Search PubMed⌕ Search

Biomedical subjects

K Peter

Publications and source records attributed to K Peter.

At least 271 records · Page 15Linked to original sources
PubMed1986

[Imaging of prostatic cancer by 1.5 Tesla nuclear resonance tomography].

Twenty-two patients with histologically confirmed carcinomas of the prostate were examined by nuclear magnetic resonance, using a 1.5 Tesla magnet (stage T1: one patient, T2: eight patients, T3: six patients, T4: seven patients). In 19 out of the 21 patients in stages T2 to T4, the tumour showed a specific signal intensity. In 12 cases, the tumour signal was more intense than from a normal prostate when using medium repetition and echo delay times; in 19 cases, multi-echo sequences with increasing echo delay time (30 to 240 ms) and long repetition times (usually 1600 ms) showed less reduction in signal intensity than surrounding structures (except urine). Unlike computed tomography, 1.5 Tesla MR is able to demonstrate carcinomas confined to the prostate. Demonstration of infiltration is possible with MR with great accuracy because of the ability to obtain images in three planes and because of the accurate rendering of soft tissue detail. In particular, MR differentiates between stages T2 and T3 more clearly than does CT. The best demonstration of anatomical structures in the true pelvis is achieved with a repetition time of 800 ms and an echo delay time of 30 ms, the best demonstration of tumour with corresponding 1600 ms and 120 ms. The effect of catheters in the bladder, or previous transurethral resection on the MR images is discussed.

Aged↗
PubMed1986

[Thiopental distribution in the blood of surgical patients].

The influence of hematocrit, of the concentration of plasma proteins, and of CO2 pressure on the distribution of thiopental in the blood was studied in vitro in 30 venous blood samples. Thiopental was bound to plasma proteins to 80.3-89.2%, mean 85.0%, at a plasma protein concentration of 60 g/l and a pH of 7.37. Considerable changes in the plasma protein concentration had a considerable influence on the binding rate. By halving the protein concentration the free fraction was almost doubled. Increasing the protein concentration to 90 g/l led to binding rates of around 88-89%. When the pCO2 was increased from 40 to 60 torr protein binding decreased slightly, indicating that this barbiturate is mainly bound in its anionic form. At a hematocrit of just under 40 vol.%, 14-34% of the thiopental was absorbed by the erythrocytes. Changes in the plasma protein binding rate influenced the thiopental proportion of erythrocytes, as changes in the hematocrit influenced the plasma thiopental proportion. The concentration of liposoluble thiopental acid physically dissolved in the plasma fluid, just under 8% of the thiopental in the blood, changed relatively little on variation of the hematocrit and the CO2 pressure, thanks to the compensatory function of the plasma proteins and erythrocytes. Since most of the thiopental in the blood is bound to plasma proteins, changes in the protein concentration had the greatest effect on the proportion of thiopental acid of the barbiturate content of the blood.

Anesthesia, General↗
PubMed1986

[Liver perfusion and oxygenation with isoflurane].

The influence of 0.7, 1.4 or 2.1 vol % isoflurane on hepatic blood flow and hepatic tissue oxygenation was studied in 12 dogs under basal anaesthesia with i.v. piritramid. Blood flow was measured by the microsphere method (phi = 15 micron). Tissue pO2 was determined by a platinum multiwire electrode and by measuring hepatic venous pO2. Isoflurane effected a marked fall in arterial blood pressure in these surgically not stimulated animals. However, cardiac output fell only moderately due to a considerable reduction in systemic vascular resistance. Both local tissue pO2 and venous pO2 were decreased with isoflurane. A potentially hazardous reduction in hepatic tissue pO2 was found predominantly with high isoflurane concentrations. The decrease in hepatic tissue pO2 results from disadvantageous effects on hepatic O2-balance: total hepatic blood flow decreases, whereas splanchnic O2 consumption increases. The lower blood flow is due to a reduction of portal blood flow whereas arterial perfusion remains unchanged. The increase in splanchnic O2 consumption possibly results from an elevated O2 consumption of the liver. Further studies have to clarify whether the disadvantageous effects of high isoflurane concentrations fail to appear when pain-induced stimulation of the sympathico-adrenergic system counteracts the fall in arterial blood pressure.

Animals↗
PubMed1986

[Thiopental levels in the plasma during induction of anesthesia].

The thiopentone sodium surge in plasma was investigated in 15 elderly surgical patients and 10 young adults during injection, over a period of 1 minute, of 4 mg of anaesthetic per kg of fat-free body weight (in 18 patients), and 5 mg per kg of fat-free body weight (7 patients). In keeping with prolonged circulation time in old age, thiopentone sodium reached the sampling site faster in the younger patients than it did in the older patients. In the majority of cases, thiopentone sodium concentrations in plasma reached a maximum of between 60 and 80 micrograms/ml. Mean thiopentone sodium concentrations in the older patients were 10% higher, but here values differed so widely that this result must be regarded as coincidental. It was, accordingly, impossible to establish any statistically verifiable differences between young and old patients by estimating the volume of thiopentone sodium distribution shortly after the end of injection. Plasma protein binding, 85% on average, with extremes ranging from 79% to 89% did not depend on thiopentone concentration or age. In the group of patients studied, it was not possible to confirm statistically that the plasma protein concentration influenced the rate of binding. Dosage according to fat-free body weight did not diminish inter-individual differences in plasma concentration-time profiles.

Adult↗
PubMed1986

[Initial results with bright light (phototherapy) in affective psychoses].

The biological foundations of light-treatment and their relation to neurophysiological and biochemical mechanisms were discussed. We developed an apparatus for treatment and report of first experiences in affective psychosis. In addition to a decrease of depressivity and anxiety we found an unequivocal tendency to normalization of sleep-behaviour. The farther clinical and paraclinical investigations has to show the position of this method of treatment in the total conception of a biological therapy.

Adult↗
PubMed1986

[Thiopental kinetics in high-dose use].

The kinetics of thiopentone when administered in high doses were investigated in two patients with elevated intracranial pressure and three patients with focal cerebral ischemia. Initial saturation of the tissues is best achieved by a series of infusions with decreasing infusion rate. Administration of a bolus followed by maintenance doses proved unsuitable. The course of concentration under maintenance dosage was extremely variable, mainly due to interindividual and intraindividual variations in clearance. The apparent distribution volumes in these patients (1.38-3.10 l/kg, mean 2.43 l/kg) corresponded to the volumes determined after bolus administration. The total body clearance was low (45.8-103.4 ml/min, mean 72.3 ml/min) and was the reason for long elimination half-times (15.6-25.0 h, mean 23.2 h). Four patients biotransformed thiopentone regardless of the concentration. In one female patient the biotransforming enzyme systems may have been saturated. While conversion of thiopentone to pentobarbitone is generally only of secondary importance, an unusually high plasma pentobarbitone concentration was observed in one patient, reaching 50% of the concentration of the original substance. On the average, thiopentone was 75-80% proteinbound. The binding rate changed considerably with time. It could not be shown that this was influenced by albumin concentration between 25 and 50 g/l. The thiopentone concentration in the ventricular fluid corresponded approximately to that in the plasma fluid. Owing to the variability of the total body clearance and plasma protein binding, and the possibility of changes in tolerance, thiopentone administration must be controlled individually according to the EEG and intracranial pressure. Monitoring of the drug concentration in plasma is recommended.

Adult↗
PubMed1985

Effects of enflurane on myocardial ischaemia in the dog.

The effects of experimentally induced, severe coronary artery stenosis on regional changes in myocardial blood supply, cardiac function, and metabolism were studied in 14 dogs. The anterior interventricular branch of the left coronary artery (LAD) was constricted such that arterial inflow was reduced by 80%. Nine dogs were given enflurane in a concentration of 2.2 vol.% (1 MAC) in air, and five animals received no enflurane (controls). Regional myocardial blood supply was measured by the tracer microspheres technique, using 8-micron microspheres labelled with five different radioisotopes. Regional cardiac function (end-diastolic length of the muscle fibres = EDL; segmental shortening during systole = delta L) was estimated with the aid of two ultrasonic crystals which were placed in the subendocardial layer of the myocardium supplied by the LAD. Regional myocardial metabolism (oxygen consumption; lactate extraction) was evaluated from arterial and coronary venous blood samples. The latter were collected selectively from the region supplied by the LAD via the great cardiac vein. The results showed that, during severe coronary artery stenosis comparable to clinical conditions, apart from the known actions on systemic haemodynamics and contractility, enflurane had beneficial effects on regional myocardial variables. This was indicated by reduced regional contraction, measured as EDL and delta L; unchanged subendocardial blood flow without any redistribution; and improved lactate extraction in the ischaemic region.

Animals↗
PubMed1985

Hemodynamics and oxygen transport after partial and total blood exchange with pyridoxalated polyhemoglobin in dogs.

The effects of a pyridoxalated polyhemoglobin solution (SFH-PLP)n-solution) on cardiovascular hemodynamics and oxygen transport were investigated in a model of partial and total blood exchange in seven dogs. Cardiac output, mean arterial pressure and heart rate were essentially unchanged, even after total blood exchange, due to the long plasma half-disappearance time of (SFH-PLP)n (36 h) and due to the addition of albumin to the solution. The oxygen-binding capacity of (SFH-PLP)n was 1.1 to 1.2 ml O2/g hb. Oxygen availability was reduced to about 50%, resulting from the low hemoglobin concentration and the decreased oxygen-binding capacity of (SFH-PLP)n. Since cardiac output did not increase, O2-consumption was maintained by an increase in O2-extraction from 21 to about 50%. However the decrease in mixed venous PO2 to values not below 30 mmHg (4.00 kPa) proves the sufficient unloading capacity of (SFH-PLP)n. The adequate tissue oxygenation of (SFH-PLP)n could be demonstrated by the lack of a metabolic acidosis, the essentially unchanged PO2-histograms of the skeletal muscle and the only moderate decrease in mixed venous PO2. Four dogs survived for more than 3 days; three of them were long-term survivors. This suggests that oxygen supply was maintained by (SFH-PLP)n until red blood cells were restored.

Animals↗
PubMed1985

[Not Available].

Explore the source record for details and available documents.

History, Modern 1601-↗
PubMed1985

[Animal experiment studies on hemodynamics following partial and total blood exchange with a pyridoxalated polyhemoglobin solution].

The effects of a pyridoxalated polyhaemoglobin (SFH-PLP)n-solution on haemodynamics were investigated in a model of partial (hct = 12%) and total blood exchange (hct less than 1%) in 7 dogs. Partial blood exchange resulted in a slight increase in right atrial pressure (RAP) and pulmonary capillary wedge pressure (PCWP) and in a marked decrease in heart rate (HR). Cardiac output (CO) did not increase as would be expected from haemodilution. After total blood exchange, arterial pressure, HR, RAP, PCWP and CO were unchanged compared to the pre-exchange values during the 90 minutes of observation. However, pronounced pulmonary vasoconstriction was observed in 4 dogs. The beneficial effects on haemodynamics are due to the long intravascular persistance of the polymerized haemoglobin molecules (plasma half-disappearance time = 36 hours) and the addition of albumin supplying a sufficient colloid-osmotic pressure of the solution. These characteristics and the good oxygen unloading capacity of the pyridoxalated polyhaemoglobin resulted in longterm survival of three dogs. These results demonstrate a better haemodynamic efficacy of the (SFH-PLP)n-solution compared to previous investigations with unmodified haemoglobin solutions. However, there are still many problems, which have to be clarified prior to its clinical application.

Animals↗
PubMed1982

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH)--treatment with lithium.

Two patients with SIADH after brain trauma are described. Features of SIADH are "inappropriate" antidiuresis and excessive natriuresis with negative sodium balance resulting in hyponatremia and plasma hypoosmolality which may lead to cerebral dysfunction. Oral lithium carbonate was beneficial in both patients. With plasma levels of lithium around 1 mmol/l a temporary impairment of renal concentrating ability and antinatriuresis with normalization of plasma sodium and plasma osmolality was observed. The SIADH subsided about 4 months after the original trauma, long after gross neurological symptoms had resolved.

Accidents, Traffic↗
PubMed1982

[The effect of pentobarbital on the microcirculation of skeletal muscles and the subcutis. An animal-experimental study].

The effects of pentobarbitone anaesthesia on the macrohaemodynamics and the microvasculature of subcutaneous tissue and skin muscle were studied in hamsters (n = 14) utilizing intravital microscopy, quantitative video techniques and a platinum multiwire electrode for local PO2 measurements. After achieving anaesthesia with 35 mg/kg b.w. pentobarbitone, changes in macrohaemodynamic parameters, blood cell velocity and vessel diameters were not observed. However, after 30 min of pentobarbitone anaesthesia, 25% of the arteriolar blood volume coursed through arteriovenous shunts. The increase in a-v shunting was accompanied by a significant decrease of functional capillary density. As a result, local PO2 values decreased slightly after 30 min of pentobarbitone anaesthesia. These findings provide evidence that 35 mg/kg b.w. pentobarbitone cause alterations in capillary density and perfusion. It is concluded that with a dose of up to 35 mg/kg b.w. pentobarbitone, these changes have little effect on local tissue oxygenation.

Animals↗