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Biomedical subjects

I Larsson

Publications and source records attributed to I Larsson.

At least 73 records · Page 4Linked to original sources
PubMed1979

The effect of propranolol on the serotonin concentration in the portal plasma after vagal nerve stimulation in the cat.

Efferent cervical vagal nerve stimulation in the cat caused a marked increase of the portal plasma 5-HT concentration. This increase was more than two-fold within 15 min of stimulation. After cessation of stimulation portal plasma 5-HT returned to basal levels within 10 min. Treatment with the beta-adrenoceptor antagonist propranolol, in various doses (0.1-2 mg/kg b.wt.), did not abolish but significantly reduced the response to vagal stimulation, particularly during the final part of the stimulation period. The results confirm the existence of a beta-adrenoceptor-mediated release of 5-HT, but also suggest that other mechanisms for 5-HT release may be involved in the response on vagal nerve stimulation.

Adrenergic beta-Antagonists↗
PubMed1979

Characterization of specific antisera to native human luteinizing hormone.

Antisera against highly purified native hLH (10 000 IU/mg = 0.5 mg hLH/mg protein) were raised in 4 rabbits. The antisera were invariably of high titre and high avidity. They were purified by affinity chromatography on a column with hCG-Sepharose 4 B. Before and after adsorption the antisera were tested in a double antibody radioimmunoassay. Before adsorption hCG cross-reacted in all antisera, but in none were the inhibition curves identical. No such cross-reaction remained after the affinity chromatography. These purified antisera made it possible to develop highly specific and sensitive assays for measuring native hLH. We conclude from studies of the effect of native glycoprotein hormones and their subunits that there are probably differences in the antigenic sites of the complete hLH molecule and in the isolated beta-subunit of hLH. The investigation also indicates that even highly purified preparations of hTSH may be contaminated with hLH and that the preparations of hLH-subunits may contain a certain amount of the native hormone.

Adsorption↗
PubMed1979

Phosphate buffer stimulates somatostatin release into the antral lumen of anaesthetized cats.

The effect of variations of intra-antral pH on the intraluminal release of somatostatin was studied. Acute pouches were created in anaesthetized cats, and the pouches were perfused with solutions differing in pH. Somatostatin levels were then measured in the perfusates. In this model phosphate buffer was a potent stimulator of intra-antral somatostatin release, whereas perfusion with 0.1 M HCl failed to release somatostatin by itself. Since phosphate buffer also releases gastrin, the releasing effect ought to be exerted beyond the mechanism that can be blocked by somatostatin. (Thus the stimulatory effect of phosphate buffer might be exerted on the membranes of the endocrine cells.)

Animals↗
PubMed1978

The release of serotonin from rat duodenal enterochromaffin cells by adrenoceptor agonists studied in vitro.

The serotonin (5-HT) content of enterochromaffin cells (EC) was studied by a cytofluorimetric method in biopsies from rat duodenal mucosa after in vitro incubation with different adrenoceptor agonists and antagonists and acetylcholine (ACh). Noradrenaline (NA), Adrenaline (A) and Isoprenaline (IP) caused a decrease of 5-HT in EC down to 40--60% and for NA and A this effect was concentration-dependent. The effect was antagonized by d,1-propranolol but not by d-propranolol, metoprolol, phentolamine or phenoxybenzamine indicating that the 5-HT release from EC is probably mediated via a true beta-adrenoceptor mechanism possibly of the beta2 type. ACh also decreased the 5-HT content of EC but was much less potent than the adrenergic substances. Dopamine (DA) had no effect.

Acetylcholine↗
PubMed1978

Ultrastructural evidence for an innervation of epithelial enterochromaffine cells in the guinea pig duodenum.

The innervation of the duodenal enterochromaffine cells (E.C.) of the guinea pig was studied at the electronmicroscopic level. Pretreatment with 5-OH-dopamine was performed to visualize catecholaminergic (CA) nervous elements. Near the basement membrane of all examined E.C. in the crypts, bundles of unmyelinated nerve processes were observed, only partly ensheathed in a Schwann cell cover. At least 4 types of processes could be observed. 1) Boutons containing only small clear vesicles, probably cholinergic fibres; 2) boutons with small clear vesicles, and in addition large (greater than 200 nm) granules with a dense matrix (P-type-fibres); 3) boutons with small electron-dense vesicles, probably CA-fibres; and 4) processes with few vesicles but having the appearance of dendrites. No typical synaptic arrangements were observed, but the minimal distance between the E.C. and the nerve bundles was 150 to 250 nm, thus well within the functional limits of the "autonomic gap". Thus epithelial E.C. may be influenced by several types of nervous elements, including CA-fibres.

Adrenergic Fibers↗
PubMed1978

Efferent innervation of the small intestine by adrenergic neurons from the cervical sympathetic and stellate ganglia, studied by retrograde transport of peroxidase.

The nervous pathways between the small intestine of cat and guinea pig and various sympathetic ganglia were investigated by the retrograde horse-radish peroxidase (HRP) technique. HRP was injected at multiple sites in the wall of the duodenum and the first third of the jejunum. At 1--5 days after the injections, the HRP reaction product was searched for in various sympathetic ganglia. Not only the coeliac and nodose ganglia, but also the superior cervical, medial cervical, stellate and thoracic ganglia contained HRP-positive nerve cells. Crushing the cervical vagal nerve prevented the occurrence of HRP-reaction in the cervical ganglia, indicating that the HRP was transported from the gut to the cervical ganglia via axons in the vagal nerve. The results demonstrate that the sympathetic ganglia in the neck (sup, and med. cerv. ganglia and stellate ggl.) send efferent fibres to the small intestine.

Animals↗
PubMed1978

Modulation of immune responses in newborn and adult mice by interferon.

Interferon was found to have both suppressive and enhancing effects on the antibody response in newborn and adult mice. Evidence was obtained that these effects are primarily evoked during the initial steps controlling cell proliferation. Stimulation of thymus and spleen cells with a T-cell mitogen was enhanced by low doses and suppressed by high doses of interferon. Treatment of parental spleen cells with interferon before injecting them into immunized F1 hybrid mice resulted in an enhanced allogeneic effect. These results are compatible with the hypothesis that interferon affects T cells and has an immunoregulatory role, either by inhibiting the action of suppressor cells or by promoting immunological maturation.

Animals↗
PubMed1978

Interferon production in glia and glioma cell lines.

Interferon (IF) was produced in glia and glioma cell lines in titers comparable to those produced by human fibroblasts. It was inducible by both Sendai virus and polyriboinosinic:polyribocytidylic acid. "Superinduction" resulted in up to 500-fold-higher titers of IF. The IF appeared to be of the fibroblast type, as revealed by experiments using heat treatment, assay of antiviral activity in heterologous cell lines, and neutralization with specific antisera. Since large amounts of IF may easily be produced with glioma cell lines, such cells may be suitable for mass production of IF.

Cell Line↗
PubMed1978

Image artifacts at high photon fluence rates in single-crystal NaI(T1) scintillation cameras.

A method that simulates a clinically relevant situation is used to measure the amount of pulse pileup in the gamma image by distinguishing between correctly and incorrectly positioned events. Comparison was then made between responses from different cameras. These investigations show the influence of pileup rejection on counting rate. Pileup effects can be determined for some cameras at such low count rates as about 10,000/sec with a 30% energy window. Parameters affecting the total count rate of the scintillation camera--such as scattering media, source geometry, collimator, and energy window--have been investigated. It is shown that the energy distribution of the photon fluence striking the crystal determines the counting losses and image distortion, rather than the counting rate in the energy window. The approach described here might fulfill the requirements for a new method to compare scintillation cameras. It is important to note that measurements without scattering medium yield results irrelevant for clinical situations.

Radionuclide Imaging↗
PubMed1977

Distribution of intravenously injected 201thallium in the legs duging walking. A new test for assessing arterial insufficiency in the legs.

There is a multitude of method for assessing the efficiency of the arterial circulation in the legs. Most of these methods can give conclusive information about the patency of the main arteries in the leg; the level of an arterial obstruction can also be estimated. However, none of these methods provides a direct estimate of the functional importance of arterial lesions of light to moderate severity. The present report describes preliminary findings of the distribution of intravenously injected 201Thallium, a potassium analogue, in the legs during exercise provoking symptoms of ischemia. From this pilot study the general impression is that the thallium uptake pattern corresponds well with the clinical, physiologic, and angiographic picture.

Arterial Occlusive Diseases↗
PubMed1977

Myocardial scintigraphy as a supplementary diagnostic tool in heart disease.

Myocardial scintigraphy with cesium-131 and thallium-201 was performed in 191 patients. Previous myocardial infarctions localized to the anterior and lateral wall of the left ventricle were correctly diagnosed with both radionuclides. Inferior and posterior infarctions were only detected when thallium was used. In patients with non-informative ECG changes like bundle branch block, non-specific ST-T changes or with atypical symptoms, myocardial imaging made an essential contribution to the establishment of a correct diagnosis. The potential value of myocardial imaging in patients with valvular heart disease and in cardiomyopathy is described.

Adolescent↗
PubMed1977

Surgical management of gastroduodenal haemorrhage.

We have presented a retrospective study of the surgical management of 299 patients bleeding from duodenal ulcer, gastric ulcer or gastritis. The overall mortality rate was 15%-5% for elective and 25% for emergency operations. The mortality increased with age and reached 50% for emergency operations in patients over the age of 70. Patients with low admission haemoglobin values, who had episodes of hypovolemic shock or who required immediate transfusions were also at risk. A Billroth I gastric resection proved to be the safest operative procedure. Based on our results, we are supporting a program calculated to reduce the mortality attending gastroduodenal bleeding, especially in those patients requiring an emergency operation. The basic principles of this program are constant observation, prompt diagnosis and early surgical intervention.

Blood Transfusion↗
PubMed1977

An evaluation of angiography, 75Se-methionine scintigraphy and the Lundh test in the diagnosis of pancreatic disease.

In order to asses accuracy and consistency of diagnostic opinion in suspected pancreatic disease, using available diagnostic procedures 74 patients, subjected to selective angiography, pancreatic function test (Lundh test), and scintigraphy, were studied retrospectively. The patients were divided into four diagnostic subgroups, three of which represented defined pancreatic disease, the fourth serving as a control group since such disease could be excluded. The primary diagnostic results were compared. After a stipulated minimum of six months the angiographic films and scintigraphic recordings were re-appraised in a randomized manner without access to clinical data. The evaluations thus achieved were compared to those delivered primarily. The results of the present study seem to indicate that the Lundh test and pancreatic scintigraphy are screening tests with a high level of diagnostic reliability and consistency; when normal, practically ruling out pancreatic disease. Angiography is recommendable only if one or both of the above mentioned screening methods yield pathologic results, supported by clinical evidence. The principal aims of selective angiography in suscepted pancreatic disease, are to map vascular anatomy, to differentiate non-neoplastic disease from cancer and to assist estimation of operability. The results of the reappraisal indicate that the diagnostic accuracy of angiography, more than that of scintigraphy, is dependent on the experience of the examiner.

Angiography↗
PubMed1976

Improved radioiodination of glucagon with the lactoperoxidase method. Influence of pH on iodine substitution.

To produce a 125I-labelled glucagon suitable for radioligand assays, we studied the influence of variations in the lactoperoxidase iodination method. Both the degree of iodine substitution and the formation of monoiodo- or diiodo-tyrosines were pH dependent. The substitution increased and the diiodo-/monoiodotyrosine ratio decreased when pH increased. These two factors affected the immunoreactivity of the iodoglucagon relatively independently of each other. It was found that iodination at pH 10.0 with an average of 0.3 gatom I/mol glucagon resulted in 125I-labelled glucagon with higher immunoreactivity and stability than that produced at the conventional pH 7.5 and 8.5.

Antigen-Antibody Reactions↗