Biomedical subjects

S Jansson

Publications and source records attributed to S Jansson.

At least 19 recordsLinked to original sources

PubMed2006

The genome of black cottonwood, Populus trichocarpa (Torr. & Gray).

We report the draft genome of the black cottonwood tree, Populus trichocarpa. Integration of shotgun sequence assembly with genetic mapping enabled chromosome-scale reconstruction of the genome. More than 45,000 putative protein-coding genes were identified. Analysis of the assembled genome revealed a whole-genome duplication event; about 8000 pairs of duplicated genes from that event survived in the Populus genome. A second, older duplication event is indistinguishably coincident with the divergence of the Populus and Arabidopsis lineages. Nucleotide substitution, tandem gene duplication, and gross chromosomal rearrangement appear to proceed substantially more slowly in Populus than in Arabidopsis. Populus has more protein-coding genes than Arabidopsis, ranging on average from 1.4 to 1.6 putative Populus homologs for each Arabidopsis gene. However, the relative frequency of protein domains in the two genomes is similar. Overrepresented exceptions in Populus include genes associated with lignocellulosic wall biosynthesis, meristem development, disease resistance, and metabolite transport.

Arabidopsis↗

PubMed2005

Long-term outcome of a large series of patients surgically treated for pheochromocytoma.

OBJECTIVE: To analyse the morbidity, mortality and long-term outcome in a consecutive series of surgically treated patients with pheochromocytoma (PC), or paraganglioma (PG), from the western region of Sweden between 1950 and 1997. PATIENTS: All patients (n = 121) who had been hospitalized and treated for PC/PG over 47 years. DESIGN: Retrospective review of patients with PC/PG regarding presenting symptoms, tumour characteristics, clinical management and long-term outcome after treatment. SETTING: One referral centre for all patients from the western region of Sweden. RESULTS: During an observation of 15 +/- 6 years, 42 patients died vs. 23.6 expected in the general population (P < 0.001). There was no intra- or post-operative mortality. Four patients with sporadic disease died of malignant PC and six with hereditary disease of associated neuroectodermal tumours. Five patients died of other malignancies, 20 of cardiovascular disease and seven of other causes. Besides older age at primary surgery, elevated urinary excretion of methoxy-catecholamines was the only observed risk factor for death (P = 0.02). At diagnosis 85% of the patients were hypertensive; one year after surgery more than half were still hypertensive. However, pre- and post-operative hypertension did not influence the risk for death versus controls. CONCLUSION: Pheochromocytoma/PG can be safely treated by surgery. Death of malignant PC/PG was unusual, but the patients as a group had an increased risk of death. We recommend life-long follow-up of patients treated for PC/PG with screening for recurrent tumour in sporadic cases and for associated tumours in hereditary cases. This strategy would also be helpful in diagnosing cardiovascular disease at an early stage.

Adrenal Gland Neoplasms↗

PubMed2004

Annotation of a 95-kb Populus deltoides genomic sequence reveals a disease resistance gene cluster and novel class I and class II transposable elements.

Poplar has become a model system for functional genomics in woody plants. Here, we report the sequencing and annotation of the first large contiguous stretch of genomic sequence (95 kb) of poplar, corresponding to a bacterial artificial chromosome clone mapped 0.6 centiMorgan from the Melampsora larici-populina resistance locus. The annotation revealed 15 putative genetic objects, of which five were classified as hypothetical genes that were similar only with expressed sequence tags from poplar. Ten putative objects showed similarity with known genes, of which one was similar to a kinase. Three other objects corresponded to the toll/interleukin-1 receptor/nucleotide-binding site/leucine-rich repeat class of plant disease resistance genes, of which two were predicted to encode an amino terminal nuclear localization signal. Four objects were homologous to the Ty1/ copia family of class I transposable elements, one of which was designated Retropop and interrupted one of the disease resistance genes. Two other objects constituted a novel Spm-like class II transposable element, which we designated Magali.

Amino Acid Sequence↗

PubMed2004

Phenotypic expression of a family with multiple endocrine neoplasia type 2A due to a RET mutation at codon 618.

BACKGROUND: Multiple endocrine neoplasia type 2A (MEN2A) is caused by missense mutations in the RET proto-oncogene on chromosome 10. This paper reports the phenotypic expression of a family with MEN2A, in which serine substitutes for cysteine at codon 618 in exon 10 of the RET gene. It was first claimed that medullary thyroid cancer (MTC) with this rare mutation led to mild disease; this has recently been updated to intermediate-high risk, based on stratified genetic information. METHODS: The family was mapped over six generations. In 1971 family members were invited to join a screening programme. Genetic testing was started in 1994. RESULTS: Twenty-two individuals with MTC were identified, 16 by the screening programme. One screened patient had a phaeochromocytoma and four had hyperparathyroidism. At surgery for MTC 12 patients had local tumour metastases and two young patients also had liver metastases. No screened patient died from MTC during a mean observation time of 19 years. Six other family members were diagnosed with MTC by signs and symptoms, five of whom died from MTC. CONCLUSION: Because of the great interindividual differences in tumour aggressiveness within the family it is impossible to predict whether an individual gene carrier will have an aggressive MTC or not. This unpredictability is an additional argument, besides those obtained in stratified genetic studies, for operating on gene carriers at young age.

Adolescent↗

PubMed2004

Mortality associated with pheochromocytoma in a large Swedish cohort.

BACKGROUND: The aim of the present study was to report the risk of death in a national cohort of patients with aPC (adrenal PC) and their risk of developing a second tumour. METHODS: Using the National Cancer Registry, 481 patients (222 men and 259 women) with aPC in Sweden (1958-1997) were identified. Autopsy-based diagnoses were excluded. As control group the entire Swedish population was used and the risk of death in patients after diagnosis of aPC was compared with the normal risk taking age, sex and calendar year into account. The risk for a second tumour disease after diagnosis of aPC was also calculated. RESULTS: Patients with aPC had an increased tumour-related mortality after diagnosis of aPC. For both men and women this mortality was four times higher than for controls. Liver/biliary tract and CNS tumours in men; and malignant melanoma and uterine cervical cancer in women were significantly over-represented in the cohort of patients with aPC. CONCLUSION: Patients with aPC run an increased risk of developing additional cancers. Surveillance strategies may thus be necessary for these patients.

Adolescent↗

PubMed2003

Neoadjuvant, adjuvant and palliative treatment of gastrointestinal stromal tumours (GIST) with imatinib: a centre-based study of 17 patients.

Malignant gastrointestinal stromal tumours (GIST) have a poor prognosis. Since these tumours are resistant to conventional radiation and chemotherapy, surgery has been the mainstay of treatment. However, surgery is usually inadequate for the treatment of malignant GIST. Imatinib, a KIT tyrosine kinase inhibitor, has recently been found to have a dramatic antitumour effect on GIST. In this centre-based study of 17 consecutive patients with high-risk or overtly malignant GIST, imatinib was used in three different settings - palliatively, adjuvantly, and neoadjuvantly. The treatment was found to be safe and particularly effective in tumours with activating mutations of exon 11 of the KIT gene. Clinical response to imatinib treatment correlated morphologically to tumour necrosis, hyalinisation, and reduced proliferative activity. The value of neoadjuvant imatinib treatment was illustrated in one case.

Adult↗

PubMed2003

Plants lacking the main light-harvesting complex retain photosystem II macro-organization.

Photosystem II (PSII) is a key component of photosynthesis, the process of converting sunlight into the chemical energy of life. In plant cells, it forms a unique oligomeric macrostructure in membranes of the chloroplasts. Several light-harvesting antenna complexes are organized precisely in the PSII macrostructure-the major trimeric complexes (LHCII) that bind 70% of PSII chlorophyll and three minor monomeric complexes-which together form PSII supercomplexes. The antenna complexes are essential for collecting sunlight and regulating photosynthesis, but the relationship between these functions and their molecular architecture is unresolved. Here we report that antisense Arabidopsis plants lacking the proteins that form LHCII trimers have PSII supercomplexes with almost identical abundance and structure to those found in wild-type plants. The place of LHCII is taken by a normally minor and monomeric complex, CP26, which is synthesized in large amounts and organized into trimers. Trimerization is clearly not a specific attribute of LHCII. Our results highlight the importance of the PSII macrostructure: in the absence of one of its main components, another protein is recruited to allow it to assemble and function.

Arabidopsis↗

PubMed2002

Radioiodine ablation and therapy in differentiated thyroid cancer under stimulation with recombinant human thyroid-stimulating hormone.

We investigated whether recombinant human TSH (rhTSH) safely and effectively induces uptake of high-dose 131-iodine (131I) to ablate thyroid remnant or treat disease, in patients with well-differentiated thyroid carcinoma. Eleven consecutive patients unable to tolerate thyroid hormone withdrawal received one im injection of 0.9 mg rhTSH on 2 consecutive days before receiving 4000 MBq (approximately 108 mCi) radioiodine orally. Eight patients received one, and 3 patients 2 courses. Our series comprised 7 women and 4 men (mean age, 78 yr, range: 56-87 yr). Ten patients had undergone total or near-total thyroidectomy up to 19 yr earlier. rhTSH-stimulated single course radioiodine with the intention to ablate thyroid remnant was performed in 3 patients, with following estimation of radioiodine uptake and TG measurements. Of another 8 patients given this treatment palliatively, 5 had radiological, clinical and/or laboratory response, including: 80% decreased pathological uptake between treatment courses; pronounced decrease in bone pain; diminished symptoms; improved physical condition and quality of life; lower serum TG concentration; and/or normalization of TG recovery test. Two patients with small lung metastases on computed tomography had no detectable radioiodine uptake or other response; they also lacked uptake after withdrawal-stimulated radioiodine treatment. Despite being elderly and frail, patients generally tolerated treatment well; rhTSH caused nausea in one patient and transiently increased pain in bone and soft tissue lesions in another. We conclude that rhTSH-stimulated high-dose radioiodine for remnant ablation or tumor treatment is safe, feasible and seemingly effective, enhancing quality of life and offering reasonable palliation in patients with advanced disease.

Aged↗

PubMed2001

[Phenotypic expression of a mutation in MEN 2A documented in a family in the western part of Sweden].

A missense mutation at codon 618 of the RET proto-oncogene is a rather unusual cause of multiple endocrine neoplasia 2A. We report the phenotypic expression of this specific RET mutation in a large Swedish family. The family was mapped back to the 18th century. Since 1971 the family has been included in a biochemical screening program, and since 1994 has undergone genetic screening. Twenty-seven individuals were found to have medullary thyroid carcinoma (MTC). Eighteen were detected by screening. The incidence of pheochromocytoma (4%) and hyperparathyroidism (7%) was low. Five individuals died of MTC, but of these none had been included in the screening program. One patient underwent prophylactic thyroidectomy after positive genetic screening. MTC tumor aggressivity differed markedly between gene carriers. The screening program shows that the clinical aggressivity of MTC can be mitigated by early and adequate surgical intervention.

Female↗

PubMed2001

[Hereditary thyroid cancer can be cured by prophylactic surgery].

Multiple endocrine neoplasia type 2 (MEN 2) is a rare syndrome in which the consequences for the patient and family members are considerable. Mutation analysis of the RET proto-oncogene is crucial for decision-making regarding each patient. Today, carriers of MEN 2 mutations should be offered prophylactic thyroidectomy with the potential to eliminate the risk for potentially lethal medullary thyroid carcinoma (MTC). Here, we present the first Swedish experience of such operations performed mainly on the basis of genetic analysis. Twenty patients underwent total thyroidectomy at a mean age of 13.5 (6-43) years. In all cases, either manifest MTC (n = 11) or C-cell hyperplasia was found. So far, no patient has any sign of recurrence or developmental insufficiency at 1-5 years follow-up. As the medical and ethical problems in this group of patients are substantial, and as the operations are performed in otherwise healthy children, they should be treated at centers with adequate multidisciplinary expertise and competence.

Adolescent↗

PubMed2001

Identification of Lhcb1/Lhcb2/Lhcb3 heterotrimers of the main light-harvesting chlorophyll a/b-protein complex of Photosystem II (LHC II).

Using non-denaturing isoelectric focusing in polyacrylamide vertical slab gel, we have purified to homogeneity three trimeric subcomplexes of LHC II from Arabidopsis thylakoid membranes. The polypeptide composition of the subcomplexes were studied by immunoblotting. Our results indicate the existence in vivo of LHC II heterotrimers containing Lhcb1, Lhcb2 and Lhcb3 gene products.

Apoproteins↗

PubMed2001

Cytotoxic treatment of adrenocortical carcinoma.

Adrenocortical carcinoma (ACC) is a rare, aggressive tumor that is often detected in an advanced stage. Medical treatment with the adrenotoxic drug mitotane has been used for decades, but critical prospective trials on its role in residual disease or as an adjuvant agent after surgical resection are still lacking. The concept of a critical threshold plasma level of the drug must be confirmed in controlled studies. Because individual responsiveness cannot be predicted, the use mitotane is still advised for nonresectable disease. In case of cortisol or other steroid overproduction, several drugs (e.g., ketoconazole or aminoglutethimide) may be used. Chemotherapy with single agents (e.g., doxorubicin or cisplatin) have been disappointing, with low response rates (< 30%) and a short response duration. Part of this refractoriness may be explained by the fact that ACC tumors express the multidrug-resistance gene MDR-1. Chemotherapy with multiple agents has been tested in smaller series and has resulted in significant side effects. The best results were achieved by the combination of etoposide, doxorubicin, and cisplatin associated with mitotane, achieving a response rate of 54%, including individual complete responses. To be able to make progress in treating advanced ACC disease, adjuvant multicenter trials must be encouraged. When mitotane-based therapies are used, monitored drug levels are mandatory.

Adrenal Cortex Neoplasms↗

PubMed2001

Acclimation of Arabidopsis thaliana to the light environment: the existence of separate low light and high light responses.

The capacity for photosynthetic acclimation in Arabidopsis thaliana (L.) Heynh. cv. Landsberg erecta was assessed during growth over a broad range of irradiance. Discontinuities in the response to growth irradiance were revealed for the light- and CO2-saturated rate of photosynthesis (Pmax) and the ratio of chlorophyll a to chlorophyll b (Chl a/b). Three separate phases in the response of Pmax and Chl a/b to growth light were evident, with increases at low and high irradiance ranges and a plateau at intermediate irradiance. By measuring all chlorophyll-containing components of the thylakoid membrane that contribute to Chl a/b we reveal that distinct strategies for growth at low and high irradiance underlie the discontinuous response. These strategies include, in addition to changes in the major light-harvesting complexes of photosystem II (LHCII), large shifts in the amounts of both reaction centres as well as significant changes in the levels of minor LHCII and LHCI components.

Acclimatization↗

PubMed2001

Effects of preoperative parathyroid localisation studies on the cost of operations for persistent hyperparathyroidism.

OBJECTIVE: To find out whether preoperative parathyroid localisation studies are cost-effective in patients with persistent hyperparathyroidism (HPT). DESIGN: Retrospective study. SETTING: University hospital, Sweden. PATIENTS: 29 consecutive patients with persistent HPT who were reoperated on with or without localisation studies. 15 other patients had initial operations for HPT without localisation studies. INTERVENTIONS: Initial or repeat operation for HPT, localisation studies with 99mTc sestamibi scintigraphy, and catheterisation of large cervical and mediastinal veins with measurements of serum concentrations of parathyroid hormone. MAIN OUTCOME MEASURES: Operative time. Cost of operations, frozen section biopsy and localisation studies. RESULTS: The mean durations of reoperation with localisation studies and for the initial operation without them, were 124 and 135 minutes, respectively, while it was 269 minutes for reoperation without studies. For patients who had localisation studies the mean total cost of the investigations, operating time, and frozen section biopsy was 28% less than for patients who were reoperated on without such studies. CONCLUSION: Preoperative localisation studies before repeat operations for HPT were cost-effective. Even if it has not been shown in this series, the reduction in operating time and the extent of dissection by localisation studies has the potential to decrease morbidity.

Biopsy↗

PubMed2001

Oxygen consumption in patients with hyperthyroidism before and after treatment with beta-blockade versus thyrostatic treatment: a prospective randomized study.

OBJECTIVE: To evaluate randomly the effect of thyrostatic treatment (tiamazole) versus selective (metoprolol) and nonselective beta-blockade (propranolol) on whole-body energy metabolism in women with hyperthyroidism. SUMMARY BACKGROUND DATA: beta-blockade is used as an alternative to thyrostatic drugs in the preoperative treatment of patients with hyperthyroidism. beta-blockers have well-established symptomatic effects, but in contrast to antithyroid drugs beta-blockade is thought to lack direct effects on the increased metabolism in hyperthyroidism. METHODS: Whole-body oxygen consumption and carbon dioxide production was measured in a semiopen canopy system with paramagnetic O2 and infrared CO2 sensors. A constant flow generator and the gas-dilution method for calculation of gas flow were used. Anabolic parameters were body weight, triceps skinfold, and arm muscle circumference. RESULTS: Tiamazole normalized oxygen consumption and induced signs of anabolism with improved nutritional state. Metroprolol did not affect oxygen consumption. Propranolol reduced elevated oxygen consumption by 54%. Body weight and other anthropometric assessments were stable after specific and nonspecific beta-blockade, which also led to symptomatic relief in approximately 90% of the patients. CONCLUSION: Tiamazole was the most effective drug to oppose the adverse effects of hyperthyroidism. Therefore, thyrostatic agents are recommended for preoperative treatments of patients with severe catabolic hyperthyroidism. Whenever beta-blockers are chosen for treatment of hyperthyroidism, propranolol (beta 1 + beta 2) has an advantage because it reduces the metabolic rate, whereas selective beta 1-blockade seemed to provide only symptomatic relief, related to the normalization of heart rate.

Adrenergic beta-Antagonists↗

PubMed2001

The properties of the chlorophyll a/b-binding proteins Lhca2 and Lhca3 studied in vivo using antisense inhibition.

The specific functions of the light-harvesting proteins Lhca2 and Lhca3 were studied in Arabidopsis ecotype Colombia antisense plants in which the proteins were individually repressed. The antisense effect was specific in each plant, but levels of Lhca proteins other than the targeted products were also affected. The contents of Lhca1 and Lhca4 were unaffected, but Lhca3 (in Lhca2-repressed plants) was almost completely depleted, and Lhca2 decreased to about 30% of wild-type levels in Lhca3-repressed plants. This suggests that the Lhca2 and Lhca3 proteins are in physical contact with each other and that they require each other for stability. Photosystem I fluorescence at 730 nm is thought to emanate from pigments bound to Lhca1 and Lhca4. However, fluorescence emission and excitation spectra suggest that Lhca2 and Lhca3, which fluoresce in vitro at 680 nm, also could contribute to far-red fluorescence in vivo. Spectral forms with absorption maxima at 695 and 715 nm, apparently with emission maxima at 702 and 735 nm, respectively, might be associated with Lhca2 and Lhca3.

Antisense Elements (Genetics)↗

PubMed2001

Antisense inhibition of the photosynthetic antenna proteins CP29 and CP26: implications for the mechanism of protective energy dissipation.

The specific roles of the chlorophyll a/b binding proteins CP29 and CP26 in light harvesting and energy dissipation within the photosynthetic apparatus have been investigated. Arabidopsis was transformed with antisense constructs against the genes encoding the CP29 or CP26 apoprotein, which gave rise to several transgenic lines with remarkably low amounts of the antisense target proteins. The decrease in the level of CP24 protein in the CP29 antisense lines indicates a physical interaction between these complexes. Analysis of chlorophyll fluorescence showed that removal of the proteins affected photosystem II function, probably as a result of changes in the organization of the light-harvesting antenna. However, whole plant measurements showed that overall photosynthetic rates were similar to those in the wild type. Both antisense lines were capable of the qE type of nonphotochemical fluorescence quenching, although there were minor changes in the capacity for quenching and in its induction kinetics. High-light-induced violaxanthin deepoxidation to zeaxanthin was not affected, although the pool size of these pigments was decreased slightly. We conclude that CP29 and CP26 are unlikely to be sites for nonphotochemical quenching.

Amino Acid Sequence↗

PubMed2000

A pigment-binding protein essential for regulation of photosynthetic light harvesting.

Photosynthetic light harvesting in plants is regulated in response to changes in incident light intensity. Absorption of light that exceeds a plant's capacity for fixation of CO2 results in thermal dissipation of excitation energy in the pigment antenna of photosystem II by a poorly understood mechanism. This regulatory process, termed nonphotochemical quenching, maintains the balance between dissipation and utilization of light energy to minimize generation of oxidizing molecules, thereby protecting the plant against photo-oxidative damage. To identify specific proteins that are involved in nonphotochemical quenching, we have isolated mutants of Arabidopsis thaliana that cannot dissipate excess absorbed light energy. Here we show that the gene encoding PsbS, an intrinsic chlorophyll-binding protein of photosystem II, is necessary for nonphotochemical quenching but not for efficient light harvesting and photosynthesis. These results indicate that PsbS may be the site for nonphotochemical quenching, a finding that has implications for the functional evolution of pigment-binding proteins.

Amino Acid Sequence↗