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Biomedical subjects

A Svensson

Publications and source records attributed to A Svensson.

At least 19 recordsLinked to original sources
PubMed1992

Crystallization and preliminary X-ray diffraction studies of a peroxidase from barley grain.

Crystals suitable for X-ray diffraction analysis of both glycosylated and non-glycosylated forms of a barley peroxidase have been grown. The crystals of the glycosylated peroxidase have been grown by the hanging drop vapour diffusion method using polyethylene glycol 4000 as the precipitant in the presence of n-propanol and potassium iodide at pH 8.5. The crystals are needles belonging to the orthorhombic spacegroup P2(1)2(1)2(1) with unit cell dimensions a = 62.95 A, b = 66.24 A and c = 70.78 A. There is one barley peroxidase molecule in the asymmetric unit. The crystals contain approximately 38% solvent and appear to be stable to lengthy X-ray exposure. They diffract to beyond 1.9 A.

Crystallization↗
PubMed1992

Interaction between glutamatergic and dopaminergic tone in the nucleus accumbens of mice: evidence for a dual glutamatergic function with respect to psychomotor control.

The rotation induced by a unilateral injection of the competitive NMDA receptor antagonist AP-5 was studied in mice with different tone in the central dopaminergic systems. AP-5 induced contralateral rotation in monoamine-depleted mice and in monoamine-depleted mice treated with a dopamine D-1 receptor agonist. In contrast, AP-5 induced predominantly ipsilateral rotation in monoamine-depleted mice treated with a mixed D-1/D-2 or a D-2 selective dopamine agonist and in mice with intact monoaminergic systems.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1992

Differential locomotor interactions between dopamine D1/D2 receptor agonists and the NMDA antagonist dizocilpine in monoamine-depleted mice.

Previous work in our laboratory has shown that the non-competitive N-methyl-D-aspartate antagonist dizocilipine (MK-801) interacts synergistically with the mixed dopamine (DA) receptor agonist apomorphine and the DA D 1 agonist SKF 38393 to promote locomotion in monoamine-depleted mice. The purpose of the present study was to compare the roles of DA D 1 and DA D 2 receptors in this interaction. To that end, dizocilpine was given in combination with either the DA D 1 receptor agonist SKF 38393 or the selective DA D 2 receptor agonist quinpirole or the preferential DA D 2 agonist bromocriptine. In general, the locomotor stimulatory effects produced by SKF 38393 were potentiated by dizocilpine, whereas the locomotor stimulation produced by quinpirole and bromocriptine was counteracted. However, baseline activity, which partly depends on how much time is allowed to elapse between administration of the DA agonist and commencement of locomotor recording, and partly on the dose of the DA agonist, seems to be an important factor that determines whether dizocilpine will have a weakening or a potentiating effect. Interestingly, the competitive NMDA antagonist D-CPPene displayed a different pattern of interaction with SKF 38393 and quinpirole in that synergistic effects were observed with both DA agonists, most conspicuously so with the DA D 2 receptor agonist. The results are interpreted in the light of present knowledge of basal ganglia neuroanatomy; they are discussed in relation to the "direct" and "indirect" pathways from the striatum to the thalamus, proposed to form part of positive and negative cortico-striato-thalamo-cortical loops, respectively, as well as to the presumed presynaptic D 2 receptors on corticostriatal glutamatergic neurons.

Animals↗
PubMed1992

Injection of the competitive NMDA receptor antagonist AP-5 into the nucleus accumbens of monoamine-depleted mice induces pronounced locomotor stimulation.

Following injection of 5 micrograms of the competitive NMDA receptor antagonist AP-5 into the nucleus accumbens of monoamine-depleted mice a pronounced locomotor stimulation was produced. Additional treatment with an intraperitoneal (i.p.) injection of the alpha-adrenoceptor agonist clonidine markedly increased the locomotor effects of AP-5 administration into the nucleus accumbens. Injection of 5 or 10 micrograms AP-5 into the dorsal striatum was ineffective with regard to locomotor stimulation. However, when AP-5 (10 micrograms) was combined with an i.p. injection of clonidine, a marked locomotor stimulation was produced following application into the dorsal striatum, but not following application into the prefrontal cortex. The present results are in line with the idea that corticostriatal glutamatergic pathways, especially those projecting to the ventral striatum, exert an inhibitory influence on psychomotor functions.

2-Amino-5-phosphonovalerate↗
PubMed1992

A 15-year surveillance study of antibodies to herpes simplex virus types 1 and 2 in a cohort of young girls.

A cohort of 839 young girls at the ages of 14 and 15 years was screened for total antibodies to herpes simplex virus (HSV) and, if positive, for specific antibodies to HSV-2, by means of a sensitive, enzyme-linked immunosorbent assay (ELISA). The cohort was followed from 1972-1987. Blood samples were obtained on six occasions during these 16 years. In total, 2270 blood samples were taken. The number of sero-converting girls was studied in relation to calendar time. Two methods were constructed for the statistical analyses. The first of these gave an estimate of the sero-prevalence at different points in time. This analysis showed that the sero-prevalence which was 23% against HSV-1 in 1972 had increased to 36% in 1976. At the end of the study in 1987, 50% of the cohort had sero-converted against HSV-1. The proportion of girls who had sero-converted against HSV-2 was 0.4% in the 14-15-year-olds and had reached 22% by the end of the study. The second statistical method used all the available information implicit in the observations so as to obtain a maximum-likelihood (ML) estimate of the prevalence. The ML estimates were slightly more precise, but the two estimates did not differ significantly. The observations were further analysed by the Mantel-Haenszel test in order to see if there was any dependence between positivity to HSV-1 and HSV-2 respectively but none was found.

Adolescent↗
PubMed1992

The impact of changing BCG coverage on tuberculosis incidence in Swedish-born children between 1969 and 1989.

In April 1975, the mass vaccination of newborns against tuberculosis was replaced by selective vaccination of groups at risk. BCG coverage fell from more than 95% before 1974 to 1.8% between 1975 and 1982 and thereafter reached an average of 13.7% up to 1989. The cumulative incidence of tuberculosis before 5 years of age was estimated among children born in Sweden during periods of high, low and moderate increasing BCG coverage. The incidence figures per 100,000 children was 0.8, 3.9 and 2.9, respectively, for children born to Swedish parents and 2.6, 39.4 and 13.2, respectively, for those born to foreign parents. The observed incidence of tuberculosis among non-BCG vaccinated children born to Swedish parents was within the expected limits given by a prognostic model based on the natural change of the risk of infection. The effectiveness of the selective BCG vaccination programme, which was intensified after 1981 for the second generation of immigrants, was estimated to 0.82 (95% confidence interval 0.38, 0.95) assuming that there was no change of the risk of infection for children born to foreign parents over the period studied. From April 1975 to December 1989, tuberculosis was notified in 85 children born in Sweden during the same period, 7 of them were BCG vaccinated and 78 non-vaccinated, 45 were symptomatic, 3 of them with disseminated tuberculosis.

Adolescent↗
PubMed1992

Assessing the extent of the HIV epidemic in Sweden, using information on the extent to which people who develop AIDS are already known to be HIV infected.

In Sweden, cases of both HIV infection and AIDS are registered. By looking at the extent to which people who develop AIDS are already known to be HIV-infected, we can assess the coverage of the HIV registration. It was found that virtually all those who were infected by injecting themselves with drugs, blood transfusions, blood products or congenitally were already known to be infected when AIDS developed. However, when homosexual or heterosexual transmission had occurred, 20.5% and 33.3% respectively of these cases were not previously known. Working with different assumptions regarding the development of the epidemic, we find that the true number of sexually infected people is roughly twice the number of registered HIV-infected people in these groups. Our estimate is that between 3300 and 6300 people were infected with HIV in Sweden up till the end of 1990.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Skin rashes and stomatitis due to parenteral treatment of rheumatoid arthritis with sodium aurothiomalate.

In a prospective study of 45 patients with rheumatoid arthritis mucocutaneous symptoms and signs were evaluated before and during treatment with intramuscular sodium aurothiomalate (Myocrisin). The work, performed in close collaboration between dermatology and rheumatology departments, showed that there was no significant increase in mucocutaneous side effects in patients with pre-existing mucocutaneous disease. It is concluded that pre-existing dermatitis is not a contraindication for treatment with gold salts and that a previous mucocutaneous reaction to gold salts is not an absolute contraindication for a new trial of chrysotherapy.

Adult↗
PubMed1992

A novel dithranol formulation in the over night treatment of psoriasis at home.

The objective of this study was to compare the clinical efficacy and acceptability of two dithranol creams (Micanol and Amitase) in patients with plaque type psoriasis treating themselves daily at home. Thirty-five patients started with Amitase (0.1%) and 37 with Micanol (0.1%) applied at night in this 6-week single-blind parallel groups comparison study. Patients who responded more slowly than a theoretically estimated "standard" rate of improvement had their concentration increased to 0.25% at the visit after 2 or 4 weeks. By the end of the study slightly more than half of the number of patients remained on 0.1%. There was no difference between the treatment groups. In comparison with the level at start the composite sign severity score for patients in the Amitase group was reduced by 24% after 1 week, 36% after 2 weeks, 49% after 4 weeks and 62% after 6 weeks. The reduction in the Micanol group was similar. Patients in the Micanol group showed after 1 week of treatment more irritative reactions than patients in the Amitase group. At all follow-up visits, staining of perilesional skin was more prevalent in the Micanol group. Staining of clothing was, however, far more prevalent and severe for patients given the Amitase cream. It may be concluded that Micanol is an important alternative for home treatment of psoriasis.

Adult↗
PubMed1991

Synergistic interactions between muscarinic antagonists, adrenergic agonists and NMDA antagonists with respect to locomotor stimulatory effects in monoamine-depleted mice.

The purpose of the present investigation was to study the effects of simultaneous manipulations of central cholinergic, adrenergic and glutamatergic systems on locomotion in an animal model of Parkinson's disease. Mice were deprived of their monoamine stores by pretreatment with the monoamine depleter reserpine and the catecholamine synthesis inhibitor alpha-methyl-p-tyrosine, given 18 h and 60 min, respectively, before the acute experiment. Traditionally, only dopaminergic agonists have been shown to reverse the akinesia thus produced. However, in the present study it is demonstrated that if a muscarine receptor antagonist (atropine or biperiden) is combined with an alpha-adrenergic agonist/alpha-adrenergic agonist precursor (clonidine or L-alpha-methyl-dopa), a marked locomotor stimulation can be achieved, although either agent given alone is ineffective. Adding an NMDA antagonist (MK-801, ketamine or SDZ EAA 494) to the combination biperiden + clonidine resulted in further potentiation of the locomotor stimulatory effects.

Adrenergic alpha-Agonists↗
PubMed1991

Synergistic interactions between the NMDA antagonist dizocilpine and the preferential dopamine autoreceptor antagonists (+)-AJ 76 and (+)-UH 232 with regard to locomotor stimulation in monoamine-depleted mice.

When administered to mice pretreated with the monoamine-depleter reserpine and the catecholamine synthesis inhibitor alpha-methyl-para-tyrosine, the preferential autoreceptor antagonists (+)-AJ76 and (+)-UH 232 induced weak locomotor stimulation. When either (+)-AJ 76 or (+)-UH 232 was combined with a subthreshold dose of the selective NMDA antagonist dizocilpine (MK-801), a marked locomotor stimulation was produced in monoamine-depleted mice. The mechanism of this stimulation, although reduced by dopamine antagonists, remains to be clarified.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1991

A comparison between the non-competitive NMDA antagonist dizocilpine (MK-801) and the competitive NMDA antagonist D-CPPene with regard to dopamine turnover and locomotor-stimulatory properties in mice.

Following intraperitoneal administration of the non-competitive N-methyl-D-aspartate (NMDA) antagonist dizocilpine (MK-801), levels of the dopamine (DA) metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) increased in mouse striatum and limbic forebrain. When dizocilpine was given to animals treated with NSD 1015, an inhibitor of 3,4-dihydroxyphenylalanine (DOPA) decarboxylase and monoamine oxidase, there was an increase in levels of DOPA and 3-methoxytyramine (3-MT). These findings suggest that dizocilpine stimulates DA synthesis and release in mouse brain. Following dizocilpine treatment a clear-cut increase in spontaneous locomotor activity was observed, probably partly due to enhanced dopaminergic tone. The competitive NMDA antagonist D-CPPene produced locomotor stimulation as well, but in contrast to following dizocilpine treatment levels of 3-MT decreased. Thus the stimulation of locomotor activity following D-CPPene treatment does not seem to be mediated through activation of central dopaminergic systems. However, haloperidol pretreatment antagonized this locomotor response, indicating that the dopaminergic system plays a permissive role in this context.

Animals↗
PubMed1991

Analyzing effects of vaccines.

A population with (individually) varying susceptibilities to infection and a vaccine with (individually) varying protective effect are considered. A simple stochastic model is used to illustrate different effects of the vaccine on the spread of the infection. The behavior of different estimators of the vaccine efficacy using data from a clinical trial and the relation between vaccine efficacy and the effectiveness of a vaccination program are discussed.

Disease Outbreaks↗
PubMed1991

Elastic outward bending of loaded buccal and lingual premolar walls in relation to cavity size and form.

The aim was to study effects of the size and form of the occlusal part of Class II cavities on elastic outward bending during loading of buccal and lingual walls, separated by the preparation. Twenty newly extracted caries-free premolars were used. A special arrangement for standardized cavity preparation was set up. In order to obtain accurate measurements of the outward bending of loaded cavity walls, an electronic tensile test device was constructed. Methodologic studies showed an insignificant departure from linearity between between outward bending and load. All deformation was elastic. Correction factors were determined for strain of the apparatus as well as for indentation in the tooth substance. Measurement accuracy was calculated to +/- 0.12 N for force and +/- 0.2 micron for movement. In accordance with statistical principles, a few outlying measurements were discarded. The outward bending of buccal and lingual walls of cavities suitable for conservative restoration with dental amalgam was about 0.15 micron per Newton. Outward bending increased dramatically with exaggerated cavity depth and width. In the light of present knowledge of average chewing forces and tooth contacts in the habitual intercuspal position in young dentate adults, there seems to be little risk of leakage between conservative restorations and cavity walls as a result of elastic outward bending, though the risk certainly does increase with the depth and width of the cavity.

Bicuspid↗
PubMed1991

Evaluation of an infrared light absorption method for objective assessment of oral mucosal dryness.

The aim of this study was to evaluate an infrared light absorption (ILA) method for registration of dryness of the oral mucosa. Measurements were performed in the buccal and in the lip mucosa immediately before and every 30 min after submucosal injection of 1.0 ml methylscopolamine nitrate in nine healthy subjects. For comparison, a dental mirror sliding friction test was used. About 1.5 h after injection the ILA method showed statistically significant (P less than 0.01) decreases of values in both the buccal and the lip mucosa. However, in the individual subjects the deviations from initial values showed only slight agreement when measured with the ILA method and the mirror friction test. Thus, the ILA method does not seem to be suitable for registration of individual variations in oral mucosal dryness.

Absorption↗