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Biomedical subjects

A Björnsson

Publications and source records attributed to A Björnsson.

18 recordsLinked to original sources
PubMed1991

Temperature sensitivity caused by missense suppressor supH and amber suppressor supP in Escherichia coli.

The temperature-sensitive missense suppressor supH and amber suppressor supP in Escherichia coli are mutations of the serU and leuX genes, respectively. The supH tRNA, tRNA(SerCAA), is expected to recognize UUG codons, which are normally read by tRNA(LeuCAA) and tRNA(LeuUAA), coded for by the leuX gene and the leuZ gene, respectively. We show that supP and supH are incompatible and that strains carrying both supP and a restrictive rpsL allele are temperature sensitive. It is suggested that the temperature sensitivity of both supH and supP strains is caused by deficient reading of UUG codons by tRNA(LeuUAA).

Base Sequence↗
PubMed1990

Microsurgery versus standard removal of the herniated lumbar disc. A 3-year comparison in 150 cases.

The outcome of 150 patients with herniated lumbar disc treated by either microsurgical or standard discectomy were retrospectively reviewed after an average of 3 years. Both techniques provided satisfactory results, with 85 percent good or excellent outcome. Microsurgery gave less intraoperative bleeding, shorter hospitalization, and more rapid return to work. The main drawback was a higher recurrence rate of disc prolapse.

Adolescent↗
PubMed1990

Clinical factors predicting outcome after surgery for herniated lumbar disc: an epidemiological multivariate analysis.

A 5-year retrospective study of 150 patients operated on for lumbar disc herniation was conducted to evaluate the prognostic significance of several clinical variables in outcome. Patients with a clear lumbar herniated disc as diagnosed by computed tomography and/or myelography were operated on after a failed conservative treatment. Excellent outcome was defined as complete relief of complaints and neurological deficits. Mean follow-up period comprises 4 years; range, 2-6. At review, an excellent outcome was obtained in 73 patients (49%). Analyzing each variable separately, the application of autotraction during conservative treatment showed the major prognostic value, predicting excellent outcome. Other statistically significant parameters were a sedentary type of work and absence of motor or sensory deficits. The presence of intraoperative complications, namely dural tears, level errors, or root damage, indicated a poor prognosis. When the combined influence of all epidemiological variables was assessed by multiple regression analysis, a significant correlation could be found; the use of autotraction prior to surgery was the most important predicting factor. This study shows that there are some clinical factors that could fairly predict the surgical outcome of patients with lumbar disc herniation.

Adult↗
PubMed1989

X-linked cleft palate and ankyloglossia in an Icelandic family.

Information was available on 293 family members and spouses of seven generations in an Icelandic family with high frequency of cleft of secondary palate and ankyloglossia. The authors have personally investigated 182 individuals in generations IV-VII and have drawn blood from over 100 members for genetic marker studies. The senior author, Dr. Björnsson, has operated on two-thirds of the affected individuals. Twenty-six family members had cleft palate (CP) and, of these, 19 (17 male and two females) had ankyloglossia as well (CP + A). Twenty females and one male had only ankyloglossia (A). All mothers in one of two branches of the family who had sons with CP + A had ankyloglossia themselves. This was not the case in the other branch, in which the mothers of affected sons were themselves unaffected. Fathers affected with CP, CP + A, or high vaulted palate (HVP) never had affected sons. As reported earlier, the condition has been mapped to the q13-q21 region of the X chromosome using restriction fragment length polymorphism (RFLP) techniques (Moore et al, 1987). Our conclusion is that this midline defect is X-linked but varies in the severity of expression.

Chromosome Mapping↗
PubMed1985

The penetration of metrizamide into the brain after routine lumbar myelography as shown by cerebral computed tomography and its effect on auditory brainstem transmission time.

Metrizamide is a widely used contrast medium with some well known adverse reactions. In a preliminary study, CT scans and brain stem evoked potentials (BAEP) were done before and 18 hours following lumbar myelography on 12 patients. A statistically significant prolongation of the BAEP was observed. Metrizamide therefore seems to be a potent substance in clinical use as indicated by its effect on BAEP. BAEP should not be done within the first few days after myelography with metrizamide.

Aged↗
PubMed1984

Anti-IgE-induced histamine release from rat tissues passively sensitized in vivo with myeloma IgE differs with strain and mast cell source.

Four different strains of rats, BDII, E3, LE, and OM/N, each with a low basal serum level of IgE, were examined with respect to anti-IgE- and ConA-induced release of histamine from serosal mast cells and chopped lung tissue. Tests were performed before and three days after i.p. injection of a graded dose of myeloma IgE (IR 162)-containing ascitic fluid. There was a clearcut strain difference in response capacity with respect to ConA- and anti-IgE-induced release of histamine from serosal mast cells before myeloma IgE-injection. Response capacity increased in some but not all strains after myeloma IgE injection; increase in response capacity of serosal mast cells did not correlate to that of chopped lung tissue. Analogous findings were observed when two of the strains, LE and E3, were passively sensitized by i.p. injection with serum containing another myeloma IgE (IR2). These results indicate that differences exist between mast cells of different rat strains, and within strain between mast cells of various tissues in capacity to become sensitized to myeloma IgE.

Animals↗
PubMed1984

Immunologically induced pleural and peritoneal mast cell histamine release: difference in responsiveness in relation to secretagogue and rat strain used.

Responsiveness was compared for cell populations harvested from the peritoneal and pleural cavities of rats with respect to histamine release induced by specific antigen, anti-IgE, and Con A. Cell populations were obtained from Fischer, PVG or Sprague-Dawley (SD) rats, which were either untreated or immunized with 10 micrograms ovalbumin together with 100 mg alum intraperitoneally. Mast cell histamine release was examined with crude cell populations. The results show that differences in response capacity to the various secretagogues employed do exist between pleural and peritoneal cells in Fischer and PVG strains but under the present circumstances apparently not in SD rats. These differences vary in magnitude with the secretagogue employed and (for cells from immunized animals) with the time elapsed between immunization and test. In PVG rats, neither pleural nor peritoneal mast cell histamine release induced by antigen paralleled serum OA-IgE antibody levels. Furthermore, an increase in anti-IgE induced release of histamine from serosal mast cells occurred in parallel with a decrease in total serum IgE levels. These data indicate that the functional differences observed with respect to release properties of the two cell populations are due not only to intrinsic differences in mast cell populations but also to differences in reaginic antibodies sensitizing the cells.

Animals↗
PubMed1984

Anti-IgE-and ConA-induced histamine release from human basophilic leukocytes: the existence of differences in relative responses within individuals.

Histamine release was induced from human blood leukocytes with Concanavalin A (ConA) and two different preparations of anti-IgE. A dose-response curve was constructed for each cell population and secretagogue. No qualitative difference in response pattern was observed with the two anti-IgEs; however, the relative release-inducing efficacy of ConA and anti-IgE seemed to vary with the individual providing the cells. These findings indicate that release induced by ConA is not completely equivalent to that induced by anti-IgE.

Antibodies, Anti-Idiotypic↗
PubMed1984

Inhibitory effect of glucocorticosteroids on anti-IgE-induced histamine release from human basophilic leukocytes: evidence for a dual mechanism of action.

Anti-IgE-induced histamine release from human leukocytes is inhibited when the cells before challenge are cultured overnight in the presence of glucocorticoids (GCSs). The present report suggests that the GCSs might exert their effect by at least a dual mechanism of action. Histamine release was induced by a suboptimum concentration of anti-IgE. When the release recorded in the presence of the steroid is plotted against the release recorded in its absence, the data points of several experiments fit a regression line characterized by two parameters: its slope and its intercept with the abscissa. Structure-activity examination with selected GCSs indicates that the orders of potency for affecting these two parameters are not identical. Furthermore, pulse experiments suggest that the cells require different times of contact with the steroid to express inhibition according to the two parameters. The removal of adherent cells or platelets did not markedly affect the degree of leukocyte histamine release or its inhibition by a given GCS, suggesting that the steroid interacts directly with the basophil. Finally, steroid-induced inhibition was not affected by the putative phospholipase A2-inhibitor p-bromophenacylbromide (BPB) or the 5-lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA).

Antibodies, Anti-Idiotypic↗
PubMed1983

Antigen-induced release of histamine from serosal mast cells, lung, and tracheal tissue: variation with tissue and rat strain in relation to serum IgE-antibody level.

Rats of the Brown Norway (BN)2, Fischer, PVG and Sprague Dawley (SD) strains were immunized intraperitoneally with graded doses of ovalbumin (OA) together with either alum or Silica gel. At specified times after immunization, in vitro histamine release from serosal mast cells and from chopped lung and tracheal tissue was determined after challenge with OA. The development of the capacity to respond in these tests seemed to vary within strain independently for mast cells, lung, and tracheal tissue with immunization dose of antigen and nature of adjuvant. These variations were not closely correlated to observed variations in serum levels of OA-IgE antibody or ratio OA-IgE to total IgE as determined by radioimmunoassay. Furthermore, variations between strains in response capacity did not correlate to inter strain variation in median serum OA-IgE antibody level. These results do not clearly conform to the possibility that one single class of IgE mediates anaphylactic reactivity of various tissues of the rat.

Animals↗
PubMed1983

Formic acid burn--local and systemic effects. Report of a case.

Formic acid is an organic acid which has mainly been used in industry, but in recent years its use in agriculture has greatly increased in the Scandinavian countries. Formic acid is more caustic to the skin than acetic acid. However, reports on formic acid burns are scarce in the medical literature, and no serious burn has previously been described. A few reports on formic acid ingestion have been published. It is of great interest that formic acid has been shown to play the major role in the methanol poisoning syndrome. A case of severe burn with undiluted formic acid is reported. In the beginning, the dermal injury seemed to be of minor degree, but then the patient, a 15-year-old girl, developed signs of systemic formic acid intoxication, including metabolic acidosis, intravascular hemolysis and hemoglobinuria. These signs were similar to those described as a result of formic acid ingestion. The systemic effects were successfully treated without late sequelae, but the burn turned out mainly to be full-thickness, resulting in major scarring, as commonly seen after various chemical burns.

Acidosis↗
PubMed1982

Anti-IgE and Con A-induced histamine release from mast cells of four rat strains: correlation with total serum IgE.

Anti-IgE- and Con A-induced histamine release from serosal mast cells were compared to each other and to total serum levels of IgE in non-immunized, alum-injected, and Silica gel-injected rats of the BN, Fischer, PVG, and SD strains. The results indicate that the degree of anti-IgE- and Con A-induced release is strain-dependent and varies with immunization conditions. Furthermore, there is a gross but not complete correlation between the degree of serosal mast cell histamine release induced by the two secretagogues. However, Con A- or anti-IgE-induced release could significantly be correlated to serum levels of total IgE only in the Fischer strain but not in the BN or the PVG strains. In the SD strain, Con A-induced release correlated to serum IgE levels in Silica gel-injected but not in alum-injected animals.

Animals↗
PubMed1982

Anti-IgE-induced histamine release from human basophilic leukocytes: inhibition depends on nature and concentration of inhibitor and secretagogue.

Histamine release from human basophilic leukocytes was induced by increasing concentrations of anti-IgE in the presence of various concentrations of 2-deoxyglucose (2-DOG), the histamine H2-receptor agonist dimaprit, theophylline, or enprofylline (a new antiasthmatic xanthine derivative). The results show that the degree of inhibition produced by each agent differed with the concentration of anti-IgE used and with the nature and concentration of the inhibitor. These data indicate that great care should be used when characterizing an inhibitor of mediator release by simply giving a figure for the per cent inhibition of release observed in its presence.

Antibodies, Anti-Idiotypic↗