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Biomedical subjects

O Jansson

Publications and source records attributed to O Jansson.

27 records · Page 2Linked to original sources
PubMed1992

Mammalian thymidine kinase 2. Direct photoaffinity labeling with [32P]dTTP of the enzyme from spleen, liver, heart and brain.

Thymidine kinase 2 (TK2), also called mitochondrial thymidine kinase, is a pyrimidine deoxyribonucleoside kinase expressed in all cells and tissues. It was recently purified to apparent homogeneity from human leukemic spleen and the active enzyme was shown to be a monomer of a 29-kDa polypeptide. The enzyme is feedback-inhibited by both end products, dCTP and dTTP. Here we show that TK2 purified from several different sources, including purified beef heart mitochondria, could be directly photoaffinity labeled with radioactive dTTP (approximately 18% of all TK2 molecules were cross-linked to dTTP after 20 min of ultraviolet irradiation) or to a lower extent with dCTP. Photo-incorporation was inhibited by the presence of the other effector but also the phosphate donor ATP blocked photolabeling, with dTTP. Addition of nucleoside substrates gave only a marginal inhibition of photo-incorporation. There were no detectable difference in the molecular size of photolabeled TK2 isolated from human spleen, brain or placenta, monkey liver, beef heart and beef heart mitochondria. Nor was there any significant differences in the enzyme kinetic properties of these enzymes. Cleavage of labeled TK2 with cyanogen bromide showed that dTTP was incorporated into a single 3-kDa peptide. TK2 was the only pyrimidine deoxynucleoside kinase expressed in liver, heart and brain. A detailed characterization of the subunit structure and substrate specificity of this enzyme is of importance for the design of new antiviral and cytostatic therapies based on nucleoside analogs.

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PubMed1992

A randomized, double-blind, placebo-controlled study to evaluate topical anaesthesia of the pharynx in upper gastrointestinal endoscopy.

Reduction of discomfort during diagnostic upper endoscopy may not be desired by patients if the medication has long-lasting and severe after-effects. The present study was designed to examine whether topical anaesthesia of the pharynx without concomitant sedation is of overall benefit to patients undergoing diagnostic upper endoscopy. Two hundred out-patients were randomized to receive in the form of a pharyngeal spray either 80-120 mg lidocaine or placebo. Patients assessed discomfort on a 100 mm visual analogue scale the day after examination. Patients undergoing endoscopy who received lidocaine spray experienced significantly less discomfort from the intubation (p = 0.0001), and discomfort induced by the rest of the examination was also reduced (p = 0.003). The outcome of the endoscopists' assessment was also in favour of lidocaine spray for intubation (p = 0.157) and ease of examination (p = 0.0014). The assessment of throat discomfort suffered by patients after endoscopy did not differ between the groups. A majority of patients, the same proportion in each group, stated they would prefer their next endoscopy to be performed with topical anaesthesia.

Adult↗
PubMed1990

Direct photoaffinity-labelling of human deoxycytidine kinase with the feedback inhibitor dCTP.

Deoxycytidine kinase (dCyd kinase, EC 2.7.1.74) is a key enzyme in the salvage pathway of deoxyribonucleosides, and the human enzyme is a dimer of two 30 kDa polypeptides with a broad substrate specificity, phosphorylating both purine and pyrimidine nucleosides and using various nucleoside triphosphates as phosphate donors. The enzyme is efficiently feedback-inhibited by dCTP, which presumably is the main regulator of its activity in vivo. Submicromolar concentrations of [32P]dCTP could be used for direct photoaffinity labelling of pure dCyd kinase isolated from leukaemic spleen. A clearcut saturation of photoincorporation occurred with half-maximal incorporation at 0.07 microM-dCTP. However, the total molar incorporation of dCTP was very low (approx. 0.1%), in part due to a substantial u.v. inactivation of the enzyme. Proteinase digestion of labelled enzyme showed that dCTP was incorporated predominantly into a single peptide. Addition of equimolar concentrations of dCyd or dCMP as compared with dCTP inhibited photoincorporation approx. 50%. The presence of other nucleoside substrates, as well as phosphate donors, also inhibited photolabelling of the enzyme. Thus photoincorporation of dCTP seems to occur at a site which can bind both the phosphate donors and acceptors of dCyd kinase, which strongly support the hypothesis that dCTP functions as a multi-substrate analogue, binding and bridging both substrate sites of the enzyme.

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PubMed1985

Endoscopic findings in patients with ulcer-like dyspepsia.

One hundred and sixty-seven patients in a single general practice who presented with ulcer-like dyspepsia were offered an upper gastrointestinal fibre endoscopy. Twenty-two patients had a peptic ulcer while only three had a gastric ulcer. One patient had a carcinoma of the cardia, one an adenocarcinoma in the body of the stomach and one a carcinoma at the ampulla of Vater. In another 55 patients the main findings at endoscopy were edema/reddening or erosions in the antral or duodenal mucosa. Endoscopic findings were normal in 46 patients. Malignancies were found only in patients over 50 years of age and only 4 ulcers were seen in patients under 40. The clinical findings of presence of night pain, pain relief after food intake and history of peptic ulcer were more common in patients with an existing peptic ulcer than in those with a normal endoscopy.

Adolescent↗
PubMed1983

Infectious complications of the abdomen following gastric operations.

A retrospective study of postoperative abdominal infectious complications has been carried out for 625 consecutive patients operated upon for various gastroduodenal disorders during a ten year period; 14.7 per cent of the patients had a wound infection postoperatively and 6.6 per cent, an intra-abdominal abscess. In two-thirds of the patients with an abscess, a leakage was noted from an anastomosis. The patients who seemed to possess a particular risk of having septic complications postoperatively were those operated upon to control bleeding, patients having a second operation during the same hospital stay, patients operated upon for a recurrent ulcer and those operated upon for cancer. Furthermore, the type of operation performed, the age of the patient and some other patient related and hospital related factors, particularly coexisting hypoproteinemia or hypoalbuminemia, or both, seemed to influence adversely the infectious morbidity. The significance of these postoperative complications is also illustrated by the mortality figures and by the increased hospital stay brought about by these complications.

Abdomen↗
PubMedDate not supplied

Determination of electrolytes in the myocardium as a tool for the post-mortal diagnosis of recent infarction.

The K/Na quotient in the myocardium has been compared to the result of the PTAH staining method in an autopsy material of verified myocardial infarctions, suspected but macroscopically unverified infarctions and controls. The control cases regularly had quotion showed ischemic changes in PTAH staining. These and additionally 10 cases had K/Na quotients below 1.2. The electrolyte method thus appears to be a more sensitive method for the diagnosis of recent myocardial infarction.

Adolescent↗