Biomedical subjects
Publications and source records attributed to O Nilsson.
Several genes that are normally involved in flower initiation have recently been shown to induce early flowering when expressed ectopically in transgenic plants. These findings permit the development of strategies for the rational manipulation of flowering time in agronomically important plants.
Verification of the presence of somatostatin receptors on neuroendocrine tumour cells opened up unique diagnostic and therapeutic possibilities. Long-acting somatostatin analogues are currently used to alleviate symptoms of excessive hormone synthesis in patients with such tumours. Radiolabelled somatostatin analogues can be used both for high specificity and high sensitivity scintigraphic localisation of such tumours and for intraoperative scintillation detection. Detailed studies in patients and in tumour cells in vitro have shown 111In-octreotide uptake to be high and retention times long in tumour tissue, and have yielded evidence of intracellular localisation of the radionuclide. These findings thus showed somatostatin receptor-mediated radiotherapy to be a possible treatment alternative after close characterisation of the individual tumour. In the future, it may be possible to use other peptide receptors (e g, growth factor receptors) according to the same principles as applied in the case of somatostatin receptors.
BACKGROUND: . Development of petals and stamens in Arabidopsis flowers requires the function of the organ-identity gene APETALA3 (AP3), whose RNA is expressed specifically in petal and stamen primordia. AP3 expression is positively regulated by the meristem-identity gene LEAFY (LFY), which is expressed ubiquitously in young flowers. It is unknown how the transition from ubiquitous expression of LFY to region-specific expression of AP3 is made. It has previously been proposed for Antirrhinum that another gene, FIMBRIATA (FIM), mediates between the LFY and AP3 orthologs, with the three genes acting in a simple regulatory hierarchy. FIM is activated later than the LFY ortholog, and its expression is more restricted than that of the LFY ortholog. RESULTS: . We have tested whether the model proposed for Antirrhinum applies to Arabidopsis, by creating transgenic plants in which the FIM ortholog UNUSUAL FLORAL ORGANS (UFO) was expressed constitutively from the promoter of the cauliflower mosaic virus 35S gene. In 35S::UFO flowers, AP3 was expressed precociously and ectopically, confirming that UFO is an upstream regulator of AP3. However, 35S::UFO could not restore petal and stamen development in lfy mutants, indicating that UFO can only function in the presence of LFY activity. The failure of 35S::UFO to rescue lfy mutants is consistent with our observation that UFO expression levels are not markedly changed in lfy mutants. CONCLUSIONS: . We conclude that UFO is not a simple mediator between meristem- and organ-identity genes, but is likely to be a partially dispensable co-regulator that acts together with LFY. The interplay between LFY and UFO provides a paradigm for how a global regulator such as LFY activates selected target genes only in restricted regions within its expression domain.
We compared the sensitivity and specificity of the two metabolite tests, methylmalonic acid (MMA) and total homocysteine (Hcy) in serum, and serum cobalamin (Cbl) in patients referred to our hospital because of suspected cobalamin deficiency and a serum cobalamin value at the referring unit <200 pmol/L. All 111 patients included were investigated using upper gastrointestinal endoscopy with biopsy specimens taken from the gastric and duodenal mucosa to find a morphological basis for cobalamin malabsorption as well as the Schilling test for the validation of the serum tests. All patients were treated with cobalamin and new blood samples were taken after 4 weeks. We found no difference in sensitivity and specificity between serum MMA, Hcy, and Cbl in identifying patients with and without conditions compatible with cobalamin malabsorption. Elevated serum MMA and Hcy were also found in about 15% of the group of patients with normal Schilling tests and without a morphological basis for cobalamin malabsorption. Moreover, most patients in this group responded with decreased values of the metabolite tests following cobalamin treatment, suggesting that neither elevated metabolites nor a decrease in these values following cobalamin treatment are specific for cobalamin deficiency.
Hormonal overproduction is a significant problem in patients with disseminated midgut carcinoid tumors. Serotonin (5-HT) is one major product secreted from such tumors and the urinary excretion of its metabolite (5-hydroxyindoleacetic acid, 5-HIAA) serves as an important tumor marker. The present study aimed at elucidating mechanisms of tryptophan metabolite secretion to facilitate the treatment of the carcinoid syndrome. When midgut carcinoid tumors were studied in primary cell cultures, several similarities with adrenergic neurons could be demonstrated. A marked dose-dependent depletion of intracellular 5-HT could be induced by reserpine, and monoamine oxidase-activity was revealed both in functional studies and by immunocytochemistry. Differences between tumors in the ratios of tryptophan metabolites released indicated that enzymes for synthesis and degradation of 5-HT were individually expressed. Treatment with the somatostatin analogue octreotide or with dexamethasone decreased the extracellular levels of tryptophan metabolites, but the mechanisms were partly different. In some tumors octreotide also decreased the synthesis of 5-HT, while dexamethasone markedly increased the intracellular 5-HIAA levels. It is of clinical interest to further elucidate these mechanisms, since the two drugs may have complementary actions in carotid crisis reactions.
Monoclonal antibodies were raised against prostate-specific antigen (PSA) by immunization with purified free PSA, i.e. not in complex with any protease inhibitor (F-PSA) and PSA in complex with alpha1-anti-chymotrypsin (PSA-ACT). Epitope mapping of PSA using the established monoclonal antibody revealed a complex pattern of independent and partly overlapping antigenic domains in the PSA molecule. Four independent antigenic domains and at least three partly overlapping domains were exposed both in F-PSA and in the PSA-ACT complex, while one antigenic domain was specific for F-PSA. The different domains contained both continuous and discontinuous epitopes. The combination of antibodies recognizing antigenic domains exposed both in F-PSA and PSA-ACT made it possible to develop several highly sensitive sandwich immunoassays for determination of total PSA, i.e. F-PSA + PSA-ACT, with the same molar response for F-PSA and PSA-ACT. Assays specific for F-PSA (cross-reactivity between F-PSA and PSA-ACT < 1%) were developed by the combination of antibodies recognizing epitopes exposed only in F-PSA and antibodies recognizing epitopes exposed both in F-PSA and PSA-ACT.
OBJECTIVES: To assess the advantage of a protein-bound cobalamin absorption test (PBAT) over the Schilling test in patients with suspected cobalamin (vitamin B12) malabsorption. DESIGN: Clinical study of consecutive patients referred from primary care units, medical and neurological clinics. SETTING: The catchment area of Sahlgrenska University Hospital, Göteborg. SUBJECTS: Referred patients (n = 155) with suspected cobalamin deficiency and at least one serum cobalamin value < 200 pmol L-1. INTERVENTIONS: All patients were investigated with upper gastrointestinal endoscopy with biopsies taken from the gastric body and duodenal mucosa. Serum methylmalonic acid (MMA) and homocysteine (Hcy) were determined in all 109 patients not on cobalamin substitution. A dual isotope cobalamin absorption test was then performed with the concomitant administration of crystalline (Schilling) and protein-bound cobalamin (PBAT). MAIN OUTCOME MEASURES: Number of patients with gastric body atrophy diagnosed with each absorption test and the relation between these results and functional cobalamin deficiency defined as elevated MMA and Hcy, that normalized after cobalamin substitution treatment. RESULTS: The majority of patients with abnormal absorption tests had already developed elevated MMA and/or Hcy. PBAT was more sensitive than the Schilling test in identifying patients with gastric body atrophy but the sensitivity was too low for clinical use. About 1/3 of the patients with gastric body atrophy and normal absorption tests had elevated MMA and/or Hcy, indicating cobalamin deficiency. CONCLUSION: PBAT may be somewhat more sensitive than the Schilling test but neither test is sensitive enough for diagnosing cobalamin malabsorption at an early stage.
Multiple endocrine neoplasia type 1 (MEN-1) is characterized by primary hyperparathyroidism, endocrine pancreatic-duodenal and anterior pituitary tumors. The diagnosis is challenging and involves the exclusion of other endocrine neoplasia syndromes with overlapping features. The predisposing genetic defect was assigned to chromosomal region 11q13 based on linkage analysis. Combined tumor and pedigree genotype analysis showed that allele losses in pancreatic, parathyroid and pituitary tumors eliminated the wild-type allele at the 11q13 loci, suggesting inactivation of a tumor suppressor gene in this region. A 5-Mb integrated map of the region has been established by the European consortium on MEN-1. Based on this mapping the critical interval was restricted to 2 Mb, a region within which eight candidate genes are located.
We investigated the effects of various pro-inflammatory cytokines on the proliferation rate of isolated human osteoblastic cells in primary cultures. Interleukin-1 beta (IL-1 beta) and tumor necrosis factor-beta (TNF-beta) time- and dose-dependently enhanced the proliferation of human osteoblasts. Both of these cytokines also enhanced endogenous prostaglandin E2 (PGE2) formation. Exogenous PGE2 dose- and time-dependently-stimulated cell proliferation. However, the stimulatory effects of IL-1 beta and TNF-beta on osteoblast proliferation were not abolished by indomethacin, indicating a direct effect by these cytokines on the rate of proliferation. TNF-alpha stimulated proliferation at low doses, while it significantly inhibited proliferation at higher concentrations (at and above 100 pM) and with prolonged incubation times. This biphasic effect was unaffected by indomethacin. Interleukin-6, finally, did not affect the rate of proliferation. Our findings show that inflammatory cytokines may stimulate or inhibit the proliferation of isolated human osteoblasts, depending on concentration and time.
The expression of somatostatin receptors in neuroendocrine tumors has facilitated the diagnosis and surgical treatment of patients with these tumors. After injection of a radiolabeled long-acting somatostatin analog, (111)In-octreotide, scintigraphic tumor imaging can ben performed as well as intraoperative tumor localization. During localization studies very high (111)In concentration values were found in tumor tissues versus normal tissues, especially in carcinoid tumors and endocrine pancreatic tumors. Studies on such tumors in cell culture further indicated internalization of (111)In into tumor cells, which is a prerequisite for a radiobiological effect from short range Auger and conversion electrons. Attempts to systemic radionuclide therapy via somatostatin receptors in patients with neuroendocrine tumors have been initiated.
BACKGROUND: 111In-radiolabelled (DTPA-D-Phe1)-octreotide scintigraphy can be used to localize neuroendocrine tumours expressing somatostatin receptors (SSTRs). The aim of this paper was to analyse the importance of tumour volume and growth for the visualization by SSTR scintigraphy of metastases from medullary thyroid carcinoma (MTC). METHODS: Serum calcitonin concentrations were used to estimate volume and growth rate of MTC. Twenty-two patients who had persistent hypercalcitoninaemia after total thyroidectomy for MTC, indicating the presence of metastases, were studied. RESULTS: SSTR scintigraphy visualized 15 tumours in 11 patients. Patients with scintigraphically visualized tumours had higher serum calcitonin and carcinoembryonic antigen concentrations and larger tumours, and the serum calcitonin concentration increased more rapidly with time. Tumour-associated symptoms and death from MTC occurred only in patients with scintigraphically visualized tumours. CONCLUSION: Scintigraphically visualized tumours grow more rapidly and are more aggressive than nonvisualized lesions. SSTR scintigraphy can be helpful in the planning of palliative surgery for MTC and for diagnosing distant metastases, but cannot localize microscopic metastases.
A survey was performed on the occurrence of some internal parasites in 461 horses (1-30 years old) slaughtered from October 1992 to September 1993 at the Linköping abattoir in central Sweden. Macroscopical examination was carried out specifically for parasites of the tear ducts and conjunctival sacs of the eyes, and of selected parts of the alimentary tract and cardio-vascular system. The following parasites were found in selected parts of the large intestine: encapsulated cyathostome larvae (in 35.6% of the horses), and mature strongyle worms (17.4%); in the stomach: Gasterophilus intestinalis (12.3% during October-June) and Habronema muscae (1.1%); and in the conjunctival sac: Thelazia lacrymalis (3.1%). Significantly more encapsulated cyathostome larvae were found during January to June than during other times of the year, and horses aged 1-5 years harboured significantly more larvae than older horses. Severe damage to the cranial mesenteric artery and its main branches was noticed in 16 (6.1%) out of 263 horses specifically examined. However, the 4th stage larva of Strongylus vulgaris was only recovered in 6 (2.3%) of the horses. Quantitative and qualitative faecal egg counts were done on 412 and 384 of the horses, respectively. Eggs of strongyles, Parascaris equorum and Strongyloides westeri were found in 78.1%, 1.9% and 0.2% of the faecal samples, respectively. Highest prevalence of strongyle eggs was found during July to September. Third stage larvae of the following nematodes were recovered from faecal cultures: subfamily Cyathostomum sensu lato (78.1%) Triodontophorus spp. (6.5%), Strongylus vulgaris (3.6%), Trichostrongylus axei (1.3%), while Gyalocephalus sp., Oesophagodontus sp., Poteriostomum sp. and Strongylus edentatus each comprised less than 0.5%.
The effects of cyclosporin A on the occurrence of neuroendocrine peptides in bone induced by demineralized allogeneic and xenogeneic bone matrix were studied in rats. Cyclosporin A enhanced bone induction in demineralized allogeneic bone matrix implants by 40% to 50% at 4 weeks, whereas there was no difference to the control group at 8 weeks. In demineralized xenogeneic bone matrix implants there was virtually no cartilage or bone formation at 4 weeks, but some bone and cartilage formation was seen at 8 weeks. In both cyclosporin A treated groups the net bone formation in demineralized xenogeneic bone matrix implants was increased four to five times at 4 weeks. Cyclosporin A treatment did not alter the temporal occurrence or distribution of neuropeptide containing nerve fibers in the bone induced by allogeneic bone matrix. Fibers containing substance P, calcitonin gene related peptide, neuropeptide Y, vasoactive intestinal peptide, and tyrosine hydroxylase were detected in the ossicles of cyclosporin A treated and control rats. In the xenogeneic bone matrix of the control group, no immunoreactive nerve fibers could be detected at 4 weeks, but at 8 weeks all five neuropeptides were detected. However, after cyclosporin A treatment immunoreactive nerve fibers could be seen at 4 weeks in the demineralized xenogeneic bone matrix implants. Thus, immunologic properties of the inductive matrix affect the yield of mineralized bone and the degree of innervation. Cyclosporin A decreases the immune response and enhances the formation of bone and the number of transmitter identified nerves in demineralized xenogeneic bone matrix induced ossicles.
Glucagon-producing neoplasms are rare pancreatic tumours that may give rise to a characteristic syndrome including, diabetes and typical skin manifestations (necrolytic migrating erythema). Dermatological problems are often the first signs of the disease and the diagnosis is easily overlooked. In most series reported to date, glucagonomas had already metastasized at diagnosis, which means that curative surgery was possible to perform in less than half of the patients. To increase awareness of glucagonoma symptomatology a review of the syndrome is presented together with the clinical histories of three patients, recently treated. These cases illustrate aspects of modern diagnosis and treatment.
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The effect of vagotomy on the development of ECL cell tumours was analyzed during drug-induced hypergastrinemia in Mastomys natalensis, a rodent prone to develop ECL cell tumours. Untreated animals were compared with animals receiving the histamine2-receptor blocker loxtidine (LOX) and with animals subjected to unilateral subdiaphragmatic vagotomy prior to loxtidine treatment (VAG+LOX). Loxtidine (2g/l) was administered in drinking water for 48 weeks to allow multiple ECL cell carcinoids to develop. Plasma gastrin levels were increased in LOX animals (94 +/- 31 pmol/l) and in VAG+LOX animals (181 +/- 59 pmol/l) compared to controls (45 +/- 4 pmol/l). Corpus weight and oxyntic mucosal thickness was almost doubled in all loxtidine-treated animals and the density of mucosal endocrine cells was increased by 65% in the LOX group and by 135% in VAG+LOX animals. No significant differences in mucosal thickness and endocrine cell density were seen when denervated and intact parts of the stomach were compared. In the VAG+LOX animals endocrine cell neoplasia was seen in 60% and dysplasia in 40% of animals compared to 40% neoplasia, 45% dysplasia and 15% hyperplasia in LOX animals. The frequency of neoplastic and dysplastic lesions did not differ between denervated and intact parts of the stomach. Untreated animals showed no neoplastic or dysplastic lesions. It is concluded that unilateral vagotomy has no protective effect on the development of ECL-cell tumours in Mastomys during hypergastrinemia, as opposed to previous studies in the rat.
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The prognostic value of the immunohistochemical expression of Sialyl Tn antigen (STn) was evaluated in 242 patients with gastric carcinoma. Formalin-fixed, paraffin-embedded specimens of gastric adenocarcinomas were stained with the monoclonal antibody C1282, produced by immunization with ovine submaxillary mucin (OSM). Positive immunoreactivity for STn was observed in 149 (62%) patients. The expression of STn did not correlate with stage of disease (TNM), tumour location, presence of lymph-node or distant metastases, histological type, age or gender. STn immunoreactivity correlated strongly with overall survival in univariate analysis. The median survival in the STn-positive group was 21 months, in comparison to 38 months in the STn-negative group. The difference in survival between STn-negative and STn-positive tumours was significant in patients with stage-I cancer, but not in patients with stage-II -III or -IV disease. STn immunoreactivity emerged as an independent prognostic factor in Cox multivariate analysis. It is concluded that the immunohistochemical expression of STn is a good marker in the prediction of survival in patients with stage-I gastric carcinoma.