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Biomedical subjects

G Dahlen

Publications and source records attributed to G Dahlen.

At least 19 recordsLinked to original sources
PubMed2006

Supportive periodontal therapy using mechanical instrumentation or 2% minocycline gel: a 12 month randomized, controlled, single masked pilot study.

OBJECTIVE: To compare the short-term performance of subgingival local delivery of 2% minocycline gel and conventional subgingival debridement in supportive periodontal therapy (SPT) patients. METHODS: Forty adult patients having completed active treatment for moderate to advanced chronic periodontitis were included in a randomized, controlled, single masked maintenance care pilot study. Sites with residual pocket probing depths > or =5 mm and bleeding on probing were treated with either minocycline gel (minocycline-group) or scaling and root planing only (debridement-group) at baseline, 3, 6, and 9 months. Clinical and microbiological examinations were performed at baseline, 3, 6, 9, and 12 months. RESULTS: Full-mouth plaque and bleeding scores remained <10% and <20%, respectively, for both groups throughout the study. In both groups there was a persistent reduction in number of teeth and sites with probing pocket depths > or =5 mm (p<0.05) with no significant differences between the groups. The prevalence of Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Actinobacillus actinomycetemcomitans, Prevotella intermedia, and Prevotella nigrescens, remained at levels < or =10(5) in the majority of patients and sites in both groups. CONCLUSION: This pilot study failed to show a difference between local delivery of 2% minocycline gel as mono-therapy and traditional subgingival debridement in patients on SPT.

Adult↗
PubMed2001

Homozygosity for the C677-->T mutation of 5,10-methylenetetrahydrofolate reductase and total plasma homocyst(e) ine are not associated with greater than normal risk of a first myocardial infarction in northern Sweden.

BACKGROUND: Results of several case-control studies have shown elevated total plasma homocyst(e)ine (TPH) and homozygosity for the point mutation C677-->T in the gene for 5,10-methylenetetrahydrofolate reductase (MTHFR) to be associated with a greater than normal risk of atherosclerotic vascular disease. However, there have been few epidemiologic studies and the interpretation of the results is not clear-cut. OBJECTIVE: To elucidate whether homozygosity for the point mutation C677-->T in the gene for MTHFR, and TPH are risk factors for a first myocardial infarction. DESIGN: A prospective nested case-control study in Northern Sweden. METHODS: Among more than 36000 persons screened, 78 cases satisfied the inclusion criterion of having developed, after sampling, a first myocardial infarction. For each case, two controls matched for sex and age were randomly selected. RESULTS: We found no statistically significant difference among the prevalences of the three possible MTHFR genotypes -/- (no mutation), +/+ (both alleles have the mutation), and +/- among cases and controls in univariate conditional logistic regression analysis. Mean levels of TPH in patients and controls were 12.2+/-4.9 and 12.2+/-3.5 micromol/l (means +/- SD), respectively (NS). CONCLUSIONS: In this study neither homozygosity for the point mutation C677-->T in the gene for MTHFR nor TPH was related to a greater than normal risk of a first myocardial infarction for members of the population of northern Sweden. Further research is needed in order to show whether TPH is an independent risk factor for a first myocardial infarction.

Case-Control Studies↗
PubMed1997

Characterization of Bacteroides forsythus isolates.

Fifteen Bacteroides forsythus strains freshly isolated from patients with periodontitis were used together with three collection strains and one type strain for characterization of growth on various media; determination of enzymatic profiles, antibiotic susceptibility profiles, 16S rRNA ribotypes, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) outer membrane protein profiles, and pathogenicity; and gas chromatography analysis by using a wound chamber model in rabbits. All strains were stimulated by N-acetylmuramic acid, while one strain needed a further supplement such as yeast extract for optimal growth. All strains showed trypsin-like activity. While 10 different ribotypes were found, the SDS-PAGE profiles revealed similar patterns for all strains. All strains were sensitive to penicillin G (MICs, <0.5 microg/ml), ampicillin (MICs, <1.0 microg/ml), amoxicillin (MICs, <0.38 microg/ml), metronidazole (MICs, <0.005 microg/ml), tetracycline (MICs, <0.19 microg/ml), doxycycline (MICs, 0.05 microg/ml), erythromycin (MICs, <0.4 microg/ml), and clindamycin (MICs, <0.016 microg/ml), while they were less sensitive to ciprofloxacin (MICs, <4 microg/ml). B. forsythus did not cause abscess formation by monoinoculation. B. forsythus coinoculated with Fusobacterium nucleatum ATCC 10953 caused abscess formation in 75% of rabbits, while it caused abscess formation in 100% of rabbits when it was coinoculated with Porphyromonas gingivalis FDC 381. In the case of the latter combination, four of six rabbits died of sepsis after 6 to 7 days, and P. gingivalis and B. forsythus were recovered from the heart blood at a proportion of 10:1. B. forsythus strains were highly virulent and invasive in combination with P. gingivalis.

Abscess↗
PubMed1995

Effect of titanium on selected oral bacterial species in vitro.

Titanium granules were tested for their antibacterial effect on strains of Streptococcus sanguis, Streptococcus mitis, Actinomyces naeslundii, Haemophilus parainfluenzae, Fusobacterium spp. and Prevotella intermedia in comparison with amalgam and two of its components, copper and tin. Glass beads were used as controls. The number of viable bacteria was estimated in samples exposed to the various materials for 1, 3, 6 and 24 h, respectively, and the viable counts were related to the baseline value. Titanium showed low antibacterial effect on the species tested. Copper and amalgam showed an expressed toxicity to all species and differed significantly from titanium and glass particles. Gram positive Streptococcus spp. and A. naeslundii showed a lower susceptibility to the metals than the Gram negative species. The antibacterial effect of copper and amalgam test particles on S. sanguis and P. intermedia was significantly decreased in the presence of serum. This study showed that some metals have a toxic effect in vitro on oral bacteria, a fact that may play a role in plaque formation when these materials are used for dental restorations. Titanium did not have a similar antibacterial effect.

Actinomyces↗
PubMed1994

Host-related genotypic heterogeneity of Porphyromonas gingivalis strains in the beagle dog.

The present investigation explored the genotypic heterogeneity of Porphyromonas gingivalis using restriction endonuclease analysis and ribotyping of 64 P. gingivalis isolates, recovered from the periodontal pockets of 3 beagle dogs, 2 of which were reared together. The isolates originated from both healthy and periodontal disease affected sites and thereby enabled the study of bacterial genotype with respect to (i) individual host, (ii) ecological niche (site within host) and (iii) level of periodontal health. Whole genomic DNA was extracted from each isolate and digested by the restriction endonuclease KpnI. Digestion fragments were separated by electrophoresis and transferred onto nylon membranes. The blots were hybridized with a digoxigenin-labeled 16S rDNA probe, and hybridization bands were detected using an anti-digoxigenin antibody conjugated with alkaline phosphatase and enhanced chemiluminescence. Fourteen genomic fingerprints and 13 ribotypes were observed among the 64 isolates. As many as 8 distinct fingerprints were detected within a single host and up to 4 fingerprints within a single periodontal pocket. The dogs reared together shared 2 common clonal types but also exhibited clonal types unique to each dog. No clear association between clonal type and periodontal health status could be made. The results revealed an extensive intra-host genotypic heterogeneity of P. gingivalis strains in the beagle dog and indicated that ribotyping was a sensitive method for differentiating clonal types within species.

Animals↗
PubMed1993

Six-year progression of destructive periodontal disease in 2 subgroups of elderly Chinese.

Two groups of elderly chinese were selected from a large epidemiological sample on the basis of a low ("best" group) or a high ("worst" group) number of sites with attachment loss levels > or = 6 mm and/or pocket depth > or = 4 mm and at least 16 teeth present. Six years later the patients were clinically reexamined and the subgingival microflora was assessed. This paper presents the clinical characteristics of destructive periodontal disease progression among the two subgroups. The "best" group lost an average of 1.8 teeth, contrasting the average loss of 5.3 teeth among the "worst" group. Virtually all teeth lost among the "worst" group had a baseline attachment loss level > or = 4 mm, in contrast to 48% among the "best" group. While dental caries could be identified as a cause of tooth loss in both groups, the excess tooth loss among the "worst" group seems attributable to periodontal destruction. The average of 1.21 mm attachment/site lost among the "best" group was not statistically significantly different from the 1.36 mm/site lost among the "worst" group during the 6 years. Individual mean losses of attachment ranged from a gain of 0.03 mm to a loss of 3.19 mm. An attachment loss > or = 2 mm at a site was highly positively associated with a high initial attachment loss level (> or = 4 mm) at that site among the "best" group, whereas a highly negative association was seen among the "worst" group.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1991

Lp(a) lipoprotein in patients with arterial insufficiency of the lower extremities.

The serum concentration of Lp(a) lipoprotein was determined in 66 patients with peripheral arterial insufficiency of the lower extremities (PAI) and 164 controls. The mean level was higher among the patients than among the controls (236 +/- 248 vs. 129 +/- 159 mg/l, p = 0.01), and values above 300 mg/l were more common among the patients (22/66 vs. 21/164, p less than 0.001). The difference between the 26 female patients and the 94 female controls was statistically significant (280 +/- 268 vs. 118 +/- 141 mg/l, p less than 0.001), but not the difference between the 40 male patients and the 70 male controls (208 +/- 235 vs. 142 +/- 182 mg/l). A high Lp(a) lipoprotein level was not associated with a high LDL-cholesterol level, and there was no significant correlation between the serum levels of Lp(a) lipoprotein and triglycerides++, total cholesterol or HDL-cholesterol. The results indicate, that high Lp(a) lipoprotein levels may be a risk factor for PAI in women.

Adult↗
PubMed1991

A 4-quadrant comparative study of periodontal treatment using tetracycline-containing drug delivery fibers and scaling.

The present study describes results on selected clinical and microbiological parameters obtained by periodontal treatment with ethylene vinyl acetate fibers containing 25% by weight tetracycline hydrochloride placed into the periodontal pocket alone or in combination with scaling. Supragingival plaque control was maintained throughout the study by weekly professional cleaning and 0.2% chlorhexidine mouthrinses. Controls included untreated sites and sites treated by conventional scaling alone in a 4-quadrant split-mouth design. The experiment was conducted on 95 teeth from 10 subjects with periodontal pockets greater than or equal to 6 mm which initially bled on probing. All treatments resulted in changes indicative of effective therapy. Pocket depth was reduced, bleeding on probing decreased and gingival index scores decreased. Parallel to the clinical changes, all treatments reduced total bacterial numbers, % black-pigmented Bacteroides, motile bacteria, non-motile rods, and produced a proportionate increase in cocci. Fiber therapy with or without scaling reduced bacterial counts by approximately 2 orders of magnitude when evaluated at 62 days post-therapy. The combination of fiber therapy with scaling was particularly effective, suggesting a possible synergy between these forms of therapy. The combined therapy eliminated bleeding on probing, and black-pigmented Bacteroides, and produced the greatest mean reduction in pocket depth.

Adult↗
PubMed1990

Apolipoprotein E phenotypes in Finnish youths: a cross-sectional and 6-year follow-up study.

Apolipoprotein E (apoE) polymorphism is a genetic determinant of plasma lipid levels and of coronary heart disease (CHD) risk. We determined the apoE phenotypes and plasma lipid levels in 1577 youths aged 3 to 18 years in 1980. The subjects were randomly selected from five areas of Finland. ApoE phenotyping was performed directly from plasma by isoelectric focusing and immunoblotting. The apoE allele frequencies in the population sample were epsilon 2 = 0.039, epsilon 3 = 0.767, and epsilon 4 = 0.194. There were no differences in the apoE phenotype distribution between East and West Finland or between sexes. The concentrations of serum total cholesterol, low density lipoprotein cholesterol, and apolipoprotein B increased with apoE phenotype in the order of E2/2, E3/2, E4/2, E3/3, E4/3, and E4/4. This increase was already seen in 3-year-old children; it was observed in both sexes, but was clearer in males than in females. The mean levels of high density lipoprotein (HDL) cholesterol, apolipoprotein A-I, triglyceride, Lp[a] lipoprotein, and the activity of lecithin:cholesterol acyltransferase did not differ between the apoE phenotypes. The observed differences in serum cholesterol remained fairly stable during the 6-year follow-up from 1980 to 1986, while the mean serum cholesterol concentration in the whole study population decreased by 6.3%. This study confirms the reported higher frequency of the epsilon 4 allele in Finns as compared to most other populations; this may contribute to the high rates of CHD in Finland as compared to most other populations. The results do not, however, explain the higher rate of CHD in East Finland in comparison to the western part of the country.

Adolescent↗
PubMed1988

Recurrence of angular cheilitis.

The incidence of recurrence of angular cheilitis following a successful antimicrobial treatment was studied in 48 patients. Clinical assessments including a microbial examination were carried out 8 months and 5 yr after termination of treatment. Eighty percent of the patients reported recurrence of their angular cheilitis on one or more occasions during the observation period. Patients with cutaneous disorders associated with dry skin or intraoral leukoplakia had an increased incidence of recrudescence. Neither the presence of denture stomatitis nor the type of microorganisms isolated from the original lesions of angular cheilitis, i.e. Candida albicans and/or Staphylococcus aureus, were associated with the number of recurrences. The present observations indicate that treatment of the majority of patients with angular cheilitis should be considered in a longer perspective than previously supposed, due to the short lasting therapeutic effects of the antimicrobial therapy.

Adult↗
PubMed1986

Lp(a) lipoprotein as a risk factor for myocardial infarction.

The Lp(a) lipoprotein is structurally related to low-density lipoprotein but is found in lower plasma concentration. It has been associated with coronary disease in several white populations. To test the generalizability of this association, we measured serum Lp(a) by quantitative immunoelectrophoresis in 303 Hawaiian men of Japanese ancestry with a prior myocardial infarction (MI) and in 408 population-based controls. Mean values were 17.1 and 13.7 mg/dL (0.171 and 0.137 g/L), respectively. Increased risk for MI was shown mainly for men in the upper quartile of the Lp(a) lipoprotein distribution (greater than or equal to 20.1 mg/dL [greater than or equal to 0.201 g/L]). Odds ratios at younger than 60, 60 to 69, and 70 years of age or older were 2.5, 1.6, and 1.2 times those for men in the lower three quartiles, respectively. In a multiple logistic model the association with MI remained significant and was not explained by differences in total cholesterol levels, high-density lipoprotein or low-density lipoprotein cholesterol levels, subscapular skin fold, systolic blood pressure, history of smoking, alcohol consumption, or age. We conclude that Lp(a) is an important attribute that should often be considered when coronary heart disease risk is assessed.

Aged↗
PubMed1986

Relationship of angiographically defined coronary artery disease to serum lipoproteins and apolipoproteins in young survivors of myocardial infarction.

The relationship of serum lipoprotein and apolipoprotein concentrations to angiographically determined coronary artery disease was investigated in 105 consecutive male survivors of myocardial infarction under the age of 45. Concentrations and composition of lipoproteins, lipid indexes, and nonlipid risk factors (tobacco consumption, hypertension, reduced glucose tolerance, and obesity) were related to a recently developed scoring system for semiquantitative estimation of diffuse coronary atheromatosis, as well as to the number and severity of significant coronary artery stenoses. The concentrations of cholesterol in very low-density lipoprotein (VLDL), low-density lipoprotein (LDL), and high-density lipoprotein (HDL), in combination with serum triglyceride or VLDL triglyceride level, comprised the best set of independent discriminatory lipid variables between patients and control subjects. In the patients, LDL cholesterol and apolipoprotein B levels showed strong relationships to the extent and severity of coronary atheromatosis but not to the number and severity of distinct coronary stenoses. HDL2 cholesterol concentration correlated inversely with the coronary atheromatosis score, whereas other variables reflecting HDL concentration and composition or VLDL lipids were not independently related to any of the coronary scores. The LDL triglyceride level, an index of intermediate-density lipoprotein (IDL) accumulation, was significantly correlated to the coronary atheromatosis score in univariate analysis. Nonlipid risk factors were correlated neither to coronary atheromatosis nor to severity of stenoses. Stepwise multiple regression analyses of data adjusted for age, cumulative tobacco consumption, and weight indicated that 18% of the variation in the coronary atheromatosis score could be accounted for by levels of apolipoprotein B. Addition of other lipoprotein variables or the nonlipid variables hypertension and glucose tolerance did not significantly increase the value of R2. When ratios of lipoprotein lipids and apolipoproteins were included in the regression model, the highest multiple correlation coefficient was obtained with the LDL/HDL cholesterol ratio alone (R2 = .22). The present data demonstrate the importance of elevated LDL cholesterol and apolipoprotein B concentrations for the development of coronary atheromatosis in young male survivors of myocardial infarction. The lack of correlations between the levels of lipoprotein lipids and serum apolipoproteins and the severity of coronary stenoses suggests that mechanisms other than disturbances of lipoprotein metabolism may be involved in the progression of more advanced coronary lesions.

Adult↗
PubMed1985

Genetics of the Lp lipoprotein in Japanese-Americans.

Segregation analysis of four Lp assays on 557 children in 227 families reveals a dominant major gene and a residual heritable component that may reflect one or more alleles of weaker effect. Close or moderate linkage to esterase-D (ESD) is excluded.

Aged↗
PubMed1979

Ultrastructural localisation of lipopolysaccharide-binding sites with peroxidase-conjugated lipopolysaccharides.

The localisation of lipopolysaccharide-binding sites on erythrocytes with peroxidase-coupled LPS is described. LPS was isolated from Fusobacterium nucleatum (Fus MC-8) by phenol-water extraction. The LPS was coupled to horseradish peroxidase by the two-step method of Avrameas and Ternynck (1971). The biological and serological activities of the conjugated LPS were compared with those of the native material. Peroxidase could be coupled to LPS without significant loss of endotoxic or serological activity. The LPS-peroxidase conjugate could be demonstrated on erythrocytes by light and electron microscopy.

Animals↗
PubMed1979

Effect of smoking on serum levels of HDL apoproteins.

Quantitative determination of HDL apoproteins in serum from 97 healthy men showed a significantly lower apoA-I and apoA-II level in smokers than in non-smokers. Also a significant, negative correlation was found between the apoA-I or apoA-II levels, and the number of cigarettes smoked per day.

Adult↗