Biomedical subjects

T Johnsson

Publications and source records attributed to T Johnsson.

At least 19 recordsLinked to original sources

PubMed2001

Detection of aflatoxins (G(1-2), B(1-2)), sterigmatocystin, citrinine and ochratoxin A in samples contaminated by microbes.

A method is described for the simultaneous determination of common aflatoxins (G1, G2, B1, B2) and their precursor sterigmatocystin, and also citrinine and ochratoxin A. The method was applied to a building material matrix artificially contaminated with mycotoxin-producing fungi. The method includes extraction, sample pre-treatment and reversed-phase HPLC separation with tandem mass spectrometric identification and quantification using electrospray ionisation on a quadrupole ion trap mass analyser (ESI-MS-MS). Aqueous methanol was used in the initial extraction and solvent partitioning and solid phase extraction in the purification of samples. The HPLC separation was run on-line with the ESI-MS-MS detection. The limit of quantification of the procedure was 200 ng for all compounds. Recoveries of the sample pre-treatment varied from 28 to 99%. The average compound- and concentration-dependent accuracy and precision (RSD) were 21 and 113%, respectively. The method includes small sample volumes (approximately 1 g in 20 ml) and few, non-labour intensive, sample treatment steps. It should allow for a high throughput of samples with good prospects of automation.

Aflatoxins↗

PubMed2000

Potent and nontoxic antisense oligonucleotides containing locked nucleic acids.

Insufficient efficacy and/or specificity of antisense oligonucleotides limit their in vivo usefulness. We demonstrate here that a high-affinity DNA analog, locked nucleic acid (LNA), confers several desired properties to antisense agents. Unlike DNA, LNA/DNA copolymers were not degraded readily in blood serum and cell extracts. However, like DNA, the LNA/DNA copolymers were capable of activating RNase H, an important antisense mechanism of action. In contrast to phosphorothioate-containing oligonucleotides, isosequential LNA analogs did not cause detectable toxic reactions in rat brain. LNA/DNA copolymers exhibited potent antisense activity on assay systems as disparate as a G-protein-coupled receptor in living rat brain and an Escherichia coli reporter gene. LNA-containing oligonucleotides will likely be useful for many antisense applications.

Animals↗

PubMed2000

Mycotoxins in crude building materials from water-damaged buildings.

We analyzed 79 bulk samples of moldy interior finishes from Finnish buildings with moisture problems for 17 mycotoxins, as well as for fungi that could be isolated using one medium and one set of growth conditions. We found the aflatoxin precursor, sterigmatocystin, in 24% of the samples and trichothecenes in 19% of the samples. Trichothecenes found included satratoxin G or H in five samples; diacetoxyscirpenol in five samples; and 3-acetyl-deoxynivalenol, deoxynivalenol, verrucarol, or T-2-tetraol in an additional five samples. Citrinine was found in three samples. Aspergillus versicolor was present in most sterigmatocystin-containing samples, and Stachybotrys spp. were present in the samples where satratoxins were found. In many cases, however, the presence of fungi thought to produce the mycotoxins was not correlated with the presence of the expected compounds. However, when mycotoxins were found, some toxigenic fungi usually were present, even if the species originally responsible for producing the mycotoxin was not isolated. We conclude that the identification and enumeration of fungal species present in bulk materials are important to verify the severity of mold damage but that chemical analyses are necessary if the goal is to establish the presence of mycotoxins in moldy materials.

Aspergillus↗

PubMed1999

Analysis of nicotine, 3-hydroxycotinine, cotinine, and caffeine in urine of passive smokers by HPLC-tandem mass spectrometry.

BACKGROUND: A method is described for the simultaneous analysis of nicotine and two of its major metabolites, cotinine and 3-hydroxycotinine, as well as for caffeine from urine samples. The method was developed to assess exposure of restaurant and hotel workers to environmental tobacco smoke. METHODS: The method includes sample pretreatment and reversed-phase HPLC separation with tandem mass spectrometric identification and quantification using electrospray ionization on a quadrupole ion trap mass analyzer. Sample pretreatment followed standard protocols, including addition of base before liquid-liquid partitioning against dichloromethane on a solid matrix, evaporation of the organic solvent using gaseous nitrogen, and transferring to HPLC vials using HPLC buffer. HPLC separation was run on-line with the electrospray ionization-tandem mass spectrometric detection. RESULTS: The detection limits of the procedure were in the 1 microg/L range, except for nicotine (10 microg/L of urine). Still lower detection limits can be achieved with larger sample volumes. Recoveries of the sample treatment varied from 99% (cotinine) to 78% (3-hydroxycotinine). CONCLUSIONS: The method described is straightforward and not labor-intensive and, therefore, permits a high throughput of samples with excellent prospects for automation. The applicability of the method was demonstrated in a small-scale study on restaurant employees.

Caffeine↗

PubMed1998

Effects of 1-chloro-2,4,6-trinitrobenzene on 5-lipoxygenase activity and cellular leukotriene synthesis.

5-Lipoxygenase (EC 1.13.11.34) is the key enzyme in the regulation of leukotriene synthesis. Here, the effects of various substituted nitrobenzene compounds on 5-lipoxygenase activity and the formation of leukotriene B4 (LTB4) were studied in polymorphonuclear leukocytes (PMNL), B lymphocytes, and human whole blood. 1-Chloro-2,4,6-trinitrobenzene (TNCB) was found to inhibit calcium ionophore A23187-induced leukotriene synthesis in PMNL in a biphasic manner. Thus, 1.0 microM TNCB caused 50% inhibition of LTB4 formation, but only 16% inhibition was found at 10 times higher concentration. In contrast, this higher concentration of TNCB activated the synthesis of LTB4 when PMNL were stimulated with arachidonic acid alone, demonstrating that TNCB can exert both stimulatory and inhibitory effects on leukotriene synthesis depending on the experimental conditions. The inhibitory effect of 1.0 microM TNCB on ionophore A23187-induced leukotriene synthesis could be circumvented by addition of exogenous arachidonic acid. At high concentrations of TNCB (25-100 microM), the drug blocked ionophore A23187-induced leukotriene synthesis. TNCB also inhibited LTB4 formation in B lymphocytes, as well as in human whole blood. The activity of recombinant 5-lipoxygenase was inhibited by TNCB, and reduced glutathione or beta-mercaptoethanol counteracted this inhibition. This suggests that TNCB might inhibit 5-lipoxygenase by alkylating thiol groups. TNCB possessed a high specificity for 5-lipoxygenase with only modest inhibitory effects on 12-lipoxygenase (EC 1.13.11.31), 15-lipoxygenase (EC 1.13.11.12), and phospholipase A2 (EC 3.1.1.4) activities. Taken together, these results show that TNCB can both specifically inhibit and stimulate leukotriene formation and might be useful in further studies on the regulation of 5-lipoxygenase.

Arachidonate 12-Lipoxygenase↗

PubMed1997

Surface-dimpled commercially pure titanium implant and bone ingrowth.

The purpose of this investigation was to examine the effect of the surface macrostructure of a dimpled commercially pure titanium (cp Ti) implant on bone ingrowth in vivo by means of histological examination and a push-out test. Cylindrical implants were inserted in one femur of each experimental rabbit and the animals were killed at 1.5, 3 and 13 months after implantation. The femur with the implant of each animal was then examined in a push-out test. The fracture surfaces of the bone-implant interface after the push-out test were examined under light and electron microscopy. It seems that the dimpled cp Ti surface results in the increased retention of the cp Ti implant in bone due to interlocking between vital bone and the dimples.

Animals↗

PubMed1997

On longitudinal caries index data. A comparison study between cohort and cross-sectional attempts.

The aim of the present study was to compare registered data of caries prevalence and incidence from cross-sectional studies of specified age groups with the corresponding caries data from cohorts of individuals receiving dental health service from the same dental clinic during the years studied. The study covered two 15-19-year groups, who had been offered complete dental care from three years of age in the City of Göteborg for the time periods 1986/7-1990/1. When compared, the longitudinal cohort attempts often gave statistically significant different values to those of the cross-sectional year classes, which should be considered when presenting caries index mean values in dental health reviews. It is not indifferent to choose between longitudinal cohort and cross-sectional year class attempts when searching for dental health treatment effects. Due to the advantages of using longitudinal cohort study methods, and with regard to the differences of the study design used, as pointed out in the study, the use of longitudinal cohort patient material, extracted from cross-sectional epidemiological data bases, could favour analysis of the effects of different preventive dental care programs.

Adolescent↗

PubMed1995

Cellular Fatty Acid profiles of lactobacillus and lactococcus strains in relation to the oleic Acid content of the cultivation medium.

Cellular fatty acids of 10 strains of lactic acid bacteria were analyzed. The purpose of this work was to find lactic acid bacteria with high lactobacillic acid contents. The bacteria studied were unable to synthesize oleic acid. Some strains did not synthesize lactobacillic acid, although all were able to form dihydrosterculic acid. Twenty-one to thirty-four percent of the fatty acid content of Lactobacillus fermentum and L. buchneri was lactobacillic acid, and these species were chosen for future studies of environmental factors affecting cyclopropane fatty acid synthesis.

Journal Article↗

PubMed1993

Microbial associations in periodontitis sites before and after treatment.

Duplicate samples from 110 periodontal sites of 6 mm or more pocket depth in 16 patients were analyzed for the presence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Capnocytophaga spp., Campylobacter rectus, Eikenella corrodens and Fusobacterium nucleatum. The sites were sampled before and after nonsurgical periodontal treatment. No statistically significant associations were found before treatment between any of the analyzed species. After treatment, statistically significant associations were found between E. corrodens and all the other species, F. nucleatum and P. intermedia; Capnocytophaga spp. and C. rectus; P. intermedia vs Capnocytophaga spp. and P. gingivalis; and C. rectus vs Capnocytophaga spp. and A. actinomycetemcomitans. Some of these associations could be explained either by patient-related factors or site-related characteristics such as the pocket depth. The proportion of P. gingivalis seemed to be unrelated to the proportion of P. intermedia in the samples. If one of the analyzed microbes was found in one of the sampled pockets in a patient, the probability of finding that microbe in all the sampled sites in the same patient before treatment was more than 50%. This probability was reduced after treatment for many species, especially P. gingivalis, which showed a probability of zero. The probability of detecting a bacterial species on at least one additional site if it was present on one in the same individual was nearly 100%, both before and after treatment, for all species studied. This study has shown several potential microbial associations in the subgingival plaque flora of deep periodontal pockets.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Extent and severity of periodontal destruction based on partial clinical assessments.

The aim of the present study was (i) to identify the 10 approximal tooth sites that provide Extent and Severity estimates of clinical attachment loss which are maximally coherent to the full mouth scores, and (ii) to evaluate the applicability of such a partial recording system. Data from two subject samples, comprising 192 subjects aged 30-64 yr (sample A) and 175 subjects aged 35-80 yr (sample B), were involved in the development and the evaluation of the system, respectively. Approximal probing attachment loss (PAL) measurements were available from all subjects. A PAL value of > 1 mm was required for a tooth site in order to qualify for the Extent and Severity computations. A full mouth bivariate Extent and Severity Index (FESI) was firstly calculated for every subject in sample A. Multiple regression models applied on data derived from the same sample identified the 10 approximal tooth sites which provided the best correlation to the full-mouth scores (correlation coefficients between partial and full mouth scorings of Extent and Severity 0.85 and 0.88, respectively). All tooth types were found to be represented in this set of sites and the ratio of mesial/distal sites was 6/4. The applicability of a partial recording system (PESI) based on these sites was evaluated in sample B. Fully comparable estimates between PESI and FESI values were obtained, but the degree of correlation varied at different ages. Further adjustments by means of regression models failed to increase the validity and reliability of the PESI.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Structure of perceived handicap in middle-aged males with noise-induced hearing loss, with and without tinnitus.

By using a modified stepwise regression analysis technique, the structure of self-perceived handicap and tinnitus annoyance in 89 males with noise-induced hearing loss was described. Handicap was related to three clusters of variables, reflecting individual, environmental, and socioeconomic aspects, and 60% of the variance in self-perceived handicap was explained by the representatives of these clusters: i.e. 'acceptance of hearing problems', 'social support related to tinnitus' and 'years of education'. Tinnitus had no impact of its own on self-perceived handicap and only a modest portion (36%) of the variance in tinnitus annoyance was explained by 'sleep disturbance' and 'auditory perceptual difficulties'.

Adaptation, Psychological↗

PubMed1993

Accuracy among dentists experienced in forensic odontology in establishing identity.

The aim of this study was to investigate the accuracy of 17 forensic odontologists identifying individuals from two sets of radiographs, one regarded as ante- and the other as postmortem. Each case was observed twice and only one pair out of 31 did not match. The observers were asked to comment about each case, classifying it as easy, moderate or difficult. The results show that one observer was totally correct in the first analysis while four observers made no errors the second time. In the first evaluation 14 observers made between one and seven errors and two observers made 11 errors each. In the second evaluation 12 observers made between one and seven errors and one observer made 13 errors. At the first evaluation, the observers judged 18 of the cases as easy, eight as medium and five as difficult. At the second evaluation, the observers pronounced 13 of the cases as easy, 13 as medium and five as difficult. The corresponding values for the authors were 6, 12 and 13. Most of the mistakes were made on the cases with no restorations and the incorrect answers were found mostly among the difficult cases. In practical forensic work however additional dental chart information is usually available to the forensic odontologist.

Dentists↗

PubMed1993

A method for dental care activities time study using observer monitored counting of frequencies.

In dentistry, there is a need for better understanding of the distribution of the time spent on different activities at dental clinics. In order to investigate these resource aspects, both for the total time and for various categories of personnel and/or patients in dental clinics at the Public Dental Service (PD), Göteborg, Sweden, a time study method was used. The present study reports on the development of the PD's time study method (TSM) and analyses its functionality. The TSM, based on formulated criteria, used a method for an observer-monitored counting of frequencies. Specially trained observers registered the sampled observations for each professional, using a separate code list for each personnel group to which the professional belonged. The observer registered the on-going activity, not the duration of the procedure. Each observer followed several persons working in separated areas of the dental clinic. In 1989, the TSM was tested with the purpose of obtaining mean time values for dental care activities in the PD clinics performing general dental care. This study comprised all personnel categories in the clinic teams. Clinics were randomly selected and stratified according to the amount of dentistry for children in relation to the total time for dental care, reported as the parameter "dentist hours". Eight out of a total of 36 clinics were randomized, two from each strata.(ABSTRACT TRUNCATED AT 250 WORDS)

Dental Assistants↗

PubMed1991

Variance in recovery of periodontitis-associated bacteria caused by sampling technique and laboratory processing.

The influence of sampling procedure and of laboratory processing on the recovery of Bacteroides gingivalis, Bacteroides intermedius, and Actinobacillus antinomycetemcomitans from periodontitis sites was evaluated. Thirty-three adult subjects with severe periodontitis participated in the study. In all, 462 samples from 81 sites were examined. The samples were taken using the paper point technique. The cultivations were performed by use of enriched Brucella agar for determination of total colony-forming units and Bacteroides species, and trypticase soy bean agar for determination of A. actinomycetemcomitans. The risk of getting a false negative result was 4% for B. gingivalis, 20% for B. intermedius, and 38% for A. actinomycetemcomitans. It was considerably reduced if duplicate samples were taken. The sampling procedure alone explained up to 98% of the false-negative results.

Adult↗

PubMed1991

Extent and Severity Index based on assessments of radiographic bone loss.

The purpose of the present study was to develop a partial recording system based on the principles of the Extent and Severity Index, aiming at describing the degree of radiographic alveolar bone loss on a population level. The data analyzed were derived from a subject sample comprising 531 individuals aged 25-75 yr. In these subjects alveolar bone level (ABL) was radiographically assessed at all approximal tooth surfaces. An ABL value of greater than 2 mm was required for a tooth site to be included in the computation of a full mouth bivariate Extent and Severity Index (FESI). A partial recording index (PESI-2) based on 18 ad hoc selected tooth sites depicted in one periapical and one vertical bitewing radiograph was evaluated in comparison with the FESI as well as with partial recording indices based on the 9 and 18 tooth sites which displayed the highest correlation with full mouth scores (PESI-9 and PESI-18, respectively). It was shown that all three partial recording systems generated values reasonably close to the full-mouth scores. However, the fitness of all partial indices varied with age. The potential of the partial indices to predict full-mouth scores could be further enhanced via simple regression models. Such an evaluation should, ideally, be carried out in an independent subject sample.

Adult↗

PubMed1991

Evaluation of a radiographic partial recording system assessing the extent and severity of periodontal destruction.

The purpose of the present study was to evaluate the validity and reliability of a partial radiographic bivariate index system (PESI-2). The principles of the index were applied to data from a random sample of 192 industrial employees aged 30-65 yr. Estimates of Extent and Severity of radiographic bone loss provided by the PESI-2, as well as adjusted estimates by means of simple regression models, were compared to values obtained by a full mouth radiographic examination. It was shown that the values provided by the PESI-2 were of rather high validity and reliability. The use of the adjusting models resulted in increased validity of the severity estimates and enhanced reliability of both components of the bivariate. The results verified the applicability of the PESI-2 in epidemiologic research of destructive periodontal disease.

Adult↗

PubMed1991

Reliability of hypocycloidal tomography for the evaluation of the distance from the alveolar crest to the mandibular canal.

When implants are to be inserted in the mandible posterior to the mental foramen, tomography is required to determine the exact location of the mandibular canal and assess the dimensions of the body and alveolar process. Previous studies have shown discrepancies between the true distance between the alveolar crest and the upper border of the mandibular canal and that measured from computed tomograms. This study evaluates the reliability of such measurements made from hypocycloidal tomograms. Six examiners, three radiologists and three oral surgeons, independently measured the distance from the alveolar crest to the upper border of the mandibular canal in transverse hypocycloidal tomograms of the mandible. Analysis of variance showed an average standard deviation between observers of 1.33 mm. This variation, which is the total of inter- and intra-observer variation conditional upon patient and radiograph, was mainly due to the latter which amounted to a mean of 1.04 mm. Calculation of lower confidence limits showed that these could be decreased by the use of several observers. Various confidence levels, equal to the probabilities of obtaining lower confidence limits which are below the true values, can be used to choose acceptable levels of risk in overestimating the true distance.

Alveolar Process↗

PubMed1990

Periodontal treatment needs assessed by the use of clinical and radiographic criteria.

The aim of the present study was to use a decision making model in order to assess the periodontal treatment needs of a random sample of employees in a large Swedish industrial corporation. The model used provided data on critical bone loss limits for different tooth types and ages, beyond which treatment must be initiated, in order to fulfill the goal of maintaining all teeth in a functional state throughout life. A sample comprising 192 subjects belonging to four age strata (31-35 yr, 41-45 yr, 51-55 yr, and 61-65 yr) was involved. From each subject, a full mouth series of intra-oral radiographs were available. The radiographic bone height was assessed at the mesial and distal aspect of all teeth by measuring the distance between the cementoenamel junction and the bone crest. The clinical examination included assessments of plaque, gingivitis, probing pocket depth, and probing attachment level. The results revealed that (i) only 3.1% of all approximal tooth sites exhibited radiographic bone loss exceeding the critical limit, (ii) all individuals and 70% of the approximal tooth sites were in need periodontal treatment when presence of gingival inflammation (bleeding on probing) was employed as the single criterion for therapeutic intervention, (iii) the proportion of individuals and tooth sites requiring treatment amounted to 98% and 27%. respectively, when a probing pocket depth of at least 4 mm was included as an additional criterion, and 54% and 4.1%, respectively, if a probing depth threshold of 6mm was used, while (iv) the use of bleeding on probing in combination with radiographic bone loss beyond the critical limits disclosed a need of treatment in 40% of the subjects and 2.5% of the approximal tooth sites.

Adult↗