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Biomedical subjects

J Ekstrand

Publications and source records attributed to J Ekstrand.

At least 37 records · Page 2Linked to original sources
PubMed2000

Fluoride intake and prevalence of dental fluorosis: trends in fluoride intake with special attention to infants.

BACKGROUND: Although the predominant beneficial effect of fluoride occurs locally in the mouth, the adverse effect, dental fluorosis, occurs by the systemic route. The caries attack rate in industrialized countries, including the United States and Canada, has decreased dramatically over the past 40 years. However, the prevalence of dental fluorosis in the United States has increased during the last 30 years both in communities with fluoridated water and in communities with nonfluoridated water. Dental fluorosis is closely associated with fluoride intake during the period of tooth development. METHODS: We reviewed the major changes in infant feeding practices that have occurred since 1930 and the changes in fluoride intakes by infants and young children associated with changes in feeding practices. RESULTS AND CONCLUSIONS: Based on this review, we conclude that fluoride intakes of infants and children have shown a rather steady increase since 1930, are likely to continue to increase, and will be associated with further increase in the prevalence of enamel fluorosis unless intervention measures are instituted. RECOMMENDATIONS: We believe the most important measures that should be undertaken are (1) use, when feasible, of water low in fluoride for dilution of infant formulas; (2) adult supervision of toothbrushing by children younger than 5 years of age; and (3) changes in recommendations for administration of fluoride supplements so that such supplements are not given to infants and more stringent criteria are applied for administration to children.

Adult↗
PubMed2000

New filling materials--an occupational health hazard.

The acrylic content of dental composites poses a risk of adverse reactions. Although the quantities of the substances released are probably too small to cause systemic reactions, local skin or mucosal reactions may arise from direct contact with dental composites. In fact, epidemiological data suggest that most known side effects of dental resins are occupational dermatoses. They may either be due to irritation or allergy. In the Scandinavian countries, occupational dermatoses are relatively common among dental staff, sometimes entailing occupational disability and re-schooling. Most of these reactions can be avoided by observing precautions such as the minimization of the oxygen-inhibited-layer (OIL) in set composites and by using the resin-paste enamel bonding technique. The risk of occupational dermatoses could be reduced by the development of new bonding techniques and careful risk-benefit assessments in the use of dental composites.

Acrylic Resins↗
PubMed1999

Cytotoxicity tests of in situ polymerized resins: methodological comparisons and introduction of a tissue culture insert as a testing device.

The in vitro cytotoxic potential of six commonly used methacrylate polymers was evaluated using human oral fibroblast cultures with different cell-material contact systems. A tissue culture insert was introduced to test resin-released components. Both acute and delayed cytotoxic effects of resin were quantified by cellular enzymatic and DNA synthetic activities of fibroblasts over a 6-day exposure period. Resin toxicity was material-dependent. Statistical analysis showed that the experimental conditions significantly contributed to the overall toxicity and the cytotoxicity pattern for a given material. DNA synthesis activity of human oral fibroblasts assayed by 3H-thymidine incorporation was more sensitive to resins than cellular enzyme activity, as determined by tetrazolium bromide reduction. However, extended exposure increased the cytotoxicity of all resins, as measured by tetrazolium bromide reduction, which seemed to be a better indicator of the development of resin toxicity than 3H-thymidine incorporation. Removal of the oxygen inhibition layer on resin specimens partially enhanced cell viability, indicating that this surface layer together with other unknown factors contributed to resin toxicity.

Cell Survival↗
PubMed1999

Differential regulation of in vitro cytokine production by human blood cells in response to methylmethacrylate.

The effect of methylmethacrylate (MMA) on human whole blood cultures (WBC) obtained from healthy donors was investigated. Lymphocyte transformation and cytokine production, that is, interleukin 6 (IL-6), interferon-gamma (IFN-gamma), and tumor necrosis factor-alpha (TNF-alpha), were used to evaluate the immunological activities of MMA. Primary cytotoxicity testing of MMA in Jurkat cells showed that this compound decreased the cell proliferation to 50% at a concentration of >60 mmol/L. Similarly, MMA significantly decreased lymphocyte transformation in either phytohemagglutinin (PHA) or Staphylococcus aureus protein A (SpA) activated WBC at 100 mmol/L. In contrast to activated WBC, MMA had no observed effect on resting blood cells. Cytokine expression in WBC seemed differentially modulated by MMA. There was a tendency for IL-6 production in both resting and PHA-stimulated WBC to be upregulated, while IL-6 induced in SpA stimulated cultures was downregulated. TNF-alpha was slightly increased by MMA in resting WBC at early incubation periods, and it was slightly downregulated in response to PHA or SpA activation. Suppression of IFN-gamma secretion was observed in WBC with or without PHA or SpA stimulation. The overall results demonstrated that MMA at physiological levels could influence the cytokine production in normal human blood cells in vitro. Alterations of cytokine production patterns by MMA indicate that this compound has multiple regulatory effects on immune reactions in normal human blood.

Adolescent↗
PubMed1999

[A common symptom among athletes and persons who exercise. Correct treatment of groin pain requires a meticulous diagnosis].

Groin pain is common among athletes. In its acute form the pain is usually overuse-related and is treated conservatively, whereas in chronic groin pain the clinical picture is often more complex. Successful treatment is dependent on correct diagnosis, as there are multiple differential diagnosis. Surgery has been associated with good results in chronic cases, the most common interventions being adductor tenotomy, abdominal wall repair, and neurotomy of the ilioinguinal and/or iliohypogastric nerve. Which surgical approach should be adopted is dependent on the results of investigation to identify the causative factor.

Adult↗
PubMed1999

Results of reconstruction of acute ruptures of the anterior cruciate ligament with an iliotibial band autograft.

Forty patients with an acute complete tear of the anterior cruciate ligament (ACL) underwent primary reconstruction with an iliotibial band autograft after median 15 (range 0-90) days. Objective and functional evaluation was performed after median 37 (range 24-87) months by two independent observers using the International Knee Documentation Committee (IKDC) knee evaluation form, the Lysholm knee function score, and the Tegner activity score. During the observation period 5 patients sustained an ACL tear in the contralateral knee, and 1 patient (2.5%) sustained a graft rupture and underwent re-reconstruction. For the remaining 34 knees the Lysholm score at follow-up was median 100 (range 84-100, mean 97 [+/- 4]), all patients scoring excellent (n = 28) or good (n = 6). Three patients (9%) had more than 3 mm side-to-side difference in anteroposterior laxity. All 4 ligament failures occurred in patients operated on within the first 2 weeks after the injury. Twenty-six patients (76%) returned to the same level of activity as prior to the injury. Of 8 who dropped to a lower activity level, only one ascribed this to problems with the operated knee, meaning that 26 of 27 (96%) returned to their desired level of activity. According to the overall IKDC evaluation, 14 patients (40%) had a normal knee (A), 13 (37%) had a nearly normal knee (B), 5 (14%) had an abnormal knee (C), and 2 (9%) had a severely abnormal knee (D). Ten patients (25%) had the staples removed due to local irritation, and further 6 (15%) had local symptoms from the tibial staples. The harvest site gave 8 (20%) patients cosmetic complaints, but all graded this as slight, and 3 (8%) had slight pain during activity from the lateral muscular hernia. In selected individuals performing vigorous knee activities, autologous reconstruction of acute ACL disrupted knees with a combined internal and external iliotibial band transfer demonstrates excellent results after median 3 years. The failure rate is comparable to other techniques.

Acute Disease↗
PubMed1999

In vitro cytotoxicity of orthodontic bonding resins on human oral fibroblasts.

Polymerization of bonding resins is compromised by atmospheric oxygen, giving rise to a layer of low molecular weight chemical species commonly known as the oxygen inhibited layer. The aim of this study was to evaluate the cytotoxic effect of this layer on primary cultures of human oral fibroblast. The cytotoxic effect related to the modes of polymerization of seven commercially available orthodontic bonding resins was also evaluated statistically. Each material was polymerized into 12 resin disks of standardized dimensions. Half of them were washed with 99% acetone to remove the oxygen inhibited layer. In duplicates, human oral fibroblasts were exposed to the intact and washed resin disks in tissue culture inserts. Cell viability was assessed by tetrazolium bromide reduction assay (MTT) 1, 3, and 6 days after exposure. Glass disks served as controls. ANOVA was used to test for statistical significance. Overall, the presence of an oxygen inhibited layer renders bonding resins 33% more cytotoxic (P <.01, F = 11.83, DF = 1). Light-cured and chemically cured 2-pastes materials had their mean cytotoxicities approximating their inert controls over 6 days. In chemically cured liquid-paste materials, the viability of human oral fibroblasts was only 37% (P <.001, F = 26.4, DF = 2) comparing to the control, 64% on day 1, 30% on day 3 and 14% on day 6. This suggested that the oxygen inhibited layer formed on the surface of bonding resins is an important cytotoxic source in vitro. Chemically cured liquid-paste materials were more cytotoxic than light-cured and chemically cured 2-paste materials. Further investigation into the influence of the modes of polymerization on materials' toxicodynamic effect is warranted to verify its clinical implication.

Analysis of Variance↗
PubMed1999

Fluoride in the oral environment.

A predominant part of the cariostatic activity of fluoride is a function of its concentration in the fluid environment of the teeth. The fluoride exposure results in a slightly elevated steady-state level of fluoride in the oral fluids, primarily in saliva and plaque fluid. So far, however, little is known about the intra-oral fluoride concentration necessary to achieve a cariostatic effect at the site of action. Following fluoride intake, the fluoride remaining in the oral cavity is diluted by the saliva pool. The remaining fluoride may be found in several compartments in the oral cavity. It may be ionized in saliva, ionized in plaque (plaque fluid), bound in plaque, bound as calcium fluoride, bound to enamel, and bound to soft tissues. Fluoride is also distributed to the oral tissues and into the dental plaque by diffusion. It is well established that plaque, after fluoride exposure, becomes a fluoride reservoir which stores for some time and releases fluoride. The present review gives an insight into the important parameters that determine the disposition and fate of fluoride in the oral environment. To achieve in-depth understanding, and hence formulation of the optimal fluoride therapy, more information is needed to consolidate our understanding of the distribution, retention, and elimination of fluoride in the oral cavity. Such knowledge will form a better basis for providing our patients with more effective dental fluoride products and regimens.

Dental Plaque↗
PubMed1999

Highly cross-linked networks for dental applications obtained by photocuring of tris[2-(acryloyloxy)ethyl]isocyanurate, 2-ethyl-2-(hydroxymethyl)-1,3-propanediol triacrylate, and pentaerythritol triacrylate.

Highly cross-linked networks have been obtained by photoinitiated camphorquinone-amine polymerization of tris[2-(acryloyloxy)ethyl]isocyanurate alone and/or with 2-ethyl-2-(hydroxymethyl)-1,3-propanediol triacrylate or pentaerythritol triacrylate, which can be considered a new class of dental restorative resins. The most effective coinitiators in this system are amines such as ethyl-4-dimethylaminobenzoate, N,N-dimethyl-benzylamine, and 2,4,6-tris(dimethylaminomethyl)phenol. The volume shrinkages of polymerized samples were 8%-13%. The hardness of photocured resins in the presence of an inorganic filler (aluminum/fluoro/silicate glass, Ketac-Fil was slightly less than that of a restorative composite material (Z100 MP).

Acrylates↗
PubMed1999

Portfolio of qualifications: a tool for evaluating academic productivity at the Karolinska Institutet.

A Portfolio of Qualifications for academic appointments at the Karolinska Institutet has been developed to define more clearly the competence and qualifications which are given high priority for academic appointments at the Karolinska Institutet. The major fields of application are for new appointments and promotions, providing guidelines for the individual for improving his/her proficiency, and as a basis for determining individual salary rates. Four portfolios have been developed, a pedagogical, a clinical, a scientific, and a leadership, development and workplace relations portfolio. Attached to the portfolios are assessment forms. We consider the Qualifications Portfolio to be a reflection of changes in attitudes and values at the Karolinska Institutet. The system offers a method for the recognition of faculty productivity in different dimensions. This may be beneficial for the university in view of the increasing diversity and complexity of academic institutions. The Qualifications portfolio can be obtained from the world wide web, http:/(/)www.ki.se/ki/merit.se.html (in Swedish), http:/(/)www.ki.se/ki/merit.html (in English).

Dental Research↗
PubMed1999

No evidence for specific in vitro lymphocyte reactivity to HgCl2 in patients with dental amalgam-related contact lesions.

Blood lymphocytes from 20 patients with oral contact lesions to dental amalgam and 10 healthy individuals were analyzed for HgCl2-induced proliferation in vitro, using both a modified assay and a conventional assay. The release of interferon-gamma (IFN-gamma) was measured in cell supernatants. Six patients displayed positive reactions in patch tests to mercuric compounds. No significant differences were recorded in HgCl2-induced proliferation in cells from patients and controls, since only few in the whole material responded to submitogenic concentrations. IFN-gamma was detectable in cell supernatants from some patients but also from controls and is not predictive of mercury allergy. Neither the phenotypes of peripheral lymphocyte subsets, the frequency of circulating cells expressing the interleukin-2 (IL-2) receptor, spontaneous lymphocyte proliferation nor concentrations of serum interleukin-6 differed between patient and control samples. In contrast to what has been claimed before, we did not find any evidence for specific in vitro lymphocyte reactivity in patients with oral contact lesions.

Adult↗
PubMed1999

The incidence and differential diagnosis of acute groin injuries in male soccer players.

This prospective cohort study evaluated the incidence of acute groin injuries and estimated the distribution of differential diagnoses in male soccer players. Two senior male soccer divisions (21 teams, 326 players) were followed for 1 year. Patients with groin injuries were examined clinically as well as by herniography, sonography and by plain x-ray of the pelvic bones. Groin injuries accounted for 8% of all injuries. The incidence of groin injury was 0.8/1000 h of exposure. Thirteen (52%) of the 25 patients were clinically considered to have a muscle/tendon injury. However, when using sonography, muscle/tendon injury was only verified in 1 patient. Clinical suspicion of hernia or incipient hernia was evident in 4 (16%) of the patients, while 14 (56%) had a pathological finding at herniography. Clinical and paraclinical (i.e. diagnostic methods using imaging and other advanced techniques) diagnoses do not correspond very well in acute groin injury.

Acute Disease↗
PubMed1999

Fluoride intake by infants.

Many infants are fully or partially breast fed during the early months of life; however, the percentage of such infants decreases to about 30 percent by 4 months of age. The majority of US infants are fed formulas for most of the first 10 months of life. Although fluoride (F) intakes by fully breast-fed infants are low, F intakes by partially breast-fed infants and by formula-fed infants are highly variable, depending primarily on the F content of the water used to dilute concentrated liquid or powdered infant formula products. In communities with F content of the drinking water less than 0.3 ppm, F consumption by many infants will be 30 to 40 micrograms.kg-1.d-1. The addition of a F supplement of 0.25 mg/d for a 4 kg infant would increase the F intake by 63 micrograms.kg-1.d-1, resulting in a total intake of about 100 micrograms.kg-1.d-1, an intake in the range believed to be associated with development of fluorosis of the permanent teeth. However, for the US infant population generally, many fewer infants are exposed to high F intakes from formula plus a supplement (recommended only for communities with water providing less than 0.3 ppm F) than from formula alone in communities with F content of 1 ppm in the drinking water. In assessing the possible effects of F intake during infancy on development of fluorosis, it is important to recognize that infant feeding practices have changed greatly during the past 30 years. In the 1960s, most infants over 4 months of age were fed fresh cow's milk and intakes of F were therefore low. By the mid 1970s a trend toward more extended feeding of formula was evident and this trend has continued into the 1990s. Prolonged exposure to high intakes of fluoride during infancy is much more common now than in the past.

Animals↗
PubMed1999

Fluoride augments the mitogenic and antigenic response of human blood lymphocytes in vitro.

It has been shown that fluoride, the agent responsible for reduction of dental caries worldwide and a recognized proliferative agent, is an adjuvant when given intragastrically to rats. Furthermore, plasma fluoride levels increase in humans after various fluoride treatments. The studies presented here show that fluoride also has the ability to affect the cells of the human immune system. This was tested by measuring the effect of sodium fluoride (NaF) on cytokine production by human whole blood cells stimulated in vitro. These studies revealed that NaF augments the human lymphocyte response from human blood to a mitogen (phytohemagglutinin, PHA) or a specific antigen (morbilli antigen from infected cells, MorbAg). The cytokine interferon-gamma (IFN-gamma), released from activated T and/or NK cells, was significantly (p<0.01) increased when whole blood cells were simultaneously incubated with 0.62 mmol/l NaF and PHA compared to PHA alone. This tendency was also true for NaF and MorbAg. The lymphocyte activation marker interleukin-2 receptor (measured in soluble form) increased after simultaneous stimulation of the cells with PHA and 0.62 mmol/l NaF compared to stimulation with PHA only. However, 0.62 mmol/l NaF did not enhance interleukin-6 release, in blood mainly produced by monocytes. The ability to influence the IFN-gamma release during an immune response could be one of the primary means by which the fluoride ion influences the immune system.

Adjuvants, Immunologic↗
PubMed1999

HgCl(2)-induced human lymphocyte activation in vitro: a superantigenic mechanism?

Mercuric chloride (HgCl(2)) has been proposed to be a mitogen for human blood lymphocytes in vitro. In our previous study, we demonstrated that HgCl(2) preferentially stimulates the CD4+ T cell subset to blast transformation and DNA synthesis and that the reaction is dependent on CD14+ accessory cells. In order to characterise the responding cells further and to elucidate the mechanism of T cell activation, the T cell receptor (TCR) Vbeta chain expression of the blast-transformed cells was analysed by monoclonal antibodies and flow cytometry. The 22 TCR-Vbeta-specific antibodies used were found to react with 55-80% of the naive CD4+ and CD8+ blood T cells from the different donors. Six to 18% of the lymphocytes, mainly CD4+ T cells, were blast transformed after addition of HgCl(2). The distribution of the lymphoblasts carrying certain TCR Vbeta chains were skewed, and 15-40% expressed the TCR Vbeta2 chain. Furthermore, if cells were pretreated for 5 days with HgCl(2), whereafter recombinant interleukin-2 in fresh medium was added, the TCR Vbeta7+ T cell subset was also stimulated to blast transformation. The superantigen staphyloccal enterotoxin B, as a control, induced blast transformation in 10-26% of the lymphocytes, mainly CD4+ T cells, which were, as expected, positive for Vbeta3, Vbeta12, Vbeta14 or Vbeta17. We conclude that HgCl(2) has characteristics of a superantigen, activating the human lymphocytes in a Vbeta-chain-selective manner in vitro.

CD4-Positive T-Lymphocytes↗
PubMed1998

[Can sports injuries be prevented? Troubling shortage of controlled trials on the effects of prevention].

A review of literature on the prevention of sports injuries shows many preventive measures to have been suggested, but few clinical trials to have been performed. A database search yielded only seven prospective, randomised studies, of which two showed soccer and running injuries to be preventable using a combination of preventive measures. Other clinical trials have shown it possible to prevent certain types of injury in other sports as well. The use of prophylactic ankle stabilisers and/or proprioceptive ankle disc training to reduce the incidence of ankle sprain is well documented. Of two studies presenting preventive measures to reduce the incidence of knee ligament injuries, one showed the risk of knee sprain in American football to be reducible by means of a knee brace, and the other that the risk of anterior cruciate ligament injuries in soccer could be reduced by proprioceptive training. Several commonly used preventive measures, such as stretching, taping, mental training and controlled rehabilitation, still await further documentation or the scrutiny of a clinical trial.

Athletic Injuries↗
PubMed1998

Acute exposure to mercury from amalgam: no short-time effect on the peripheral blood lymphocytes in healthy individuals.

Mercury, released from dental amalgam, has been considered to adversely affect the human immune system. This study has been performed in order to evaluate if an acute low-dose mercury exposure, achieved by total amalgam removal in 10 healthy individuals, would affect the immunocompetent cells in human blood when the mercury level in blood and plasma was increasing. Induction of lymphocyte proliferation, measured as spontaneous de novo DNA synthesis, and total T cells, CD4+ T cells, CD8+ T cells, and B cells, was studied prior to and 7, 31, and 48 h after amalgam removal. In addition, the levels of interleukin-6 (IL-6) and C-reactive protein (CRP) in serum/plasma were measured. Despite a significant increase of the plasma mercury levels within 24 h after intervention, no significant influence on the peripheral blood lymphocytes could be detected during the first 48 h. The serum IL-6 levels increased significantly within 48 h after intervention, but were still low and within normal range. No influence on the CRP levels up to 7 d after amalgam removal was detected.

Adult↗