Search PubMed⌕ Search

Biomedical subjects

L Johansson

Publications and source records attributed to L Johansson.

At least 235 records · Page 13Linked to original sources
PubMed1981

Radiation effects on cultured human lymphoid cells. Analysis using the growth extrapolation method.

The cloning efficiency of human normal and malignant lymphoid cells is usually low. Radiation effects in vitro on such cells can therefore not be analysed with conventional cloning. However, this problem can be circumscribed by using the growth extrapolation method. A panel of human leukemia-lymphoma cell-lines representing Epstein-Barr virus carrying lymphoblastoid cells of presumed nonneoplastic derivation and neoplastic T- and B-lymphocytes was used to test the efficiency of this method. The sensitivity to radiation could be determined for all these cell types. The growth extrapolation method gave generally the same result as conventional cloning demonstrated by comparison with one exceptional cell-line with capacity for cloning in agar. The sensitivity varied largely between the different cell types. A common feature was that none of the cell lines had a good capacity to accumulate sublethal radiation injury.

Cell Division↗
PubMed1980

Formation of electron-capturing derivatives of alprenolol by transboronation: application to the determination of alprenolol in plasma.

The reaction between 2,4-dichlorobenzeneboronic acid, 3,5-bis(trifluoromethyl)benzeneboronic acid or the 1,3-propanediamine derivatives of the boronic acids and the 3-isopropylaminopropan-2-ol side chain of the beta-blocking drugs occurs essentially as an on-column thermal reaction in the gas phase. Derivatization of the side chain of the beta-blocking drugs by transboronation is shown to be the method of choice for general application as it affects the detector background signal very little compared to the use of the boronic acid itself. The transboronation reaction can be used for the determination of alprenolol in plasma extracts with a detection limit of 2.5 ng ml-1 using the electron-capture detector. The ultimate sensitivity of the method is limited by the detector background signal resulting from some column decomposition of the transboronation reagent.

Alprenolol↗
PubMed1980

A gas chromatographic technique for determination of blood flow and metabolism in individual organs (with special reference to the heart).

A method for determining blood flow, oxygen uptake and carbon dioxide release in individual organs is presented. For blood flow measurement an inert gas (N2O) technique was used. Blood contents of O2, CO2 and N2O were measured by a gas chromatographic method with use of a special vacuum chamber for extracting the gases from blood. There was a strong correlation between the contents of O2 determined by the gas chromatographic and a spectophotometric method (correlation coefficient 0.953). Good agreement was found between CO2 in gas samples analysed by the Scholander technique and by the gas chromatographic method. A correlation coefficient of 0.998 was obtained between the N2O content calculated theoretically and that determined by the gas chromatographic technique. The new technique presented makes it possible to calculate blood flow in ml/100 g tissue/min, O2 uptake and CO2 production in an individual organ, whereby the predominant type of metabolism in the organ can be ascertained.

Blood Gas Analysis↗
PubMed1980

Plutonium in [99mTc] Pertechnetate for clinical use: concise communication.

Pertechnetate from 31 different Tc-99m generators was analyzed to determine if alpha-emitting radionuclides were present. Significant amounts of Pu(239 + 240) were found in the pertechnetate eluted from neutron-activated molybdenum distributed by one manufacturer. The Pu(239 + 240)/Tc-99m activity ratio in the first eluate from these generators varied between 1.3 . 10(-12) and 1.4 . 10(-11). The Pu(239 + 240) contamination is believed to originate from uranium impurities in the molybdenum batch. The build-up of Am-241, the daughter decay product of Pu-241, has also been demonstrated. The estimated Pu-241/Pu(239 + 240) activity ratio at the reference time was 8:1. It is strongly recommended that upper limits for the plutonium content of eluates from nonfission-produced molybdenum should be included in the various pharmacopoeias and that restrictions be placed on the uranium content of molybdenum used for the production of Mo-99 by neutron activation.

Americium↗
PubMed1979

Ethanol inhibition of vinyl chloride metabolism in isolated rat hepatocytes.

Isolated rat liver cells convert [14C]vinyl chloride into non-volatile metabolites. The metabolism is not increased by in vivo pretreatment with phenobarbital. It is sensitive to inhibition by ethanol, which at a concentration of 4 mM inhibits vinyl chloride metabolism to 50% in hepatocyte suspensions. The metabolic activity is NADPH-dependent and is localized in the microsomal fraction of the liver. The enzyme is also strongly inhibited by tetrahydrofuran, indicating that it could be identical to an ethanol-inducible cytochrome P-450 described in the literature [1].

Animals↗
PubMed1979

Myocardial performance early after aorto-coronary bypass surgery and the influence of nitroprusside infusion.

The central and peripheral circulation were studied in 12 patients after aortocoronary bypass surgery. During the initial 5 h after termination of cardiopulmonary bypass, the oesophageal temperature rose from 36.5 degrees C to 39.4 degrees C, concomitant with cutaneous vasoconstriction and an increase in systemic vascular resistance (SVR) and mean arterial blood pressure (MABP). The oxygen uptake index (Vo2I) increased by 57% during the rewarming period. The cardiac index (CI), which was constant at 2.8 l.min-1.m-2, was too low to satisfy this oxygen demand and the arterio-venous oxygen content difference (AVDo2) increased to 3.0 mmol . l-1 by the 3rd hour. After 5 h, SVR had decreased and cutaneous vasodilation began. Vo2I and AVDo2 decreased. The postoperative myocardial function was moderately impaired and deteriorated after the cutaneous vasodilation. Twelve patients were given an infusion of sodium nitroprusside during the postoperative period (0.25--2.5 micrograms . kg-1 . min-1). The rewarming pattern was not influenced by this infusion, but the initial increases in MABP and SVR were eliminated. The myocardial performance was better in the nitroprusside group. CI was significantly higher than in the control group (3.5 l.min-1.m-2) and AVDo2 remained normal.

Adult↗
PubMed1979

Myocardial performance early after aorto-coronary bypass surgery. Cardioplegic arrest versus coronary perfusion.

Haemodynamic adaptation was studied during the first 10 h after aorto-coronary bypass surgery. In a control group of 12 patients the heart was fibrillating and perfused during cardiopulmonary bypass (at 30 degrees C), and in 11 patients cold cardioplegic arrest was used. The first 4--5 h were characterized by rewarming, with increasing oesophageal temperature, cutaneous vasoconstriction and elevated systemic vascular resistance (SVR). A phase of vasodilation followed. In the control group the oxygen uptake index increased by 57% during rewarming, but the cardiac index (CI) was constant (about 2.9 l . min-1.m-2). The arterio-venous oxygen content difference (AVDo2) therefore increased (max. 3.0 mmol . l-1). The postoperative left ventricular performance was better and the serum levels of aspartate aminotransferase (ASAT) during the first 2 days postoperatively were lower in the cardioplegic patients than in the controls, indicating more efficient myocardial preservation. In the cardioplegic-hypothermic group, CI was constant at about 3.2 l . min-1.m-2 (significantly higher than in the control group) and AVDo2 remained normal during the rewarming period. The heart rate was lower initially in the cardioplegic patients than in the controls, implying a favourable influence on myocardial oxygen consumption. The better myocardial function in the cardioplegic-hypothermic group was associated with an only moderately increased SVR. This suggests that the elevated SVR in the control group could have been due to myocardial depression.

Adult↗