Biomedical subjects

U Ahlström

Publications and source records attributed to U Ahlström.

At least 19 recordsLinked to original sources

PubMed1996

Segregation of motion structure from random visual noise.

A potential source of information about spatial layout, surface slant, and self-motion is provided by transformations of the optic flow field. Theoretical analyses have demonstrated that such flow fields can be decomposed into translation, rotation, expansion, and deformation components. The objective in this study was to investigate the effectiveness of these motions as visual primitives for preattentive scene segregation. The stimuli consisted of two-frame patterns containing 998 dots. A variable number of these dots (5 to 50) were defined as target dots, representing a specific motion structure, with the residual dots defined as a noise field. The observers' task was to identify the location and type of motion structure. On the basis of the number of target dots needed to detect and correctly identify the target structure, it was determined that translation was the most easily detected structure, followed by rotation, expansion, and compression. Deformation was found to have a detection threshold as high as compression. The results are related to other studies of these motion components.

Adult↗

PubMed1995

Perceptual unit formation in simple motion patterns.

The present study investigated the proximal constraints that determine perceptual unit formation under minimal stimulus conditions. Projections of three moving dots, which could form two possible two-dot configurations, were presented to naive observers. In a forced-choice situation, their task was to report which two-dot configuration was perceived as a distinct perceptual unit. The results showed that common motions (arbitrary translations and rigid rotations in the frontoparallel plane) have stronger grouping as compared to different relative motions (expansion/contractions, or simultaneous expansions/contractions and deformations in the frontoparallel plane). It was found that proximal changes of distances between elements in two-dot structures reduce grouping power. Changes of proximal directions, however, did not affect unit formation in two-dot structures at all. The effect of vector algebraic combinations on grouping power in three-dot structures was also investigated. Evidently, visual vector analysis splits up motion combinations into their constituents, and in some cases this contributes to additive effects.

Adult↗

PubMed1994

Immunohistochemical studies of neurochemical markers in normal human buccal mucosa.

The content of various substances, such as regulatory peptides, hormones and structural proteins, was investigated in normal buccal mucosa using indirect immunofluorescence. Thin nerve fibres, which from a morphological point of view were most probably sensory, showed immunoreactivity for substance P (SP), calcitonin gene-related peptide (CGRP), neuropeptide K (NPK) and neurokinin A (NKA). Also galanin (GAL), gamma-melanocyte stimulating hormone (gamma-MSH) and somatostatin (SOM) stained thin fibres were found in the propria, which were, however, few in number and the gamma-MSH staining was weak. CGRP, vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine amide (PHI) and neuropeptide Y (NPY) immunoreactive nerve fibres were observed in close connection to blood vessels. SOM positive cells with processes were found, mostly scattered, in the connective tissue. A population of cells within the epithelium also showed somatostatin immunoreactivity. Protein S-100 (S-100) stained distinct populations of cells at two separate locations. In the propria, cells with one or two slender processes were seen, being mostly single but sometimes forming groups. In the epithelium, dendritic cells with many processes with or without 'spines' were observed, mainly located to the basal layer of the lamina epithelialis. Single nerve fibres and nerve bundles were also stained. Neurofilament (NF) positive fibres, singly and in bundles, as well as endorgan-like structures were seen. Neuron-specific enolase (NSE) and protein gene product 9.5 (PGP 9.5) both stained the same structures, namely single fibres, nerve bundles, nerves surrounding vessels and innervating muscles and glands (if present in the section), as well as Merkel cells. Also with these two markers endorgan-like structures were seen. No clear innervation of the epithelium could be observed with the markers used. No methionine-enkephalin (ENK) or synaptophysin (SYN) immunoreactive material was found.

Adolescent↗

PubMed1994

Hg-provocation of oral mucosa in patients with oral lichenoid lesions.

Five amalgam-bearing patients, with clinically and histologically confirmed oral lichenoid lesions, were tested by applying 0.5% Hg in petrolatum for 10 min to clinically normal mucosa. Control sites were exposed to petrolatum only. Four amalgam-bearing patients with no clinical evidence of oral lichenoid lesions served as controls; they were subjected to similar Hg and petrolatum exposure. After 24 h, biopsies were taken and immunocytochemically analyzed with monoclonal antibodies to lymphoid and nonlymphoid cells. No distinct differences could be detected between the Hg-exposed areas of the lichen patients and those of the nonlichen patients. Furthermore, normal mucosa exposed to petrolatum only showed a staining pattern in the lichen patients which was no different from the nonlichen patients. The findings are discussed with respect to possible mechanisms of development of lichen-like lesions in oral mucosa.

Adult↗

PubMed1993

The analgesic efficacy of diclofenac dispersible and ibuprofen in postoperative pain after dental extraction.

We have compared single oral doses of drinkable diclofenac dispersible (50 mg) with ibuprofen (400 mg) and placebo in a randomized, double-blind, parallel-group trial in 127 adults complaining of at least moderately severe pain after removal of an impacted third molar. Within 40 min both diclofenac and ibuprofen produced significant pain relief that persisted for 6 h. There were no differences between diclofenac and ibuprofen in analgesic efficacy.

Administration, Oral↗

PubMed1993

Motion structure in five-dot patterns as a determinant of perceptual grouping.

The effect of basic motion structures on perceptual grouping was studied with five-dot motion patterns. Four basic motion structures were identified in terms of proximal common and relative motion vectors. In a forced-choice situation, the observers had to decide to which of two pairs of dots a fifth critical dot seemed to belong. Thus, one of two possible three-dot units was chosen by the observers. The two possible three-dot units defined different motion structures, and the chosen motion structure was considered to have stronger grouping power than the alternative structure had. It was found that parallel common motions (perceived translation in the plane) had the strongest grouping power; these were followed by circular common motions (perceived rotation in the plane), concurrent relative motions (perceived translation in depth), and, finally, parallel relative motions (perceived rotation in depth). The results also suggested effects of proximity and orientation of axis of rotation. It is further argued that the relative grouping power of the motion structures could not solely be interpreted in terms of changes of directions and distances between the dots. Instead it is suggested that vector analysis is a fundamental perceptual activity and that basic motion structures determine grouping power.

Adult↗

PubMed1992

Analgesic efficacy of an ibuprofen-codeine combination in patients with pain after removal of lower third molars.

A double-blind, randomised analgesic trial was carried out in 165 patients undergoing surgical removal of one impacted lower wisdom tooth. In a two-dose regimen, the analgesic efficacy of the combination ibuprofen-codeine 200 mg : 30 mg was compared with that of acetylsalicylic acid-codeine 500 mg : 30 mg and codeine 30 mg. Each dose was taken when the patient needed pain relief. The intensity of the pain was measured on a visual analogue scale during the 10-h period after the first dose. The mean pain reduction by Dose 1 in patients on ibuprofen-codeine, acetylsalicylic acid-codeine and codeine was 64%, 45% and 26%, respectively, and the mean duration of effect was 8.3, 6.3 and 5.6 h. According to the pain reduction, duration of effect and pain reduction index after Doses 1 and 1 + 2, there was a significant difference between ibuprofen-codeine and the other two drugs. The maximum pain reduction within 4 hours was 84% with ibuprofen-codeine. This was significantly different from the reduction achieved both with acetylsalicylic acid-codeine (64%) and codeine (35%). Seventeen patients reported adverse events: 5 on ibuprofen-codeine, 4 on acetylsalicylic acid-codeine and 8 on codeine. The most common events were tiredness and vertigo. It is concluded that the combination ibuprofen-codeine 200 mg : 30 mg had greater analgesic efficacy compared to the combination acetylsalicylic acid-codeine 500 mg : 30 or codeine 30 mg in patients with pain after removal of the lower third molars.

Adolescent↗

PubMed1991

Periodontal healing after impacted lower third molar surgery in adolescents and adults. A prospective study.

The effects of impacted lower 3rd molar surgery on periodontal tissues in the adjacent 2nd molar area have been investigated in a prospective study comprising 176 cases from 2 age groups: less than or equal to 20 years (n = 93) and greater than or equal to 30 years (n = 83), respectively. The preoperative and 1-year postoperative examinations included both clinical and radiographic variables. All patients were subjected to a standardized surgical procedure and optimal plaque control pre-, intra- and postoperatively. Early removal of impacted lower 3rd molars with large angulation and close positional relationship to the adjacent 2nd molar proved to have a beneficial effect on periodontal health.

Adolescent↗

PubMed1991

The influence of anatomical, pathophysiological and other factors on periodontal healing after impacted lower third molar surgery. A multiple regression analysis.

A multifactorial approach has been used to identify some predictors of postoperative intrabony defects (IBD) on the distal surface of the adjacent second molar (M2) after impacted lower third molar (M3) surgery. The material consisted of 215 lower third molar removals, performed on 144 persons (age range 16-53 years; mean 27.2 years). The postoperative examination took place 2 years after impaction surgery and included both clinical and radiographic variables. Statistically significant (5% significance level) predictors of IBD found in stepwise multiple regression analyses were: (1) preoperative intrabony defect M2 distal; (2) age at the time of surgery; (3) size of contact-area M3/M2; (4) root resorption M2 distal; (5) probing dept distal surface of adjacent first molar postoperatively; (6) pathological follicle M3. The regression model with IBD as regressand produced a total R2 of 0.45. When the regressand was the difference between IBD and the preoperative intrabony defect, the regression analysis explained 62% of the variance (R2 = 0.62). These regression models explained the variance in terms of the size of the remaining postoperative intrabony defect as well as in terms of periodontal healing after impacted lower third molar surgery.

Adolescent↗

PubMed1989

Immunohistochemical study of neurochemical markers in gingiva obtained from periodontitis-affected sites.

Immunohistochemical methods have been used to study the occurrence of neuronal markers in human gingiva from periodontitis-affected sites. In periodontitis-affected buccal gingiva densely distributed neurofilament (NF)-immunoreactive (IR) fiber bundles were observed in the deeper parts of the propria, while NF-IR single fibers occurred in the superficial propria and occasionally in the buccal epithelium. Periodontitis-affected gingiva obtained from interproximal sites showed only sparsely distributed NF-IR fibers. Single nerve fibers immuno-reactive to the peptides substance P and calcitonin gene-related peptide occurred close to or within the epithelium in both buccal and interproximal gingiva. Around blood vessels neuropeptide Y-, peptide histidine-isoleucine amide- and vasoactive intestinal polypeptide-IR fibers were occasionally observed, while clusters of gamma-melanocyte-stimulating hormone-IR cells were found in the propria, in addition to gamma-melanocyte-stimulating hormone IR nerve fibers. Somatostatin-IR dendritic cells were seen in epithelium and propria of buccal and interproximal gingiva, although a high variability in the number of SOM-IR cells was observed. All neuronal markers studied showed a similar distribution in material obtained from young patients with clinically healthy gingivae, although the number of NF-IR fibers in the propria in these subjects was lower. The results demonstrate that in gingiva obtained from periodontitis-affected sites several different biologically active peptides occur in both nerve fibers and cells. At least some of these substances could possible play a role in the inflammatory process. However, since clinically normal gingiva was shown to contain nerve fibers and cells expressing immunoreactivity to the substances studied, no unique periodontitis-induced expression of the neuronal markers studied was found. Thus, any alteration of these substances during the periodontitis process remains to be elucidated.

Adolescent↗

PubMed1988

Immunohistochemical studies of the neurochemical markers, CGRP, enkephalin, galanin, gamma-MSH, NPY, PHI, proctolin, PTH, somatostatin, SP, VIP, tyrosine hydroxylase and neurofilament in nerves and cells of the human attached gingiva.

Punch biopsies were obtained from the buccal gingiva of the lower third molars. Thin nerve fibres, immunoreactive for calcitonin gene-related peptide (CGRP) or substance P (SP), with possible sensory function, were found in the propria often close to the epithelium, sometimes even penetrating into the basal layers. gamma-Melanocyte stimulating hormone (gamma-MSH)-like immunoreactivity was found in sparsely distributed single cells (except in one specimen containing a dense infiltration), resembling neutrophilic granulocytes of the propria. gamma-MSH was present in several single smooth axons and in thick axon bundles of the propria. Surrounding the blood vessels, neuropeptide Y (NPY), tyrosine hydroxylase (TH), vasoactive intestinal polypeptide (VIP) and peptide histidine isoleucine amide (PHI) immunoreactive nerve fibres were observed. NPY and TH-positive fibres probably represent sympathetic nerve terminals and VIP/PHI-immunoreactive ones may have a parasympathetic function. Papillae of the propria contained VIP-positive fibres not obviously related to blood vessels. The distribution in papillae of PHI-like immunoreactivity was similar but the PHI-positive reaction was also present in a few cells of the propria, especially near blood vessels. Somatostatin (SOM)-positive reaction occurred in a few dendritic-type cells near or in the epithelium and single nerve fibres close to the epithelium. Several thick axon bundles of the propria contained neurofilament (NF)-immunoreactive material. Some thin NF-fibres were found in the papillae and some seemed to penetrate into the epithelium. No galanin, methionine-enkephalin, parathyroid hormone or proctolin immunoreactive material was found. The rather rich content of several neuropeptides in human attached gingiva, as well as other neurochemical markers, is probably associated with sensory and autonomic functions.

Adult↗

PubMed1986

Periodontal healing after impacted lower third molar surgery. Precision and accuracy of radiographic assessment of intrabony defects.

The effect of periodontal tissues of impacted lower 3rd molar surgery has been investigated in a retrospective study comprising 215 cases, 2 years postoperatively. In order to evaluate the precision and accuracy of the radiographic assessment of intrabony defects on the distal surface of the lower 2nd molar using conventional free hand technique, a methodological study was performed on 25 patients. The error variance due to variability in the radiographic reproduction and examiner inconsistency was between 3 and 4% of the total variance. In order to evaluate the radiographic assessment of intrabony defects, intraoral radiographs were taken in the deepest part of the intrabony defect with and without a probe as an indicator. Comparing the 2 sets of radiographs, the deviation was 1 mm or less in 87.9% of the cases. The radiopaque marker enhanced the accuracy of assessment of intrabony defects to 96.7%. The study shows the intraoral freehand technique to be sufficiently reliable as regards radiographic reproduction of the mandibular molar area. It also demonstrates that the radiographic method describes the depth of postoperative intrabony defects on the distal surface of the lower 2nd molar more accurately than probing depth measurements alone.

Adolescent↗

PubMed1985

Multiple doses of paracetamol plus codeine taken immediately after oral surgery.

A double-blind randomized analgesic trial was carried out in 180 patients undergoing surgical removal of an impacted lower wisdom tooth. The patients received the first dose of either paracetamol 1000 mg plus codeine 60 mg, paracetamol 500 mg plus codeine 30 mg or placebo immediately after surgery during the effect of the local anaesthetic. The mean pain intensity, the duration of effect and the number of patients needing additional analgesics were all significantly dose related. In the evaluation procedure a pain intensity index was defined which took into account both the efficacy and the duration of effect. In addition, the analgesic efficacy was calculated over a 12 hour period after first medication and thereby including the efficacy of a second dose, if taken. Paracetamol 1000 mg plus codeine 60 mg followed by paracetamol 500 mg plus codeine 30 mg after around 5 hours was a very effective treatment and over 40% of these patients did not need any further pain relief during the evaluation period. In conclusion, an effective analgesic taken immediately after oral surgery reduces the total pain and diminishes the need of analgesics.

Acetaminophen↗

PubMed1985

Periodontal healing after impacted lower third molar surgery. A retrospective study.

The effect on periodontal tissues of lower third molar surgery, due to impaction or semi-impaction, has been investigated in a retrospective study comprising 215 cases. The post-operative examination took place 2 years after the surgical treatment and included both clinical and radiographic variables. Clinical registrations included the amount of plaque, and presence of gingivitis and periodontal pockets. The results showed a higher incidence of plaque, gingivitis and pockets on the distal surface of the second molar than on other surfaces of the first and second molars. The alveolar bone level distal to the second molar was registered by radiographic examination with a periodontal probe as indicator. 2 years post-operatively, 43.3% of the cases exhibited pocket depths exceeding 7 mm and 32.1% showed intrabony defects exceeding 4 mm. Some factors affecting the periodontal healing after lower third molar surgery are discussed.

Adolescent↗

PubMed1982

Paracetamol plus supplementary doses of codeine. An analgesic study of repeated doses.

A double-blind, multicentre analgesic trial was carried out in patients suffering from pain after removal of an impacted lower wisdom tooth. 266 patients were evaluated after random allocation to treatment with paracetamol 500 mg, paracetamol 500 mg plus codeine 20 mg, paracetamol 500 mg plus codeine 30 mg, or paracetamol 500 mg plus codeine 40 mg. On the day of surgery the patients assessed their own pain intensity hourly on a visual analogue scale. The analysis of the results was carried out according to the method which considered repeated dose intake. A statiscally significant dose-response relationship was obtained between the supplementary doses of codeine and analgesic efficacy. In the comparison of side effects, their frequency increased with increasing amounts of codeine. In clinical practice codeine 30 mg appeared to be the optimal supplement for paracetamol 500 mg.

Acetaminophen↗

PubMed1979

Periapical surgery.

A retrospective study of 572 teeth treated with periapical surgery was undertaken in order to evaluate the influence of preoperative, operative and postoperative factors in the healing process as well as the operation method used. It was also the aim to assess whether the histophatological diagnosis of biopsies taken at the operation could be correlated to healing. Statistical analyses by the AID method and conventional cross-classification methods were performed. Factors of importance were found to be the extent of the destrucion, the operation method used, the bone surrounding the destruction, the quality of the orthograde root filling, the age of the patient, and the marginal bone buccally. The operation method was of importance in large destructions where root fillings were considered as not having properly sealed the canals, and when treating inflamed cysts. The histopathological diagnosis could not be ascribed any definite prognostic value.

Adolescent↗

PubMed1979

Analgesic efficacy and safety of Fenbufen following surgical removal of a lower wisdom tooth: a comparison with acetylsalicylic acid and placebo.

In a double-blind clinical trial a new, non-steroidal anti-inflammatory agent with analgesic properties, Fenbufen, was compared to acetylsalicylic acid (ASA) and placebo. Six hundred (600) out-patients, following surgical removal of an impacted lower wisdom tooth, were divided into three groups and randomly given either Fenbufen (500 mg capsules), ASA (750 mg capsules), or placebo. One capsule was taken immediately after the surgical procedure, followed by another capsule every 6 hours. The duration of treatment was 24 hours. Thus, a total of 4 capsules were taken. Self-evaluation forms were provided to the patients and were returned to the investigators the following day. The results were statistically analyzed. Both Fenbufen and ASA were statistically superior (p less than or equal to 0.01) to placebo in relieving pain. A comparison of the Fenbufen and ASA groups demonstrated a statistically significant (p less than or equal to 0.05) superiority for Fenbufen in relieving pain. Also sleep was less disturbed in the Fenbufen group. Side-effects reported were few, minor in character, and fewer in number in the Fenbufen group.

Adult↗

PubMed1975

Cytogenetic and histochemical analysis of experimental oral carcinogenesis in the rat.

The present investigation has shown that in chemical carcinogenesis progression of malignant epithelial changes in associated with an increased number of cells with chromosomal deviations. Each out of two oncogenic agents with different chemical characteristics had its own non-random pattern. There was usually a close relationship between such chromosomal changes and the simultaneous presence of morphological atypia (dysplasia) and metabolic atypia (aberrant G-6-P.DH activity) from moderate dysplasia and onwards during carcinogenesis. Changes in X-chromosomes, which i.a. in human code the synthesis of G-6-P.DH molecules, could perhaps explain and be reflected in deviating metabolic reactions in premalignant cells.

Animals↗