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Biomedical subjects

H Johnsen

Publications and source records attributed to H Johnsen.

At least 19 recordsLinked to original sources
PubMed1992

Intrapulmonary thrombin generation and its relation to monomethylmethacrylate plasma levels during hip arthroplasty.

Frequent peroperative sampling of arterial and mixed venous blood was undertaken in eight consecutive patients during cemented hip arthroplasty to obtain a sequential picture of thrombin-antithrombin (TAT) and methylmethacrylate monomer (MMA) concentrations. TAT, detected neo-antigenically, reached its maximum levels after bone preparation, prior to introduction of cement and prosthesis. Furthermore, TAT values were higher in arterial than in mixed venous blood, indicating generation and inactivation of thrombin when blood is passing the lung. MMA concentration, measured by high pressure liquid chromatography, increased very rapidly and declined within 1 min following socket as well as shaft implantation, reaching the highest mean value of 3599 ng/ml only 30 s after femoral impaction of cement. MMA concentration was higher in mixed venous than in arterial blood, indicating elimination of the monomer during lung passage. This study confirms our previous observation that coagulation is activated prior to the implantation of bone cement and prosthesis into the femoral shaft; in addition, it provides further evidence of the thrombin-generating potential of the pulmonary capillary bed. Very frequent sampling was necessary to reveal the sharp rise in MMA levels following impaction of cement. Further investigations are needed to establish whether interaction between activated coagulation and MMA may predispose to cardiovascular complications.

Aged↗
PubMed1991

Carboxylesterases in guinea pig. A comparison of the different isoenzymes with regard to inhibition by organophosphorus compounds in vivo and in vitro.

The different isoenzymes of carboxylesterase (CarbE) from guinea pig liver, lung and plasma were separated by gel filtration and chromatofocusing. The isoenzymes were characterized by inhibition with several different organophosphorus compounds. The bimolecular rate constants showed the same tendency of decreased inhibition for all of the isoenzymes in the order; paraoxon greater than soman greater than diisopropylphosphofluoridate (DFP) greater than bis(p-nitrophenyl)phosphate. With two exceptions the inhibition constants for the different isoenzymes differed little. Subcutaneous and intraperitoneal administration of DFP and paraoxon rapidly inhibited the CarbE activity in guinea pig plasma. Much higher doses were necessary to obtain a marked inhibition in lung and liver. About 25% of CarbE activity in lung was resistant to paraoxon and DFP inhibition. Gel filtration of lung homogenate after treatment with the organophosphorus compounds showed that the CarbE activity of the medium molecular mass fractions was inhibited only weakly. This could be due to reduced accessibility to some of the lung CarbE isoenzymes.

Animals↗
PubMed1991

Diurnal intraocular pressure after successful primary laser trabeculoplasty.

In 20 patients who were successfully treated with laser trabeculoplasty as the primary therapy for glaucoma, we measured the intraocular pressure every two hours between 8:00 A.M. and 8:00 P.M. Success was defined as intraocular pressure of 22 mm Hg or less without medication. Of 20 patients, three had open-angle glaucoma and 17 had exfoliative glaucoma. Intraocular pressure was stable with small fluctuations during the daytime.

Aged↗
PubMed1991

Pilocarpine to prevent acute pressure increase following primary laser trabeculoplasty.

The effect of pilocarpine pretreatment on the transient pressure elevations immediately following primary laser trabeculoplasty was investigated in a prospective, randomised study. Fifty eyes of 50 patients, 33 with exfoliative and 17 with simple glaucoma, were treated in 360 degrees of the trabecular meshwork. The mean maximum pressure increase was 2.4 (SD = 4.4)mm Hg with pilocarpine pretreatment and 12.8 (SD = 11.2)mm Hg without pretreatment (p less than 0.05). Except in two cases, all peak pressures appeared during the first two hours after treatment. The degree of chamber angle pigmentation was predictive of the magnitude of the post laser hypertensive pressure response in eyes without pretreatment (p less than 0.05).

Aged↗
PubMed1991

Long-term efficacy of primary laser trabeculoplasty.

Sixty glaucomatous eyes of 60 patients treated with laser trabeculoplasty as primary therapy were reviewed retrospectively. There were 42 eyes with capsular glaucoma and 18 with simple glaucoma. The mean prelaser intraocular pressure (IOP) was 35.2 (SD = 6.5) mmHg. Success was defined as IOP less than or equal to 22 mmHg without medication. The probability of success was 0.73 at 1 year, 0.66 at 2 years, 0.57 at 3 years, and 0.50 at 4 years. Three eyes experienced progressive visual field loss or disc damage in spite of an intraocular pressure below 22 mmHg without medication. High prelaser pressure and the severity of the visual field defects were significant predictors of treatment failure.

Aged↗
PubMed1989

[Orbital blow-out fractures. Therapeutic results].

37 patients treated surgically for orbital blow-out fractures were reviewed retrospectively. 29 had diplopia before and four after operation. The diplopia was present only in extreme gaze positions and was not troublesome to the patients. Enophthalmus was present in 19 patients preoperatively and in six postoperatively. Of six patients treated conservatively one developed a moderate enophthalmus. There were no significant postoperative complications.

Adolescent↗
PubMed1989

The immediate pressure response to primary laser trabeculoplasty--a comparison of one- and two-stage treatment.

The immediate pressure response to primary LTP was studied prospectively in 40 eyes randomised to one- and two-stage treatment in 360 degrees of the trabecular meshwork. There were 26 eyes with glaucoma capsulare and 14 with glaucoma simplex. Mean prelaser IOP was 32.8 mmHg in the former, and 35.5 mmHg in the latter group. The frequency and magnitude of postlaser pressure increase were the same in both groups when taking into consideration the pressure spikes in both 180 degrees sessions. The pressure increase was higher than in earlier reports on LTP in presurgical glaucoma patients on maximum medication. Almost all IOP elevations appeared during the first 2 h following laser treatment. The results were the same in both groups 6 months after LTP.

Aged↗
PubMed1988

Metabolism of T-2 toxin by blood cell carboxylesterases.

Human and rat blood hydrolysed T-2 toxin along two different pathways giving HT-2 toxin and neosolaniol as primary metabolites, respectively. Neosolaniol represents a metabolic pathway different from that obtained by liver. Rat erythrocytes formed neosolaniol as a primary metabolite whereas white blood cells hydrolysed T-2 toxin to HT-2 toxin. Human erythrocytes formed both HT-2 toxin and neosolaniol whereas all human white cells produced only HT-2 as the primary metabolite. The enzymes responsible for hydrolysis of T-2 toxin to HT-2 toxin in white blood cells and T-2 toxin to neosolaniol in red blood cells were all identified as carboxylesterases by use of specific inhibitors. The ratio between trichothecene hydrolysis and 4-nitrophenyl butyrate hydrolysis varied among the different cell fractions indicating that specific isoenzymes are involved.

Animals↗
PubMed1988

Cytotoxicity and effects of T2-toxin on plasma proteins involved in coagulation, fibrinolysis and kallikrein-kinin system.

The activity of both the coagulation and fibrinolytic systems was markedly depressed 24 h after a sublethal dose of T-2 toxin. T-2 toxin was active as an anticoagulant at low doses, which did not affect the basal state of the animals. The kallikrein-kinin system was also affected by depletion of the prekallikrein, which indicates increased bradykinin levels in plasma. At the same time there was an increased activity of some clinically relevant enzymes in serum, indicating tissue injuries caused by T-2 toxin. All effects observed in this study reached their maximum within 24 h after administration, which corresponds to the time animals usually die when receiving a lethal dose. T-2 toxin does not, however, seem to affect the protease enzymes by reduced protein synthesis, because of early onset of the effects, nor does it act as a trigger itself. The effect of T-2 toxin on plasma protease enzymes is probably secondary to cytotoxic effects in the vascular endothelium.

Animals↗
PubMed1988

The Middle-Norway eye-screening study. I. Epidemiology of the pseudo-exfoliation syndrome.

This is the first population-based PE prevalence study allowing comparison of observations from different geographical areas. The prevalence of the PE syndrome for persons above 64 years of age was found to be 10.2, 21.0 and 19.6% in three municipalities lying distinctly apart. Of 343 married couples the man was PE-positive in 36, the woman in 34, and both in 12 cases. One of the 12 couples was excluded because the spouses were cousins. The observed number of 11 couples is significantly higher (P = 0.022) than expected assuming independent occurrence of PE syndrome. Two homozygote pairs of twins were found in this material, both of them discordant for the presence of PE syndrome. This fact along with the discrepancy between observed and expected numbers of PE positivity in both spouses may indicate environmental influence on the distribution of the syndrome.

Aged↗
PubMed1986

Metabolism of T-2 toxin by rat liver carboxylesterase.

The trichothecene T-2 toxin was rapidly hydrolyzed by rat liver microsomal fraction into HT-2 toxin which was the main metabolite. The metabolism was completely blocked by paraoxon, a serine esterase inhibitor, but not affected by EDTA or 4-hydroxy mercury benzoate, inhibitors of arylesterase and esterases containing SH-group in active site, respectively. Among the serine esterases carboxylesterase (EC 3.1.1.1), but not cholinesterase (EC 3.1.1.8) hydrolysed T-2 toxin to HT-2 toxin. Carboxylesterase activity from liver microsomes was separated into at least five different isoenzymes by isoelectric focusing, and only the isoenzyme of pI 5.4 was able to hydrolyse T-2 toxin to HT-2 toxin. The toxicity of T-2 toxin in mice was enhanced by pre-treatment with tri-o-cresyl phosphate (TOCP), a specific carboxylesterase inhibitor. This confirms the importance of carboxylesterase in detoxification of trichothecenes.

Animals↗
PubMed1986

Amylase, pancreatic isoamylase and lipase in serum before and after endoscopic pancreatography.

Serum amylase, isoamylase and lipase were determined in 17 patients with pancreatic or biliary diseases before and after endoscopic retrograde pancreatography (ERP). Within 1/2-2 hours after cannulation of the pancreatic duct, serum lipase was increased to approximately 4 times the upper reference level and normalized almost completely at 24 hours. A much smaller increase was found in amylase and isoamylase. The elevation in enzyme activities was less in patients with abnormal than with normal ERP. The results suggest that lipase is a more sensitive indicator of pancreatic injury than amylase and isoamylase.

Amylases↗
PubMed1985

Carboxylesterases, importance for detoxification of organophosphorus anticholinesterases and trichothecenes.

Several different types of experiments, including the use of inhibitors, have shown that carboxylesterases are a major factor in the metabolism and therefore detoxification of organophosphorus compounds such as soman and trichothecene toxins. The development of a new assay method for the enzyme has allowed us to separate the carboxylesterases into two major groups. The carboxylesterases can, however, be further separated by gel filtration, affinity chromatography, isoelectric focusing, and chromatofocusing into several isoenzymes. Liver microsomal carboxylesterases can be separated into five or six isoenzymes whereas guinea-pig plasma contains two isoenzymes. The isoenzymes differ in molecular weights, isoelectric points, substrate specificities, and affinity for inhibitors. Intravenous administration of a carboxylesterase preparation lowered the toxicity of soman in young rats. Carboxylesterases from rat and guinea-pig plasma inhibited by soman could be reactivated by DAM, whereas enzymes from porcine liver were not reactivated. Only one of the isoenzymes from rat liver microsomal preparation was responsible for the metabolism of T-2 toxin to HT-2. The further metabolism of HT-2 was performed by esterases from rat liver cytoplasma. Long-term exposure of the bronchial muscle to low concentration of soman modulate the bronchial contraction.

Animals↗
PubMed1985

Ascorbic acid determination in serum and aqueous humour by high-performance liquid chromatography.

High-performance liquid chromatography on a Supelcosil LC-HN2 analytical column in weak anion exchange mode has allowed separation of ascorbic acid, in less than 5 min, from other interfering substances in serum and aqueous humour. UV monitoring at 254 nm enables ascorbic acid to be detected at 20 pmol level. A method for determination of ascorbic acid concentration in serum and aqueous humour is described, and values from 10 cataract patients are reported.

Aged↗
PubMed1985

Senile cataract and ascorbic acid loading.

Serum, aqueous humour, and lens ascorbic acid levels were determined by high-performance liquid chromatography in cataract-, closed-angle glaucoma-, and aphakic patients. The total number of 108 patients were subdivided into different groups. In several groups the pre-operative serum and aqueous amounts were tested, whereafter patients in some groups were loaded with ascorbic acid orally. Finally, a second test was performed on samples taken during operation. It turned out that the ascorbic acid concentration mechanism in cataractous eyes needed more than 12 h for maximum reaction on the loading stimulus. The slow reaction is surprising compared to other species, and it may reflect an affection of the secretory process itself in this disease.

Aged↗
PubMed1982

Gas chromatographic mass spectrometric identification of O-demethylated and mono-hydroxylated metabolites of levomepromazine in blood from psychiatric patients by selected ion recording with high resolution.

An O-demethylated and two mono-hydroxylated metabolites of levomepromazine have previously been identified as conjugates in the urine from psychiatric patients. The three metabolites were identified in hydrolysed and nonhydrolysed plasma and erythrocytes from three patients by selected ion monitoring of the trimethylsilyl derivatives, with a mass spectrometric resolution of 5000. The three metabolites were mainly found as conjugates in the plasma, and smaller amounts were found unconjugated in the plasma and the erythrocytes.

Adult↗