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Biomedical subjects

O Nilsson

Publications and source records attributed to O Nilsson.

At least 217 records · Page 12Linked to original sources
PubMed1988

Sympathetic innervation of the cardiovascular system in the giraffe.

The extreme blood pressure gradients in the giraffe, produced by gravity and behaviour, present a special challenge to blood flow and vascular capacity regulation, e.g. via sympathetic nerves. We report the distribution of nerves in vascular tissue from giraffe extremities and neck based on immunofluorescence against specific antisera to dopamine-beta-hydroxylase, neuropeptide Y, neurofilament, and synapsin I. Sympathetic innervation of gravitation-dependent arteries in the limbs was restricted to the adventitia-media border, while in carotid arteries fibers penetrated deep into the media. Surprisingly, limb veins appeared to be devoid of sympathetic innervation, while jugular veins had a sparse innervation. The morphological response, medial hypertrophy, that parallels the hydrostatic pressure gradients in the circulation combines with the thick skin and tight underlying fascia, the 'g-suit', and an exquisitely distributed sympathetic innervation pattern to provide an effective array of mechanisms for cardiovascular regulation in the adult giraffe.

Animals↗
PubMed1988

Appearance of rats sensitive to experimental autoimmune encephalomyelitis in a previously resistant strain.

Changes are described in the PVG strain with respect to susceptibility for induction of experimental autoimmune encephalomyelitis. During a period of 8 years, the strain changed from a nearly resistant to a partly susceptible strain. Selective breeding of susceptible and resistant rats showed that the cause was genetic. This could also be seen in the susceptibility of F1 hybrids with the resistant Brown-Norway strain; such hybrids were strongly susceptible at the beginning but showed about 40% susceptibility during the later part of the period. It is argued that the genetic changes probably occurred in loci regulating mechanisms of resistance.

Animals↗
PubMed1987

Bipolarity of duodenal enterochromaffin cells in the rat.

Enterochromaffin cells of the rat duodenum have been studied immunocytochemically by use of a specific antiserum to serotonin. At the light-microscopic level serotonin immunoreactivity was observed in enterochromaffin cells located in the epithelium of the duodenal mucosa. Most of the serotonin-immunoreactive material was localized to the basal portion of the enterochromaffin cells, but small amounts of immunoreactive material were regularly observed in the apical portion. At the electron-microscopic level serotonin immunoreactivity in enterochromaffin cells was found to be concentrated over the dense cores of the cytoplasmic granules. The majority of these granules was located in the basal cytoplasm of the enterochromaffin cells, but serotonin-immunoreactive granules were also observed in the apical cytoplasm immediately beneath the microvilli. These observations indicate that duodenal enterochromaffin cells are bipolar and that they secrete serotonin both basally, to the circulation, and apically, to the gut lumen. Rat duodenal enterochromaffin cells thus appear to have an exocrine as well as an endocrine function.

Animals↗
PubMed1987

Vagal release of serotonin into gut lumen and portal circulation via separate control mechanisms.

The mechanisms controlling vagally induced serotonin-like immunoreactivity (5-HTLI) release into portal circulation and jejunal lumen were studied in individual cats. In control animals, electrical vagal nerve stimulation significantly enhanced both the endoluminal secretion rate of 5-HTLI and the release of 5-HTLI to the portal vein. The vagally induced release of 5-HTLI to the portal circulation was blocked by pretreatment with propranolol or phenoxybenzamine, or by prior removal of the superior cervical ganglia, but was not blocked by atropine or hexamethonium. On the contrary, the luminal secretion of 5-HTLI after vagal stimulation was not blocked by adrenoceptor blocking agents or ganglionectomy, but instead was inhibited by cholinoceptor antagonists. Thus, in the same experimental animal it was shown that vagally induced release of 5-HTLI to the portal circulation was mediated by adrenoceptor mechanisms, while the luminal release of 5-HTLI was regulated via cholinoceptors. Based on indirect estimations, the apical release of 5-HT seems to be qualitatively small in comparison with the release into the portal circulation.

Animals↗
PubMed1987

Adrenergic control of serotonin release from carcinoid tumor cells in vitro and in vivo.

Serotonin (5-HT)-producing human carcinoid tumors of midgut origin were transplanted to the anterior eye chamber of cyclosporine-treated rats. The release of 5-HT from in oculo transplants was studied after stimulation with adrenoceptor agonists applied locally to the eye. Chamber fluid was collected by micropuncture of the eye. 5-HT levels were determined by liquid chromatography with electrochemical detection. The release of 5-HT in cell suspensions of the same tumors was similarly studied after incubation with adrenoceptor agonists. In both experimental models activation of adrenoceptors caused release of 5-HT from carcinoid tumor cells. Individual variations in the type of response to adrenoceptor stimulation could be demonstrated for the different tumors. In two tumors there was good agreement between in vitro and in vivo findings with release of 5-HT at selective activation of beta-adrenoceptors with isoprenaline. In a third tumor there was a release of 5-HT at activation of alpha-adrenoceptors with norepinephrine in vitro. However, 5-HT release from this tumor in vivo was demonstrated at activation of beta-adrenoceptors. This finding may reflect different adrenoceptor populations on the tumor cell surface, each population activated to various degrees in the in vivo and in vitro situation.

Animals↗
PubMed1987

Neuropeptide Y: presence in perivascular noradrenergic neurons and vasoconstrictor effects on skeletal muscle blood vessels in experimental animals and man.

The presence of neuropeptide Y (NPY)-like immunoreactivity (-LI) in sympathetic perivascular nerves and the functional effects of NPY and noradrenaline (NA) on vascular tone were studied in skeletal muscle of various species. A dense network of NPY-LI was found around arteries and arterioles but not venules in the gluteus maximus muscle of man, gracilis muscle of dog, tenuissimus muscle of rabbit and quadriceps muscle of cat, rat, guinea pig and pig. The distribution of NPY-immunoreactive (-IR) nerves was closely correlated to the presence of tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH)-positive fibers, two markers for noradrenergic neurons. Double-staining experiments revealed that NPY- and TH-IR as well as NPY- and DBH-IR nerve fibers around arteries and arterioles were identical. The veins and venules, however, lacked or had a very sparse innervation of NPY-, TH- and DBH-positive fibers. The NPY- and TH-IR nerves in quadriceps muscle of the guinea pig were absent after treatment with 6-hydroxydopamine. Lumbosacral sympathetic ganglia from the same species contained many NPY-positive cells which were also TH- and DBH-IR. NPY-LI was also detected by radioimmunoassay in extracts of skeletal muscle from guinea pig, rabbit, dog, pig and man as well as of lumbosacral sympathetic ganglia. The content of NPY-LI in skeletal muscle was relatively low (0.1-0.4 pmol/g), whereas lumbosacral sympathetic ganglia had a much higher content (48-88 pmol/g). NPY (10(-7) M) contracted arterioles in the tenuissimus muscle of the rabbit to a similar extent (by 65%) as NA (10(-6) M), as studied by intravital microscopy in vivo. NPY had no effect on the corresponding venules while NA caused a slight contraction of these vessels. In vitro studies of small human skeletal muscle arteries and veins revealed that NPY was more potent than NA in contracting the arteries, and the highest concentration of NPY (5 x 10(-7) M) caused a contraction of a similar magnitude as NA 10(-5) M. NA contracted veins from human skeletal muscle, while NPY had only small effects. It is suggested that NPY, together with NA, could be of importance for sympathetic control of skeletal muscle blood flow.

Aged↗
PubMed1987

Myelopathy patients studied with magnetic resonance for multiple sclerosis plaques.

Seven patients with isolated spinal cord symptoms, and with evoked potential (EP) recordings and/or cerebrospinal fluid (CSF) findings supporting a demyelinating cause for their myelopathy, were examined with cervical and cranial magnetic resonance imaging (MRI). Lesions in the cervical spinal cord were detected in 6 of the patients, including 2 who also had disseminated lesions in the brain compatible with multiple sclerosis (MS). In one patient MRI of the cervical spinal cord was normal, while plaques were seen in the periventricular region of the brain and in the brain stem. Thus, in the 3 patients with cerebral plaques, MRI supported the diagnosis of MS by showing dissemination in space. In the remaining 4 patients MRI provided support for the diagnosis of MS by demonstrating the cervical spinal cord plaques while excluding other potential causes of myelopathy, such as spinal cord compression and intramedullary tumor.

Adult↗
PubMed1987

An improved immunocytochemical method for subcellular localization of serotonin in rat enterochromaffin cells.

Serotonin-like immunoreactivity (5-HT-LI) has been localized at the ultrastructural level in enterochromaffin (EC) cells of rat gastrointestinal tract. Ultra-thin sections of tissues embedded in epoxy resin were incubated with 5-HT antisera and antibody binding sites were visualized with protein A-gold. Three different antisera were compared and were shown to require different fixation regimens for optimal preservation of 5-HT-LI. For one antiserum, tissues fixed in glutaraldehyde and osmium tetroxide could be used to demonstrate 5-HT-LI in EC cells. Immunocytochemical localization of 5-HT can thus be performed with good ultrastructural preservation of tissues. Quantitative evaluation of the intracellular distribution of 5-HT-LI was performed on EC cells from antrum, duodenum, and proximal colon, fixed in glutaraldehyde only. In all three locations, the majority of the gold particles (90%) in EC cells were localized over the dense core of the secretory granules, while a minor fraction (10%) were localized in parts of the cytoplasm devoid of granules. In EC cells fixed in glutaraldehyde and post-fixed in osmium tetroxide, 5-HT-LI was reduced by about 85%, although intracellular distribution was essentially the same as in cells fixed in glutaraldehyde alone. The results indicate that 5-HT in EC cells is stored mainly in secretory granules, with a small fraction of 5-HT being localized outside the granules.

Animals↗
PubMed1987

Bone regeneration under the influence of a bone morphogenetic protein (BMP) beta tricalcium phosphate (TCP) composite in skull trephine defects in dogs.

Beta tricalcium phosphate (TCP) was employed as a nonimmunogenic biodegradable delivery system for bovine bone morphogenetic protein (BMP). A BMP/TCP composite was implanted in adult dogs with skull trephine defects of a critical size of 1.4 cm that would otherwise remain unhealed in the lifetime of the individual. BMP/TCP implants induced 91%-100% incorporation by deposits of new bone. In comparison, control implants of TCP impregnated with bovine serum albumin (BSA/TCP) induced 0%-8% incorporation, or only marginal host bed reactive bone formation. The retention of unabsorbed TCP in the host bone four months after implantation suggests that further research should be encouraged to obtain a formulation of sintered calcium phosphate that could be resorbed more rapidly and in the process more completely replaced by bone.

Animals↗
PubMed1986

Release of serotonin from human carcinoid tumor cells in vitro and grown in the anterior eye chamber of the rat.

Serotonin (5-HT)-producing human carcinoid tumors have been successfully transplanted to the anterior eye chamber of cyclosporine treated rats. Tumor transplants were rapidly vascularized and viable tumor cells could be demonstrated in transplants grown for 2 to 3 weeks in oculo. The release of 5-HT from carcinoid tumor cells grown in the anterior eye chamber and from tumor cells in suspension was studied after stimulation with various adrenoceptor agonists. A dose dependent release of 5-HT upon stimulation with isoprenaline was demonstrated for all viable carcinoid tumors in oculo. The isoprenaline-stimulated release of 5-HT from the tumor cells was further studied in vitro, and was efficiently antagonized by propranolol or nadolol, but not by phenoxybenzamine, indicating activation of beta-adrenoceptors on carcinoid tumor cells upon isoprenaline stimulation. Incubation of tumor cells with verapamil, a calcium channel inhibitor, also prevented the release of 5-HT upon isoprenaline stimulation. Thus, carcinoid tumors can be successfully transplanted to the anterior eye chamber of cyclosporine treated rats, offering new possibilities to study the pharmacologic and biologic features of this tumor. In the future, carcinoid tumors, as well as other endocrine tumors, may be grown in oculo in rats and receptor pharmacology and individual sensitivity to cytotoxic drugs can be studied, thus enabling optimal clinical treatment.

Aged↗
PubMed1986

Binding specificity of monoclonal antibodies to ganglioside, Fuc-GM1.

The binding specificity of thirteen mouse monoclonal antibodies reacting with Fuc-GM1, Fuc alpha 1-2Gal beta 1-3GalNAc beta 1-4(NeuAc alpha 2-3)-Gal beta 1-4Glc beta 1-1Cer, a ganglioside found to be associated with small cell lung carcinoma (O. Nilsson et al. (1984) Glycoconjugate J. 1, 43-49) was studied. The results are based upon radioimmunodetection of their binding to structurally related glycolipids adsorbed to microtiter plates or chromatographed on thin-layer plates. Four of thirteen antibodies reacted only with Fuc-GM1 and both the fucose and the sialic residues were necessary for binding. Optimal binding was obtained when the sialic acid was N-acetylneuraminic acid. When this sialic acid residue was substituted with N-glycoloylneuraminic acid the binding activity was reduced and up to 10-times more Fuc-GM1 was needed for detection. The ceramide composition did not influence the binding. The other nine monoclonal antibodies cross-reacted with glycolipids containing structures closely related to Fuc-GM1 and differed from the specific ones by recognizing a smaller portion of the carbohydrate moiety in Fuc-GM1. These results indicate that anticarbohydrate monoclonal antibodies, recognizing structures involving a large proportion of the sugar in the glycolipid, possess a high specificity and might be useful for detection of tumor-associated ganglioside antigen.

Animals↗
PubMed1986

Growth of human pheochromocytomas in the anterior eye chamber of the rat. A histochemical study on amine and peptide content of pheochromocytoma tumour cells.

Tissue pieces from seven benign human pheochromocytomas have been successfully transplanted to the anterior eye chamber of cyclosporin-treated rats. In vivo observations showed that 74-99% of the tumour transplants were vascularized within one to two days after transplantation. No increase in the size of the transplants was noted during the observation period (1-4 weeks). Tumour transplants grown in non-immunosuppressed rats were initially vascularized but rejection started to occur one week after transplantation. Histochemical analysis of tumour transplants grown in immunosuppressed rats demonstrated numerous tumour cells with strong catecholamine fluorescence, some of which formed long cell processes on the host iris. Immunocytochemical analysis of tumour transplants demonstrated positively labelled tumour cells after incubation with antisera against neuropeptide Y, enkephalin, vasoactive intestinal polypeptide, somatostatin, substance P, dopamine-beta-hydroxylase, tyrosine hydroxylase and serotonin. A similar histochemical and immunocytochemical pattern was observed in primary tumours but tumour cells sending out cell processes were observed less frequently. Human pheochromocytomas may thus be successfully grown in oculo in cyclosporin-treated rats. This may prove to be a suitable model for the study of storage and release of catecholamines and neuropeptides from pheochromocytoma tumour cells.

Adrenal Gland Neoplasms↗
PubMed1986

Verapamil and diarrhoea in the carcinoid syndrome--clinical and experimental observations on serotonin release.

A patient with the midgut carcinoid syndrome with severe diarrhoea and proven hypersecretion of serotonin (5-HT) was treated with low doses of verapamil perorally. During treatment the patient was completely relieved of diarrhoea but discrete facial flushing persisted during treatment. When treatment was cessated, diarrhoeas recurred. This patient underwent pentagastrin (PG) provocation repeatedly; during untreated conditions injection of PG released 5-HT, detectable in peripheral venous blood. Such release was abolished during verapamil treatment, but recurred after withdrawal of the drug. Surgical biopsies from this tumour were studied in two experimental models: cell suspensions and heterotransplants grown in the anterior eye-chamber of immunosuppressed rats. Release of 5-HT from the cell suspensions was elicited in a dose-dependent manner after stimulation with isoprenaline (IP) suggesting activation of beta-adrenoceptors on the tumour cells. Such release was reduced after pretreatment with verapamil indicating a calcium dependent mechanism. Intraocular tumour transplants also responded with release of 5-HT into the chamber fluid after conjunctival application of IP. However, pretreatment of the rats with verapamil significantly reduced the IP-stimulated release of 5-HT.

Aged↗