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Biomedical subjects

P Stenberg

Publications and source records attributed to P Stenberg.

16 recordsLinked to original sources
PubMed1992

A reversed activity staining procedure for detection of an acquired antibody against factor XIII in a girl with factor XIII deficiency.

A new method for detection of inhibitors against factor XIII is described. Agarose gel electrophoresis with normal platelet poor plasma as a factor XIII source included in the gel was combined with reversed activity staining. The procedure was applied to a 10-year-old girl with factor XIII deficiency where substitution therapy had failed. Plasma samples from the patient inhibited the factor XIII catalysed incorporation of the fluorescent monodansylthiacadaverine into casein at a position corresponding to the migration of gamma-globulins. Treatment with Sepharose-bound protein A effectively adsorbed the factor XIII antibody in the patient's plasma.

Antibodies↗
PubMed1992

Histologic studies of splenic megakaryocytes after bone marrow ablation with strontium 90.

We previously showed that purified strontium 90 produced sustained bone marrow ablation in mice, lowering platelet levels to less than 10% of normal 11 days after administration. Platelet levels later rose exclusively from splenic production and were maintained at a stable level (58% of normal) from 20 to 115 days after injection. However, there was no change in the total number or ploidy distribution of splenic megakaryocytes, as immunologically detected by flow cytometry. To further study the characteristics of splenic thrombopoiesis after bone marrow ablation by 90Sr, we measured the frequency, cross-sectional area, and endomitotic figures of histologically recognizable megakaryocytes (as well as bare megakaryocyte nuclei) in mouse spleen sections. During the hematopoietic nadir 9 days after injection of yttrium 90-free 90Sr, the size (area) of megakaryocyte cross-sections (mean +/- SD, 1079.3 +/- 661.6 microns 2; normal, 398.7 +/- 192.8 microns 2) was greater than for any other time studied, but megakaryocyte frequency (corrected for size) did not increase until day 16. Overall, splenic megakaryocytes in marrow-ablated mice 16 or more days after 90Sr injection showed substantial increases (p = 0.001 for both comparisons) in mean area (707.5 +/- 386.2 microns 2) and sectional frequency (mean +/- SEM, 4.52 +/- 0.20 per 1.83 mm2; normal, 0.78 +/- 0.06 per 1.83 mm2). Megakaryocyte bare nuclei and endomitotic figures were also more numerous after 90Sr, injection, suggesting acceleration of megakaryocyte maturation and platelet production. The induction of splenic platelet production after bone marrow ablation is associated with increased size of recognizable megakaryocytes, despite lack of change in overall splenic megakaryocyte ploidy.

Animals↗
PubMed1979

Specificity of guinea pig liver transglutaminase for amine substrates.

The amine specificity of guinea pig liver transglutaminase, a model enzyme for endo-gamma-glutamine:epsilon-lysin transferases, was explored with the aid of synthetic substrates of high apparent affinities. As exemplified by dansyl- (5-dimethylamino-1-naphthalenesulfonyl), (2,4-dinitrobenzenesulfonyl)-, and (2,4,6-triisopropylbenzenesulfonyl)-cadaverines--each of which showed affinities of approximately 4 x 10(7) M-1--the best amine substrates carried a large hydrophobic substituent attached to an alkylamine side chain of about 7.2 A in length. Altogether, our results point to the importance of a hydrophobic binding region in the enzyme from where the alkyl side chain reaches into a narrow crevice toward the active center and positions the primary amine of the substrate for attacking the carbonyl group of the acyl enzyme intermediate.

Amines↗
PubMed1979

Food-induced reduction in bioavailability of atenolol.

The influence of food intake on the bioavailability of the beta-adrenoceptor blocker atenolol was assessed by measurement of its single-dose kinetics in ten healthy volunteers, who took 100 mg both in the fasting state and together with a standardized breakfast. Food intake significantly shortened the time to reach peak concentration (2.7 h vs 1.5 h), but caused a significant reduction in AUC values, the mean decrease being 20%. The elimination half-life was unaffected. Atenolol, which is relatively hydrophilic, is incompletely absorbed in the fasting state, and escapes first-pass metabolism. The present findings indicate that food intake causes further impairment of its absorption, even though the absorption rate may initially be enhanced. This contrasts with previous observations on the more lipophilic beta-adrenoceptor blockers propranolol and metoprolol.

Adult↗
PubMed1979

Ketamine infusions: pharmacokinetics and clinical effects.

The clinical effects and pharmacokinetics of ketamine, administered as an i.v. infusion, were studied in 31 patients. Anaesthesia was induced with ketamine 2 mg kg-1 i.v. and maintained using an i.v. infusion of ketamine, supplemented by nitrous oxide. The plasma concentrations of ketamine, nor-ketamine and dehydro-nor-ketamine were analysed using gas-liquid chromatography. The average maintenance dose of ketamine was 41 +/- 21 microgram kg-1 min-1, but there was an obvious decrease in the dose required as anaesthesia progressed. This dose gave a stable plasma concentration of ketamine of 9.3 +/- 0.8 mumol litre-1. Patients recovered at 2.7 +/- 0.9 mumol litre-1. Plasma half-life of ketamine was 79 +/- 8 min. Maximum concentration of nor-ketamine was 4.7 +/- 2.4 mumol litre-1 and of dehydro-nor-ketamine 3.2 +/- 1.9 mumol litre-1. There were transient increases (15-30% of pre anaesthetic values) in arterial pressure, heart rate and cardiac output during operation. No post-operative respiratory depression was seen.

Adult↗
PubMed1979

Fatal iron intoxication with multiple coagulation defects and degradation of factor VIII and factor XIII.

A severe iron intoxication in a 15-year-old girl resulted in profound damage to vital organs and multiple clotting defects, but no haemorrhagic diathesis. Investigation revealed not only impaired synthesis of coagulation factors but also abnormal proteolysis by plasmin as well as by other proteolytic enzymes liberated from leucocytes and damaged tissue cells affecting especially factor VIII and factor XIII.

Adolescent↗
PubMed1979

A new gel for intracervical application of prostaglandin E2.

A new gel-formulation for intracervical application of prostaglandin E2 (PGE2) has been prepared. As a vehicle for the gel a cross-link starch polymer is used. PGE2 substance is added to the starch polymer and after homogenization and lyophilization a PGE2 powder is obtained. The powder can be stored at room temperature for more than four months without inactivation of the prostaglandin. Before clinical application a few ml of saline is added to the powder giving, within 30 seconds, an easily-handled ready to use PGE2-gel. Chemical analysis by spectrophotometric technique reveals that the amount of unchanged PGE2 is the same in the new gel-formulation as in a conventional cellulose gel. In a randomized double-blind study the new PGE2-gel was intracervically applied to twenty nulliparae before abortion by dilatation and evacuation (D & E). Ten women were given a gel containing 0.25 mg PGE2 (PGE2-gel) and ten a gel without PGE2 (placebo gel). It was found that the PGE2-gel, in contrast to the placebo gel, produced a rapid ripening of the cervix facilitating the subsequent D & E. No adverse systemic or local reactions were found during or after the treatment.

Abortion, Induced↗
PubMed1978

Effects of apomorphine and apomorphine-L-dopa-carbidopa on alcohol post-intoxication symptoms.

In a randomised double-blind clinical trial on 58 gamma-alcoholics, the effect of apomorphine given orally in individual subemetic doses was compared with apomorphine-L-dopa-carbidopa and with placebo. No positive effects of treatment with apomorphine, or with the combination apomorphine-L-dopa-carbidopa, on alcohol consumption or post-intoxication symptoms could be demonstrated. In the group which received the combination apomorphine-L-dopa-carbidopa, the post-intoxication symptoms lasted significantly longer than in the other two groups.

Adult↗
PubMed1975

Fibrin-stabilizing factor inhibitors. 12. 5-Dibenzylaminopentylamine and related compounds, a new type of FSF inhibitors.

A series of omegadibenzylaminoalkylamines and related compounds have been prepared and tested as inhibitors of fibrin cross-linking. This structural type was chosen in an attempt to develop noncompetitive inhibitors of fibrinoligase. By the combination of the dibenzylamino moiety at one end and the primary amino group at the other end of a polymethylene chain, the same compound could function both as a pseudo donor substrate and as a noncompetitive alkylating inhibitor. Some of the compounds, notably 74-79, are among the most active fibrinoligase inhibitors described. However, the data indicate that the compounds probably function only as pseudo donor inhibitors.

Benzyl Compounds↗
PubMed1975

Transamidase kinetics. Amide formation in the enzymic reactions of thiol esters with amines.

1. Beta-Phenylpropionylthiocholine and N-(5-aminopentyl)-5-dimethylaminonaphthalene-1-sulphonamide (dansylcadaverine) serve as a pair of water-soluble (pH7.5) model substrates for transamidating enzymes. Amide formation could be followed directly through fluorescence measurements by monitoring the continuous extraction of the water-soluble coupling product, N-(beta-phenylpropionyl)dansylcadaverine, into n-heptane. By this procedure, the steady-state kinetics of glutamine-lysine endo-gamma-glutamyltransferase from human plasma (fibrinoligase, thrombin- and Ca2+-activated blood coagulation Factor XII) and from guinea-pig liver (liver transglutaminase) were investigated at 25 degrees C. 2. With beta-phenylpropionylthiocholine as the varied substrate, Lineweaver-Burk plots with various concentrations of dansylcadaverine intercept on the horizontal axis, suggesting that formation of the acyl-enzyme is rate limiting. 3. On the basis of functional normality of active sites, kcat. values of 1.8 s(-1) and 0.9 s(-1) were obtained for the plasma and liver gamma-glutamyltransferase respectively. The two enzymes show identical affinities for the first substrate, beta-phenylpropionylthiocholine, with Ka 4 times 10(-4) M. 4. Utilization of the second substrate, dansylcadaverine, appears to be an order of magnitude more efficient with the liver enzyme. 5. N-(5-Amino-3-thiapentyl)-5-dimethylaminonaphthalene-1-sulphonamide (dansylthiacadaverine) could be used instead of dansylcadaverine in the fluorescent kinetic system. 6. Competitive inhibition by a non-fluorescent amine substrate histamine was also evaluated.

Amides↗