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M J Olsson

Publications and source records attributed to M J Olsson.

At least 19 recordsLinked to original sources
PubMed2001

Evidence of odor priming: edibility judgements are primed differently between the hemispheres.

In olfaction, there is only weak evidence of repetition priming. Repetition priming was therefore investigated in two experiments using birhinal presentation of odors at study and monorhinal at test. Experiment 1 demonstrated repetition priming for repeated judgements of edibility in terms of response latency, but not in terms of correctness. No differences were found between the hemispheres (nostrils). Experiment 2 utilized a slightly different design, in which identity of odors was studied and judgement of edibility was tested. This time, only the right hemisphere (RH) was associated with priming. This persistence of RH priming should be seen in the light of a general tendency for superiority of the left hemisphere for correctly judging edibility. It is concluded that the olfactory system benefits from previous exposure/processing just as do vision, audition and touch. In line with previous research in vision, it is suggested that RH priming may be more associated with perceptual priming and left-hemisphere (LH) priming with conceptual priming.

Adult↗
PubMed2000

Quantification of odor quality.

The relationship between odor quality and molecular properties is arguably the most important issue in olfaction. Despite sophistication in the chemical characterization of molecules, accompanying perceptual characterization has had little quantitative usefulness, relying mostly on enumerative description. As a result of weak interest in the topic outside industry and little agreement regarding how to measure quality, the field of olfactory psychophysics has failed to develop a substantial database for odor quality and has offered little help to other researchers, e.g. neurobiologists, in choice of stimuli, interpretation of outcome or testable hypotheses. This review scrutinizes how psychophysicists and others have measured quality and offers criteria for useful techniques. Most measures have had a subjective component that makes them anachronistic with modern methodology in experimental behavioral science, indeterminate regarding the extent of individual differences, unusable with infrahumans and of unproved ability to discern small differences. Techniques based upon performance, rather than on the more common reporting of mental content, offer firmer possibilities for growth. These techniques inevitably tap the discriminative basis of perception. The nonsubjective techniques have high sensitivity, can have counterparts in infrahuman research, are suitable to examine individual differences and yield non-negotiable answers with potential archival value. Discriminative techniques have their limitations, too-principally excess sensitivity that abridges their use to comparisons between similar-smelling stimuli. Research has begun to extend that range and may overcome the limitation. Application of discriminative methods may have the side-effect of shifting focus in structure-activity research from searches for molecular least common denominators that underlie often vague similarity to the search for molecular properties of importance in discrimination of small differences.

Humans↗
PubMed2000

Psychometrics of odor quality discrimination: method for threshold determination.

There is no natural physical continuum for odor quality along which an odor quality discrimination (OQD) threshold can be measured. In an attempt to overcome this problem, the substitution-reciprocity (SURE) method defines a framework for the measurement of an OQD threshold. More specifically, it (i) defines a threshold concept for OQD, including the quantification of qualitative change of the stimulus, and (ii) suggests how to avoid perceived intensity as an unwanted cue for discrimination. In doing this, the psychometric properties of odor quality in the case of eugenol and citral are investigated using both discrimination (experiment 1) and scaling (experiment 2). Based on discriminatory responses, a change of approximately one-third in stimulus content was needed to reach the OQD threshold for eugenol and citral.

Adult↗
PubMed1999

Implicit testing of odor memory: instances of positive and negative repetition priming.

The study provides a test and evaluation of a new repetition priming procedure designed to solve problems in investigating olfactory-specific priming. Although the results did not reveal any overall priming effect, a post-hoc analysis showed that incorrectly identified odors were more quickly processed than control odors, whereas correctly identified odors were processed more slowly These results are discussed and interpreted as instances of positive and negative repetition priming respectively.

Adult↗
PubMed1998

An integrated model of intensity and quality of odor mixtures.

Several models of how odors mix to form new percepts have been presented during the last decades. Almost all these models have concerned the perceived intensity of mixtures rather than the perceived quality of mixtures. In 1994 Olsson suggested an integrated model for how perceived intensity and quality of the mixture can be predicted from the perceived intensities of the single substances. A generalized version of this model is proposed here. The model can be viewed as an extension of vector summation. The current study reviews support for this model. In doing that, assumptions of the model are defined and tested against data. It is shown how odor interaction, when the process is seen from the view of the observer, reduces to a set of simple rules that are consistent across levels of intensity and combinations of odorants.

Humans↗
PubMed1998

Leucoderma treated by transplantation of a basal cell layer enriched suspension.

The aim of this study was to test the usefulness of a melanocyte-enriched cell suspension for the treatment of leucoderma. After removal of a superficial (4-30 cm2) skin sample, the cells were mechanically separated in a trypsin-EDTA solution, centrifuged and washed in a melanocyte medium. The melanocyte-enriched epidermal cell suspension devoid of stratum corneum and stratum granulosum was then applied to the dermabraded depigmented skin. The 26 patients treated had piebaldism (three), vitiligo vulgaris (17), segmental vitiligo (three), halo naevi (one), naevus depigmentosus (one) and chemical leucoderma (one). In patients with widespread piebaldism we found that by diluting the cell suspension the recipient area could be increased to up to 10 times the size of the donor area with the same good results as without or with less dilution. In patients with vitiligo areas of between 50 and 90 cm2, the recipient areas were increased three- to fivefold in the donor area. Patients with piebaldism, segmental vitiligo and halo naevi healed completely, as did most patients with vitiligo. In naevus depigmentosus no effect was seen. Our new method for treatment of leucoderma has the advantage that cell culture is not needed and that it is more suitable than epidermal sheet grafts when several small areas are to be treated.

Adolescent↗
PubMed1998

A serotonin-like immunoreactivity is present in human cutaneous melanocytes.

Immunohistochemistry was applied in the investigation of the possible existence of serotonin in human skin. It was found that epidermal melanocytes express a serotonin-like immunoreactivity. The immunoreactivity was associated with both the cytoplasm and the cellular membrane, though the latter was only found in certain cells. The serotonin anti-serum labeled the same cells as NKI-beteb, which is known as a reliable marker of melanocytes. Blocking experiments showed that both serotonin and NKI-beteb have different epitopes in the melanocytes. In in vitro studies, serotonin-like immunoreactivity appeared in approximately 90% of cultured human melanocytes, and was found both in the cytoplasm and also in the nuclei. Thus, we believe the melanocytes to be the origin of serotonin (or a serotonin-like molecule) in the skin.

Antibodies, Monoclonal↗
PubMed1997

Improvement of vitiligo after oral treatment with vitamin B12 and folic acid and the importance of sun exposure.

The aim of this 2-year study was to test the hypothesis that folic acid, vitamin B12 and sun exposure could be helpful in treating vitiligo. One hundred patients with vitiligo were treated with oral folic acid and vitamin B12 after being informed that sun exposure might enhance repigmentation. They were requested to keep a record of sun exposure in summer and UVB irradiation in winter. The minimal treatment time suggested was 3-6 months but should be longer if improvement was achieved. Clear repigmentation occurred in 52 patients, including 37 who exposed their skin to summer sun and 6 who used UVB lamps in winter. Repigmentation was most evident on sun-exposed areas, where 38% of the patients had previously noted repigmentation during summer months. Total repigmentation was seen in 6 patients. The spread of vitiligo stopped in 64% of the patients after treatment. Folic acid and vitamin B12 supplementation combined with sun exposure can induce repigmentation better than either the vitamins or sun exposure alone. Treatment should continue as long as the white areas continue to repigment. Further studies are needed to determine ideal minimal dosages of vitamins and UV exposure, as well as treatment time.

Administration, Oral↗
PubMed1997

Epidermal sheet grafts for repigmentation of vitiligo and piebaldism, with a review of surgical techniques.

Thin epidermal sheets, obtained by a high-speed air-driven dermatome, were used to repigment white areas in 19 patients with vitiligo and one boy with piebaldism. In the depigmented skin to be treated the epidermis was removed by a rotating diamond fraise under topical and/or local anaesthesia injections. The method was used on most parts of the body, including the eyelids and genitalia. The maximum total area treated on each occasion was 190 cm2. Excellent results could be obtained if the vitiligo had been stable and had not increased anywhere during the last 2 years. Lack of immobilization could explain a poor result in some areas. The donor area on the buttocks healed quickly without depigmentation. In the transplanted area milia were observed in the first 6 months. No scarring was seen. The technique has a niche in the treatment of depigmented skin, especially in larger areas.

Adolescent↗
PubMed1996

Differential uptake of chloroquine by human keratinocytes and melanocytes in culture.

The antimalarial drug chloroquine has a high affinity for melanin and accumulates in melanin-rich compartments such as those of the eye. Chloroquine is also deposited in cutaneous tissue, but whether the drug distribution is restricted to melanin-producing cells of the skin is not known. In the present study, the uptake of chloroquine by normal human epidermal keratinocytes was compared with that by melanocytes. Selectively cultivated cells were incubated at drug concentrations ranging between 0 and 10000 ng/ml for periods of up to 48 h. Chloroquine was quantified in cells and medium using high performance liquid chromatography and fluorometric detection. In both types of cells there was a rapid uptake of chloroquine within the first 2 h, followed by a slower uptake for 2-6 h until a steady-state condition was reached. Dose dependency was linear, with no sign of saturation, and approximately ten times higher drug concentrations were attained in melanocytes as compared with keratinocytes. No formation of desethylchloroquine, the major systemic metabolite, was detected in either cell type. The observed affinity of chloroquine for normal epidermal melanocytes in vitro suggests that the density and melanogenic activity of skin pigment cells may influence the cutaneous drug disposition of chloroquine.

Adult↗
PubMed1996

Magnitude estimation of perceived odor intensity: empirical and theoretical properties.

Four subjects judged the odor intensities of 7 pyridine concentrations and a blank. Computer simulations of a judgment model were compared with the empirical data. The model generates data patterns that closely mimic empirical findings. The following patterns were confirmed: (a) A power function relates magnitude estimates and concentration with an exponent in the range of 0.7 to 1.0 (b) The exponent fluctuates so that the level constant is negatively correlated with the exponent. (c) The standard deviation of the responses is a negatively accelerated function of the mean. (d) The skewness of the responses is relatively high for low concentrations and declines toward zero with increasing concentration. (e) The correlation between responses to successive stimuli is highest when successive concentrations are similar.

Adult↗
PubMed1996

Vitiligo.

Explore the source record for details and available documents.

Anesthetics, Local↗
PubMed1995

Ca(2+)-induced Ca2+ oscillations in parathyroid cells.

Parathyroid cells from patients with hyperparathyroidism were first cultured in a growth cocktail supplemented version of Dulbecco's MEM/F12 medium and then used for measurements of the cytoplasmic Ca2+ concentration ([Ca2+]i). Elevation of extracellular Ca2+ from 0.5 to 1.5-3 mM often triggered rhythmic oscillations of [Ca2+]i. Whereas the amplitude of the oscillations remained constant their frequency (0.4-2.6 /min) increased with the Ca2+ concentration and there was sometimes transformation into sustained increase of [Ca2+]i at the highest extracellular Ca2+ concentration. The oscillations were abolished by the inorganic Ca2+ channel blocker Ce3+ and by K+ depolarisation, which lowered [Ca2+]i, as well as by thapsigargin, an inhibitor of the intracellular Ca(2+)-pumping ATPase. The data indicate that extracellular Ca2+ can trigger [Ca2+]i oscillations in parathyroid cells, dependent on mobilisation of the ion from intracellular Ca2+ stores and on influx through non-voltage dependent channels.

Adenoma↗
PubMed1995

Comparison of models of odor interaction.

Subjects rated the overall perceived intensity of concentrations of the odorants cineole, geraniol, hexyl salicylate, and linalyl acetate smelled alone and in binary mixtures. The subjects also rated intensity of specified constituents (e.g. amount of cineole in cineole, and in mixtures of cineole and linalyl acetate). The intensity of the stronger component alone offered a close description of perceived intensity. In addition to the Stronger Component model, two other psychological models (Vector and U model) and two psychophysical models (UPL2 and Equiratio Mixture model) offered descriptions ranging from fair to very good. Psychological models gave better fits, but lack explanatory power. Some results indicated that weaker odors add more potently than stronger odors, an outcome incompatible with these models. The psychophysical models, based on the additivity of single components, generally overestimated perceived intensity. Judgments of individual qualities gave only slight encouragement to any expectation of differences in masking or maskability among odorants. The results highlight the need to test particular critical hypotheses regarding how people perceive mixtures.

Acyclic Monoterpenes↗
PubMed1995

Transplantation of melanocytes in vitiligo.

We report the results of a study on 100 patients (aged 12-68) with vitiligo, who were treated by transplantation of cultured autologous melanocytes to the depigmented areas, after removal of the epidermis at the recipient site by dermabrasion. The melanocytes were cultured from a 2 x 3 cm2 superficial shave biopsy taken from pigmented buttock skin. After 2-3 weeks in culture, 700-1000 cells per mm2 were applied on 60-500 cm2 dermabraded areas, and occluded for 1 week. The repigmented portion of the total treated area amounted to 95-100% in 40 patients, 65-94% in 32, 20-64% in 22, and 0-19% in six. It was more difficult to achieve complete pigmentation on the fingers, elbows and knees. In the first few months following the procedure, the treated areas were often hypo- or hyperpigmented, but after 6-8 months they had acquired the same colour as the surrounding skin. No scarring or other side-effects occurred. The donor site had repigmented after 3-6 months in all but two patients, who also showed poor pigmentation in the transplanted areas. At follow-up after 1 and 2 years in 50 and 10 patients, respectively, the repigmented areas remained unchanged. The method is time-consuming, but the results obtained indicate that the procedure can be valuable in motivated patients, when the extent of vitiligo does not exceed 30% of the total body area, and when the areas to be treated are not actively extending.

Adolescent↗
PubMed1994

Pigment cell transplantation for treatment of vitiligo: a progress report.

BACKGROUND: Because available treatments for vitiligo generally provide unsatisfactory results, the search for viable therapeutic alternatives continues. OBJECTIVE: Our purpose was to evaluate several transplantation procedures with cultured autologous melanocytes for their practicality in treating patients with vitiligo. METHODS: Twenty-seven patients with stable or active vitiligo were treated after superficial dermabrasion with application of suspensions of autologous cultured melanocytes, melanocyte-keratinocyte mixtures, or epidermal sheets established in vitro. RESULTS: Regardless of disease activity, use of each method resulted in repigmentation to a similar degree and without scarring in all patients. Melanocyte suspensions offer several advantages: They are easily prepared, can be applied in a controlled manner, permit coverage of large areas, and produce a homogeneous skin color that affords the best cosmetic restoration. The ultrastructure of transplant sites resembled that of uninvolved skin, with one exception: the melanocytes were located slightly higher than in uninvolved skin. CONCLUSION: Application of cultured autologous melanocytes to lightly abraded skin is an advantageous addition to the treatments available for patients with vitiligo.

Adolescent↗
PubMed1994

Vitiligo: repigmentation with cultured melanocytes after cryostorage.

We have developed a technique through which we can multiply melanocytes in culture from a small specimen of normally pigmented buttock skin and reimplant them into depigmented sites of vitiligo. To date, 90 patients have benefited in our hands from such autologous transplantation of pigment cells. Often we have an excess of cells which we would like to store for later use in the event a patient requires further treatment. We report here on 4 cases in which we have cryostored cultured melanocytes for 6-12 months, reimplanted them into vitiliginous sites of the donor after one week of reculture, and obtained optimal repigmentation. We now routinely freeze melanocytes left over after treatment.

Adult↗