Biomedical subjects
Publications and source records attributed to T Sorensen.
We report 2 patients with congestive heart failure and concomitant toxic serum digoxin levels in whom cholestyramine administration increased clearance of digoxin and decreased serum digoxin elimination half-lives. Cholestyramine's gastrointestinal binding of enterohepatically-recycled and enterally-secreted digoxin enhanced elimination, allowing a more rapid return to therapeutic drug levels.
The highly conserved lysine residue Lys758 in the fifth stalk segment of the sarcoplasmic reticulum Ca2+-ATPase was substituted with either isoleucine or arginine by site-directed mutagenesis. The substitution with arginine was without significant effects on Ca2+-ATPase function, whereas multiple changes of functional characteristics were observed with the Lys758 --> Ile mutant. These included insensitivity of ATPase activity to the calcium ionophore A23187, an alkaline shift of the pH dependence of ATPase activity, reduced maximum molecular turnover rate and steady-state phosphorylation level, reduced apparent affinities for Ca2+ and inorganic phosphate, as well as increased sensitivity to inhibition by vanadate. Analysis of the partial reaction steps of the enzyme cycle traced these changes to two steps. The rate of dephosphorylation of the ADP-insensitive phosphoenzyme intermediate (E2P) was increased, irrespective of variations of pH, K+, Ca2+, and dimethyl sulfoxide concentration. In addition, the rate of conversion of the dephosphoenzyme with low Ca2+ affinity (E2) to the Ca2+-bound form activated for phosphorylation (E1Ca2) was reduced in the mutant, and the ATP-induced rate enhancement of this step required higher ATP concentrations in the mutant compared with the wild type.
Various chemicals and proteins of industrial importance are known to cause respiratory allergy, with occupational asthma being the most important manifestation of the disease. This paper describes clinical syndromes, mechanisms associated with occupational respiratory hypersensitivity, and methods available currently for the prospective identification of potential respiratory allergens. Certain classes of chemicals are commonly associated with occupational respiratory allergy. There is insufficient information, however, to predict respiratory sensitization potential from analysis of structure alone, although reactivity with proteins is likely to be relevant. As yet there exist no fully validated or widely applied predictive methods or internationally harmonized guidelines. The most promising predictive animal methods are the mouse IgE test and guinea pig models. Work in mice has focused upon events occurring during the induction phase of sensitization following primary encounter with the test chemical. In contrast, guinea pig models have been used primarily to identify respiratory allergens (chemicals or proteins) as a function of elicitation reactions induced in previously sensitized animals. Given the possible serious health manifestations of respiratory allergy, early identification of respiratory sensitizers is urgently required. The two methods should, as a priority, be developed further and the production of a detailed protocol for these methods be undertaken to facilitate further validation. Together, this information will allow for two types of risk assessment associated with respiratory allergy: the risk that exposure to a material will (1) induce sensitization in an individual and (2) elicit allergic reactions in a previously sensitized individual.
OBJECTIVES: Our objectives were to describe the maternal and fetal hemodynamic impact of a 1 U acute blood loss during pregnancy and to compare the hemodynamic responses of pregnant women with those of nonpregnant controls. STUDY DESIGN: With Doppler techniques cardiac output and total peripheral vascular resistance were determined in 16 pregnant women in the third trimester and in 16 nonpregnant volunteers before and during orthostatic stress, before and after donation of 450 ml of whole blood. In pregnant women the fetal umbilical artery systolic/diastolic ratio was also determined. Data were subjected to multiple logistic regression analysis. RESULTS: In both groups orthostasis provoked significant decreases in cardiac output and increases in total peripheral vascular resistance. The hemodynamic effects of blood loss were less pronounced and did not significantly change the hemodynamic response to orthostasis in either group. Neither orthostasis nor blood loss caused significant changes in the umbilical systolic/diastolic ratio. CONCLUSION: These data support the hemodynamic safety of uncomplicated autologous blood donation during late pregnancy.
Amnioinfusion has become a common intrapartum procedure for the relief of cord compression. We report a case of acutely increased intrauterine pressure during amnioinfusion with maternal but not fetal distress. An important decrease in pressure and symptomatology occurred with withdrawal of only a small amount of fluid. Further study is needed of pressure-volume relationships in the uterus and effects on uteroplacental perfusion. Careful attention must be paid to infusion volumes and intrauterine pressure during amnioinfusion.
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Theoretical considerations on a simplified biological system representing the tear pathways lead to the assumption of an exponential pattern of elimination of tracer substances from the conjunctival sac. The tracer used in the present study was technetium, Tc99m, as sodium pertechnetate. The detection system consisted of a gamma camera coupled to a digital system, a minicomputer and a magnetic tape unit. After instillation of 10 microliter normal saline solution containing Tc99m the decay of activity was followed by means of an activity-time function curve to which exponential curves were approximated by the computer. As a parameter for tear flow the fractional turnover rate was calculated from 7 to 15 min after instillation. An initial faster elimination was found in the first 7 min following instillation. Corrections for background radiation, evaporation of water and transconjunctival transport of Tc99m were estimated.
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Central corneal thickness was measured optically in premature and full-term babies and in children. The thickness was found to decrease from the values found in premature and full-term babies to those found in small children aged between 2-4 years. The thickness of the adult cornea is reached at the age of about 3 years. These findings are discussed with respect to the possible role of corneal thickness as a biometric parameter, to intraocular pressure measurement, and to corneal thickness steady state regulation.
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In spite of a growing interest in clinical psychiatry to experiment with new treatment programs, not least in the field of milieu-therapy, the effect of these programs on the behavior of patients and staff are rarely subjected to systematic evaluation. So the progress in the field is hampered by a lack of clearly defined behavioral data which lends itself to critical analysis, and generally speaking is based on rather loose clinical impressions which make scientific verification difficult the present describes an admittedly crude attempt at systematic evaluation of what happened to staff's and patients' behavior when a relatively intensive milieu-therapy program was introduced in a traditional psychiatric unit, using relatively simple but clearly defined parameters of change in behavior over time. Certain hypotheses about what would happen in terms of group behavior if the new program worked according to its intentions were tested, and generally speaking the conclusion was that the program developed successfully as far as this could be measured by the selected parameters. Data about the patients' evaluation of the effect of the treatment program on themselves, and how this relates to attitudes towards own mental disorders and expectation towards psychiatric treatment at admission to the clinic, as well as social background and group behavior, is analysed, and wil be published in a subsequent paper. So the present paper should be considered as a preliminary report, mainly focusing on certain methodological aspects.
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