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Biomedical subjects

K Karlsson

Publications and source records attributed to K Karlsson.

At least 109 records · Page 6Linked to original sources
PubMed1986

Interval from rupture of the membranes to delivery and neonatal respiratory adaptation.

The influence of the time interval from rupture of the membranes to delivery on neonatal respiratory adaptation was analysed in a prospective study of all infants born in Göteborg, Sweden in one year. The correlation between the incidence of respiratory disorders and the rupture-delivery interval was analysed in all preterm infants (less than or equal to 36 weeks, n = 240) and in all term infants born by caesarean section (n = 452). A uniform pattern was found for all preterm infants, irrespective of mode of delivery, and for the term infants born by caesarean section. The curve was 'U-shaped' with higher incidence of respiratory diseases in infants born immediately after rupture of the membranes than in those born 3-36 h after membrane rupture. The incidence increased again in infants born greater than 36 h after membrane rupture. The same pattern was found for all kinds of respiratory diseases including idiopathic respiratory distress syndrome. Therefore, there seems to be no advantage in postponing delivery greater than 36 h after rupture of the membranes.

Cesarean Section↗
PubMed1985

Atypical hemangioendothelioma of venous origin. A clinicopathologic, angiographic, immunohistochemical, and ultrastructural study of two endothelial tumors within the concept of histiocytoid hemangioma.

Two patients, a 62-year-old man and a 50-year-old woman, both with deep-seated atypical endothelial tumors within the wide concept of histiocytoid hemangioma, are reported. In case 1, the tumor involved the brachial vein, and, in case 2, a medium-sized vein of the anterior neck. In both cases the involved vein was occluded. Angiography in case 1 suggested a tumor that was enclosed by the same fibrous sheath, the conjunctiva vasorum, that enclosed the occluded vein and its concomitant artery. Both tumors were solid, without conspicuous vascular differentiation by light microscopy. Such differentiation, however, was evident from the electron-microscopic examination, which showed tumor cells with endothelial features forming primitive vascular structures. Positive lectin histochemistry (Ulex Europeus I) and positive immunohistochemistry for factor-VIII-related antigen, actin, and vimentin also gave strong support for the endothelial differentiation of the tumor cells. Immunohistochemical studies of markers for histiocytic (alpha 1-antitrypsin, ferritin, lysozyme), epithelial (cytokeratin, epithelial membrane antigen), and neuroectodermal (S-100 protein) and skeletal muscle (myoglobin) differentiation were negative. At follow-up, after 7 years and 2 years, respectively, there were no signs of local recurrence or metastasis.

Angiography↗
PubMed1985

ST waveform changes of the fetal electrocardiogram during labour--a clinical study.

Waveform changes in the fetal electrocardiogram (ECG) are under reassessment as a means of fetal surveillance. The purpose of the study was to identify ST waveform changes from the fetal scalp lead during labour and to compare any change with conventional signs of fetal distress. Two scalp electrodes provided a sufficiently stable signal from which ST waveform changes could be identified and measured as the T/QRS ratio. No infant was clinically hypoxic. Only 26% of the 46 patients studied had a continuously normal CTG whereas 67% had no ST waveform abnormalities. A relation was found between the two variables as the mean T/QRS ratio increased from 0.20 (SD 0.11) during epochs of normal CTG to 0.27 (SD 0.17) with CTG changes. A linear correlation (r = 0.58, P less than 0.01) was found between the T/QRS ratio before birth and the cord plasma lactate values.

Electrocardiography↗
PubMed1985

Maternal treatment with a cardioselective beta-blocking agent--consequences for the ovine fetus during intermittent asphyxia.

To evaluate the effect of chronic beta 1-adrenoceptor blockade on physiological adaptation to asphyxia a study was done on exteriorized sheep fetuses of 127-142 days gestational age. Eleven pregnant ewes were infused with metoprolol for 5 days prior to experiment. Another 10 ewes were infused with saline and served as controls. Asphyxia was induced by intermittent complete obstruction of maternal placental blood flow. Fetal electro-cardiogram, heart rate, cardiac output, myocardial contractility and cerebral blood flow were measured together with blood pH, lactate and hypoxanthine. Neurophysiological responses were evaluated by changes in somatosensory evoked electroencephalogram. The beta 1-blocked fetuses showed less responsiveness in myocardial contractility and heart rate during reoxygenation. This curtailed reaction resulted in accelerated lactic acidosis, increased break-down of intracellular energy rich substances and impaired cerebral function. Nine of the ten controls survived the experiment and 8 of them regained their somatosensory evoked EEG potentials, whereas 7 of the 11 beta-blocked fetuses survived and only 3 regained original somatosensory evoked EEG potentials. It is concluded that beta 1-adrenoceptor blockade impairs the adaptive responses to asphyxia in the ovine fetus and decreases its ability to survive severe asphyxia.

Animals↗
PubMed1984

Contribution of heart muscle, liver, skeletal muscle and placenta to the asphyxial hypoxanthine elevation in the acutely exteriorised fetal lamb.

The metabolic response to different degrees of hypoxia was studied in 14 lamb fetuses. We have previously found a substantial rise in the fetal arterial plasma hypoxanthine (HX) level, in parallel with alterations of other hypoxia indices during induced asphyxia. Measurements of the arterio-venous (A-V) difference in the HX level across the CNS demonstrated a late efflux of this substance from the fetal brain, with a high resistance to asphyxia. In this study, the effluxes of HX, lactate, and in some cases glucose, from the myocardium, liver, hindleg (skeletal muscle) and placenta were investigated in acutely exteriorised sheep fetuses with graded asphyxia. The main findings were as follows: (a) myocardium: a release of HX early during asphyxia, the magnitude of which paralelled the amount of mechanical work performed by the heart; a significant lactate influx into the heart during normoxia and recovery period; (b) liver: hepatic HX release even during normoxia, increasing to substantial amounts in connection with increasing asphyxia; (c) hindleg: release of HX only during the recovery period; lactate efflux during all periods apart from severe asphyxia, when an influx was seen for both substances; (d) placenta: production of lactate during normoxia, and an efficient clearance of both lactate and HX from the fetal plasma in combination with their concentration increasing during asphyxia. It is concluded that the myocardium and liver are the main contributors to the elevated HX level during fetal asphyxia among the fetal organs investigated, while skeletal muscle releases HX mostly during the period of reoxygenation.

Animals↗
PubMed1984

Heart rate variability and electrocardiogram changes in the fetal lamb during hypoxia and beta-adrenoceptor stimulation.

Hypoxic changes in the ST waveform of the fetal electrocardiogram (FECG), with elevated T waves as the main response, have earlier been described in the fetal lamb as mediated via the beta-adrenoceptor cells, initiated by catecholamine release. A similar background to the increase in fetal heart rate variability (FHRV) during hypoxemia has been suggested. The aim of the present study was to elucidate this question and also to compare FHRV and changes in the ST waveform of the FECG as indicators of fetal distress. Twenty-six acutely exteriorized mature lamb fetuses were submitted to periods of graded hypoxemia. Fetal blood gases were measured and oxygen content was calculated. The FHRV was analyzed by a computer program and calculated as the differential index (DI) and the interval index (II). Eighty seconds of the recorded ECG coinciding in time with each fetal blood sample were analyzed using a PDP 11/40 minicomputer. The ECG signal was sampled at a rate of 1250 samples per second giving a resolution in time of 0.8 msec. Each QRS complex was detected with a semi-automatic program using a cross-correlation algorithm. QRS complexes that by the program were signalled to be doubtful were visually examined and either rejected or approved. Hence, the resulting list of R-R intervals was practically free from artefacts. From this list of R-R intervals the DI and II were computed according to YEH et al. [30]. Hypoxemia resulted in initially strongly increased DI from 3.1 +/- 2.5 to 17.7 +/- 13.8 (p less than 0.001) and in II from 1.88 +/- 0.65 to 3.77 +/- 2.06 (p less than 0.001) (Fig. 1). Obviously the change in oxygen content per se was strongly associated with the variability indices, as we found a strong correlation between delta oxygen content/min and delta DI/min (r = 0.81). In five fetuses the effect of prolonged hypoxemia on DI was studied (Fig. 2). After the initial rise from 1.6 +/- 1.1 to 31.2 /+- 9.0 (p less than 0.02) DI decreased to 19.4 +/- 20.7. A regression analysis showed a strong connection between DI and PaO2, (n = 93, T = - 5.34), whether there was no relation between DI and pH (T = - 1.85). There is strong evidence that hypoxemia and asphyxia induce an increase in the concentration of catecholamines in fetal blood [2, 23].(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Treatment of intrauterine supraventricular tachycardia with digoxin and verapamil.

Intrauterine fetal supraventricular tachycardia (ISVT) is a rare condition which is connected with organic heart disease in only 4-10 per cent. However, neonatally these children develop heart failure in a high frequency (62 per cent). Intrauterine digitalization has been suggested as treatment, especially if the fetus is preterm. Fetal therapeutic concentrations might demand doses inconvenient to the mother. We hereby report one case of intrauterine SVT in the 26th gestational week treated with a standard dose of digoxin resulting in subtherapeutic umbilical digoxin levels. When no consistent influence on fetal heart rate could be seen, verapamil (80 mg x 3) was added to the treatment. A reversion of the tachycardia and the fetal ECG changes was achieved within two days. The verapamil treatment could be withdrawn after ten days, while the digoxin treatment was continued. An initial discrete heart enlargement also was reversed by the treatment. The delivery in gestational week 38 was uneventful and the child did well. A neonatal ECG showed a sinus rythm interfoliated with supraventricular extrasystoles. No signs of organic heart disease have appeared. When last seen at nine months of age, the ECG was normal and digoxin had been discontinued without recurrence of tachycardia.

Adult↗
PubMed1984

Does glucose administration affect the cerebral response to fetal asphyxia?

This study was designed to test whether the fetal brain has an increased resistance towards asphyxia at high levels of blood-glucose, compared with low levels. 35 fetal sheep were exteriorized and investigated under general anesthesia. Cerebral blood flow (CBF) was estimated with the 133Xenon-washout method. Cerebral uptake of oxygen, glucose, and lactate was measured. Somatosensory evoked potentials (SEP) were recorded. The fetuses were subjected to controlled asphyxia by ventilating the ewes with gas mixtures low in oxygen. The blood sugar levels of the fetuses were varied over a four-fold range. During normal oxygenation of the fetus variations in the blood glucose concentration induced considerable changes in the cerebral glucose uptake, whereas CBF and oxygen uptake were unaffected. During asphyxia, hyperglycemia was associated with rapid development of acidosis and reduction in cerebral oxygen consumption together with deterioration of the neurophysiological characteristics of the brain. Far from being beneficial during asphyxia, fetal hyperglycemia appeared to reduce the tolerance of the fetal brain towards asphyxia. This report together with other evidence provides support for the view that extra glucose might be disadvantageous for the asphyxiated fetus.

Animals↗
PubMed1984

Fibrinopeptide A and intravascular coagulation in normotensive and hypertensive pregnancy and parturition.

Fibrinopeptide A (FpA), fibrin monomers, fibrinogen, fibrin degradation products (FDP) aand platelets have been studied during pregnancy, parturition and during toxemia and compared with normal non-pregnant controls in order to evaluate thrombin activity under these conditions. We found a significant rise in fibrinopeptide A levels in late pregnancy and even more so during parturition with a maximum immediately after placental expulsion. We also found elevated FpA levels in toxemic patients, but no significant differences from normal pregnancies. Fibrin monomers were more often elevated during delivery and toxemia during normal pregnancy. One case report concerning a patient with deficient thrombin activation and heavy postpartum bleeding is added. Our studies indicate an increased thrombin activity and fibrinogen turnover in both normal and toxemic pregnancies. During normal childbirth, coagulation activity seemed to reach a maximum immediately after placental separation.

Adult↗
PubMed1984

Maternal beta-adrenoceptor blockade reduces fetal tolerance to asphyxia. A study in pregnant sheep.

Maternal and fetal beta 1-adrenoceptor blockade was induced in sheep by infusing i.v. 11 pregnant ewes with metoprolol in doses producing maternal plasma concentrations of metoprolol comparable to those obtained in clinical use. Ten other ewes and their fetuses served as controls. Under acute anaesthesia the fetus was exteriorized and subjected to two levels of controlled asphyxia by intermittent, complete obstruction of the maternal placental blood flow. Fetal haemodynamic reactions were assessed by measuring fetal heart rate, cardiac contractility, cardiac output and cerebral blood flow. The metabolic reactions were evaluated from blood gases, pH, lactate and hypoxanthine concentrations, while the electrophysiological status of the brain was evaluated from the somatosensory evoked EEG potentials (SEP). Already during the period of moderate asphyxia the beta-blocked fetuses demonstrated a blunted haemodynamic response, in comparison with the control fetuses, resulting in an accelerating lactic acidosis, signs of a breakdown of intra-cellular energy-rich phosphates and an impaired cerebral function. During the period of severe asphyxia, both groups of fetuses exhibited signs of extensive cerebral deterioration. During the ensuing recovery phase, 80% of the control fetuses regained their brain function, as assessed by SEP, whereas this was true for only 30% of the beta 1-blocked fetuses. It is concluded that the ovine fetus relies heavily on greatly increased sympatho-adrenal activity to adapt itself to asphyxia and that blockade of the fetal beta 1-adrenoreceptors by maternal medication is a hazard to the potentially asphyctic fetus.

Adrenergic beta-Antagonists↗
PubMed1984

The acute effects of a non-selective beta-adrenergic blocking agent in hypertensive pregnant rats.

It is generally accepted that hypertensive cardiovascular complications can be prevented by treatment. However, during pregnancy, antihypertensive drugs might be hazardous in view of their influence on the fetus. Nevertheless, in spite of the diverging published results, even beta-blockers have been used in the pregnant patient. As our basic knowledge concerning the circulatory and fetal effects is minimal, we decided to elucidate the influence of the non-selective beta-blocker, propranolol, on the haemodynamic circumstances in hypertensive pregnant rats. Renal hypertension was induced by clamping both renal arteries 4 weeks before pregnancy. Shortly before term, cardiac output was determined with the dye-dilution technique and utero-placental blood flow was determined with the microsphere technique, both before and after propranolol injection. Mean arterial pressure and heart rate were registered continuously. The acute propranolol injection reduced mean arterial pressure by 26%. This was due mainly to a 32% decrease in cardiac output, which in turn was due to a 24% decrease in stroke volume and a 6% decrease in heart rate. Both myometrial and placental blood flow decreased significantly, by 45 and 50%, respectively. It was furthermore of interest to observe the significant increase in blood flow resistance in both myometrium and placenta. In conclusion, it can be stated that the non-selective beta-blocker propranolol, which lacks intrinsic stimulating activity, reduces mean arterial pressure mainly by a cardiac output decrease. The present results further indicate that the influence on peripheral blood flow might be caused by cardiac output changes as well as by direct effects on the uteroplacental vascular bed.

Adrenergic beta-Antagonists↗
PubMed1984

Acute haemodynamic effects of pindolol during pregnancy in experimental renal hypertension.

Clinical as well as experimental studies have demonstrated a 70% reduction in utero-placental blood flow in pregnancies affected by severe hypertension (13, 19). In pregnant renal hypertensive rats, propranolol administration causes a further 50% reduction in utero-placental blood flow (16). The present study on renal hypertensive rats was performed in order to explore the acute effects on central haemodynamics and utero-placental blood flow of the non-selective beta-blocker pindolol, which also has an intrinsic beta-stimulatory effect. Renal hypertension was induced by partial clamping of both renal arteries in female Wistar rats 4 weeks before pregnancy. Some 2-4 days before expected parturition, cardiac output was determined with the dye-dilution technique and blood flow to the reproductive organs with the microsphere technique, both before and after acute pindolol administration. Mean arterial pressure and heart rate were recorded continuously during the experiment. After pindolol injection, mean arterial pressure fell by 22% due to a 38% reduction in total peripheral resistance. No significant changes in cardiac output, stroke volume or heart rate were found. Placental blood flow was significantly reduced, by 30%, whereas myometrial and ovarian blood flows were reduced by only 18 and 9%, respectively. Thus, the reduction in blood supply to the reproductive organs in renal hypertensive rats after acute pindolol administration was most pronounced in the placenta. This reduction in placental flow was, however, only about half as pronounced as after propranolol, which lacks intrinsic beta-stimulatory effects. This may suggest that vasodilating beta-receptors may play an important role in the maternal placental vascular bed.

Animals↗
PubMed1984

A clinical comparison between a laboratory and a commercial impedance audiometer.

Impedance audiometry is a useful tool in the diagnosis of retrocochlear lesions, provided that adequate normal values regarding the stapedius reflex thresholds and decay are used. The normal values in Sweden (and elsewhere) have been obtained with a laboratory impedance audiometer that is not in common use. We have compared a commercial impedance audiometer, the Grason-Stadler 1723, with this laboratory model to determine whether the normal values are valid. We found that the Grason-Stadler 1723 audiometer gives reliable stapedius reflex thresholds, but at 2-4 dB higher levels. The reflex decay curves, however, are unsatisfactory. Possible explanations for the results are discussed. We have also proposed a modification of the recorder of the commercial audiometer. The study demonstrates that normal values cannot be transferred freely between different equipments.

Acoustic Impedance Tests↗
PubMed1984

The humoral antibody response to Shigella dysenteriae type 1 infection, as determined by ELISA.

An enzyme-linked immunosorbent assay (ELISA) for determining the class-specific humoral antibody response to the lipopolysaccharide antigen from Shigella dysenteriae serotype 1 bacteria has been tested. Two or more serum samples from each of 60 persons infected with this organism during a dysentery outbreak in a boarding school for young men near Haiphong, Viet Nam, and single serum samples from 39 healthy Vietnamese and from 20 healthy Swedes were included in the study. Comparison of the titres in the sera from the patients and the Vietnamese controls showed that the patients had significantly elevated IgA titres in sera collected 10, 30 and 45 days after onset of infection, and significantly elevated IgG titres in sera collected 30, 45 and 180 days after the onset. The titres in the patients' sera, compared with those in the Swedish controls, were significantly elevated for IgA and IgM as well as IgG in the samples collected after 10, 30, 45 and 180 days. The use of rabbit antisera, specific for enteropathogenic bacteria, and absorption experiments with human sera indicated that the S. dysenteriae type 1 lipopolysaccharide antigen is specific with respect to the O-antigenic polysaccharide chain.

Adolescent↗
PubMed1983

The hearing of symphony orchestra musicians.

The question has recently been raised as to whether the performance of symphony orchestra music involves a risk of sustaining hearing impairment. The following investigation presents a population study of 417 musicians, of whom 123 were investigated twice, at an interval of 6 years. Median values of screened tone thresholds were compared with a reference material, according to Spoor & Passchier-Vermeer (1969). The tone thresholds measured did not differ from the reference values although the actual sound exposure in some situations exceeded the permitted sound levels applied to industrial noise. We suggest that the sound exposure criteria for industrial noise are not valid when discussing such sounds as are produced by acoustic instruments in a symphonic environment.

Adult↗