Search PubMed⌕ Search

Biomedical subjects

G Nilsson

Publications and source records attributed to G Nilsson.

At least 181 records · Page 10Linked to original sources
PubMed1989

Deduction of biphasic phase response curves from ventricular parasystole.

The mechanisms behind ventricular premature beats may be divided into two main categories, reentry and modulated parasystole. Although it is relatively easy to distinguish among arrhythmia generating mechanisms on the cellular level, it is far more difficult in the clinic. Modulation of ventricular parasystole by sinus beats has been shown to result in a biphasic phase response curve. Two cases are reported where the deduction of such phase response curves from long-term ECG recordings is discussed and described as a stepwise procedure.

Aged↗
PubMed1989

Deduction of triphasic phase response curves from ventricular parasystole.

Modulation of ventricular parasystole by sinus beats has been shown to result in a biphasic phase response curve. Some reports also indicate that the modulation effect could be described by a triphasic response with an early phase of acceleration, which would correspond to the supernormal phase of excitability. Two cases of such triphasic phase response curves are reported. The coexistence of ventricular couplets and parasystole is also discussed. The second beat of the couplet has often been explained by reentry or reflection, but could also be interpreted as due to supernormal modulation, resulting in an accelerated second ectopic response.

Aged↗
PubMed1989

Inhibition of acid formation and stimulation of somatostatin release by cholecystokinin-related peptides in rabbit gastric glands.

1. The purpose of the present study was to investigate the role of somatostatin in the inhibition of acid production induced by caerulein and cholecystokinin (CCK) in isolated rabbit gastric glands. Acid production was estimated by the aminopyrine technique. 2. Exogenous somatostatin 14 and somatostatin 28 (10(-7) M) reduced to a similar extent the aminopyrine uptake produced by 5 x 10(-5) M-histamine during the course of 40 min incubation. 3. Significant inhibition of histamine-stimulated aminopyrine accumulation occurred at a somatostatin 14 concentration of 10(-9) M. 4. Caerulein and CCK octapeptide (10(-13)-10(-7) M) were found to release somatostatin from isolated gastric glands in a dose-dependent manner. The dose-response relationships for somatostatin release and inhibition of aminopyrine uptake were similar. Thus, the half-maximal dose approximations for somatostatin release and inhibition of aminopyrine uptake were 0.5 and 1.4 x 10(-9) M respectively for CCK octapeptide and 0.9 and 2.5 x 10(-11) M for caerulein. Heptadecapeptide gastrin proved to be a very poor releaser of somatostatin in the system used. The CCK octapeptide-induced somatostatin release was time dependent and the concentrations of somatostatin that accumulated in the incubation medium were similar to those of exogenous somatostatin that were needed to evoke inhibition. 5. The present results support the concept that cholecystokinin inhibits gastric acid secretion by releasing somatostatin from endocrine-like cells in the gastric mucosa. It is suggested that cholecystokinin-related peptides may play a physiological role in inhibiting gastric acid secretion. A similar role for gastrin is not supported by the present study.

Animals↗
PubMed1989

Isotype-specific suppression of IgE synthesis in a human myeloma cell line (U-266) by an IgE-binding protein derived from normal human peripheral blood cells.

Human peripheral blood cells produce immunoglobulin-binding factors upon stimulation with purified protein derivative. The binding factors from 2 healthy individuals were purified by IgE affinity chromatography. IgE-suppressive activity was demonstrable using the IgE-producing human myeloma cell line U-266 as an assay system. The effect of the suppressive factor seems to be reversible, isotype specific, as the immunoglobulin synthesis in the IgGk-producing U-1958 myeloma line was not affected, and selective for the epsilon heavy chain. The results also suggest that this suppression is not the result of a decrease in DNA synthesis or suppression of protein synthesis in general.

Humans↗
PubMed1989

Effect of neonatal or later capsaicin treatment on bronchial reactivity in sensitized rats. Relation to humoral changes.

Treatment of ovalbumin-sensitized rats with capsaicin resulted in altered bronchial reactivity to both ovalbumin and serotonin. The increase in bronchial reactivity to ovalbumin in neonatally capsaicin-treated rats compared to animals only sensitized may be influenced by the changed ratios of IgA, IgE, and IgG antibodies, together with the inflammation in the lung. Thus, capsaicin given neonatally inhibited the formation of antibodies, both specific titers and total levels, in bronchial lavage.

Age Factors↗
PubMed1989

Increased delayed-type hypersensitivity reaction in rats neuromanipulated with capsaicin.

We studied the neuroimmunomodulatory effect of capsaicin on the development of delayed-type hypersensitivity (DTH) reaction and antibody formation after reduction of neuropeptides in the peripheral sensoric nervous system. Rats were sensitized with picryl chloride on their shaved abdomen or by subcutaneous injections with picrylsulfonic acid (PSA). Manipulation of the content of neuropeptides in the sensory nerve system with capsaicin was performed 1 week before or after sensitization. An increase of the DTH reaction assessed as increased ear thickness after challenge was seen especially when the rats were given capsaicin after sensitization. The formation of specific antibodies was not affected, although the level of total IgG was decreased in PSA-sensitized rats treated with capsaicin after sensitization. The results demonstrated that the DTH reaction in rat was slightly but significantly affected by the abolishment of neuropeptides in sensoric nerve endings with capsaicin. Even if the direct effect of capsaicin on the immune system still has to be elucidated, these results indicate that neuropeptides in sensory nerves are involved in the pathogenesis of DTH.

Animals↗
PubMed1989

Cholecystokinin and gastrin inhibit histamine stimulated aminopyrine uptake in isolated rabbit gastric glands.

In the present study we have analyzed if cholecystokinin (CCK) or gastrin (G) can inhibit acid production in isolated rabbit gastric glands as revealed by the aminopyrine technique. The results show that G 17 I, CCK 8 NS, CCK 8 S, ceruletide and CCK 39 significantly inhibit histamine induced aminopyrine accumulation. No significant inhibition was noted for G 4, G 34 and NT G 1-13. As a group the CCK peptides were more effective than the gastrin peptides in inhibiting the aminopyrine uptake. CCK 8 S and ceruletide, the most potent inhibitors, reduced histamine induced aminopyrine accumulation with an ED50 of 10(-9) and 10(-10) M respectively. These potencies are similar to those by which CCK peptides stimulate isolated pancreatic acini to secrete amylase. Inhibition evoked by CCK 8 S was most effective following 20-40 min of incubation time, possibly indicating that the effect is mediated by the release of an intermediate substance. The results may therefore indicate a role for cholecystokinin as a physiological inhibitor of acid secretion in the rabbit. The results may also contribute to explain why the potent gastric secretagogue gastrin per se fails to stimulate acid formation in gastric glands isolated from the rabbit.

Aminopyrine↗
PubMed1988

The differential stability of the Escherichia coli ompA and bla mRNA at various growth rates is not correlated to the efficiency of translation.

Using two monocistronic gene transcripts, bla and ompA, we have studied the relationship between mRNA stability and translational efficiency. It was found that changes in the ompA mRNA stability are not correlated with an alteration in translational efficiency. In addition, at slow bacterial growth rates, the ompA transcript is translated ten times more efficiently than the bla messenger although the stability of the two transcripts is about equal. At rapid bacterial growth rate, chloramphenicol slightly stabilises both the bla and ompA transcripts without affecting their characteristic difference in half-life. Thus, control of mRNA stability seems not necessarily to be mediated either by the efficiency of loading ribosomes on a transcript, or by the arrest or slowing down of translating ribosomes.

Bacterial Outer Membrane Proteins↗
PubMed1988

Low-molecular-mass surfactant protein type 1. The primary structure of a hydrophobic 8-kDa polypeptide with eight half-cystine residues.

The low-molecular-mass surfactant protein fraction, soluble in chloroform/methanol, contains at least two separate polypeptide chains. The 8-kDa form (type I) was isolated, [14C]carboxymethylated after reduction, and submitted to structural analysis. Its highly hydrophobic nature complicated purification, proteolytic cleavages, and sequence analysis. Acid hydrolysis in 6 M HCl for 7 days was necessary for release of branched-chain residues in full yield. Pepsin was the only enzyme found to cleave the surfactant protein and was used to complement peptide generation by chemical cleavage with CNBr. The primary structure deduced consists of 79 residues with 8 half-cystine residues, and a total of 39% branched-chain hydrophobic residues. However, 11 residues are charged at physiological pH, and all properties of the primary structure are not entirely outstanding in relation to those of other proteins. Hydrophobic segments, coupled with a presumably tight folding from the presence of disulfide bridges, probably explain the unusual properties and the solubility in organic solvents.

Amino Acid Sequence↗
PubMed1988

In vivo and in vitro identity of site specific cleavages in the 5' non-coding region of ompA and bla mRNA in Escherichia coli.

The bla and ompA gene transcripts were used as substrates to probe Escherichia coli extracts for ribonucleolytic activities. A site specific endoribonucleolytic activity was identified that cleaves ompA and bla mRNA. The cleavages occur in vitro and in vivo. For both the bla and ompA mRNA most of the cleavage sites which were identified map in the 5' non-coding region. The cleavages of the ompA transcript have been previously suggested to regulate the growth rate dependent stability of this mRNA. Thus we propose that the identified endoribonucleolytic activity may be involved in the degradation of mRNA. Analysis of mutants revealed that the cleavages are mediated by endonucleases which do not seem to be identical to RNase III, RNase E or RNase P.

Bacterial Outer Membrane Proteins↗
PubMed1988

Altered lymphocyte proliferation of immunized rats after neurological manipulation with capsaicin.

The neurotoxic agent capsaicin was used for depletion of the content of neuropeptides in c-fibers of the sensory nerve system in rats. The effect of the capsaicin treatment on the immune response was assessed as lymphocyte proliferation of spleen cells, stimulated with Con A. Treatment of 2 day old rat pups and adult rats did not alter the lymphocyte proliferative response to Con A in nonimmunized rats. Spleen cells from capsaicin-treated and subcutaneously immunized rats showed a decreased proliferation response to Con A. Capsaicin treatment of aerosol immunized rats did not affect the proliferation level of the spleen cells to the same extent. The results indicate that abolishment of the content of neuropeptides in the c-fibers of sensory nerves with capsaicin, affects the immune response.

Animals↗
PubMed1988

Time-course of development and reversal of gastric endocrine cell hyperplasia after inhibition of acid secretion. Studies with omeprazole and ranitidine in intact and antrectomized rats.

In intact rats plasma gastrin levels were increased during a 20-wk treatment course with either omeprazole or ranitidine. Although plasma gastrin levels were the same during treatment, the enterochromaffinlike (ECL) cell density increased approximately linearly with time at a rate correlated to the plasma gastrin level. Antrectomy prevented the ECL cell hyperplasia seen in omeprazole-treated rats, suggesting that it was not caused by omeprazole per se. Changes in ECL cell density roughly paralleled changes in oxyntic mucosal histidine carboxylase activity and histamine concentration. Treatment with omeprazole also raised stomach weight and antral gastrin and gastrin cell density, reduced antral somatostatin cell density, but did not affect enterochromaffin cell density. Within 19 days of cessation of a 10-wk treatment course, plasma gastrin levels, oxyntic mucosal histidine decarboxylase activity, and antral gastrin and somatostatin cell densities had returned to control levels. The stomach weight was normal within 5-10 wk, antral gastrin concentration within 10 wk, and oxyntic mucosal ECL cell density and histamine concentration within 20 wk. After renewed treatment with omeprazole for 10 wk starting 10 wk after completion of the first omeprazole treatment period, changes in all parameters were of similar magnitude in animals previously treated with omeprazole and those previously treated with vehicle. The results suggest that the effects described are reversible and that gastrin cells turn over more rapidly than ECL cells.

Animals↗
PubMed1988

Propafenone versus disopyramide for treatment of chronic symptomatic ventricular arrhythmias. A multicenter study.

The efficacy and safety of propafenone, 150 mg four times daily, were compared with those of disopyramide, 100 mg four times daily, in a randomized single-blind, cross-over study in 38 patients with symptomatic premature ventricular complexes (PVCs). The 24-hour ambulatory ECG, employed for assessing antiarrhythmic efficacy, was analyzed blindly. The median reduction in the number of PVCs was higher with propafenone than with disopyramide (91.4% vs. 63.5%, respectively, p less than 0.01). A reduction of at least 80% was achieved by propafenone in 22 (59%) and by disopyramide in 16 patients (43%) (NS). Ventricular tachycardias (VTs) were abolished by propafenone in eight out of 11, and by disopyramide in five out of nine patients with VTs (NS) a possible proarrhythmic effect was seen in three patients during disopyramide and in one patient during propafenone treatment. Micturition disturbances (p less than 0.001) and a dry mouth (p less than 0.01) were more commonly associated with disopyramide than with propafenone. In conclusion, in the given dosages, propafenone was superior to disopyramide in suppressing PVCs and had fewer side-effects.

Adult↗
PubMed1988

Glucagon and glucagon-like immunoreactive cells in mid- and hindgut carcinoids.

The occurrence of glucagon/glucagon-like immunoreactivity in 31 small intestinal, 34 rectal and 18 appendiceal carcinoids were investigated immunocytochemically using, sequence specific antisera. Glucagon/GLI immunoreactive cells were found in five small-intestinal and five rectal carcinoids, but none were observed in any of the appendiceal carcinoids examined. Glucagon/GLI immunoreactive cells constituted a minor cell population, except in one rectal carcinoid, where most of the tumour cells were of this type. Glucagon/GLI immunoreactive cells were detected with only some sequence-specific antisera, and not with antisera directed against the rest of the glucagon/glicentin molecule. This might indicate that these cells contain a molecule which shares some antigenic binding sites with glucagon/glicentin rather than genuine glucagon/glicentin. It is concluded that this finding contributes to explain why hindgut carcinoids rarely give rise to symptoms related to neuro-endocrine product(s).

Appendiceal Neoplasms↗
PubMed1987

Distribution patterns of ventricular premature complexes at different heart rates.

The relation between distribution patterns of ventricular premature complexes (VPCs) and heart rate in Holter recordings abundant in VPCs was analyzed using computer-assisted determination of the number of interectopic sinus beats at different heart rates. Within the complete 24-hour heart rate spectrum, zones were demonstrated that were characterized by manifest or concealed bigeminy or manifest or concealed trigeminy. Bigeminy zones were found in 26 and trigeminy zones in 21 of 42 patients. Bigeminy zones were found at a significantly lower heart rate, on the average, then trigeminy zones. In 10 patients both bigeminy and trigeminy zones were observed. Bigeminy and trigeminy zones probably correspond to the distribution patterns of VPCs predicted from modulation of a pacemaker and reflected reentry, both of which can be induced by electrotonically mediated impulses across a zone of impaired conduction in isolated bundles of Purkinje fibers. The bigeminy and trigeminy zones will correspond at least partly to the entrainment zones found during electrotonic modulation of parasystolic foci. The bigeminy zones will correspond to 2:1 entrainment and the trigeminy zones mainly to 3:1 entrainment.

Adult↗