Biomedical subjects

Konrad S Schulze

Publications and source records attributed to Konrad S Schulze.

4 recordsLinked to original sources

PubMed2005

Investigation of fundo-antral reflex in human beings.

AIM: To examine the sensory and motor response(s) of the stomach following fundic distention and to assess whether cholinergic mechanisms influence these responses. METHODS: Fundic tone, gastric sensory responses and antral motility were evaluated in eight healthy volunteers after a probe with two sensors was placed in the antrum and a highly compliant balloon in the fundus. Isobaric balloon distentions were performed with a barostat. Study was repeated in six volunteers after intravenous atropine was given. RESULTS: Fundic distention induced large amplitude antral contractions in all subjects. The area under the curve was higher (P<0.05) during fundic distention. First sensation was reported at 12+/-4 mmHg, moderate sensation at 18+/-4 mmHg and discomfort at 21+/-4 mmHg. Discomfort was associated with a decrease in antral motility. After atropine was given, the area under the curve of pressure waves and fundic tone decreased (P<0.05). Sensory thresholds were not affected. CONCLUSIONS: Fundic balloon distention induces an antral motor response, the fundo-antral reflex, which in part may be mediated by cholinergic mechanisms.

Adult↗

PubMed2003

Ulcerative ileitis encountered at ileo-colonoscopy: likely role of nonsteroidal agents.

BACKGROUND & AIMS: Ileoscopy is increasingly practiced, but it is unclear what diagnostic and management decisions should ensue if ulcerations are encountered. METHODS: The lead author identified 40 patients with ulcerative ileitis during 1900 consecutive ileoscopies in a community practice. We analyzed the clinical, endoscopic, and histopathologic findings in these patients and related them to drug usage. RESULTS: Although most patients were asymptomatic, ileitis likely contributed to blood loss in 14 and to right lower quadrant pain in one. Endoscopy revealed multiple, discrete, fibrin-covered ulcerations in the prevalvular segment with patches of erythematous stippling, normal intervening mucosa, and occasional mucosal scars or webs. Histologic findings included focal superficial neutrophilic infiltrates, edema, mucosal hemorrhage, lymphatic dilatation, fibromuscular hyperplasia, prominence of the muscularis mucosae, and antral and Paneth cell metaplasia. Granulomas, fissure ulcers, and apoptosis were notably absent. No specific disease process developed in a median follow-up of 3.2 years. Thirty-three patients admitted recently taking nonsteroidal anti-inflammatory drugs (NSAIDs), notably: enteric-coated aspirin at 325 mg/day or less (19), selective cyclooxygenase-2 inhibitors (5), and nonacetylated salicylates (3). Three fourths of nonsteroidal users were taking agents with low or intermediate gastroduodenal toxicity. Lesions disappeared after drug withdrawal, and reappeared on resumption. CONCLUSIONS: Ileoscopy during colonoscopy may identify an ulcerative ileitis. This lesion likely contributes to gastrointestinal blood loss and other clinical manifestations, and likely is caused by NSAID use, including those usually associated with low toxicity or at low doses. Features of NSAID-ileitis overlap with Crohn's ileitis, but differentiation of the 2 entities is critical for appropriate management.

Adult↗

PubMed2003

Gastroduodenal motility.

PURPOSE OF REVIEW: The neuromuscular function of the stomach and duodenum provides the mechanical forces that drive digestion and are responsible for sensations of satiety and of dyspepsia. This article reviews (1) the neuroendocrine factors controlling upper gastrointestinal motility, (2) noninvasive techniques to evaluate gastroduodenal motility, and (3) the pathophysiology and treatment of gastroparesis. RECENT FINDINGS: Nutrients in the duodenum inhibit gastric emptying via a feedback pathway that involves release of cholecystokinin and serotonin (5-HT) from neuroendocrine cells; both act peripherally, cholecystokinin via cholecystokinin A receptors and serotonin via 5-HT3 receptors. The dorsal vagal complex plays a central role in the gastric inhibition mediated by tumor necrosis factor-alpha. The construction of maps that define intestinal movements in time and space has now been extended to the stomach. MRI compares favorably with the barostat in assessing gastric volume accommodation to meals and drugs and has the advantage of being noninvasive and showing contractions. Gastroparesis is increasingly recognized as a complication of end-stage liver disease; ascites plays no role in this, but portal hypertension stiffens the gastric walls and creates hypoxic conditions that may interfere with the neuromuscular functions of the stomach. Promising for the treatment of gastroparesis are clonidine, sildenafil, and intrapyloric botulinum toxin. Electrical stimulation triggers a vagally mediated relaxation of the stomach. SUMMARY: Drugs may be designed that specifically act on 5-HT3, cholecystokinin, or TNF-alpha receptors. Spatiotemporal maps should boost the diagnostic yield from dynamic imaging of motility using ultrasound, computed axial tomography scan, or MRI and the understanding of the mechanical forces driving digestion. Symptomatic benefit in gastroparesis may derive more from improved accommodation than gastric emptying.

Journal Article↗

PubMed2003

Flow fields generated by peristaltic reflex in isolated guinea pig ileum: impact of contraction depth and shoulders.

The guinea pig ileum responds to distension with characteristic wall movements, luminal pressure gradients, and outflow (the peristaltic reflex). To date, little is known about whether the peristaltic reflex generates flow events other than laminar flow. Here we used a numerical method to solve for the flow generated by moving walls to assess occlusive contractions (case 1), nonocclusive contractions (case 2), and contractions with steep shoulders (case 3) for which visual parameters of wall movements are published. We found that all three contraction cases produced pressure differentials across the coapting segment, downstream and reverse flow, and vortical flow patterns that redistributed particles and mixed liquids. Contractions generated pressures and shear stresses, particularly along the moving section of the wall. The nonocclusive contraction was much less effective than the occlusive contraction with the steep shoulders; the occlusive contraction with flat shoulders had an intermediate effect. Our analysis shows that even peristaltic contractions produce not only laminar flow but also many flow events likely to promote digestion and absorption. The visual patterns of contractions impact the patterns of luminal flow, and precise definition of wall movements is critical to quantify the fluid mechanical consequences of intestinal contractions.

Animals↗