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Biomedical subjects

A Olsson

Publications and source records attributed to A Olsson.

At least 109 records · Page 6Linked to original sources
PubMed1985

Molecular cloning of Bacillus sphaericus penicillin V amidase gene and its expression in Escherichia coli and Bacillus subtilis.

The Bacillus sphaericus gene coding for penicillin V amidase, which catalyzes the hydrolysis of penicillin V to yield 6-aminopenicillanic acid and phenoxyacetic acid, has been isolated by molecular cloning in Escherichia coli. The gene is contained within a 2.2-kilobase HindIII-PstI fragment and is expressed when transferred into E. coli and Bacillus subtilis. The expression in B. subtilis carrying the recombinant plasmid is approximately two times higher than in the original B. sphaericus strain. A comparison of the purified enzyme from B. sphaericus and the expressed gene product in E. coli minicells suggests that the native enzyme consists of four identical subunits, each with a molecular weight of 35,000.

Amidohydrolases↗
PubMed1984

Uniformly spaced banding pattern in DNA sequencing gels by use of field-strength gradient.

A method is described for casting and operating ultrathin wedge-shaped field-strength gradient gels for DNA sequencing. One of the gradients results in a uniformly-spaced oligonucleotide banding pattern from 60 to 300 nucleotides in a 53 cm long 4% polyacrylamide gel. From these field-strength gradient gels, more sequencing data can be obtained with greater confidence than from gels with uniform thickness. The gel-casting method is fast and simple. At 2.5 kV two gels can be run simultaneously in 2 h with the same power supply.

Bacillus↗
PubMed1984

Efficacy of plaque-removal using interdental brushes and waxed dental floss.

The plaque-removing efficacy when using waxed dental floss and three interdental brushes was compared in an intraindividual clinical trial. Nine adult patients treated for periodontal disease, with a reduced but healthy periodontium and large interdental spaces were subjects in the study. Each subject tested the four interdental cleaning aids in random sequence over a 2-wk period. The duration of the study was 8 wk. The results indicated that the use of interdental brushes is preferable to that of dental floss in cleaning interdental areas where the papilla is missing. No difference in achieved cleanliness was noted after use of the different interdental brushes tested. No gingival damage or damage to the hard tissue of the teeth was observed after use of interdental brushes or dental floss.

Dental Devices, Home Care↗
PubMed1984

Catabolism of exogenously supplied thymidine to thymine and dihydrothymine by platelets in human peripheral blood.

The interference of platelets with the estimation of unscheduled DNA synthesis in human peripheral mononuclear leukocytes following genotoxic exposure was studied. A 96% reduction in the unscheduled DNA synthesis value was achieved by incubating [3H]thymidine with platelet-rich plasma for 5 hr at 37 degrees. Using radioactive thymine-containing compounds, together with quantitative analyses based on thin-layer and ion-exchange chromatographies, we have shown that thymidine was converted to thymine which, in turn, was converted to dihydrothymine in platelet-rich plasma. The enzymes responsible were separated from platelet lysates by gel filtration and were identified as thymidine phosphorylase and dihydrothymine dehydrogenase. The phosphorylase reversibly catalyzed the formation of thymine from thymidine and converted bromodeoxyuridine to bromouracil. The dehydrogenase reversibly catalyzed the interconversion of thymine and dihydrothymine in a reaction dependent on NADP(H), and it was inhibited by diazouracil and by thymine. Nearly all the thymidine-catabolizing activity found in whole blood samples supplied exogenously with thymidine was accounted for by the platelets. Since most genetic toxicological tests that use blood samples do not involve removing platelets from the blood cell cultures, then it is concluded that precautions should be taken in the future to determine the influence of platelets on these test systems. This is particularly true for methods dependent on thymidine pulses such as unscheduled DNA synthesis, or those dependent on bromodeoxyuridine, such as sister chromatid exchanges, since this nucleoside is also a substrate for thymidine phosphorylase.

Blood Platelets↗
PubMed1982

Metabolism of lofepramine by rat liver microsomes.

1. The metabolism of lofepramine in vitro by rat liver microsomes was studied. The enzyme system involved was dependent on cytochrome P-450 and the main metabolites were desmethylimipramine (DMI), formaldehyde and p-chlorobenzoic acid. 2. Microsomes from rats pretreated with phenobarbital or 3-methylcholanthrene showed enhanced lofepramine metabolizing activity. The induction was reflected in increased Vmax values, whereas Km values were not changed. 3. Pretreatment of rats with lofepramine or DMI did not alter the rate of aniline hydroxylation, aminopyrine demethylation or lofepramine metabolism per mg microsomal protein. Nor was the amount of cytochrome P-450 changed. 4. Lofepramine, imipramine and DMI inhibited competitively the microsomal hydroxylation of aniline in vitro. Lofepramine was the most potent inhibitor, which probably reflects the higher lipophilicity of this compound.

Aniline Hydroxylase↗
PubMed1981

Computed tomography, angiography and ultrasound in staging of renal carcinoma.

Preoperative evaluation of the extent of the renal tumor is of value in determining the prognosis of the patient and the most suitable therapy. CT and angiography were reviewed in 27 cases of renal carcinoma to evaluate tumor involvement of lymph nodes, renal vein, vena cava, and the perinephric space. In 26 of these cases the ultrasound examination was similarly reviewed. Comparison of ultrasound, CT, and angiography demonstrated that staging of renal tumors with ultrasound is mainly limited by its inability to demonstrate extrarenal infiltration. Both CT and ultrasound proved reliable in the demonstration of tumor spread to the renal vein and inferior vena cava. CT and angiography were equally effective in the evaluation of tumor extension; since CT is easier to perform, less invasive and less time consuming than angiography it should be the primary method for staging of renal neoplasms. Angiography offers detailed information on the vascular supply of the tumor important for the choice of surgical approach and should be performed only on special indications.

Adolescent↗
PubMed1981

Gingival recession in 15-year old pupils.

In a clinical examination of 174 15-year old pupils approximately 62 per cent showed some degree of gingival recession on the labial surfaces of maxillary teeth. The number of affected teeth per individual was low, one tooth in about 35 per cent and teeth in 25 per cent of the individuals. First molars and first premolars were the teeth most often affected. The majority of the defects were not extensive, i.e. the gingival margin was situated at the cemento-enamel junction. The number of cases affected by recession was lower in individuals using an "unspecific" toothbrushing technique compared with those using roll or vibratory technique. This difference may not be due to the technique but rather to a minor interest in oral hygiene measures in the "unspecific" groups. No statistically significant correlation was found between frequencies of recession and the stiffness of the toothbrushes used.

Adolescent↗
PubMed1975

Effect of quinidine on maintaining sinus rhythm after conversion of atrial fibrillation or flutter. A multicentre study from Stockholm.

In a controlled study comprising 176 patients, quinidine in the form of Kinidin Durules was found to reduced significantly the recurrence of the atrial fibrillation during a 1-year follow-up period after successful electric shock conversion. After one year, 51 per cent (52/101) of the patients in the quinidine group, and 28 per cent (21/75) in the control group remained in sinus rhythm (P smaller than 0.001). No less than 43 per cent of the patients converted to sinus rhythm during treatment with maintenance doses of quinidine sulphate before intended DC conversion. Gastrointestinal side-effects were not uncommon, and caused interruption of quinidine treatment in some cases.

Adult↗