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Biomedical subjects

A Johannesson

Publications and source records attributed to A Johannesson.

29 records · Page 2Linked to original sources
PubMed1982

Nerve regeneration across an extended gap: a neurobiological view of nerve repair and the possible involvement of neuronotrophic factors.

We have compared the anatomic and functional regeneration of a transected sciatic nerve following regrowth from its proximal stump through either preformed empty mesothelial chambers or autologous nerve grafts bridging a 10 mm gap. Within the mesothelial chambers an organized multifascicular nerve trunk forms between the proximal and distal stumps. After 3 months, distal segment cross sections from the mesothelial chamber and nerve graft groups did not differ with respect to axonal density or distribution of axonal diameters. Mean conduction velocities across the gaps were also similar, although the nerve graft group had a wider distribution of velocities. Little or no regeneration was evident when the gap between the nerve stumps was left empty. These results suggest that if the regrowing proximal stump is in an appropriate environment, it can form a well organized and oriented nerve trunk. In the mesothelial chambers, the regenerating nerve is surrounded by a loose cellular stroma and a small amount of interstitial fluid, which was found to contain trophic activity for cultured rodent sensory neurons. Such factors may also support nerve regeneration in vivo.

Animals↗
PubMed1982

The effect of occlusive treatment on human skin: an electron microscopic study on epidermal morphology as affected by occlusion and dansyl chloride.

The effect of occlusion on epidermal morphology was studied at electron microscopic resolution. the morphological changes recorded were relatively mild, though conspicuous, and consisted in dilatation of the intercellular space, appearance of cytoplasmic vacuoles and an oedematous change in the dermis. Stereological analysis showed that the dilatation of the intercellular space had a biphasic time-dependent course. Dansyl chloride applied under occlusion was shown to cause the same type of changes as did simple occlusion, but the changes appeared earlier.

Adult↗
PubMed1982

The deposition of immunoglobulins and complement in stratum corneum in microscopic lesions in patients with active psoriasis: the relationship to hyperproliferation.

The morphology of the horny layer was utilized to determine the age distribution of corneocytes in early psoriatic lesions and in their vicinity. By using the age distribution the number of corneocyte layers found in any time interval could be obtained and expressed as the rate of corneocyte layers formed. Deposits if immunoglobulins G, M and A and C3 were also age-distributed in a similar way. In the period during which the horny layer was formed, variation in the rate of corneocyte formation could be related to the appearance of immunodeposits. Hyperproliferation was found to precede deposits of immunoglobulins G, M and A and C3 by one to several days. Deposits were examined both visually and by means of microfluorometry, with the same result. The specificity of the deposits was established in two ways. A Fab2-anti-immunoglobulin conjugate was used to detect a possible Fc receptor binding. This was not demonstrated. Albumin was used as a plasma filtrate marker. Albumin was not found in the horny layer but was abundant in the intercellular spaces in the rest of the epidermis. It was concluded that the immunodeposits found in the early lesions of psoriasis are a secondary phenomenon during the initiation of a psoriatic lesion.

Adult↗
PubMed1982

Corneocyte morphology and formation rate in lichen planus and experimental parakeratosis in subjects with and without psoriasis.

In a recent paper changes in corneocyte morphology and formation rate in psoriasis have been established. In the present study the specificity of these alternations were analysed in two situations. Early lichen planus papules were chosen as a model of hyperproliferation with hypergranulosis and orthohyperkeratosis. Hyperproliferation with parakeratosis was induced by nonanoic acid (CH3(CH2)7COOH) as an experimental model in psoriatics and non-psoriatics. In lichen planus papules, the rate of corneocyte layer formation was 2.4 times that of the non-involved skin. In psoriasis, a similar rate was found in parts with hypergranulosis. A 13% decrease in corneocyte diameter took place in lichen planus lesions--similar to that found in psoriasis. The corneocytes in lichen planus were also thicker than normal cells, though their volumes were similar. Thickness decreased in more superficial locations of these corneocytes. Swelling was a finding during the histological procedure, Corneocytes in the lesion increased markedly in volume, due to swelling. The parakeratosis elicited by nonanoic acid showed cells with irregular membranes and nuclei with non-flattened and irregular borders. The rate of corneocyte layer formation was 2.6 times that of the normal skin. The epidermal reaction to the superficial damage by nonanoic acid did not differ between psoriatics and non-psoriatics. This type of parakeratosis was distinctly different from that present in psoriasis.

Adult↗
PubMed1981

The rate of corneocyte formation in microscopic lesions in patients with active psoriasis.

Microscopic lesions in active psoriasis were identified after careful examination with a magnifying glass in areas free of macroscopic lesions and of hair follicles. Biopsies were excised without anesthesia, immediately frozen and cryostat-sectioned. Care was taken to preserve the horny layer which was stained to reveal corneocyte membranes and nuclei when present. The interlocking sheets of corneocyte layers made it feasible to outline and trace intercellular spaces parallel to the surface and count the number of corneocyte layers between pairs of these. It was assumed that the location of such a space in the horny layer indicates the period of time from its formation. This information was used to assess the rate of corneocyte layer formation at specified intervals of time. The result shows that adjacent areas of the horny layer could be compared and relative rates of corneocyte layer formation computed. In the parakeratotic part of the early lesions of psoriasis studied the rate of corneocyte layer formation was 15 times higher than that in the non-involved skin. The peak rate, coincident with parakeratosis, was preceded by a number of thickened corneocyte layers. These also showed an increased rate of formation, up to 6.6 times that in non-involved skin. There was no acanthosis in the lesions studied. A subepidermal cellular infiltrate was observed. Periods of rapid corneocyte formation with parakeratosis were often short (not more than one day). These were interrupted by periods with a lower rate. The relationship between corneocyte morphology and stratum corneum kinetics is a distinct feature in the early psoriatic lesion.

Adult↗
PubMed1981

HLA-A,B,C and DR antigens in psoriasis.

51 psoriasis vulgaris patients and 93 controls were tested for HLA-A,B,C and DR antigenic frequencies. Significant increases of B17, Cw6 and DR7 were documented in the patient group, as well as a decreased frequency of DR1. The significance of these findings is discussed. DR7 occurred more often together with Cw6 in psoriasis patients than in controls, which might suggest that there are at least two interacting HLA linked genes which increase the disease susceptibility and possibly one DR1 linked gene associated with resistance to the disease.

Gene Frequency↗
PubMed1980

The rate of formation of corneocyte layers after stripping the noninvolved psoriatic skin and its relation to parakeratosis and epidermal enzyme levels.

Corneocyte layer formation rate using dansyl chloride as corneocyte marker was followed in noninvolved skin during a period of 2 weeks after that the skin had been subjected to cellophane stripping. The rate increased after stripping in 7 of 9 tested but it was not paralleled by any apparent parakeratosis. In 1 of 9 patients a Koebner reaction occurred. The corneocyte formation rate in the Koebner reaction was 6.1 times that of the noninvolved skin and with a degree of parakeratosis of 41%. In involved skin, a positive correlation, coefficient 0.81, was shown between corneocyte layer formation rate (range 3.9-15.2 layers/day) and degree of parakeratosis (range 24-100%). In the skin 5 to 14 days after stripping the rate of formation of the corneocyte layer varied from 1.6 to 8.2. In the noninvolved and involved skin the mean rate was 2.2 and 9.7, respectively. In the stripped skin epidermal glucose-6-phosphate dehydrogenase and pyruvate kinase activities generally were the same as those of the noninvolved skin. In the Koebner reacting epidermis the 2 enzymes were increased 2.2 and 1.1 times the noninvolved levels but were statistically not significantly increased from control values.

Adult↗
PubMed1978

Measurement of the horny layer turnover after staining with dansyl chloride: description of a new method.

A simple non-radioactive technique is described. The corneal layers were stained with 5% dansyl chloride ointment during 24-48 h of occlusion. The number of newly formed corneal layers were counted on sections from punch biopsies obtained at various intervals after the staining. The rate of formation is given as layers formed per 24 hours. The technique makes it possible to detect an increase in the turnover rate when it is more than 15-32% above normal. The biological material can also be utilized for comparative studies utilizing biochemical and histological methods. The average rate of formation was 1.15+-0.09 (S.E.M.) layers per 24 hours in a group of 10 subjects.

Adult↗