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Biomedical subjects

L Eriksson

Publications and source records attributed to L Eriksson.

At least 253 records · Page 14Linked to original sources
PubMed1985

Substituted benzamides as ligands for visualization of dopamine receptor binding in the human brain by positron emission tomography.

Two substituted benzamides, FLB 524 and raclopride, were labeled with 11C and examined for their possible use as ligands for positron emission tomography (PET)-scan studies on dopamine-2 (D-2) receptors in the brains of monkeys and healthy human subjects. Both ligands allowed the in vivo visualization of D-2 receptor binding in the corpus striatum caudate nucleus/putamen complex in PET-scan images. [11C]Raclopride showed a high ratio of specific striatal to nonspecific cerebellar binding, and the kinetics of binding of this ligand made it optimal for PET studies. The in vivo binding of [11C]raclopride in the striatum of cynomolgus monkeys was markedly reduced by displacement with haloperidol. This and previous in vitro data indicate that [11C]raclopride binds selectively to striatal D-2 dopamine receptors. In healthy human subjects, [11C]raclopride binding in the caudate nucleus/putamen was 4- to 5-fold greater than nonspecific binding in the cerebellum. In comparison with previously available ligands for PET-scan studies on central dopamine receptors in man, [11C]raclopride appears to be advantageous with regard to (i) specificity of binding to D-2 receptors, (ii) the high ratio between binding in dopamine-rich (caudate, putamen) and dopamine-poor (cerebellum) human brain regions, and (iii) rapid association and reversibility of specific binding. [11C]Raclopride should be a valuable tool for characterizing D-2 receptors in the brains of patients with neuropsychiatric disorders.

Animals↗
PubMed1985

Functional cyst or ovarian cancer: histopathological findings during 1 year of surgery.

The histopathological findings recorded during 1 year in 101 women undergoing surgery for palpable ovarian tumors were analyzed with respect to patient age, medical history and presenting symptoms. Almost half of the women (43%) were younger than 30 years and functional cysts or normal ovaries were found in 66 out of totally 101 women. During the following 2 years 18 of these women were subjected to further gynecological surgery and 17 women were infertile. While surgical treatment of functional cysts in young women may be deleterious, 3 cases of ovarian cancer illustrate the diagnostic difficulties and the potential risk of neglecting surgery.

Adolescent↗
PubMed1985

Inefficiency of chest percussion in the physical therapy of chronic bronchitis.

The effect of manual chest percussion was studied in 10 patients recovering from an acute exacerbation of chronic bronchitis. All patients were studied on 2 consecutive days. Physiotherapy consisting of postural drainage and instructed coughing was given on both days. Chest percussion was included in a randomized way on either day. Percussion was associated with a small but statistically significant increase in airflow obstruction, measured as a reduction in FEV1 after the treatment. There were no differences in the deposition or clearance of inhaled radiolabelled particles between the 2 forms of treatment. Changes in oxygen saturation were small and insignificant during both forms of treatment. The study indicates that manual chest percussion is of little value as an adjunct to postural drainage and instructed coughing in the treatment of patients with chronic bronchitis.

Aged↗
PubMed1984

Plasma vasopressin levels after I.C.V. infusion of histamine agonists in the conscious goat.

Histamine H1-agonists 2-pyridylethylamine (2-PEA) and 2-methylhistamine and H2-agonists 4-methylhistamine, dimaprit and impromidine were given i.c.v. to conscious goats and the release of arginine vasopressin (AVP) was measured. 2-PEA at very low doses (9 and 27 mumoles/animal, equivalent to H1-activity of about 0.5 and 1.5 mumoles histamine, resp.) significantly increased plasma AVP. The H2-agonists did not cause consistent changes in AVP even if their relative doses were higher. It is concluded that the vasopressin releasing effect of histamine is due to H1-receptor activation.

Animals↗
PubMed1984

Strategy for the measurement of regional cerebral blood flow using short-lived tracers and emission tomography.

This report describes a strategy for measurement of regional CBF that rigorously accounts for differing tracer partition coefficients and recirculation, and is convenient for use with positron emission tomography. Based on the Kety model, the measured tissue concentration can be expressed in terms of the arterial concentration, the rate constant K, and the blood flow f. The local partition coefficient may be computed as p = f/K. In our approach, maps of K and f are computed from two transverse section reconstructions. The reconstructions are based on weighted sums of projection data measured frequently during the observation period. Theoretical studies of noise propagation in the estimates of K and f were carried out as a function of tomographic count rate, total measurement time, and tracer half-life for varying input functions. These calculations predict that statistical errors in f of between 5 and 10% at a resolution of 1 cm full width at half maximum can be obtained with existing tomographs following i.v. injection. To compare theory and experiment, a series of flow studies were carried out in phantoms using a positron tomograph. These measurements demonstrate close agreement between computed flow and noise estimates and those measured in a controlled situation. This close agreement between theory and experiment as well as the low statistical errors observed suggest that this approach may be a useful tool in clinical investigation.

Cerebrovascular Circulation↗
PubMed1984

Performance study of the PC-384 positron camera system for emission tomography of the brain.

A positron camera system PC-384 has been designed and built for quantitative positron emission computed tomography of the brain. This head scanner consists of 384 bismuth germanate oxide scintillation detectors with a crystal packing fraction of 80%. The entire detector assembly rotates around a small circle (wobble) to achieve the necessary ray sampling. Seven simultaneous images are produced with four detector rings. Performances of the system are discussed and clarified based on experimental data.

Brain↗
PubMed1984

Bile reflux to the stomach and gastritis before and after cholecystectomy.

Thirty-four patients with gallstone disease were examined with cholescintigraphy and gastroscopy before and after cholecystectomy. Sixteen patients had a functioning and 23 a non-functioning gallbladder at cholescintigraphy. At scintigraphy 99Tcm-activity was found over the gastric fundus in 28% before and in 22% after cholecystectomy and there was no difference between the groups with and without a functioning gallbladder regarding bile reflux. Before cholecystectomy bile-stained contents in the stomach was significantly more often found among those with a non-functioning gallbladder (87%) than in those with a functioning gallbladder (44%). After cholecystectomy the number of patients with bile-stained contents in the stomach was high in both groups (92% and 82% respectively). No correlation could be found between the two methods to detect bile in the stomach. Before cholecystectomy patients with a functioning gallbladder had inflammatory changes in the antral as well as the fundic mucosa in 31%. Patients with a nonfunctioning gallbladder had inflammatory changes in the antral mucosa in 47% and in the fundic mucosa in 56%. These differences were however not statistically significant. No correlation could be found between bile-stained contents in the stomach and chronic gastritis or scintigraphically detected bile in the stomach and chronic gastritis. The degree and distribution of chronic gastritis was virtually unchanged one year after cholecystectomy.

Adult↗
PubMed1984

Water and electrolyte balance in male mink (Mustela vison) on varying dietary NaCl intake.

The effect of a ten-day dietary sodium load on the fluid balance of mink was studied by adding to the food NaCl 0.5, 1 or 2% of the wet weight. The basic diet without salt addition contained sodium corresponding to 0.5% NaCl of the wet weight. The animals showed no signs of discomfort, eating well in all test groups. Adding of 0.5% salt to the food did not increase drinking of water, whereas 1 and 2% salt addition doubled and quadrupled water consumption, respectively. Urine excretion was slightly higher than consumption of drinking water, and both increased parallelly to increasing salt intake. The dietary salt excess was mainly excreted in urine, whereas the alimentary canal played only a minor role. Urine sodium concentration rose with increasing salt intake, peak concentration 350 mM being reached in the diet with 1% salt addition. On higher sodium load any further increase in renal sodium excretion was achieved only by increasing the volume of urine. Urine osmolality was slightly above 2000 mOsm/kg on the control diet and on the diet with 0.5% salt addition. More diluted urine was excreted on higher salt loads, urine osmolality being 1500 mOsm/kg on the diet with 2% salt addition. Healthy minks appear to tolerate considerably high concentrations of salt in the feed. However, a sufficient supply of drinking water is of critical importance, because increased water intake and renal sodium excretion are the main means of eliminating excess salt.

Animals↗
PubMed1983

Characterization of drug-metabolizing systems in hyperplastic nodules from the livers of rats receiving 2-acetylaminofluorene in their diet.

A number of drug-metabolizing systems were measured in hyperplastic noduli from the livers of rats receiving 2-acetyl-aminofluorene in their diet and compared with corresponding activities in control liver. The level of microsomal cytochrome P-450 is reduced 54% in the nodular tissue, while 5 activities catalyzed by the cytochrome P-450 system (i.e., aminopyrine N-demethylase, benzo[a]pyrene monooxygenase, ethoxyresorufin O-deethylase, ethoxycoumarin O-deethylase, and 2-acetylaminofluorene N-hydroxylase) are all present at levels corresponding to 5-44% of the control levels. The pattern of 2-acetylaminofluorene metabolites formed by nodule microsomes also differs from the pattern observed with control microsomes. Microsomal epoxide hydrolase is increased 415%, cytosolic glutathione S-transferases 203-576%, microsomal UDP-glucuronyltransferase activity about 200%, and cytosolic DT-diaphorase 1210% in the nodules. The same changes are seen in nodules of different sizes and in individual nodules of the same size. Finally, of all of these changes only the full increase in epoxide hydrolase can be seen after 1-3 weeks of exposure to 2-acetylaminofluorene.

2-Acetylaminofluorene↗
PubMed1983

Correction for scattered radiation in a ring detector positron camera by integral transformation of the projections.

A "deconvolution" algorithm for the determination of the scatter contribution in positron emission tomography is described. The projected distributions of scattered radiation measured with a line source at different positions in water phantoms are described analytically. It is shown that an integral transformation of the observed projections with a slightly modified analytical function gives an adequate description of the scattered radiation. The scatter distribution from any composite object can thus be calculated and subsequently subtracted. The algorithm is tested on different objects. The result shows that the level of scattered radiation can be reduced from 25 to 1% of the total count rate in the center of the projection from a homogeneous phantom.

Models, Theoretical↗
PubMed1983

Discrepancies in brain tumor extent as shown by computed tomography and positron emission tomography using [68Ga]EDTA, [11C]glucose, and [11C]methionine.

A patient with an anaplastic (malignant) astrocytoma was examined with computed tomography (CT) and with positron emission tomography (PET), in the latter case using [68Ga]EDTA, [11C]glucose, and [11C]methionine. The CT examination as well as the [68Ga]EDTA study showed a small tumor located in the region of the head of the left caudate nucleus. The [11C]glucose examination showed increased uptake on the same region, as did the [11C]methionine examination, but the latter also showed a considerable uptake in the entire left thalamic region. The patient died 15 days after the [11C]methionine study and a histologic evaluation of thin sections obtained at autopsy showed excellent agreement between tumor extent and activity distribution after [11C]methionine administration. The tumor tissue seen only with [11C]methionine was histologically different from that part of the tumor observed with the other tracers. Although cytologically similar, the latter showed large necrotic areas and an ability to induce marked endothelial proliferation, whereas in the former neither necroses nor notable endothelial proliferation was seen. In this case more than 50% of the tumor would have remained radiologically imperceptible without the [11C]methionine PET examination.

Astrocytoma↗
PubMed1983

Effect of naloxone on the hypotensive action of clonidine in the conscious, normotensive goat.

The possible involvement of opioid receptors in the effects of clonidine was studied in conscious, normotensive goats. Clonidine was infused intravenously followed by an intravenous injection of naloxone. Blood pressure was recorded through an intraarterial catheter. All doses of clonidine (0.2-7 micrograms/kg) significantly lowered blood pressure and decreased heart rate. Hypotension after 0.2-0.7 micrograms/kg of clonidine was significantly reduced by naloxone (1 mg/kg), while naloxone did not antagonize hypotension induced by the larger doses of clonidine. The bradycardiac effect of 0.7-2 micrograms/kg of clonidine was reduced by naloxone while that of 0.2 and 7 micrograms/kg was not. Clonidine also induced sedation and respiratory irregularity, but these changes were not modified by naloxone. Opioid mechanisms possibly participate in the hypotensive action of clonidine, but less in the normotensive animal than in spontaneously hypertensive animals.

Animals↗