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Biomedical subjects

S Jansson

Publications and source records attributed to S Jansson.

At least 55 records · Page 3Linked to original sources
PubMed1995

Chlorophyll a/b-binding proteins, pigment conversions, and early light-induced proteins in a chlorophyll b-less barley mutant.

Monospecific polyclonal antibodies have been raised against synthetic peptides derived from the primary sequences from different plant light-harvesting Chl a/b-binding (LHC) proteins. Together with other monospecific antibodies, these were used to quantify the levels of the 10 different LHC proteins in wild-type and chlorina f2 barley (Hordeum vulgare L.), grown under normal and intermittent light (ImL). Chlorina f2, grown under normal light, lacked Lhcb1 (type I LHC II) and Lhcb6 (CP24) and had reduced amounts of Lhcb2, Lhcb3 (types II and III LHC II), and Lhcb4 (CP 29). Chlorina f2 grown under ImL lacked all LHC proteins, whereas wild-type ImL plants contained Lhcb5 (CP 26) and a small amount of Lhcb2. The chlorina f2 ImL thylakoids were organized in large parallel arrays, but wild-type ImL thylakoids had appressed regions, indicating a possible role for Lhcb5 in grana stacking. Chlorina f2 grown under ImL contained considerable amounts of violaxanthin (2-3/reaction center), representing a pool of phototransformable xanthophyll cycle pigments not associated with LHC proteins. Chlorina f2 and the plants grown under ImL also contained early light-induced proteins (ELIPs) as monitored by western blotting. The levels of both ELIPs and xanthophyll cycle pigments increased during a 1 h of high light treatment, without accumulation of LHC proteins. These data are consistent with the hypothesis that ELIPs are pigment-binding proteins, and we suggest that ELIPs bind photoconvertible xanthophylls and replace "normal" LHC proteins under conditions of light stress.

Amino Acid Sequence↗
PubMed1994

Nucleotide distribution in gymnosperm nuclear sequences suggests a model for GC-content change in land-plant nuclear genomes.

Nuclear protein coding sequences from gymnosperms are currently scarce. We have determined 4 kb of nuclear protein coding sequences from gynosperms and have collected and analyzed > 60 kb of nuclear sequences from gymnosperms and nonspermatophytes in order to better understand processes influencing genome evolution in plants. We show that conifers possess both biased and nonbiased genes with respect to GC content, as found in monocots, suggesting that the common ancestor of conifers and monocots may have possessed both biased and nonbiased genes. The lack of biased genes in dicots is suggested to be a derived character for this lineage. We present a simple but speculative model of land-plant genome evolution which considers changes in GC bias and CpG frequency, respectively, as independent processes and which can account for several puzzling aspects of observed nucleotide frequencies in plant genes.

Base Composition↗
PubMed1994

Adherence of RFD-1 positive dendritic cells to the basal surface of thyroid follicular cells in Graves' disease.

HLA-DR positive cells infiltrating Graves' thyroid tissue were examined for their expression of cell-specific immunological markers using light and electron microscopic immunostaining of frozen sections and isolated open thyroid follicles. Graves' glands (n = 21) were enriched of CD68 and Leu-M5/CD11c positive monocytes/macrophages as well as CD4 and CD8 lymphocytes. These cell types were distributed juxta-follicular as well as in other tissue areas. Only the RFD-1 antibody, considered to label antigen-presenting cells including dendritic cells, identified cells invariably located close to the interstitial follicular surface. After follicle isolation, RFD-1 cells were enriched compared to Leu-M5 cells and exclusively adherent to the follicular epithelium. The plasma membrane of RFD-1 positive cells were in intimate contact with the basolateral membrane of the thyrocytes, sometimes extending deeply into the intercellular space of the epithelium. Parallel labelling experiments suggested that the follicle-adhering RFD-1 cells also expressed HLA-DR. Our findings show that in human thyroid glands with Graves' disease RFD-1 positive cells with a dendritic morphology establish direct contact with the follicular epithelium. In view of the fact that both HLA-DR and RFD-1 are associated with antigen-presenting functions it is suggested that a direct interaction of dendritic cells with thyrocytes might be an important component of the autoimmune reaction in Graves' disease.

Antibodies, Monoclonal↗
PubMed1994

Clinical use of laboratory thyroid tests and investigations.

Laboratory thyroid testing involves in vitro tests for autoimmune thyroid disease, thyroid dysfunction and neoplasia, in vivo investigations of thyroid function, and investigations of thyroid morphology. The authors describe, in tabular form, the diagnostic information carried by the tests and their clinical utility as well as clinically relevant interferences.

Adult↗
PubMed1993

E-cadherin: a differentiation marker in thyroid malignancies.

Loss of E-cadherin (uvomorulin), a Ca(2+)-dependent cell adhesion molecule required for normal epithelial function, has been attributed a pathogenetic role in tumor invasion. The expression of E-cadherin was studied in normal and neoplastic follicular epithelium of the human thyroid by Northern blot analysis and immunofluorescence on frozen tissue sections. In the normal thyroid (n = 10) and in benign thyroid disorders (n = 21; toxic diffuse goitre; multinodular goitre; follicular adenomas), E-cadherin mRNA levels were equally high and the follicles were generally stained, mainly along the lateral surface of the epithelial cells, by the anti-E-cadherin monoclonal antibody. In anaplastic thyroid carcinomas (n = 6) E-cadherin expression was very low or lacking. In papillary carcinomas (n = 23), E-cadherin mRNA levels varied from nearly normal to highly reduced, which roughly correlated with the overall immunofluorescence intensity. However, the immunostaining also revealed a heterogeneous "all-or-nothing" expression of E-cadherin among adjacent cells in the same tumor. In the follicular carcinomas (n = 9), E-cadherin mRNA levels were in general rather high but the immunostaining varied considerably. A few papillary and follicular tumors lacked immunoreactive E-cadherin in spite of high mRNA levels. In oxyphilic (Hürthle) cell tumors, comprising both adenomas (n = 4) and carcinomas (n = 2), E-cadherin immunoreactivity was reduced and distributed intracellularly rather than at the cell surface. The expression of E-cadherin in relapsing thyroid carcinomas and in tumors with metastatic spreading was, irrespective of the histiotype, low or lacking. Sequential Northern analysis revealed a close correlation between the expression levels of E-cadherin and the thyrotropin receptor. Together, the data suggest that in human thyroid malignancies both gene expression and posttranscriptional control of E-cadherin may be impaired.

Adenoma↗
PubMed1993

Rab17, a novel small GTPase, is specific for epithelial cells and is induced during cell polarization.

The rab subfamily of small GTPases has been demonstrated to play an important role in the regulation of membrane traffic in eukaryotic cells. Compared with nonpolarized cells, epithelial cells have distinct apical and basolateral transport pathways which need to be separately regulated. This raises the question whether epithelial cells require specific rab proteins. However, all rab proteins identified so far were found to be equally expressed in polarized and nonpolarized cells. Here we report the identification of rab17, the first epithelial cell-specific small GTPase. Northern blot analysis on various mouse organs, revealed that the rab17 mRNA is present in kidney, liver, and intestine but not in organs lacking epithelial cells nor in fibroblasts. To determine whether rab17 is specific for epithelial cells we studied its expression in the developing kidney. We found that rab17 is absent from the mesenchymal precursors but is induced upon their differentiation into epithelial cells. In situ hybridization studies on the embryonic kidney and intestine revealed that rab17 is restricted to epithelial cells. By immunofluorescence and immunoelectron microscopy on kidney sections, rab17 was localized to the basolateral plasma membrane and to apical tubules. Rab proteins associated with two distinct compartments have been found to regulate transport between them. Therefore, our data suggest that rab17 might be involved in transcellular transport.

Amino Acid Sequence↗
PubMed1993

Overweight--a common problem among women treated for hyperthyroidism.

We sent out a questionnaire to 112 women treated for diffuse toxic goitre 2-5 years earlier to evaluate the prevalence of problems with overweight after the disease. Of 87 responders, about 50% (irrespective of surgical or radioiodine treatment) reported weight problems, and we randomly selected 40 of these women (20 with and 20 without reported weight problems) for a clinical follow-up (32 appearing). At the follow-up examination (mean 4 years after treatment for hyperthyroidism), 27 women had a higher weight than their estimated premorbid weight. The weight gain correlated with the estimated premorbid body mass index (BMI; P < 0.005), indicating that excess weight gainers may have had a premorbid problem now exaggerated in the post-hyperthyroid period. However, many women with a BMI within the limits stated to be ideal (21-25 kg/m2) also showed dramatic increases in weight. In contrast, the average middle-aged woman in our region did not appear to have gained in weight during a corresponding time period as judged from a longitudinal population study. Women with reported weight problems (mean weight increase 15.6%, n = 16) did not differ from women without (mean weight increase 6.7%, n = 16) as regards pretreatment hormone levels, method of treatment, (change of) smoking habits or post-treatment levothyroxine administration, or in serum concentrations of thyroid hormones, thyrotrophin, cortisol, procollagen-III-peptide, cholesterol, HDL cholesterol or triglycerides. Women with hyperthyroidism should be informed about the risk of gaining weight after therapy and given early support as to dietary and lifestyle change.

Adult↗
PubMed1993

Embolisation therapy in the midgut carcinoid syndrome: just tumour ischaemia?

Forty-eight patients with midgut carcinoid tumours and disseminated disease were treated at our unit 1986-1991. All patients underwent primary surgery with optimal tumour reduction. Twenty-seven patients with bilobar liver metastases had subsequent embolizations of the hepatic arteries to further reduce the functional tumour mass and were thereafter treated with a low dose of octreotide. The response to this treatment was evaluated by CT at 3 months postembolization. The patients could then be divided into 13 responders (no visible hepatic tumours or more than 50% reduction, group I) and 14 non-responders (less than 50 reduction or progression, group II). When these patients were studied biochemically and in terms of prognosis, the reduction of 5-HIAA levels postembolization was much more pronounced in group I (80 +/- 3%) then in group II (28 +/- 12%). The biochemical and radiological responses were long-lasting in group I, none of the patients needed further ischaemic treatment. Of specific interest were 3 patients with bilobar disease, who after selective unilobar embolisation normalised their 5-HIAA levels and had bilateral tumour regression. These findings indicate involvement of systemic effects in addition to tumour ischaemia alone. The initial biochemical response with marked decrease of 5-HIAA levels in combination with tumour regression may thus serve as an indicator of good prognosis.

Adult↗
PubMed1993

Adrenocortical carcinoma--diagnostic and therapeutical implications.

OBJECTIVE: To evaluate the results of treatment of a consecutive series of patients with adrenocortical carcinoma who presented during the six year period 1985 to 1991. DESIGN: Open study. SETTING: Departments of Surgery, Pathology, Endocrinology, and Clinical Chemistry, Sahlgren Hospital, Göteborg, Sweden. SUBJECTS: 10 consecutive patients, two with recurrent and eight with primary adrenocortical carcinoma. INTERVENTIONS: All patients were treated surgically. Two required preoperative embolisation of the tumour vessels to facilitate excision of particularly large tumours, and eight were given adjuvant treatment with mitotane (o,p'-DDD). RESULTS: At a median follow up of 1.5 years (range 3 months, to 21 years) 6 patients were alive with no radiological or biochemical signs of disease; 2 were alive, but with signs of recurrence (at 3 months and 6 years, respectively); and two had died of their disease (at 4 and 8 months, respectively). For the past two years all patients have had their urinary steroid profiles monitored by gas chromatography and mass spectrometry to detect recurrence of the tumour at the earliest possible stage. CONCLUSION: Operation is the treatment of choice for patients with adrenocortical carcinoma, particularly stages I-III. The role of mitotane as adjuvant treatment can be evaluated only in multicentre studies.

Adrenal Gland Neoplasms↗
PubMed1992

Uptake of glucose carbon in muscle glycogen and adipose tissue triglycerides in vivo in humans.

Glucose disposal into muscle glycogen has previously been directly studied after intravenous, but not after physiological, oral administration. In this study 100 g glucose, containing 50 microCi [U-14C]glucose, were taken orally by premenopausal women in the overnight fasting state or after a carbohydrate-rich meal. After 4 h, biopsies were taken from the vastus lateralis muscle and abdominal and femoral subcutaneous adipose tissue for determinations of label in isolated glycogen and triglycerides, respectively. Uptake of administered glucose carbon in muscle glycogen was estimated to be approximately 20 g in the fasting and approximately 9 g in the carbohydrate-fed groups, respectively. Total uptake in adipose tissue triglycerides was approximately 2 g. Glucose carbon uptake in muscle glycogen correlated positively with glucose infusion rates during euglycemic hyperinsulinemic glucose clamps, glycogen synthase activity in vitro, and type I muscle fiber distribution and fiber area. Negative correlations were found between glucose uptake in adipose tissue triglycerides, type II fiber distribution and fiber area, as well as the waist-to-hip circumference ratio and degree of obesity. It was concluded that muscle glycogen is probably not a major pathway for disposal of oral glucose carbon in the sedentary condition.

Adipose Tissue↗
PubMed1991

Evolutionary conservation of the chlorophyll a/b-binding proteins: cDNAs encoding type I, II and III LHC I polypeptides from the gymnosperm Scots pine.

cDNAs encoding three different LHC I polypeptides (Type I, Type II and Type III) from the gymnosperm Scots pine (Pinus sylvestris L.) were isolated and sequences. Comparisons of the deduced amino acid sequences with the corresponding tomato sequences showed that all three proteins were highly conserved although less so than the LHC II proteins. The similarities between mature Scots pine and tomato Types I, II and III LHC I proteins were 80%, 87% and 85%, respectively. Two of the five His residues that are found in AXXXH sequences, which have been identified as putative chlorophyll ligands in the Type I and Type II proteins, were not conserved. The same two regions of high homology between the different LHC proteins, which have been identified in tomato, were also found in the Scots pine proteins. Within the conserved regions, the Type I and Type II proteins had the highest similarity; however, the Type II and Type III proteins also showed a similarity in the central region. The results suggest that all flowering plants (gymnosperms and angiosperms) probably have the same set of LHC polypeptides. A new nomenclature for the genes encoding LHC polypeptides (formerly cab genes) is proposed. The names lha and lhb are suggested for genes encoding LHC I and LHC II proteins, respectively, analogous to the nomenclature for the genes encoding other photosynthetic proteins.

Amino Acid Sequence↗