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Biomedical subjects

D Schwab

Publications and source records attributed to D Schwab.

At least 19 recordsLinked to original sources
PubMed2006

"Hemodynamic efficacy" of two endoscopic clip devices used in the treatment of bleeding vessels, tested in an experimental setting using the compact Erlangen Active Simulator for Interventional Endoscopy (compactEASIE) training model.

BACKGROUND AND STUDY AIMS: Hemoclip therapy is a well-established procedure in the treatment of gastrointestinal bleeding. Although new products are provided periodically by the industry, comparative investigations are lacking. We compared two different hemoclip devices in an experimental setting, assessing them using objective hemostatic parameters. MATERIALS AND METHODS: We compared two disposable clip devices (Olympus HX-200L-135 (n = 40) vs. Wilson-Cook Tri-Clip (n = 40)) in an experimental setting using the compact Erlangen Active Simulator for Interventional Endoscopy (compactEASIE) training model equipped with an upper gastrointestinal-organ package for bleeding simulation. This was a randomized, prospective, controlled trial. Four investigators with different levels of endoscopic experience applied ten hemoclip devices of each type to the spurting vessels, the clips allocated using a randomized list for each investigator. The efficacy of hemostasis was determined by continuous measurement of the pressure within the afferent vessel before and after clip application and calculation of the relative reduction of vessel diameter by the clip device. The system pressure was recorded over the period from 1 minute before to 1 minute after clip application. A secondary end point was a subjective assessment of the whole clip application procedure by the endoscopist and the assisting nurse, using a visual analog scale (0 - 100, with 100 representing the best experience). RESULTS: A total of 39/40 clips of each type were applied successfully. Both clip devices led to a significant increase in system pressure, representing significant relative reduction of vessel diameter (Olympus 5.4 +/- 7.5 %, p < 0.001; Cook 4.9 +/- 8.0 %, p < 0.001). Overall, there was no significant difference between the two devices ( P = 0.756). However, the investigator with the least experience in endoscopy (< 100 procedures) produced significantly inferior results compared with the other three investigators, who had performed between 2000 and 6000 procedures each ( P < 0.05). We found no evidence of a learning curve from the intra-observer results. The devices received good, but not significantly different, overall ratings by the endoscopists (Olympus 69 +/- 24 vs. Wilson-Cook 65 +/- 16) and by the assisting nurses (Olympus 77 +/- 9 vs. Wilson-Cook 70 +/- 22). CONCLUSIONS: Using an established cadaveric training model, no significant difference was found between the two types of hemoclip devices with respect to their "hemostatic efficacy". However, the experience of the endoscopist appears to play a major role in successful clip application. The use of a feedback mechanism in emergency endoscopy training, using continuous intravessel pressure monitoring, may substantially enhance the efficacy of training, resulting in a similar improvement in clinical results.

Cadaver↗
PubMed2006

Hemodynamic efficacy of the new resolution clip device in comparison with high-volume injection therapy in spurting bleeding: a prospective experimental trial using the compactEASIE simulator.

BACKGROUND AND STUDY AIMS: Peptic ulcers are the most frequent cause of gastrointestinal bleeding. The use of hemoclips has become established as an effective form of treatment in addition to injection therapy. However, hemoclips have not previously been compared with injection therapy in an experimental setting using objective parameters. MATERIALS AND METHODS: In a prospective, randomized, and controlled trial, the disposable Resolution hemoclip device (Boston Scientific, n = 40) was compared with conventional injection therapy (n = 40) in an experimental setting, using the compactEASIE simulator equipped with an upper gastrointestinal organ package to simulate bleeding. Four investigators with different levels of endoscopic experience participated in the study. On a randomized basis, each investigator treated 20 bleeding sites either by applying one clip (n = 10) or by carrying out high-volume four-quadrant injection (4 x 10 ml saline) of a spurting vessel. The efficacy of the hemostasis was assessed by continuous measurement of pressure within the afferent vessel before and after clip application or injection therapy and calculating the relative reduction in the vessel's diameter with each treatment method. The system pressure was recorded 1 min before and 1 min after treatment. The ease of application of each method was rated by the endoscopist and by the assisting nurse using a visual analogue scale (0 - 100, with 100 being best). RESULTS: All of the 40 hemoclipping and injection treatments were carried out successfully. Both methods led to a significant increase in peak pressure (Resolution clip 71.8 +/- 66.8 mm Hg, P < 0.001; injection 71.9 +/- 53.8 mm Hg, P < 0.001), representing a significant relative reduction in the vessel diameter. There were no significant differences in peak pressure between the two treatments ( P = 0.995). The mean increase in pressure during the first minute after the intervention (clip 49.3 +/- 67.0 mm Hg vs. injection 19.9 +/- 41.6 mm Hg) was significantly greater with the hemoclipping procedure ( P = 0.021). More experienced investigators achieved a greater increase in system pressure, but the difference was not significant. The assessments of the ease of application by the assistants (84 +/- 13) and endoscopists (86 +/- 16) did not show any significant differences ( P = 0.402) for the clipping device. CONCLUSIONS: No significant differences between the two treatment methods were detected with regard to the immediate efficacy of hemostasis. However, long-term hemostasis was better with hemoclipping. The endoscopist's level of experience also appears to play a role, particularly when hemoclips are used.

Animals↗
PubMed2005

Effect of serotonin depletion on 5-HT2A-mediated learning in the rabbit: evidence for constitutive activity of the 5-HT2A receptor in vivo.

RATIONALE: Associative learning during Pavlovian eyeblink conditioning has been shown to be regulated by 5-HT2A receptors. The existence of inverse agonists that retard learning through an action at the 5-HT2A receptor suggests the existence of constitutive activity at that receptor and that depletion of serotonin should have minimal effects on learning. OBJECTIVES: We examined whether depletion of serotonin would impair trace eyeblink conditioning or the enhancement of conditioning produced by the agonist lysergic acid diethylamide (LSD) and the retardation of conditioning produced by the inverse agonist MDL11,939. METHODS: Animals received bilateral intraventricular injections of 5,7-dihydroxytryptamine (5,7-DHT) at doses of 760 or 1,140 microg/side (1.88 or 2.82 micromol/side) and were later exposed to eight daily conditioning sessions. RESULTS: Serotonin depletion produced by the lower dose of 5,7-DHT was 71 and 72% in cortex and hippocampus, respectively, with no change in 5-HT2A receptor density, no effect on learning, and no effect on the ability of LSD to enhance and MDL11,939 to retard learning. The higher dose of 5,7-DHT produced serotonin decreases of 85 and 90% in cortex and hippocampus, respectively, accompanied by a 96% decrease in the density of the serotonin transporter, but no significant effect on learning. CONCLUSIONS: Pavlovian trace eyeblink conditioning is regulated predominantly by the constitutive activity of the 5-HT2A receptor rather than by serotonin release onto the receptor during learning. It was suggested that the 5-HT2A receptor regulates learning by modulating the release of dopamine, acetylcholine, and glutamate, transmitters known to affect eyeblink conditioning.

5,7-Dihydroxytryptamine↗
PubMed2005

Biliary secretion of moxifloxacin in obstructive cholangitis and the non-obstructed biliary tract.

BACKGROUND: Biliary secretion of antibiotic agents into the bile is considerably compromised by biliary obstruction, a precondition of bacterial cholangitis. Moxifloxacin may be advantageous according to secretion and antimicrobial spectrum. AIM: To establish the secretion of moxifloxacin into obstructed and non-obstructed bile. METHODS: Biliary excretion of moxifloxacin was determined in plasma and bile of 10 patients with biliary obstruction and cholangitis and 10 patients without biliary obstruction 30 min after administration of 400 mg of moxifloxacin intravenously. RESULTS: The plasma concentration of moxifloxacin was similar in both groups (4.45 +/- 1.58 microg/mL; 4.33 +/- 1.23 microg/mL). The concentration of moxifloxacin in the bile was significantly lower in patients with biliary obstruction than without (4.63 +/- 3.94 microg/mL; range 0.71-14.40; vs. 16.90 +/- 13.77 microg/mL; range 1.79-42.50; P = 0.043). Although significantly different, the penetration index was extensively high in those without biliary obstruction (4.41 +/- 4.40; range 0.35-14.45) but still sufficient in those patients with obstructive cholangitis (1.02 +/- 0.74; range 0.29-2.83; P = 0.035). CONCLUSION: These findings are suggestive of an active secretion mechanism for moxifloxacin into the obstructed bile, producing a biliary concentration sufficiently above the minimal inhibitory concentrations for most of the expected bacteria.

Aza Compounds↗
PubMed2005

[A case of attenuated familial adenomatous polyposis coli (AFAP)].

We describe an asymptomatic female patient who was diagnosed with multiple tubular and tubulovillous adenomas in the right-sided colon on routine colonoscopy at the age of 59 years. Genetic testing identified a germline truncating mutation at codon 405 (R405X) of the adenomatous polyposis coli (APC) gene. This mutation is located in the alternatively spliced region of exon 9, a region that is associated with an attenuated phenotype of familial adenomatous polyposis (AFAP). To our knowledge this report describes for the first time the R405X germline mutation in association with AFAP. Our patient had no extracolonic manifestations of AFAP. Treatment consisted of a right hemicolectomy with ileotransversal anastomosis plus complete endoscopic polypectomy in the left-sided colon. AFAP is a poorly defined condition with unknown prevalence and penetrance that requires individual therapy and life-long surveillance. Because of marked intrafamilial phenotypic variance, it is crucial to identify these patients and implement proper endoscopic surveillance at an early age in family members carrying this mutation.

Adenomatous Polyposis Coli↗
PubMed2004

A comparison of morphological and chemical fruit traits between two sites with different frugivore assemblages.

Large-scale comparisons might reveal matching between fruit traits and frugivore assemblages that might be cryptic on a local scale. Therefore, we compared morphological (colour, size, husk thickness) and chemical fruit traits (protein, nitrogen, sugar, lipid, tannin and fibre content) between Malagasy and South African tree communities with different frugivore communities. In Madagascar, where lemurs are important seed dispersers, we found more tree species with fruit colour classified as "primate fruits". In contrast, in South Africa we found more tree species with fruits classified as "bird coloured". This correlated with the greater importance of frugivorous birds in South Africa vs. Madagascar. Additionally, we found higher sugar concentrations in fruits from the South African tree community and higher fibre content in fruits from the Malagasy tree community. However, fibre content could be related to differences in abiotic conditions between the two study sites. This suggests that fruit colour more than other morphological and chemical fruit traits, reflects food selection by the different frugivore assemblages of those two sites.

Animals↗
PubMed2003

[Allergy-associated colitis. Characterization of an entity and its differential diagnoses].

There is substantial evidence that allergic reactions exist in the gastrointestinal tract (GI). However, patients with food allergy-related enteropathy pose a diagnostic challenge to physicians because the clinical features are variable, unspecific, occur in other gastrointestinal disorders, and specific diagnostic tools are missing. Several recent studies and reviews have focused on the function of eosinophilic granulocytes in GI disease. The role of eosinophils in the pathophysiology of GI hypersensitivity reactions is poorly defined. However, some findings have been reported that imply an involvement of eosinophils in allergic reactions of the gut. The presumptive histology of allergy-associated colitis in colonic and ileal biopsies is based on prominent pure eosinophilic infiltration of a normal lamina propria, submucosa and epithelium with variable degrees of degranulation. An immunoperoxidase stain for eosinophilic peroxidase is supportive in establishing the diagnosis if suspected. Neutrophils or mononuclear infiltrates are not significantly increased and damage to the intestinal tissue is not prominent. Despite characteristic histologic changes in colonic biopsy specimens, a final diagnosis depends on careful clinical examination and exclusion of several differential diagnoses.

Colitis↗
PubMed2003

Enhanced histamine metabolism: a comparative analysis of collagenous colitis and food allergy with respect to the role of diet and NSAID use.

OBJECTIVES AND DESIGN: To compare clinical data and histamine metabolism of patients with collagenous colitis with those of food allergy. METHODS: In 17 patients with collagenous colitis, clinical findings (diarrhoea, abdominal pain) were recorded. Plasma (for histamine) and 12-h-urine (for histamine and n-methylhistamine, all measured by RIA) were collected during two days with an unrestricted diet followed by two days with an hypoallergenic. The clinical data and measured values were compared with those from patients with confirmed food allergy (n = 21) and controls (n = 41). RESULTS: Patients with collagenous colitis were found to present with significantly more liquid stools than patients with food allergy (p < 0.001) during both types of diet, but they did not experience more abdominal pain. N-methylhistamine in 12-h-urine was significantly increased during both types of diet in patients with collagenous colitis and food allergy when compared with controls (p < 0.001 for all). Patients with food allergy--but not those with collagenous colitis--showed a significant decrease of severity of pain (p < 0.05) when the diet was changed to the elimination protocol. CONCLUSION: Histamine is extensively produced and metabolised in patients with collagenous colitis. In contrast to food allergy, the allergenic potency of the administered food seems not to influence histamine production in collagenous colitis. However, histamine metabolism corresponds with the clinical activity in both patients with food allergy and collagenous colitis.

Aged↗
PubMed2003

Different lipid profiles as constituencies of liquid formula diets do not influence pain perception and the efficacy of opioids in a human model of acute pain and hyperalgesia.

Nutritional support and pain control by medication are often used concomitantly, but interactions are hardly investigated. A randomised, double-blind, cross-over study in ten right-handed volunteers was performed evaluating the influence of cholecystokinin (CCK)-excretion on the perception of pain in a standardised model. CCK-excretion was induced by a liquid formula diet with either long- or medium-chain triglycerides (LCT, MCT). Plasma samples were drawn over a 60 min period in 15-min intervals and CCK and somatostatin (SMS) were measured by radioimmunoassay (RIA). Gastric emptying was evaluated by C-13-breath testing. Transcutaneous electrical stimulation at a high current density (5 Hz, 70.1+/-5.8 mA) was used to provoke acute pain and stable areas of secondary mechanical hyperalgesia and pinprick allodynia for 2 h. Ongoing pain ratings as well as extension of pinprick-hyperalgesia and allodynia were compared between both liquid formula diets. In a second series of experiments, alfentanil (4.1+/-0.5 mg) was administered for 90 min using target-controlled infusions and measurements were performed as stated above. Oral administration of LCT as well as MCT may lead to different CCK blood levels, but we found no evidence for CCK-induced effects on pain sensation, touch-evoked allodynia, secondary hyperalgesia or morphine-induced anti-nociception in humans. In our studies, liquid formula diets did not influence acute pain perception or the efficacy of opioids in a human model of pain.

Acute Disease↗
PubMed2002

Urinary excretion of N-methylhistamine as a marker of disease activity in inflammatory bowel disease.

OBJECTIVE: Mast cells are thought to participate in the pathogenesis of inflammatory bowel disease (IBD). In this study, urinary excretion of N-methylhistamine (UMH), a stable metabolite of the mast cell mediator histamine, was evaluated as an indicator of disease activity in patients with IBD. METHODS: Urinary excretion of UMH (microg/mmol creatinine x m2 body surface area) was measured by radioimmunoassay in 55 controls, 56 patients with Crohn's disease, and in 36 patients with ulcerative colitis. Excretion rates were correlated with clinical, serological, and endoscopic disease activity, disease extent, and location. RESULTS: Urinary excretion of UMH was found to be significantly elevated in IBD. Patients with active Crohn's disease (7.1 +/- 4.2, p = 0.002 vs controls) and active ulcerative colitis (8.1 +/- 4.8, p = 0.02 vs controls) had higher rates of UMH excretion than patients in remission (6.3 +/- 3.8 and 5.2 +/- 2.3, respectively) or controls (4.6 +/- 1.9). In Crohn's disease and ulcerative colitis, a significant correlation of UMH excretion with clinical disease activity was obtained (Crohn's Disease Activity Index r2 = 0.58, Clinical Activity Index r2 = 0.57, p < 0.0001). Serologically, orosomucoid showed the best positive correlation with disease activity (Crohn's Disease Activity Index r2 0.80, Clinical Activity Index r2 = 0.86, p < 0.0001), but UMH excretion was found to reflect disease activity more accurately than C-reactive protein (Crohn's Disease Activity Index r2 = 0.46, Clinical Activity Index r2 = 0.42, p < 0.0001). No association between UMH excretion and disease type or localization could be found in Crohn's disease. However, UMH excretion correlated strongly with endoscopic severity of inflammation in Crohn's disease (Crohn's Disease Endoscopic Index of Severity r2 = 0.70, p < 0.0001) or disease extent in ulcerative colitis. CONCLUSIONS: Urinary excretion of the histamine metabolite UMH is enhanced in IBD. It appears to represent an integrative parameter to monitor clinical and endoscopic disease activity in IBD, which appears to be influenced most likely by mediators released from histamine-containing cells, such as intestinal mast cell subtypes.

Adolescent↗
PubMed2001

[Pathobiology of dysplasia in chronic inflammatory bowel disease: Current recommendations for surveillance of dysplasia].

Pathobiology of dysplasia in chronic inflammatory bowel disease: Current recommendations for surveillance of dysplasia. Patients with ulcerative colitis and Crohn's disease bear an about 10- and 4-fold increased risk, respectively, for developing colorectal carcinoma. Apart from typical locations of colorectal carcinoma in the sigmoid colon and rectum other locations were also often observed, e. g. right hemicolon or multifocal distribution. Histologically colorectal neoplasms frequently present as mucinous adenocarcinoma (signet-ring cell carcinoma). The risk for neoplasm depends on extension, severity, duration and therapeutic responsiveness of chronic colonic inflammation, and it seems pathogenetically to be similar in ulcerative colitis and Crohn's disease. Colorectal carcinoma in inflammatory bowel disease arises from epithelial dysplasia. Since there are no reliable biological markers available to date, surveillance-programs continue to rely on the discovery of dysplasia (unequivocal intraepithelial neoplasia). Detection of dysplasia by colonoscopy achieves 70-85 % sensitivity.Endoscopic surveillance should start after 8 years of disease's duration in pancolitis, after 10-12 years in left- sided colitis and after 12 years in Crohn's disease of the colon, with regular intervals every 1-2 years. 3-5 biopsies should be done every 10 cm from mucosa free of inflammation. Additionally, every fine or discrete alteration of the mucosal surface should be recorded. Multiple biosies should also be taken from such minimal lesions as well as from more macroscopically suspicious areas like plaques, nodular lesions or stenosis. The clinical consequence of a positive screening for dysplasia is colectomy because of an assumed risk of cancer of about 40-70 %. Dysplasia in macroscopically suspect areas bear the highest risk of cancer (non-adenoma like dysplasia), followed by multiple high-grade lesions without a macroscopic lesion, and multiple low-grade dysplasias. Detection of single dysplastic lesions in flat mucosa should be followed by a control endoscopy after 2-6 months, and if dysplasia is seen again, colectomy is recommended.

Adenocarcinoma, Mucinous↗