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Biomedical subjects

K Bech

Publications and source records attributed to K Bech.

At least 91 records · Page 5Linked to original sources
PubMed1984

Adrenergic influence on pentagastrin and bethanechol stimulated gastric acid secretion in dogs with gastric fistula.

The purpose of this study was to elucidate the effect of alpha-, beta- and dopaminergic receptor stimulation and blockade on pentagastrin and bethanechol stimulated gastric acid secretion in conscious dogs with gastric fistula. Gastric acid secretion was found to be subject to a dose related inhibition by isoprenaline. The dose of isoprenaline producing approximately 50% inhibition was higher in the bethanechol--than the pentagastrin experiments (0.10 vs. 0.03 micrograms/kg/min.) and slightly lower after parietal cell vagotomy. The antisecretory effect was mediated via the beta 1-receptors alone. The inhibitory effect of isoprenaline on pentagastrin stimulated acid secretion showed the characteristics of competitive type and on bethanechol stimulated acid secretion of non competitive type. An increasing and dose-dependent stimulation of bethanechol stimulated gastric acid secretion was found for dopamine 1, 5 and 10 micrograms/kg/min. Dopamine (40 micrograms/kg/min.) exerted an inhibitory effect on pentagastrin and bethanechol stimulated gastric acid secretion mediated, via the beta 1-receptors. The stimulatory effect of low doses of dopamine during bethanechol stimulation could not be defined as an effect via beta-receptors. This dual response, the weak inhibitory effects and the potent decreasing effect on antral gastric motility indicate that dopamine has no physiologic relevant effect on gastric acid secretion. One may conclude that beta 1- and beta 2-receptors may exert an influence on gastric acid secretion in dogs. The main effect of dopamine seems to be on gastric motility, while the effect on gastric acid secretion is of minor importance.

Adrenergic beta-Agonists↗
PubMed1984

Adrenergic influence on gastric mucosal blood flow in gastric fistula dogs.

The aim of this study was to examine the influence of alpha-, beta- and dopaminergic receptors on gastric mucosal blood flow during "high", "normal", and "low" vagal conditions obtained by stimulation with bethanechol and pentagastrin and by parietal cell vagotomy respectively. During pentagastrin and bethanechol stimulation, a linear relationship between gastric acid secretion and mucosal blood flow was observed. During pentagastrin stimulation, dopamine (40 micrograms/kg/min) did not change the blood flow values while a decrease in acid secretion was found. During bethanechol stimulation dopamine (10 micrograms/kg/min) induced an increase in mucosal blood flow and a similar increase in acid secretion. If the dopamine infusion was preceded by alpha-receptor blockade, a pronounced increase in mucosal blood flow was observed without a similar increase in acid secretion. beta-adrenergic stimulation (isoprenaline) reduced the pentagastrin and bethanechol stimulated gastric acid secretion without a similar decrease in mucosal blood flow. beta-blockade (propranolol) increased the pentagastrin stimulated gastric acid secretion in parietal cell vagotomized dogs. This increase in acid output was preceded by an initial increase in mucosal blood flow and in the last two periods a decrease in blood flow. alpha-Blockade (phentolamine) reduced the pentagastrin stimulated gastric acid secretion and gastric mucosal blood flow but the ratio between blood flow and acid secretion was increased, indicating a relatively increasing effect on mucosal blood flow. One may conclude that blood flow and acid secretion are not unconditionally linked and that at least two different mechanisms are involved in blood flow changes in the stomach.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Dopaminergic and beta-adrenergic effects on gastric antral motility.

Stimulation of splanchnic nerves and application of adrenergic drugs have been shown to give variable effects on gastric motor activity depending especially on the background activity. beta-adrenoceptors and dopaminergic receptors mediate inhibitory effect on proximal gastric motor activity. The purpose of the present study was to evaluate the effects of isoprenaline, a beta 1- and beta 2-agonist, and dopamine on gastric antral motility in gastric fistula dogs. Dopamine was used alone and in conjunction with selective blockade of adrenergic and dopaminergic receptors during infusion of bethanechol or pentagastrin inducing motor activity patterns as in the phase III of the MMC and the digestive state respectively. The stimulated antral motility was dose-dependently inhibited by dopamine. The effect was significantly blocked by specifically acting dopaminergic blockers, while alpha- and beta-adrenergic blockers were without any significant effects. Dose-response experiments with bethanechol and dopamine showed inhibition of a non-competitive type. Isoprenaline was used alone and in conjunction with selective blockade of beta 1- and beta 2-receptors during infusion of bethanechol which induces a pattern similar to phase III in the migrating myoelectric complex. The stimulated antral motility was dose-dependently inhibited by isoprenaline. The effect could be significantly blocked by propranolol (beta 1 + beta 2-adrenoceptor blocker) and by using in conjunction the beta 1-adrenoceptor blocker practolol and the beta 2-adrenoceptor blocker H 35/25. The dose-response experiments showed inhibition of a non-competitive type. These studies indicate that gastric antral motility is inhibited by isoprenaline through both beta 1- and beta 2-receptors and by dopamine through specific dopaminergic receptors.

Adrenergic beta-Agonists↗
PubMed1984

Effect of somatostatin on pentagastrin-stimulated gastric acid secretion and gastric antral motility in dogs with gastric fistula.

The purpose of the present study was to evaluate the effect of somatostatin on gastric acid secretion and gastric antral motility in conscious dogs with gastric fistula. Infusion of pentagastrin induced motility with a digestive pattern. Somatostatin inhibited dose-dependently the stimulated acid secretion, whereas the effect on antral motility was more complex, acting especially on the amplitude of the contractions. The effects of somatostatin were not altered by using alpha- and beta-adrenergic, dopaminergic, and serotonergic blocking drugs. The dose-response kinetics with seven doses of pentagastrin with and without somatostatin showed inhibition of a competitive type for gastric acid secretion and of a non-competitive type for antral motility with regard to amplitude.

Adrenergic alpha-Antagonists↗
PubMed1984

Adrenergic receptors and gastric acid secretion in dogs. The influence of beta 2-receptors.

The action of adrenergic subtypes of receptors in gastric acid secretion is still uncertain. The purpose of this study was to establish the influence of beta 2-adrenoceptors in the regulation of gastric secretion in conscious gastric fistula dogs. A dose-related inhibitory effect of beta 2-adrenergic stimulation on gastric acid secretion was found. The rank order of this inhibition was: Pentagastrin greater than bethanechol greater than histamine stimulated acid output. The strong beta 2-adrenergic induced inhibition found for pentagastrin and bethanechol stimulated acid output followed the characteristics of a non-competitive mechanism, while the weaker inhibition of histamine induced acid output seemed to follow a competitive mechanism. The inhibitory effect was not mediated through a decreased gastrin release. Dopamine receptor blockade was found to be without any influence on the inhibitory effect of beta 2-adrenoceptors. It is concluded that beta 2-adrenoceptors inhibit gastric acid secretion through an effect on gastric mucosa. A working hypothesis involving an endogenous inhibitory substance is proposed.

Animals↗
PubMed1983

The prognostic value of parallel measurements of thyrotropin binding inhibiting immunoglobulins (TBII) and thyroid adenylate cyclase stimulating antibodies (TSAb) in Graves' disease after longterm antithyroid treatment.

Thyroid stimulating immunoglobulins were measured in 43 patients with Graves' disease both before and at the end of longterm antithyroid treatment. Parallel determinations were performed of thyrotropin binding inhibiting immunoglobulins (TBII) and thyroid adenylate cyclase stimulating antibodies (TSAb). Before treatment 33 patients were TBII positive and 32 TSAb positive, and at the end of treatment 19 remained TBII positive and 14 TSAb positive. The frequency of relapse was about 70% in the positive patients and about 40% in the patients, who became negative in either test for thyroid stimulating immunoglobulins. By combination of the two assays 23 patients were positive in both before treatment. In these patients 5 relapsed of the 6 who remained positive for both, while none relapsed of the 5 patients, who became negative during treatment. In the remaining 12 patients either TBII or TSAb became negative during treatment and 7 of these relapsed. It is concluded, that the combined measurement of TBII and TSAb in this study seemed superior to the separate determinations of either activity in predicting relapse after medical treatment of Graves' disease, though this evaluation was only possible in part of the patients.

Adenylyl Cyclases↗
PubMed1983

Discrepancy between haemagglutination and radioimmunological techniques for measurement of serum thyroglobulin autoantibodies.

Recently, it has been suggested that in some patients with autoimmune thyroid diseases the tanned red cell (TRC) method for detection of thyroglobulin autoantibodies (TgAb) is negative where TgAb measured by radioimmunoassay (RIA) show positive values. To investigate this further, patients with thyroid diseases, pernicious anaemia and a control group were studied for serum concentrations of TgAb by TRC and by quantitative RIA, calibrated against MRC Standard A65/93. Antibodies for microsomes (MAb) were measured immunofluoretically. There was in all patient groups (Hashimoto's thyroiditis (n = 41), Graves' disease (n = 50), idiopathic myxoedema (n = 12), euthyroid Graves' disease (n = 7), pernicious anaemia (n = 81) a discrepancy between TgAb measured by TRC and RIA, respectively, whereas there was a reasonable correlation between the presence of TgAb by RIA and the presence of MAb. A possible interference from antinuclear antibodies and rheumatoid factors was ruled out. There was no increased frequency of TgAb measured by RIA in the control group. Fractionation of TRC negative sera revealed macromolecular TRC-activity, whereas TgAb positive sera by both methods had almost exclusively RIA and TRC activity corresponding to IgG. Based on these results and others it seems that the TRC method for measurement of serum TgAb is of limited diagnostic value. Furthermore, the TRC method is in many cases not sensitive enough for screening for TgAb prior to measurement of serum Tg, which is of importance as this method shows false values in the presence of TgAb due to methodological interference.

Autoantibodies↗
PubMed1983

Circulating immune complexes in Hashimoto's thyroiditis. Correlation to HLA and autoantibodies.

Circulating immune complexes (IC) were determined in sera from 41 patients with Hashimoto's thyroiditis by a polyclonal rheumatoid factor (pRF) assay based on the inhibition of the agglutination of IgG-coated latex particles. Elevated levels of IC were found in 63% (26/41) of the sera. There was a significant correlation (Rho = 0.91, P less than 0.001) between results obtained before and after treatment of sera with dithiothreitol (DTT). By precipitation with 2.5% polyethylene glycol (PEG) before pRF inhibition assay, the activity of IC was found in only 7% (3/41) of the sera. Size chromatography studies of the sera showed the inhibitory activity predominantly in the intermediary region. When found in the IgM-region the activity was not reduced by DTT. By use of a polyethylene glycol complement consumption test (PEG-CC) the occurrence of IC was 10% (4/41). It was not possible to find any correlation between the detectable IC and the presence of microsomal, thyroglobulin, or thyroid-stimulating antibodies. Based on our studies the sizes of IC seemed to be heterogeneously distributed and the majority were not precipitated by PEG (2.5%), final concentration). The antibodies involved in the formation of complexes seemed to be of IgG or IgA classes. HLA-D typing of the patients showed a non-significant association between HLA-Dw5 and low levels of IC while the presence of HLA-Dw4 was significantly associated with a high level of IC (P less than 0.05).

Antigen-Antibody Complex↗
PubMed1983

Autoantibodies, immune complexes and HLA-D in thyrogastric autoimmunity.

Forty-one patients with Hashimoto's thyroiditis (HT) and 82 with Pernicious anaemia (PA) were investigated. All 123 patients were HLA-D typed and results correlated to thyroglobulin antibodies (TgAB), microsomal antibodies (MAb), parietal cell antibodies (PCA), circulating immune complexes (IC), and intrinsic factor antibodies (IFA). In PA, TgAb was found less frequently in Dw2 positive patients than in Dw2 negative patients. IFA was rarely found in Dw5 positive PA patients. In HT, patients positive for Dw5 had lower levels of TgAb. IC were present in 67% of patients with HT, but only in 2.5% of patients with PA (p less than 0.01). Dw5 was associated with low levels of IC in HT. In conclusion, HT and PA seem to be related by their association with HLA-D types, but a heterogeneity in the pattern of antibodies and IC could be seen. The organ specific antibodies characteristic for each disease were present in lower levels in patients with Dw5.

Adult↗
PubMed1983

Influence of beta blockade on gastric acid secretion and changes in gastric mucosal blood flow before and after parietal cell vagotomy in dogs and man.

The aim of the present study was, in paired experiments in dogs, to examine the effect of beta-receptor blockade on gastric acid secretion and mucosal blood flow before and after parietal cell vagotomy (PCV). The secretory response to pentagastrin was reduced after vagotomy. beta-Adrenergic blockade had no effect on pentagastrin-stimulated gastric acid secretion before PCV, but after PCV beta blockade caused a modest increase in acid secretion, mediated mainly by the beta 2 receptors. A similar trend was seen in man. A marked increase in mucosal blood flow occurred 30 min after propranolol and was followed by a late decrease. One may conclude that a modest beta-adrenergic tone, which reduces secretion, becomes manifest after vagal denervation and that an increase in the ratio between mucosal blood flow and acid secretion was induced by the PCV. This increase cannot be explained as a beta-receptor-mediated effect.

Adrenergic beta-Antagonists↗
PubMed1982

Thyroid stimulating antibodies, thyroglobulin antibodies and serum proteins during treatment of Graves' disease with radioiodine or propylthiouracil.

The relation between serum concentrations of thyroglobulin antibodies (TgAb), thyroid-stimulating antibodies (TSAb) and serum immunoglobulins during treatment of Graves' disease was studied in 36 consecutive patients treated randomly with 131-iodine (n = 16) or propylthiouracil (n = 20). The patients were investigated before treatment was started and on seven occasions within the following year. In the entire patient group 78% were positive for TSAb and 47% for TgAb. There was a significant correlation between TSAb and TgAb in 15 patients concomitantly positive. There were no significant changes in serum immunoglobulins during treatment in either group of patients. In the radioiodine-treated group of patients TgAb was reduced after 1 week, whereas TSAb showed insignificant variations. After 5-10 weeks both antibodies increased, for TgAb with a median peak level 3 time above the initial concentration. Of 16 patients treated with radioiodine five developed myxoedema and four of these were positive for TgAb. There was a relation between the development of myxoedema and the ratio between increases of TSAb and TgAb. Increase in TSAb was not related to serum thyroglobulin (Tg) measured in TgAb-negative patients. Propylthiouracil showed minor effects on the studied variables, but with lower mean values of Tg, TgAb and TSAb at the end of the observation period. The results indicate an immunological relation between TSAb and TgAb, although differences between their course exist in some situations.

Adult↗
PubMed1982

Thyroid-stimulating immunoglobulins in Hashimoto's thyroiditis measured by radioreceptor assay and adenylate cyclase stimulation and their relationship to HLA-D alleles.

The relationship between thyroid-stimulating immunoglobulins, measured by both radioreceptor assay and adenylate cyclase stimulation, and the HLA alleles was studied in 41 patients with Hashimoto's thyroiditis. TSH binding-inhibiting immunoglobulins (TBII) were detected in 9 (22%) patients, and human thyroid adenylate cyclase-stimulating immunoglobulins (HTACS) were found in 21 (51%) patients. Only 2 patients were positive in both assays, and an inverse relationship was observed between TBII and HTACS. In the 21 HTACS-positive patients, HLA-Dw5 was only found in 1 subject, compared to 8 of the 20 HTACs-negative patients (P less than 0.01), while 4 of the 9 TBII-positive patients had HLA-Dw5 compared to 5 of the 32 TBII-negative subjects (P = -0.09). No significant relations were observed between the presence of HTACS or TBII and HLA-Dw3 or HLA-B8. It is concluded, that TBII and HTACS are produced independently in Hashimoto's thyroiditis, and that the production of these autoantibodies seems to be related to the HLA-D region in this disease.

Adenylyl Cyclases↗
PubMed1982

A prospective study of the differential changes in serum thyroglobulin and its autoantibodies during propylthiouracil or radioiodine therapy of patients with Graves' disease.

Measurement of serum thyroglobulin (Tg) and its autoantibody (TgAb) by radioimmunological methods was performed in 48 patients with Graves' disease during treatment with radioiodine (n = 16) or propylthiouracil (PTU) (n = 32). Twenty-five of the 48 patients were TgAb positive, their sera being inaccessible to measurement of serum Tg. TgAb showed only minor changes during PTU treatment, whereas TgAb fell rapidly after radioiodine, in 5 of 16 patients to unmeasurable levels, followed by a secondary rise to 4.5 times pre-treatment level after 20 weeks. Serum Tg showed a steady increase during the first weeks after radioiodine treatment, but fell to lower levels after one year. PTU caused only minor changes in the serum Tg concentration. There was no shift in molecular sizes of either Tg or TgAb during the course of the treatments. Five of 16 131I-treated patients developed myxoedema, 4 of whom were TgAb positive. Another 3 patients had high increases in TgAb without myxoedema. Six of 18 patients had relapse of thyrotoxicosis after withdrawal of PTU-treatment. There was no significant difference in serum concentrations of TgAb or Tg between those developing relapse and those remaining in remission, and it is concluded that serum Tg is a poor predictor of relapse in medically treated thyrotoxicosis.

Adult↗