Mean power spectra from pharmaco-electrocorticographic studies: relative baseline correction and log transformation for a proper analysis of variance to assess drug effects.

The effects of drugs on electrocorticographic activity (ECoG) of the rat are studied in a routine screen. ECoG is recorded for 6-min periods before drug/vehicle administration and starting at 20 and 45 min thereafter. For each period, a mean power spectrum is calculated. Drugs are tested in 25 rats according to a 5 x 5 Latin square design and effects are assessed with analysis of variance. The validity of this assessment depends on assumptions on the chosen statistical model and the distribution of the data. In this study we consider the relative and absolute baseline corrected data. The assumptions appear to be better fulfilled if together with a relative baseline correction a logarithmic transformation is applied to the data.

Sequence and expression of Sox-18 encoding a new HMG-box transcription factor.

The newly identified Sox gene family (Sry-like HMG-box gene) is characterized by a conserved DNA sequence encoding a domain of approx. 80 amino acids (aa) which is responsible for sequence-specific DNA binding. The first member isolated, the mammalian Y-linked testis-determining gene, Sry, is necessary and sufficient for male development. We report here the identification of two new members of this family, Sox-17 and 18. We have determined the full cDNA sequence of Sox-18 which encodes a protein of 378 aa. Sox-18 mRNA transcripts were restricted to heart, lung and skeletal muscle in the adult mouse.

Trans-activation and DNA-binding properties of the transcription factor, Sox-18.

Sox-18 is a member of the Sox multi-gene family (Sry-related HMG-box gene). We have bacterially expressed this 378 amino acid protein and demonstrated sequence-specific binding to the Sox DNA-binding motif AACAAAG. A distinct 95 amino acid activation domain was mapped in Sox-18 using GAL4-Sox-18 fusions (amino acids 160-225). Furthermore, Sox-18 was capable of trans-activating gene expression through the AACAAA motif. Our results suggest that Sox-18 functions as a classical trans-activator of gene expression.

Relationship between electrocortical activity and beta-adrenergic receptor function in the rat after chronic desimipramine treatment.

The aim of this study was to investigate the effects of chronic administration of desimipramine (DMI) after 2, 7 or 20 mg/kg per day, administered by osmotic minipumps, on electrocortical activity and beta-adrenergic receptors in rat brain. Rats receiving DMI chronically show a dose- and time-dependent increase of electrocortical activity above 15 Hz as well as a dose- and time-dependent decrease below 15 Hz. Already after 3 days of treatment a clear effect on the electrocorticogram (ECoG) was seen. The maximal change in the ECoG was reached at the end of the study, after 24 days of treatment. After acute treatment (20 and 45 minutes after 2, 4 or 10 mg/kg i.p.) with DMI, a decrease of electrocortical activity is seen above 15 Hz. Thus the effect of acute DMI treatment on the ECoG is different from that of chronic treatment. In the same group of rats the effect of chronic DMI treatment on the beta-adrenergic receptor number was determined 24 hours after the last ECoG recording. The number of beta-adrenergic receptors was dose dependently reduced in the DMI-treated rats as determined by [3H]-dihydroalprenolol binding. There was no change in affinity (KD) of the ligand for the beta-receptor. This finding was corroborated by a decrease in the functional activity of the beta-adrenergic receptors, as determined by isoprenaline stimulated efflux of cyclic-AMP in cortex slices. These data indicate that chronic treatment with DMI, resulting in a down-regulation of the cortical beta-adrenergic system, is paralleled by pronounced effects on the ECoG of rats. The different ECoG profiles after chronic DMI treatment compared with acute treatment suggest that adaptive changes in the electrical brain activity continually develop during the chronic treatment with this antidepressant drug.

Regional blood flow and metabolism in canine endotoxin shock before, during, and after infusion of glucose-insulin-potassium (GIK).

Glucose-insulin-potassium infused (GIK) during endotoxin shock causes increased cardiac output (CO) accompanied by decreased systemic vascular resistance. We have studied the effects of GIK on the distribution of cardiac output with radioactive microspheres to see if this decrease in resistance is equally distributed over all organs. GIK resulted in increased CO and increased flow to heart, splanchnic bed, kidneys, adrenals, and skeletal muscle, but fractional flow to these organs did not change. Thirty minutes after the GIK infusion, CO and organ flow had fallen again and differences between the endotoxin and control groups were no longer significant. GIK thus increases CO during endotoxin shock but does not influence its distribution. Systemic oxygen transport increased after GIK, but oxygen extraction decreased. Myocardial and splanchnic oxygen consumption did not change significantly. Oxygen extraction also diminished in these areas after GIK. GIK did not influence serum lactate: In both groups lactate increased significantly.

Myocardial metabolic and morphometric changes during canine endotoxin shock before and after glucose-insulin-potassium.

Glucose-insulin-potassium (GIK) improves myocardial function during endotoxin shock but the mechanism of this action is not clear. We have studied in open chest dogs the effects of GIK (n = 9) on haemodynamics, myocardial biochemistry (repeated drill biopsies; glucose-6-phosphate, G-6-P; fructose-6-phosphate, F-6-P; adenosine triphosphate, ATP; creatinine phosphate, CP; glycogen) and myocardial histomorphometry. The animals were anaesthetised (etomidate 4 mg X kg-1 X h-1) and artificially ventilated (N2O:O2 = 2:1). After endotoxin (1.5 mg X kg-1) cardiac output (CO) and mean arterial pressure (MAP) fell rapidly, with a temporary recovery followed by gradual circulatory collapse. Coronary blood flow (cbf; radioactive microspheres) decreased, but this was not significant. G-6-P tended to fall, as did ATP levels while CP levels were unaltered. Histomorphometrical analysis showed myocardial cell swelling with compression of capillaries and decreased interstitial volume. GIK infusion (50% glucose, 2 g X kg-1bw, 8 mmol KCl and 3 U insulin kg-1bw) increased CO and coronary blood flow. Glycogen and G-6-P levels did not change, while F-6-P tended to increase. ATP levels were not influenced by ATP/CP ratio decreased. Myocardial cell swelling markedly decreased; average capillary cross-sectional area, as an index of capillary compression, returned to control value. In two dogs, which died before the end of the experiment, myocardial oedema, with disturbed capillary volume and reduced interstitial volume was unaltered after GIK. The initial effects of GIK are most likely due to restoration of myocardial perfusion. Improved perfusion, and the influence of elevated serum osmolality and insulin levels on excitation-contraction coupling may help to improve myocardial function.

The effect of dietary linoleic acid and pectin on lipoprotein and apolipoprotein A1 concentrations in rhesus monkeys.

Medium term effects (3 months) on serum lipoprotein levels of a diet with a high P/S ratio (2.2) and a low P/S ratio (0.3) were investigated in 13 normolipoproteinemic rhesus monkeys. Both diets were studied with and without added gel-forming fibre, as pectin. Addition of pectin did not have major influences on serum lipid levels. Changing from a low to a high P/S diet resulted in a significant decrease of total cholesterol (23%) and LDL cholesterol (18%) levels, but also HDL cholesterol (23%) and apolipoprotein A1 (Apo A1; 13%) concentrations fell significantly. However, after 12 weeks on the high P/S diet, HDL cholesterol concentrations rose by 24%, not significantly different from the levels during the low P/S diet. We conclude that the medium-term effects of a high P/S diet are a decrease in LDL cholesterol with only a transient effect on HDL cholesterol.

Effects of glucose-insulin-potassium (GIK) on myocardial blood flow and metabolism in canine endotoxin shock.

Glucose-insulin-potassium (GIK) has beneficial effects during endotoxin shock, possibly through improvement of myocardial function, but the mechanism is not clear. We have studied the effects of GIK on left ventricular function, coronary flow, and oxygen consumption in controls and dogs treated with endotoxin (1.5 mg/kg-1). The animals were anaesthetized (etomidate 4 mg/kg-1/hr-1) and ventilated (N2O:O2 = 2:1). We have measured left ventricular pressure, left ventricular end-diastolic pressure (LVEDP) and LVdP/dt, systemic blood pressure, cardiac output (CO; thermodilution), coronary blood flow (CBF; radioactive microspheres), and oxygen content and lactate in arterial and coronary sinus blood. Endotoxin caused a rapid fall of CO and blood pressure with a temporary recovery followed by gradual circulatory collapse. GIK infusion (50% glucose, 2 g/kg-1 bw, 8 mmol KCl, and 3 U insulin/kg-1 bw) increased CO (56%), CBF (61%), blood pressure (21%), LVEDP (77%), and LVdP/dt (28%), and systemic vascular resistance decreased (23%). Stroke work (80%) and tension time index (42%) decreased during shock, but GIK temporarily improved these variables. The ratio of stroke work, respectively tension time index to oxygen consumption, suggests that myocardial efficiency decreased during shock and improved after GIK. Endotoxin decreased the ratio of endo- to epicardial flow. GIK did not change this ratio. However, for the same endo to epi ratio, increased CBF implies increased flow to endocardium.

Effects of glucose-insulin-potassium (GIK) on the position of the oxyhemoglobin dissociation curve, 2.3-diphosphoglycerate, and oxygen consumption in canine endotoxin shock.

The effects of glucose-insulin-potassium (GIK) on hemodynamics, oxygen transport, P50, 2,3-diphosphoglycerate (2.3-DPG), and adenosine triphosphate (ATP) were evaluated in canine endotoxin shock. Ten dogs were studied under general anesthesia and controlled ventilation. Shock was induced with Escherichia coli endotoxin (1.5 mg/kg body wt). Thereafter two groups of five dogs each were formed by randomization. The one group received GIK (glucose 50%, 2 g/kg, insulin 3 U/kg, and 10 mmole K) in the period between 90 and 120 min after endotoxin. The other group received an equal amount of NaCl infusion and served as a control group. Observations were completed at 180 min after endotoxin. GIK resulted in a significant increase of cardiac output, stroke volume, mean arterial pressure, and oxygen consumption. Serum phosphate levels decreased. No changes were observed of P50 in vitro (at 37 degrees C and pH 7.40) and of P50 in vivo, nor of 2.3-DPG and ATP in the red cells. The data suggest that the increased oxygen consumption after GIK in canine endotoxin shock is caused only by improvement of cardiac output and oxygen availability and not by an effect on oxygen unloading capacity of hemoglobin.

Effect of volume loading and dopamine on hemodynamics and red-cell redistribution in canine endotoxin shock.

We studied in 20 anesthetized dogs (11-15 kg) the effect of volume loading and dopamine in the period between 90 and 120 min after injection of E Coli endotoxin (1.5 mg/kg). Changes in red-cell distribution were estimated from changes in regional radioactivity emitted by autologous 99mTc tagged red cells. Four groups of five animals were formed by randomization, such that effects of dopamine (15 micrograms/kg/min) and isotonic gelation solution (40 ml/kg/30 min) could be analyzed separately and in combination. Ninety minutes after endotoxin a significant decrease in cardiac output, arterial, and pulmonary arterial wedge pressures were observed. Thoracic radioactivity decreased by 26% and an increase in abdominal (11%) and hindlimb (17%) activity was measured, while the changes in hepatic activity were variable. No interaction between dopamine and volume for any parameter was found. Dopamine resulted in an increase in heart rate, while the other hemodynamic parameters did not change significantly. Dopamine resulted only in a slight increase in abdominal radioactivity. Volume loading produced an increase in cardiac output to greater than 200% of the value before endotoxin. This increase was accompanied by a considerable decrease in systemic resistance. No major changes in red-cell distribution were observed. We concluded that volume loading and dopamine did not affect red-cell redistribution in a later phase of canine endotoxin shock. Furthermore, our results suggest that correction of the volume deficit in this model results in a high-cardiac-output-low-systemic-resistance hemodynamic pattern.

Effects of naloxone on hemodynamics, oxygen transport, and metabolic variables in canine endotoxin shock.

The effects of naloxone (2 mg/kg body weight) on hemodynamics, oxygen transport, and some metabolic variables were studied in mongrel dogs under general anesthesia and controlled ventilation. All 19 dogs received Escherichia coli endotoxin (1.5 mg/kg) and subsequently were randomized into three groups. The first group (N = 7) served as a control group in which at 90 min after endotoxin (t 90), NaCl (0.65%, 4 ml/kg) was infused during 30 min. In the second group (N = 7) naloxone (2 mg/kg) dissolved in the same amount of fluid was administered at t 90 in 30 min. In the third group (N = 5) naloxone (2 mg/kg) was injected as a bolus in 5 ml NaCl (0.65%) at t 90, which was followed by NaCl (0.65%, 4 ml/kg) infused in 30 min. Differences in the three groups after intervention were tested statistically. After naloxone, blood pressure, cardiac output, and left ventricular stroke work increased significantly. Although oxygen availability increased, oxygen consumption and serum lactate did not change when compared with the control group. As to all other measured and calculated variables, no systematic differences were found in the three groups. In six dogs, plasma beta-endorphins were measured and were shown to rise substantially after induction of endotoxin shock. As to the hemodynamic changes, our observations confirm data from the literature. Naloxone apparently improves hemodynamics in endotoxin shock, but at least in this study fails to influence oxygen consumption and serum lactate levels.

Reproducibility of ejection fraction measurements by gated equilibrium blood pool scintigraphy.

The reproducibility of ejection fraction measurements has been studied using gated equilibrium blood pool scintigraphy. The use of appropriate statistical tests is proposed and commented upon. The intra-observer variability for our group of patients has a standard deviation of 6.4%, the interobserver variability of 3.2% and sequential studies done on the same and different days give standard deviations (due to "time" alone) of 1.0% and 1.9%, respectively. Different factors and sources involved in variability are mentioned. Variability values reported in the literature are discussed.

Virulence of urinary and faecal Escherichia coli in relation to serotype, haemolysis and haemagglutination.

The virulence of faecal and urinary Escherichia coli strains was studied in relation to serotype, haemolysin production and haemagglutination pattern. By means of an experimental mouse model E. coli strains can be divided into avirulent (I), mouse nephropathogenic (II), and generally virulent (III) strains. Virulent group II and group III strains were more often haemolytic and haemagglutinating than avirulent group I strains. Presence of K antigen could not be associated with virulence. Discriminant analysis for qualitative variables revealed that no combination of the investigated properties contributed more to a strain's virulence level than did one single property. It is concluded that other virulence factors, apart from haemolysin production in group II strains and haemagglutinins in group III strains, must be involved in the determination of a strain's virulence level. All O2, O6 and O18 ac strains tested were virulent, and by far the most O75 strains were avirulent, whereas other O groups were more variable with regard to virulence. Pyelonephritis strains were more often mannose-resistance haemagglutinating than faecal and other urinary isolates, indicating that mannose-resistant adhesins may be important in the pathogenesis of pyelonephritis.

On the relationship between germinal layer haemorrhage and telencephalic leucoencephalopathy in the preterm infant.

The brains of 54 deceased preterm infants were retrospectively studied for signs of germinal layer haemorrhage (GLH) and telencephalic leucoencephalopathy (TLE). On the basis of presence or absence of iron laden macrophages (siderophages) the cases with germinal layer haemorrhage were sub-classified as either "old" or "fresh" haemorrhage. Cases without GLH (non-GLH) were used as a control group. The distribution of ages at death in the non-GLH group was such that comparison to both fresh GLH cases and old GLH cases was possible. The distribution of pregnancy duration in GLH and non-GLH cases was similar. Statistical evaluation showed that old GLH cases were more often associated with TLE as either fresh GLH or non-GLH cases. By comparison of the three groups it is shown that differences in age at death do not explain the higher incidence of TLE in the old GLH group compared to the fresh GLH group. Hydrocephalus was found in the majority of old GLH cases. From a neuropathological view this complication is unlikely to account for the excess of TLE-lesions in that group. A logic explanation of the findings in this study is that the association between GLH and TLE is due to a common origin: asphyxia. The relatively low incidence of TLE in fresh GLH cases may be due to early death precluding detection of TLE. It is advocated that studies on GLH or TLE be comprehensively based on both phenomena to further the understanding on how they contribute to death or handicap.