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Biomedical subjects

F A Karlsson

Publications and source records attributed to F A Karlsson.

At least 19 recordsLinked to original sources
PubMed1992

21-Hydroxylase, a major autoantigen in idiopathic Addison's disease.

Sera from patients with idiopathic Addison's disease commonly react with the zona glomerulosa of adrenal cortex. We used high-resolution western blot analysis of an adrenal microsomal fraction to investigate the target of these antibodies. A protein with an apparent molecular weight of 54 kDa was recognised as the common and major component. Sera identifying this autoantigen (from 12 of 16 patients) also showed strong immunofluorescence staining of a steroid-producing human adrenal adrenocortical cell line, NCI-H295. On application of antisera specific for different cytochrome P450 steroidogenic enzymes (side-chain cleavage enzyme, 21-hydroxylase, 17 alpha-hydroxylase, 11 beta-hydroxylase) the mobility of the 54 kDa protein in western blots corresponded to that of 21-hydroxylase. This parallel behaviour was confirmed by immunoprecipitation, electrophoresis, and autoradiography with the various sera and 35S-methionine-labelled NCI-H295 cell lysates. Preabsorptions of 35S-methionine-labelled cell lysates with the antiserum to 21-hydroxylase, but not with the other enzyme antisera, abolished precipitation of the 54 kDa autoantigen with the patient sera. These results indicate that 21-hydroxylase (P450c21), prominent in the zona glomerulosa of the adrenal cortex, is a major autoantigen in idiopathic Addison's disease.

Addison Disease↗
PubMed1992

Expression of the 64 kDa/glutamic acid decarboxylase rat islet cell autoantigen is influenced by the rate of insulin secretion.

This study examined the relationship between insulin secretion and expression of the 64 kDa/glutamic acid decarboxylase autoantigen in pancreatic islets. Islets isolated from Wistar rats were cultured for 3 days under different conditions: in 5.5 mmol/l glucose with or without alpha-ketoisocaproic acid or glipizide and in 28 mmol/l glucose with or without diazoxide. The 64 kDa/glutamic acid decarboxylase autoantigen was precipitated from lysates of [35S]-methionine-labelled islets with sera from patients with Type 1 (insulin-dependent) diabetes mellitus and identified by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and fluorography. In parallel, insulin contents of the islets and the media were determined as well as the rates of glucose-stimulated (pro)insulin biosynthesis. alpha-Ketoisocaproic acid and glipizide were found to stimulate the expression of the 64 kDa/glutamic acid decarboxylase autoantigen and also the rate of insulin secretion. Diazoxide on the other hand reduced the rate of the 64 kDa/glutamic acid decarboxylase autoantigen synthesis in parallel with an inhibition of glucose-stimulated insulin release. Under most of the conditions employed, (pro)insulin biosynthesis was not affected. The correlation found between the rate of insulin release and expression of the 64 kDa/glutamic acid decarboxylase autoantigen might provide an explanation for the earlier observed relationship between the functional demands on the Beta cells and their rate of destruction which may result in diabetes.

Animals↗
PubMed1992

Low plasma levels of insulin-like growth factor 1 (IGF-1) in male patients with idiopathic osteoporosis.

Experimental studies in vitro indicate that insulin-like growth factor 1 (IGF-1) could be of importance for normal bone growth and remodelling, but the clinical relevance of these observations is unknown. In 12 consecutive young to middle-aged male patients (mean age (+/- SD) 46 +/- 8 years, range 30-57 years) with symptomatic idiopathic osteoporosis, the plasma concentrations of IGF-1 were significantly lower than in healthy subjects (0.51 +/- 0.25 vs. 0.73 +/- 0.23 U ml-1; P less than 0.01). The bone mineral densities in the spine, the femoral neck, and the forearm were significantly different between patients and control subjects. There were positive correlations between the plasma IGF-1 concentrations and the bone densities of the spine and the forearm. Three of the patients received a 5-d course of human recombinant growth hormone (GH). During this short period significant increases in plasma IGF-1 levels and in biochemical indices of bone turnover (serum bone-specific alkaline phosphatase, urinary calcium excretion) were recorded. These observations indicate that circulating IGF-1 could have an important role in maintaining bone mass, and suggest that impairment of IGF-1 production is involved in the pathogenesis of osteoporosis.

Adult↗
PubMed1992

Hyperthyroid Graves' disease without detectable thyrotropin receptor antibodies.

TSH receptor antibodies are generally held responsible for the stimulation of the thyroid that characterizes patients with Graves' disease. Here, we describe nine patients with hyperthyroidism (triiodothyronine 4.9, 3.2-6.7 nmol/L; median, range) who were referred for radioiodine treatment and who had increased thyroid radioiodine uptake values but lacked TSH receptor antibodies determined by a radioreceptor assay. Furthermore, when serum immunoglobulins were studied in a bioassay based on a rat thyroid cell line (FRTL-5), no evidence of stimulant activity was observed. Subsequent to radioiodine therapy, TSH receptor antibodies appeared in all nine patients. The antibodies competed for TSH in the radioreceptor assay and, of the eight patient samples studied with the bioassay, six stimulated cAMP production whereas another two blocked the latter. The results show that a small proportion of patients with active hyperthyroid Graves' disease, in this study 9 out of 130 cases, do not have detectable TSH receptor stimulatory antibodies. A local production of antibodies within the thyroid can be suggested, although a more likely explanation might be that the thyroid in Graves' disease is activated also by other mechanisms than antibody-dependent ones.

Adult↗
PubMed1992

Glucose regulation of the autoantigen GAD65 in human pancreatic islets.

Recent data suggest that the enzyme glutamic acid decarboxylase (GAD) may be a primary beta-cell antigen involved in the autoimmune response leading to insulin dependent diabetes mellitus (IDDM). Following three days culture of human islets at different glucose concentrations (5.6, 11 or 28 mM), there was a single 65 kDa/GAD band in the islet extracts, as assessed by immunoprecipitation both with serum from a newly diagnosed IDDM patient and a sheep anti-GAD serum. The synthesis of GAD was strongly stimulated at the higher glucose concentrations. Likewise, Western blot analysis indicated a glucose-induced increase of GAD in the islets. The data suggest that an enhanced function of human islet cells increases expression of GAD65. Possibly, this could exacerbate the autoimmune assault in the early stages of IDDM, and be of practical importance in attempts to ameliorate the autoimmune response towards the beta-cells in IDDM.

Autoantigens↗
PubMed1992

Islet cell and thyrogastric antibodies in 633 consecutive 15- to 34-yr-old patients in the diabetes incidence study in Sweden.

The effect of age on ICA and thyrogastric antibodies at diagnosis of IDDM was evaluated in 633 consecutively diagnosed Swedish diabetic patients aged 15-34 yr and in 282 volunteers of the same age. ICAs were present in 61% (383 of 633) of the patients and in 2% (5 of 282) of control subjects. When the initial classification was considered, ICAs were detected in 69% (327 of 473) of patients with IDDM, 23% (19 of 83) of those with NIDDM, 50% (36 of 72) of those with unclassifiable diabetes, and 20% (1 of 5) of those with secondary diabetes. The frequency of ICA fell significantly (P less than 0.001) with age in IDDM patients from 77% (104/135) in those 15-19 yr old to 52% (50 of 96) in 30- to 34-yr-old IDDM patients. The low frequency of ICA in 30- to 34-yr-old IDDM patients was confined to men (42%, 28 of 66). The frequency of gastric (H+, K(+)-ATPase) antibodies was significantly (P less than 0.05) higher in IDDM patients (10%, 47 of 449) than in patients with NIDDM (3%, 3 of 80) and unclassifiable diabetes (4%, 3 of 72). In conclusion, the frequency of ICA at the diagnosis of IDDM in young adult subjects decreases with increasing age, particularly in men. The frequent finding of ICA in patients considered to have NIDDM or unclassifiable diabetes indicates that misclassification of diabetes is frequent in young adult patients recently diagnosed with diabetes.

Adolescent↗
PubMed1991

Peptic ulcer disease: absence of antibodies stimulating the histamine sensitive adenylate cyclase of gastric mucosal cells.

The possible presence of parietal cell stimulating antibodies was examined in sera from 57 patients with relapsing ulcer disease. The sera were obtained at the time of symptomatic relapse and all patients had ulcers confirmed by endoscopy. A sensitive assay based on adenosine 3':5' cyclic monophosphate (cAMP) production in isolated porcine gastric mucosal cells was used as a measure. cAMP production increased up to four hours of incubation and was histamine responsive; an approximately 20-fold increase was found with histamine 10(-4) mol/l. Sera from both patients and healthy control subjects showed some inhibitory effect on basal cAMP production compared with incubation in medium only, whereas immunoglobulin preparations had a weaker non-specific effect. No stimulation was found when the patients' sera and immunoglobulins (up to a concentration of 6 mg/ml) were examined. These results suggest that gastric acid hypersecretion in duodenal ulcer disease is not an effect of histamine receptor stimulating antibodies. The data thus argue against a recent hypothesis that severe chronic ulcer disease in some patients has an autoimmune origin.

Adenylyl Cyclases↗
PubMed1991

H+,K-ATPase antibodies in autoimmune gastritis: observations on the development of pernicious anemia.

The prevalence and development of antibodies to H+,K+-ATPase were investigated with a sensitive enzyme-linked immunosorbent assay in 86 patients with autoimmune atrophic gastritis (type A). Sixty-nine of the patients had pernicious anemia, and 17 had simple atrophic gastritis. Elevated titers were found in 93% of pernicious anemia probands. Women had higher levels than men: 3.24 versus 1.58 U/l (p = 0.002) (upper reference limit, 0.55 U/l). The antibody levels did not change over 1-4 years, but a gradual decrease in titers over decades was observed. All patients with pernicious anemia had low levels of pepsinogen A, a product of the gastric chief and mucous neck cells (median, 8.5 micrograms/l; reference range, 10-90 percentile, 64.4-195.5 micrograms/l), and elevated serum gastrin values (greater than 55 pmol/l) were found in 87%. Serum pepsinogen A, but not serum gastrin, correlated with H+,K(+)-ATPase antibody titers (r = 0.35, p = 0.01). In the 17 cases with simple atrophic gastritis, H+,K(+)-ATPase antibodies correlated inversely with fundic mucosal gland destruction. The data indicate that H+,K(+)-ATPase antibody titers reflect the immune responsiveness of a given patient as well as the antigenic amount, dependent on the degree of mucosal destruction and the duration of the disease.

Adult↗
PubMed1990

Hyperthyroidism and hypothyroidism in monozygotic twins: detection of stimulating and blocking THS receptor antibodies using the FRTL5-cell line.

We present a rare history of monozygotic twin girls who at the age of 10 yr presented with hyper- and hypothyroidism, respectively. Both girls had antibodies against thyrotropin receptors as measured by a radioreceptor assay (230 U/l and 1400 U/l; reference range less than 7 U/l). The sera were further examined in a bioassay, based on a rat thyroid cell line (FRTL5), in which release of cAMP into medium was measured. The TSH receptor antibodies of the hyperthyroid twin displayed a ratio of radioreceptor to biological activity typical of Graves' disease. In contrast, the antibodies of the hypothyroid twin acted as pure antagonists at the TSH receptor level. The occurrence of TSH receptor antibodies in these monozygotic twins suggests a similar pathogenesis of Graves' disease and that of hypothyroidism due to thyroid blocking antibodies.

Adolescent↗
PubMed1990

Autoantibodies to epithelial cells in patients on long-term therapy with leucocyte-derived interferon-alpha (IFN-alpha).

During routine screening for anti-nuclear antibodies, using rat liver tissue as substrate, a reactivity against bile duct epithelium was observed in sera from carcinoid tumour patients given human leucocyte-derived IFN-alpha (HuLe IFN-alpha). In a retrospective study, initiated by this observation, the development of serum antibodies to bile duct epithelium was observed in nine out of 12 patients with carcinoid tumours and in three out of 14 patients with hairy-cell leukaemia during their treatment with HuLe IFN-alpha. However, no bile duct reactivity was observed in sera from carcinoid or hairy-cell leukaemia in patients given recombinant IFN-alpha. When analysing the reactivity of positive sera against a panel of rat and human tissues, a uniform reactivity was observed against simple epithelial cells lining the gastrointestinal tract, pancreatic secretory ducts, fallopian tube, kidney tubuli, mesothelium and also against carcinoid tumour cells. The mechanisms promoting autoreactivity against this simple epithelial cell autoantigen is so far unknown. The cytoplasmic as well as the restricted staining pattern of simple epithelial cells may indicate autoreactivity against certain cytoskeletal intermediate filaments, such as cytokeratin 19, 18 and 8, known to be exclusively present in simple epithelial cells and tumours derived from them.

Animals↗
PubMed1990

Effects of L-thyroxine and iodide on the development of autoimmune postpartum thyroiditis.

In the present study we examined the influence of L-T4 and iodide on autoimmune postpartum thyroiditis. Women at risk of developing the disease were identified in early pregnancy by the presence of moderate or high titers of antibodies against thyroid peroxidase (TPOAb). They were given no treatment (n = 20), 0.1 mg L-T4 daily (n = 18), or 0.15 mg iodide daily (n = 20) for 40 weeks postpartum. Changes in thyroid function were seen in all women, although in nine hormone values remained within the reference ranges of erthymoid individuals. In each group of women, thyrotoxicosis occurred around 2-3 months postpartum, followed by a gradual rise of TPOAb. Subsequently, around 5-7 months postpartum, a hypothyroid phase was observed. TSH elevations (greater than 5 mU/L) occurred in 9 of 18 women in spite of treatment with 0.1 mg L-T4 although elevations were lower than in the other two groups. Among those women who developed abnormal thyroid function, the hormone changes appeared greater in the iodide-treated group than in the control group, suggesting that in certain patients iodide may aggravate rather than ameliorate the disease. All 58 women showed a reduction of TPOAb during pregnancy and a transient rise during the postpartum year. The extent of TPOAb elevations did not differ between the groups. Thus, the administration of L-T4 prevented hypothyroid symptoms, but did not alter the course of the postpartum thyroiditis, which appears not to be accelerated by events of target cell origin.

Adult↗
PubMed1990

Effects of interleukin 1 alpha on porcine thyroid follicles in suspension culture.

Interleukin 1, a product primarily of activated macrophages, was found to exert both a stimulatory and an inhibitory effect on porcine thyroid follicles in suspension cultures. A stimulatory effect on [125I] iodide incorporation into protein (iodination) was seen in cultures exposed to human recombinant interleukin 1 alpha (20 micrograms/l) for 1 h and (0.1 or 10 micrograms/l) for 18 h, whereas an inhibitory effect on iodination of interleukin 1 (10 micrograms/l) was registered after pre-incubation for 42 h and significant upon stimulation with TSH (200 mU/l). Cyclic AMP levels were stimulated in cells exposed to interleukin 1, however, significantly only after 42 h of pre-incubation, whereas TSH-stimulated cAMP response was inhibited by interleukin 1 already after 18 h of pre-incubation. The lumen of interleukin 1 incubated follicles was highly dilated and surrounded by a flattened epithelium. There were, however, no morphological signs of follicle disintegration or cellular cytotoxicity in the cultures exposed to interleukin 1. The data suggest that interleukin 1 might have a modulating role on thyroid function in autoimmune thyroid diseases associated with activation of intrathyroidal macrophages.

Animals↗
PubMed1990

Factors influencing the outcome of thyrostatic drug therapy in Graves' disease.

In patients with Graves' disease, thyrostatic drug treatment may induce definitive remission without the need of more aggressive measures such as surgery or radioiodine. Following drug therapy, however, relapses often occur. In the present study, a multivariate analysis of pretreatment variables was performed, in order to identify individuals running a high risk of an unfavourable outcome of thyrostatic drug therapy. We studied 109 consecutive patients with a mean age of 38 years, range 20-70, over a mean follow-up period of 5.3 years after cessation of therapy. The analysis showed that goitre size, age, thyroid hormone levels, HLA-DR 3 haplotype, and TSH receptor antibody levels were of prognostic significance, whereas HLA-B8 haplotype, a lymphocytic infiltrate at fine needle biopsy, thyroglobulin, and microsomal antibodies had no such value. In particular, patients characterized by young age, large goitre and high hormone values were found to be associated with an unfavourable course.

Adult↗
PubMed1989

Binding of glycosaminoglycan inhibitors to calcium oxalate crystals in relation to ionic strength.

Several inhibitors of calcium oxalate crystallization have been identified and shown to exhibit quantitative and qualitative differences in efficacy. Glycosaminoglycans are potent inhibitors of crystal growth and aggregation, and the efficiency seems to increase with an increasing charge density. In order to investigate the mechanism of inhibition, we performed binding experiments of radioactivity labelled heparin, chondroitin sulphate and the low-molecular mass heparin analogue pentosan polysulphate to calcium oxalate crystals and subsequent displacements by increasing the amounts of non-radioactive ligands or increasing ionic strength. Ligands with a high charge density bound more readily and with a seemingly higher affinity than ligands with a low charge density, but were also more susceptible to displacement when the ionic strength was increased. It is concluded that a higher affinity to the crystals may be the reason why highly charged glycosaminoglycans are more efficient inhibitors of calcium oxalate crystal growth.

Calcium Oxalate↗
PubMed1989

Parietal cell antibodies in pernicious anemia inhibit H+, K+-adenosine triphosphatase, the proton pump of the stomach.

Antibodies to a membrane-bound antigen, localized to the canalicular structures of the parietal cell, are found in most sera of patients with chronic atrophic gastritis and pernicious anemia. In the present study immunoglobulins containing parietal cell antibodies were found to inhibit the activity of H+,K+-adenosine triphosphatase (EC 3.6.1.36) in a tubulovesicular membrane preparation from porcine gastric mucosa. The degree of inhibition correlated to the titer of parietal cell antibodies as assessed by an enzyme-linked immunosorbent assay. The specificity of the enzymatic inhibition was confirmed by the lack of effect of parietal cell antibodies on membrane-bound esterase. A possible interaction of parietal cell antibodies with gastrin binding at the receptor level was investigated in a radioreceptor assay employing 125I-gastrin 1 and gastric mucosal cell suspension from the guinea pig. No blocking capacity was found with immunoglobulins from patients with pernicious anemia as compared with immunoglobulins from healthy controls. The results thus demonstrate a direct inhibitory effect of parietal cell antibodies on the acid producing H+,K+-adenosine triphosphatase of the parietal cell, but also a lack of interaction with the gastrin receptor, and indicate that in the development of hypo/achylia H+,K+-adenosine triphosphatase autoantibodies could have a major pathogenic role.

Adenosine Triphosphatases↗
PubMed1989

High-glucose stimulation of 64,000-Mr islet cell autoantigen expression.

This study examined the effect of various extracellular glucose concentrations on the expression of a previously described 64,000-Mr islet cell autoantigen associated with insulin-dependent diabetes mellitus. The protein was precipitated from patient serums incubated with Triton X-100 lysates of [35S]methionine-labeled rat pancreatic islets that had been cultured in 5, 11, or 28 mM glucose for 6 h or 3 days. In both types of experiment, 28 mM glucose was the most efficient stimulator of 64,000-Mr autoantigen production. In contrast, the class I antigens of the major histocompatibility complex, precipitated by a rabbit polyclonal antiserum, were not influenced by differences in glucose concentrations. Our data indicate that expression of islet cell antigens may be increased during the course of hyperglycemia and suggest that the functional activity of islet cells influences their antigenicity.

Animals↗
PubMed1988

Postpartum thyroiditis.

The special characteristics of postpartum thyroid syndromes are summarized in Table 8. Many of the cases will pass unnoticed, although a higher detection rate is to be expected if postpartum thyroid disease becomes better known among physicians and the general public. Screening in early pregnancy of women with a previous or family history of thyroid disease and in women with other autoimmune disorders (such as diabetes mellitus type 1) may be worthwhile. The initial manifestation of postpartum thyroiditis, often appearing during the first three months postpartum, is a thyrotoxic phase characterized by a low RAIU ('painless thyroiditis' or 'destruction-induced thyrotoxicosis'). Subsequently, a transient hypothyroid phase supervenes. In a small proportion of women hypothyroidism becomes permanent. After a subsequent pregnancy recurrence is the rule. Women who are genetically disposed to Graves' disease may experience thyrotoxicosis with a high RAIU usually appearing later than three months postpartum. As the thyroid function abnormalities are usually mild and transient it is often appropriate to withhold treatment. However, in women with pronounced symptoms treatment should be started. When the postpartum period has passed gradual withdrawal of treatment should be attempted. In women who have experienced postpartum thyroid dysfunction, the risk of developing permanent thyroid disease in later life seems important and therefore long-term follow-up is recommended.

Female↗