. The similar amounts of antigenic elastase suggests that this higher activity is possibly due to some kind of priming/activation already in the circulation.

Case-Control Studies↗

PubMed2000

Cytokine, elastase and oxygen radical release by Fusobacterium nucleatum-activated leukocytes: a possible pathogenic factor in periodontitis.

Periodontitis is characterised by tissue destruction caused by reactive oxygen species (ROS) and proteolytic enzymes, which are released by the interaction between bacteria and phagocytes. We estimated the ability of Fusobacterium species to induce release of tissue destructive and proinflammatory mediators from in vitro activated peripheral leukocytes. ROS was measured with the nitroblue tetrazolium (NBT) method, elastase with a specific chromogenic substrate and cytokines, including interleukin 1beta (IL-1beta), tumour necrosis factor alpha (TNF-alpha), and interleukin 8 (IL-8) with a sandwich ELISA method. Various clinical isolates of unopsonized Fusobacterium species stimulated the neutrophils to an increased NBT- reduction. IL-1beta, TNFalpha, IL-8 and elastase were released in significantly higher levels from neutrophils stimulated by Fusobacterium species. In conclusion, unopsonized Fusobacterium species can induce increased production of oxygen radicals, cytokines and elastase from leukocytes activated in vitro.

Analysis of Variance↗

PubMed2000

Unrelated bone marrow transplantation in children: outcome and a comparison with sibling donor grafting.

The clinical course of 59 children, who underwent BMT during 1988-1998 with a matched unrelated donor (MUD), was compared with 59 case controls receiving a sibling donor marrow. Thirty-eight patients had haematological malignancies while 21 had a nonmalignant disorder. The cumulative incidence of acute GVHD grade II-IV was 28% for MUD recipients vs 11% (P = 0.014) for sibling recipients. Extensive chronic GVHD was rare in both groups. The 5-year probability of survival was 52% for MUD vs 77% for sibling recipients (P= 0.014). For children with malignancies the 4-year probability of survival was 52% for MUD vs 67% for sibling recipients with a RFS of 49% vs 62%. In the ALL patients the survival of the MUD recipients was 77% and equalled that of the sibling group. For SAA survival was 43% vs 86% (P = 0.09) and for metabolic disorders 63% vs 89% (P = 0.025). The transplant-related mortality was higher in the MUD group, while death due to relapse was equally distributed. These results of MUD BMT in children compare favourably with most previous reports, and support the use of alternative donors in cases who lack an HLA-identical siblings. Bone Marrow Transplantation (2000).

Adolescent↗

PubMed2000

Immunolocalization of interleukin-8 and proliferating cell nuclear antigen in gingival keratinocytes in patients with periodontitis.

The aim of this study was to investigate the relation between local expression of IL-8 and the localization of neutrophilic granulocytes, using CD16 as a marker of neutrophils. We also investigated the correlation between IL-8 and epithelial proliferation using proliferating cell nuclear antigen (PCNA) as a marker of proliferation. The distribution of IL-8, CD16 and PCNA/cyclin was determined by immunocytochemical techniques. We used cryostat-cut sections from gingival biopsies harvested from 5 subjects with and 5 subjects without periodontitis. Our histological examination demonstrated that the localization of neutrophilic granulocytes in gingival tissue from patients with periodontitis did not correlate with the expression of IL-8. In all tissue sections from patients and controls, the inflammatory cells accumulated near the pocket epithelium and only a few leukocytes deviated from this pattern. In the patient group, keratinocytes not belonging to the pocket or junctional epithelium expressed IL-8 without any evidence of a chemoattractant effect on neutrophils. The marker of proliferation, PCNA/cyclin, was expressed in keratinocytes in the basal cell layer. The expression was less pronounced in the control group. Our finding that IL-8 was expressed in proliferating cells suggests that IL-8 may have a role in keratinocyte proliferation.

Adult↗

PubMed2000

Progression rate of approximal carious lesions in Swedish teenagers and the correlation between caries experience and radiographic behavior. An analysis of the survival rate of approximal caries lesions.

The objectives were to study the progression rate of approximal caries in 14 to 19-year-old adolescents and to assess the influence of experience of previous caries as a predictor of caries progression during the following years. The study population comprised 100 adolescents, all 19 years old, randomly selected. In all, there were 93 adolescents included in the study, for whom all sets of bitewing radiographs from 14 up to and including the age of 19 were assessed with respect to approximal caries. It could be noted that 32% of the adolescents had had at least one bitewing examination every year from 14 to 19 years of age. At the age of 14, 38% of the males and 24% of the females were radiographically without any sign of caries lesions (caries-free). The median survival time of initial caries in the present study was >5 years, while for manifest caries it was 3.2 years. It was found that 37% of the surfaces with manifest caries in males and 18% of the corresponding surfaces in females were restored within a year. The results show that experience of previous caries does not seem to be a significant indicator and does not influence when the next radiographic examination should be performed. It is thus concluded that individualized bitewing examination is the exception rather than the rule.

Adolescent↗

PubMed2000

Dual-window scatter correction and energy window setting in cerebral blood flow SPECT: a Monte Carlo study.

The image quality in SPECT studies of the regional cerebral blood flow (rCBF) performed with 99mTc-HMPAO is degraded by scattered photons. The finite energy resolution of the gamma camera makes the detection of scattered photons unavoidable, and this is observed in the image as an impaired contrast between grey and white matter structures. In this work, a Monte Carlo simulated SPECT study of a realistic voxel-based brain phantom was used to evaluate the resulting contrast-to-noise ratio for a number of energy window settings, with and without the dual-window scatter correction. Values of the scaling factor k, used to obtain the fraction of scattered photons in the photopeak window, were estimated for each energy window. The use of a narrower, asymmetric, energy discrimination window improved the contrast, with a subsequent increase in statistical noise due to the lower number of counts. The photopeak-window setting giving the best contrast-to-noise ratio was found to be the same whether or not scatter correction was applied. Its value was 17% centred at 142 keV. At the optimum photopeak-window setting, the contrast was improved by using scatter correction, but the contrast-to-noise ratio was made worse.

Brain↗

PubMed2000

Attenuation correction in quantitative SPECT of cerebral blood flow: a Monte Carlo study.

Monte Carlo simulation has been used to produce projections from a voxel-based brain phantom, simulating a 99mTc-HMPAO single photon emission computed tomography (SPECT) brain investigation. For comparison, projections free from the effects of attenuation and scattering were also simulated, giving ideal transaxial images after reconstruction. Three methods of attenuation correction were studied: (a) a pre-processing method, (b) a post-processing uniform method and (c) a post-processing non-uniform method using a density map. The accuracy of these methods was estimated by comparison of the reconstructed images with the ideal images using the normalized mean square error, NMSE, and quantitative values of the regional cerebral blood flow, rCBF. A minimum NMSE was achieved for the effective linear attenuation coefficient mu(eff) = 0.07 (0.09) cm(-1) for the uniform(pre) method, the effective mass attenuation coefficient mu(eff)/rho = 0.08 (0.10) cm2 g(-1) for the uniform(post) method and mu(eff)/rho = 0.12 (0.13) cm2 g(-1) for the non-uniform(post) method. Values in parentheses represent the case of dual-window scatter correction. The non-uniform(post) method performed better, as measured by the NMSE, both with and without scatter correction. Furthermore, the non-uniform(post) method gave, on average, more accurate rCBF values. Although the difference in rCBF accuracy was small between the various methods, the same method should be used for patient studies as for the reference material.

Humans↗

PubMed2000

Factors affecting late fixture loss and marginal bone loss around teeth and dental implants.

BACKGROUND: The predictability and high success rate of implant treatment have averted attention from factors affecting fixture loss and bone loss around implants. PURPOSE: The goal of this study was to retrospectively evaluate late fixture loss and marginal bone loss around implants that have been in function for 5 years and to relate these findings to bone loss in the natural dentition. MATERIALS AND METHODS: One hundred and forty-three consecutively treated patients who had received an implant-anchored fixed prosthesis and completed a 5-year follow-up were selected. Intraoral and panoramic radiographs were used to assess bone loss. RESULTS: The bone loss was greater around remaining implants in patients who had lost implants after loading. No correlation was found between bone loss around implants and that around teeth. Only 2% of the fixtures were lost during 5 years of functional load. Most fixtures losses occurred in the edentulous maxilla. Seven of the nine patients who lost fixtures were smokers. CONCLUSION: These findings show that patients who lost implants also lost more bone around the remaining implants. There was no correlation between bone loss around implants and that around teeth, indicating that different interacting mechanisms are involved.

Aged↗

PubMed1999

The C-terminal region of human glutathione transferase A1-1 affects the rate of glutathione binding and the ionization of the active-site Tyr9.

In human glutathione transferase (GST) A1-1, the C-terminal region covers the active site and contributes to substrate binding. This region is flexible, but upon binding of an active-site ligand, it is stabilized as an amphipatic alpha-helix. The stabilization has implications for the catalytic activity of the enzyme. In the present study, residue M208 in GST A1-1 has been mutated to Lys and Glu, and residue F220 to Ala and Thr. These mutations are likely to destabilize the C-terminal region due to loss of hydrophobic interactions with the rest of the hydrophobic binding site. The rate constant for binding of glutathione to wild-type GST A1-1 is 450 mM(-)(1) s(-)(1) at 5 degrees C and pH 7.0, which is less than for an association limited by diffusion. However, the M208 and the F220 mutations increase the apparent on-rate constant for glutathione binding to 640-1170 mM(-)(1) s(-)(1). The binding data can be explained by a rapid reversible transition between different enzyme conformations occurring prior to glutathione binding, and restriction of the access to the active site by the C-terminal region. The effect of the mutations appears to be promotion of a less closed conformation, thereby facilitating the association of glutathione and enzyme. Both the M208 and F220 mutants display a lowered pK(a) value ( approximately 0.3 log unit) of the catalytically important Tyr9. Residue 208 does not interact directly with Tyr9 in the active site, and the shift in pK(a) value is therefore ascribed to the proposed dislocation of the C-terminal region caused by the mutation.

Alanine↗

PubMed1999

Benzoic acid derivatives induce recovery of catalytic activity in the partially inactive Met208Lys mutant of human glutathione transferase A1-1.

Human glutathione transferase A1-1 (GST A1-1) is a detoxifying enzyme catalyzing the conjugation of glutathione with a variety of hydrophobic, electrophilic substrates. When the role of the hydrophobic substrate-binding site residue Met208 was investigated by random mutagenesis, introduction of charged amino acid residues had the greatest deleterious effect on enzyme activity. However, in the lysine mutant some of the lost activity could be regained by the addition of a benzoic acid derivative to the reaction mixture. The activating molecule has now been optimized such that all activity is recovered. The most potent activator, 4-propylbenzoic acid, has been used in studies of the mechanism behind the activation. A heterodimeric species of GST A1-1, containing only one activatable subunit, has been constructed. The heterodimer shows a strictly additive activation curve when compared to its parental forms, indicating that the activation is not due to co-operativity between the subunits. Furthermore, a novel electrophilic substrate, 4-chloro-3,5-dinitrobenzoic acid, with a carboxylate group expected to interact with residue 208 gives a higher kcat value with the lysine mutant than with wild-type GST A1-1. All results obtained in the here support the view that the positive charge introduced into the lysine mutant adversely affects the structure of the C-terminal helix of this enzyme, preventing it from adopting the conformation needed for full activity. The negatively charged carboxylate group of the activator probably neutralizes the positive charge of the side-chain amino group and thereby restores the substrate-binding site to a form that is favorable for the catalytic function.

Amino Acid Substitution↗