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Biomedical subjects

U Karbach

Publications and source records attributed to U Karbach.

At least 55 records · Page 3Linked to original sources
PubMed1988

Influence of rhein on rat colonic Na+,K+-ATPase and permeability in vitro.

Rhein, an aglucone of a laxative-acting anthraquinone, which induces net secretion in the human jejunum and colon, does not induce net secretion under open circuit current in in vitro conditions but reduces net absorption of electrolytes and water. In the stripped rat descending colon at a concentration of 2.10(-4) mol/l, the Na+, K+-ATPase is almost completely inhibited resulting in a decreased net absorption of electrolytes and water. There are no changes of the diffusional resistance of the paracellular pathway. Results point to a cellular mechanism of rhein by which absorption is inhibited so that physiological cellular secretion dominates. This does not rule out an additional activation of cellular secretion but net secretion can be explained solely by inhibition of absorption without the assumption of any additional secretory mechanism.

Animals↗
PubMed1988

Simplified determination of intestinal protein excretion based on alpha 1-antitrypsin clearance.

Intestinal alpha 1-antitrypsin clearance in 6 healthy controls and 21 patients with Crohn's disease was measured simultaneously by two different methods. Faecal alpha 1-antitrypsin loss, determined conventionally by weight and alpha 1-antitrypsin concentration of the homogenized three day stool was compared with the faecal alpha 1-antitrypsin loss, which was calculated from weight of the three day stool sample and the mean alpha 1-antitrypsin concentration determined in three 1 g aliquots of the morning stool obtained at the three consecutive days during the collecting period. There was a significant correlation when comparing faecal alpha 1-antitrypsin loss (y = 0.96x + 10; r = 0.952) and intestinal alpha 1-antitrypsin clearance (y = 1.05x - 6.5; r = 0.974) measured by the different methods. Filling the aliquots by a standardized spoon into a vial prepared with a defined volume of solvent makes it possible to take a diluted, homogenized, and centrifuged stool sample out of the vial by the laboratory staff avoiding open faecal work up. The simplified method of measuring intestinal alpha 1-antitrypsin clearance permits to integrate the determination of enteric protein loss into routine diagnostics comparable to the faecal occult blood method.

Adolescent↗
PubMed1987

Strontium transport in the rat colon.

Concentration dependence of strontium (Sr) fluxes across the colon ascendens and descendens of the rat were measured in a modified Ussing-chamber. Mucosa (m) to serosa (s) and s to m Sr fluxes across both colonic segments were linearly related to the Sr concentration from 0.125 mmol/l to 10 mmol/l. In the colon ascendens m to s Sr fluxes were slightly higher than the fluxes in the opposite direction, resulting in net Sr absorption. In the colon descendens s to m fluxes were higher than the ms fluxes, resulting in net Sr secretion. Neither Sr nor calcium (Ca) showed a concentration dependent interaction with respect to their unidirectional fluxes in both parts of the colon. Only in the colon ascendens Sr at the highest concentration (10 mmol/l) inhibited m to s calcium transport. Experiments, in which the voltage dependence of the unidirectional Sr fluxes was measured confirmed the results obtained from the concentration dependence: The unidirectional fluxes of Sr across the colon ascendens and descendens were totally voltage dependent, i.e. diffusive. In the colon descendens the voltage dependence of the s to m flux was steeper than the flux from m to s. It is hypothesized that this prevalence is caused by an anomalous solvent drag effect. 1.25-Dihydroxyvitamin D3 [1.25 (OH)2D3] stimulated m to s calcium flux in the colon descendens but had no effect on Sr flux. The results demonstrate that Sr and Ca in the rat colon are transported by different mechanisms. In contrast to the Ca transport the Sr flux is only diffusive and insensitive to 1.25 (OH)2D3.

Action Potentials↗
PubMed1987

Cellular and paracellular calcium transport in the rat ileum and the influence of 1 alpha, 25-dihydroxyvitamin D3 and dexamethasone.

Concentration dependence of unidirectional calcium fluxes across the rat ileum freed from the serosa and the muscularis externa were measured in a modified Ussing-chamber. Mucosa (m) to serosa (s) calcium flux showed a saturable component, whereas s to m calcium flux was linearly related to the calcium concentration between 0.125 mmol/l and 5 mmol/l. At all calcium concentrations used net secretion of calcium was observed. The s to m flux of the simultaneously measured paracellular marker mannitol at all calcium concentrations was remarkably higher than the m to s flux, resulting in net mannitol secretion. The results obtained from the calcium fluxes when clamping the transepithelial electrical potential agree well with those of the concentration dependence of the calcium fluxes: 1. Only m to s flux has a voltage independent, transcellular component. 2. Calcium s to m flux is totally voltage dependent, i.e. diffusive. 3. Diffusional s to m calcium flux is about 80% greater than the diffusional fraction of the m to s flux. Omitting glucose from the bathing solution effected a decrease of the transepithelial electrical potential and of the short circuit by 91% and 85% respectively; net calcium secretion was almost abolished and net mannitol secretion remarkably reduced. Addition of glucose, which stimulates water absorption in the ileum as a metabolic substrate, activated m to s but significantly more pronounced s to m calcium flux parallel to that of mannitol.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Calcium transport across the colon ascendens and the influence of 1,25-dihydroxyvitamin D3 and dexamethasone.

Concentration dependence of unidirectional calcium fluxes across the rat colon ascendens were measured in a modified Ussing chamber. Both the mucosa (m) to serosa (s) and the s to m calcium flux exhibited saturation kinetics. The maximum transport rates and the affinity to the transporter of calcium was higher in the m to s direction than that from s to m, resulting in a remarkable net calcium absorption. The results obtained from measurements of unidirectional calcium fluxes in dependence on clamped transepithelial potentials showed that: (i) calcium transport in both direction had a voltage-independent component; (ii) the voltage-independent, i.e. non diffusive fraction of the m to s calcium flux was 3.2 times greater than that in the opposite direction; (iii) the voltage dependent, i.e. diffusional fraction of the m to s calcium flux, was about two times greater than the voltage-dependent fraction of the calcium flux in the s to m direction; and (iv) in the m to s direction 62%, and the s to m direction 73%, of the total unidirectional flux was voltage-dependent. Dexamethasone, known to enhance sodium and water absorption in the colon, had no significant influence on net calcium absorption but increased the unidirectional calcium fluxes in both directions. The increase in unidirectional calcium fluxes parallel to that of the extracellular marker mannitol suggests that dexamethasone has no influence on the transcellular calcium transport but increases the calcium flux along the paracellular way. Amiloride had no influence on the dexamethasone-induced changes of the epithelial electrical parameters as distinguished from the colon descendens.(ABSTRACT TRUNCATED AT 250 WORDS)

Amiloride↗
PubMed1987

Calcium and magnesium transport and influence of 1,25-dihydroxyvitamin D3. In vivo perfusion study at the colon of the rat.

Calcium and magnesium transport at different luminal concentrations (1.25, 2.5, 5 and 10 mmol/l) and under the influence of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] were studied in vivo at the perfused colon of the rat. Net absorption of calcium and of magnesium were saturated with increasing concentrations of the perfusate. Net absorption of one ion was not affected by an increasing concentration of the other ion. 1,25(OH)2D3 (100 ng/day given subcutaneously for 4 days) stimulated net absorption of calcium and of magnesium. Presence or absence of calcium or magnesium, respectively, had no effect on the absorption of the other ion under 1,25(OH)2D3 stimulation. The results demonstrate that the colon of the rat is capable of absorbing calcium as well as magnesium. These observations suggest that calcium and magnesium in the rat colon are absorbed by two separate active transport mechanisms, which both are sensitive to 1,25(OH)2D3.

Animals↗
PubMed1986

The role of the paracellular pathway in the net transport of calcium across the colonic mucosa.

Concentration dependent calcium fluxes across the colon descendens of the rat were measured in a modified Ussing chamber. Mucosa (m) to serosa (s) calcium flux showed a saturable component, whereas s to m calcium flux was linearly related to the calcium concentration. At low calcium concentrations net absorption and at concentration above 2.5 mmol/l net secretion of calcium was observed. The results obtained from the unidirectional calcium fluxes when clamping the transepithelial electrical potential agree well with those of the concentration dependence of the calcium fluxes: Only m to s flux has a voltage independent component. Calcium s to m movement is totally voltage dependent. Diffusional s to m calcium flux is greater than the diffusional fraction of the m to s calcium flow. Dexamethasone, known to stimulate water absorption in the colon descendens by an activation of sodium transport, had no effect on the cellular mediated m to s calcium transport but significantly increased paracellular s to m flux parallel to that of the extracellular marker mannitol. This increase in paracellular s to m calcium and mannitol flux was completely abolished by amiloride, which is known to suppress the dexamethasone-induced stimulation in sodium and water absorption. The results demonstrate that the increased paracellular s to m calcium and mannitol flow is oppositely directed to the dexamethasone-induced net fluid movement as it could be expected on the basis of Ussing's "anomalous solvent drag" effect.

Amiloride↗
PubMed1986

Trans- and paracellular calcium transport across the colonic mucosa after short- and long-term treatment with 1,25-dihydroxyvitamin D3.

The electrical parameters and the unidirectional fluxes of 45Ca and 3H-mannitol were measured in preparations of rat colon descendens freed from the muscularis externa and mounted in a modified Ussing-chamber. Two criteria were used to differentiate between changes in the trans- and the paracellular calcium transport after treatment with 1,25(OH)2D3: the fluxes of the simultaneously measured 3H-mannitol as a paracellular marker; the 45Ca fluxes in preparations with clamped potentials. After a short-time (6 h) pretreatment by s.c. administration of 1,25(OH)2D3 (250 ng kg-1) in normal rats the mucosa (m) to serosa (s) 45Ca flux under short circuit conditions increased about 65%, whereas the electrical parameters and the 3H-mannitol fluxes remained unchanged. In clamped epithelia the PD-independent m to s 45Ca flux was increased, whereas the PD-dependent flux remained unchanged. In contrast, after long-time (4 days) induction by 1,25(OH)2D3 the m to s 45Ca flux increased under short circuit conditions by about 100% and the m to s 3H-mannitol flux increased by 50%, PD and Isc decreased by more than 60%, whereas tissue resistance was the same, in clamped epithelia the calculated PD-independent, transcellular m to s 45Ca flux was 2.4 times and the PD-dependent, paracellular 45Ca-flux was 1.9 times higher than in controls, whereas the s to m 45Ca flux remained unchanged. On the basis of the relevant references the following conclusions were drawn: after short-time exposure to 1,25(OH)2D3 only the PD-dependent, transcellular m to s calcium transport is increased; this is probably due to a liponomic effect of 1,25(OH)2D3 at the brush border membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Postprandial cholylglycine serum concentration and extent of ileal inflammation or resection in Crohn's disease.

Postprandial cholylglycine serum concentration was determined in 45 resected and non-resected patients with Crohn's disease of the distal ileum. Cholylglycine serum concentration after meal stimulus in patients with ileal involvement of more than 30 cm was significantly lower than in controls and in patients with minor spread of inflammation. In patients with inflammation area less than 30 cm, there was a somewhat faster and higher increase and delayed decline of postprandial cholylglycine serum concentration. The present study shows that postprandial cholylglycine serum level gives a good estimate of the extent of ileal inflammation or resection.

Crohn Disease↗
PubMed1986

Factitious diarrhoea.

Gastroenterologists often have to deal with patients with chronic diarrhoea. The vast majority will suffer from functional bowel syndrome. A few will present with a clear-cut organic disease. If chronic diarrhoea remains unexplained after extensive testing, if daily stool volume is high (greater than 500 g/24 h) and if the patient is female, factitious diarrhoea should be considered. Melanosis coli on sigmoidoscopy, cathartic colon on barium enema examination, a positive room search and chemical detection of the presence of specific laxatives in urine or stool may lead to the correct diagnosis. Treatment and management of such patients is difficult. Denial is the usual response to confrontation. Counselling and guidance by psychiatrists or psychologists is often not accepted by the patient. In many cases the role of the physician may be limited to preventing further potentially dangerous diagnostic and therapeutic interventions.

Adult↗
PubMed1985

Antiinflammatory treatment and intestinal alpha 1-antitrypsin clearance in active Crohn's disease.

Intestinal alpha 1-antitrypsin clearance was quantified in 17 patients with clinically active Crohn's disease before and after a six-week period of treatment with sulfasalazine and methylprednisolone. Before the study, alpha 1-antitrypsin clearance and, hence, enteric protein loss was elevated as being above control values in 16 patients. After therapy, clearance values decreased in 11 and were normalized in five patients. Serum albumin level was normalized in 11 of 12 patients who had hypoalbuminemia before the study. Clinical condition was improved in all but 1 patient after treatment. There was no close correlation between alpha 1-antitrypsin clearance and disease activity index. These results indicate that antiinflammatory therapy has a beneficial effect on enteric protein loss in Crohn's disease. The measurement of alpha 1-antitrypsin clearance provides a useful adjunctive technique in evaluating intestinal inflammatory activity, and it seems to be of use in following the efficacy of treatment in the course of illness in Crohn's disease.

Adolescent↗
PubMed1984

Influence of serosal hydrostatic pressure on net water and electrolyte transport across the isolated rat colonic mucosa exposed to different secretagogues.

The influence of 2 cm and 7 cm hydrostatic pressure applied upon the serosal side on net water and electrolyte transport and paracellular permeability was investigated in everted sacs of stripped rat colon mucosa exposed to different secretagogues. A 2 cm pressure abolished net fluid absorption in the presence of deoxycholic acid, bisacodyl, ethacrynic acid and rhein and reduced absorption in the tissue pretreated with cholera toxin. The paracellular permeability was increased by deoxycholic acid, bisacodyl and ethacrynic acid and diminished under the influence of rhein and cholera toxin. At a pressure of 7 cm H2O fluid movement was directed toward the mucosal side parallel to the increase of the paracellular permeability. The fluid appearing at the mucosal side was isotonic in the presence of deoxycholic acid, ethacrynic acid and rhein but hypotonic when the tissue was pretreated with cholera toxin. From the pressure-induced net water flow and the composition of the transferred fluid secretagogues acting predominantly on paracellular pathway can be distinguished from secretagogues acting on basis of other mechanisms.

Animals↗
PubMed1984

[Extent of drug compliance in Crohn disease patients--study of a special ambulatory care unit of a university clinic].

Compliance with therapeutic regimes is an important factor in treatment of chronic diseases often overlooked by therapists. In 123 out-patients with Crohn's disease the reliability in taking the prescribed therapy with salazosulfapyridine (SASP) was studied over an one year period in a special out-patient clinic. 81,3% of the patients took SASP regularly. Sex and age of patients, activity of disease and the intake of other drugs had no influence on the compliance. The patients were fully informed regarding the nature of the illness, the effect of the drug prescribed and the side-effects which may occur. We conclude that these factors; the periodical check up in a special ambulance and a close relation between patient and physician may improve compliance to therapy.

Adult↗
PubMed1983

Alpha 1-antitrypsin, a reliable endogenous marker for intestinal protein loss and its application in patients with Crohn's disease.

Intestinal protein loss is generally determined by radio-labelled macromolecules. Alpha 1-antitrypsin has been proposed as an endogenous marker for protein losing enteropathy, but different opinions exist about its reliability. In 25 patients with Crohn's disease faecal protein loss was studied with intestinal alpha 1-antitrypsin (alpha 1AT) clearance. Simultaneously, in 10 patients alpha 1AT clearance was compared with faecal 51Cr clearance after intravenous 51Cr-albumin injection. There was a linear relation (p less than 0.05) between alpha 1AT clearance and 51Cr clearance in these cases. In all patients alpha 1AT clearance was raised above control values. alpha 1AT clearance, however, did not correlate with the activity index of Crohn's disease. This index does not contain direct criteria of intestinal inflammation, does not take into account localisation or extent of inflammation, and includes complications such as extraintestinal manifestations, fistuli, stenoses not necessarily related to actual mucosal involvement. It is concluded that alpha 1AT is a reliable marker for intestinal protein loss and that the intestinal changes of Crohn's disease generally lead to an increased protein exudation into the gut.

Adolescent↗
PubMed1982

[(Quality of semen in patients with Crohn's disease) ].

Some reports point to an inhibitory effect of Salzosulfapyridin (SASP) in spermatogenesis. It is not clear whether inflammatory bowel disease itself is influencing the maturation of spermatozoa and whether the activity of the disease is reflected by changes in sperm development. 27 patients with Crohn's disease were studied. 6 were without treatment, 10 received SASP, 11 had both, SASP and methylprednisolone. The sperm analysis was not different between untreated and SASP treated patients. Sperm density was equal in both groups while number of mobile and mature sperms was slightly but not significantly decreased. Sperm quality was on the lower limit of normal. In contrast, all patients with the combined treatment of SASP and methylprednisolone had pathological findings in sperm density, morphology and motility. Crohn's activity index of the latter group was significantly higher than of the patients without or with SASP treatment. It is concluded that pathological sperm analysis of patients with Crohn's disease are not necessarily the consequence of SASP treatment. It seems likely that the disease itself plays a role in the spermatogenesis and that derangements in sperm quality increase with severity of the disease.

Adult↗