A diurnal rhythm in the absorption of glucose and water by isolated rat small intestine

1. Glucose and water absorption by isolated small intestine from rats which have had unrestricted access to food is 50-60% higher at night than during the daytime. 2. When the feeding time is restricted to 06.00-09.00 hr G.M.T. glucose and water absorption rates in the period from 3 to 7 hr after withdrawal of food are almost as high as the rates observed at night-time in the animals with unrestricted feeding. 3. These changes in absorption rates appear to be associated with feeding time and not with the pattern of illumination.     

Effect of caffeine on the human small intestine

Methylxanthines produce intracellular accumulation of cyclic 3'5'-AMP (cAMP) by inhibition of phosphodiesterase and mucosal cAMP accumulation. Cyclic AMP is thought to mediate small intestinal secretion caused by some enterotoxins, hormones, and methylxanthines. These studies were designed to evaluate the effect of caffeine on small intestinal net fluid movement and transit times. The administration of caffeine in amounts ordinarily contained in many beverages and medications (75 to 300 mg) resulted in striking net secretion in the jejunum which lasted at least 15 minutes. This occurred in six of seven studies. Baseline net absorption of 0.5 ml per cm per hr was reversed to net secretion of 6.0 +/- 2.2 ml per cm per hr after oral caffeine ingestion (P less than 0.01). Net secretion also occurred in the ileum in seven of eight studies, but the onset of secretion appeared 35 min later than in the jejunum. These patterns of secretion correlated best with the passage of the intestinal bolus of caffeine rather than plasma caffeine levels. In contrast to other net secretory conditions, which increase the speed of transit, small intestinal transit times, as determined by dye dilution methods, were unchanged by caffeine. It is possible that methylxanthine-induced small intestinal secretion may play a role in the symptoms experienced by some patients with functional diarrhea.     

Changes in the contractile and bioelectrical activities of the rat small intestine under increased intra-abdominal pressure

A relationship was established between the increased intra-abdominal pressure and decreased electrical and mechanical motor activity of the small intestine in rats. Possible pathophysiological mechanisms are discussed. A model was developed for estimation of the electrical and motor activity of the small intestine in rats, which can be used for experimental studies of conditions where intra-abdominal pressures can be elevated.     

Endocrine cells in the human fetal small intestine

In this report we describe the time of appearance and ultrastructural features of enteroendocrine (EECs) in the human fetal small intestine (SB) between 9 and 22 weeks gestation. Thirteen distinctive EECs were identified in fetal SB. Two of these, not found in normal adult SB, appeared within the stratified epithelium of the proximal SB at 9--10 weeks. They were arbitrarily termed "primitive" and "precursor" cells. As in all fetal EECs, the pale cytoplasm of the "primitive" cell contains a distinctive population of secretory granules (SGs). Primitive cell SGs average 200-330 nm; some have dense cores with lucent halos while others are filled with a homogeneous dense or flocculent material. The SGs of the "precursor" cells are larger, averaging up to 1 micron in diameter and their contents vary in electron density. A third group of cells not described in normal adult SB was arbitrarily termed "transitional" cells. These have two populations of SGs; one resembles the SGs of the "precursor" cells, and the other resembles the SGs of some of the specific adult type EECs. Transitional EC, S, I and G cells are seen. In addition, mature appearing EC, S, G, I, L, D, and D1 cells were identified by 12 weeks of gestation. The "primitive", "precursor", and "transitional" cells may represent sequential developmental precursors of adult type EECs.     

Cyclic AMP-dependent anion secretion in human small and large intestine

Cyclic AMP-dependent Cl- secretion is the major secretion pathway in human intestine. The aim of the present study was to examine mechanisms involved in cAMP-dependent anion secretion in human small and large intestine. Surgical resection specimens from both jejunum and distal colon were studied under short circuited conditions. Addition of the phosphodiesterase inhibitor IBMX induced an increase in the short-circuit current (Isc) equivalent to the net increase in Cl- secretion. The Isc was inhibited by diphenylamine decarboxylate (DPC; Cl- channel blocker), bumetanide (basolateral Na+/K+/2Cl- cotransporter), BaCl2 (basolateral K+ channel) and Cl- free buffer in both segments and indomethacin (cyclo-oxygenase inhibitor) in colon alone. Diphenylamine decarboxylate appears to directly inhibit secretion in jejunum, although its inhibitory effect is possibly mediated by inhibition of cyclo-oxygenase in the colon. A small component of IBMX-stimulated Isc was inhibited by acetazolamide. Cyclic AMP-dependent secretion is largely apical Cl- secretion, although a small component appears to be HCO3. Secretion is dependent on basolateral K+ channels and Na+/K+/2Cl- cotransporters and, in the colon, is inhibited by indomethacin, implying a role for cyclo-oxygenase metabolites. The chloride channel blocker DPC inhibits secretion in both areas. This class of compounds may have potential for treatment of secretory diarrhoea.     

Primary culture and transfection of epithelial cells of human small intestine

OBJECTIVE: To evaluate perioperative and long-term morbidity in patients undergoing selective evaluation of coronary artery disease prior to abdominal aortic aneurysm (AAA) repair. DESIGN: Case series. SETTING: University and Veterans' Administration medical centers. PATIENTS: One hundred eighty-nine consecutive patients undergoing AAA repair between January 1989 and September 1996 were selectively evaluated for coronary artery disease and assigned to 1 of 3 groups: group 1, no abnormal cardiac history, normal electrocardiogram; group 2, minimal symptoms, history of myocardial infarction (MI), older than 70 years, diabetes mellitus, or congestive heart failure; or group 3, severe or unstable angina, ventricular dysfunction. INTERVENTIONS: Group 1 patients proceeded to AAA repair without further workup. Group 2 patients underwent pharmacologic or exercise stress testing followed by coronary angiography and intervention as required. Group 3 patients went directly to coronary angiography and intervention as needed. MAIN OUTCOME MEASURES: Perioperative MI, arrhythmias, or death. Long-term follow-up measures included MI and death. RESULTS: Adequate documentation was available on 171 patients. Twenty-four patients (14%) were in group 1. Of 136 patients (79.5%) in group 2, coronary angiography was performed in 36 (26%), followed by percutaneous transluminal coronary angioplasty (PTCA) in 9 (7%) and coronary artery bypass (CAB) in 5 (4%). Of 11 patients in group 3, 3 (27%) each received PTCA and CAB. Remote CAB or PTCA had been performed in 32 (19%) and 12 (7%) patients, respectively. Two perioperative deaths (1.1%) occurred in the 189 patients, one due to MI in a group 2 patient. There were 2 (1%) nonfatal MIs, both in group 2 patients who had no preoperative intervention. Arrhythmias and/or congestive heart failure occurred in 17 (9%) cases, 7 (39%) having had recent coronary revascularization (P = .001). By univariate analysis, only preoperative renal dysfunction predicted perioperative complications (P = .03) Overall survival by lifetable analysis was 87.9% and 69.7% at 3 and 5 years, respectively. CONCLUSION: Coronary artery disease is common in patients undergoing AAA repair, with 35.7% having preoperative coronary revascularization at some point. Selective preoperative coronary artery disease screening achieves excellent perioperative and late results in this population.     

Correlation between contractile strength and myosin heavy chain isoform composition in human skeletal muscle

PURPOSE: The purpose of this study was to investigate the relationship between myosin heavy chain (MHC) composition and maximal contraction strength of the human quadriceps femoris muscle. METHODS: Muscle biopsies were obtained from m. vastus lateralis in your highly physical active males (N = 7). The MHC composition of muscle homogenates was determined by electrophoresis techniques (SDS-PAGE). Isokinetic peak torque and constant-angle torque (50 degrees knee flexion) were obtained during slow (30 degrees.s-1), medium (120 degrees.s-1), and fast (240 degrees.s-1) maximal concentric and eccentric quadriceps contractions and expressed relative to muscle volume. RESULTS: The percentage of MHC II in the quadriceps muscle was positively correlated (rs = 0.61-0.93; P < 0.05-0.01) to maximal concentric quadriceps strength obtained at medium to high knee angular velocity. In contrast, no consistent pattern of correlation was observed for maximal eccentric quadriceps strength. CONCLUSIONS: The relationship observed between muscular MHC composition and maximal contractile strength is suggested to appear as a consequence of MHC -related differences in contractile force-velocity characteristics and/or contractile Rate of Force Development (RFD).     

Carbohydrate hydrolysis and absorption in the human small intestine in aging

Veterinary dental materials (e.g. documents, images, continuing education courses, message boards, bibliographic search options) that are available as electronic media are described. These include materials available on the Internet or via commercial on-line services such as AOL-VIN and Compuserve-NOAH, and off-line materials such as CD-i, CD-ROM and floppy disk programs.     

Ganglioneuroma of the small intestine

The ganglioneuroma is a rare, benign tumor of the small bowel. The clinical symptomatology and morphology of the tumor are presented in detail. The differences in histopathology between ganglioneuroma and eosinophilic granulomatous polyp are discussed. Therapy should be resection of the tumor.     

Surgery of the small intestine

Although earlier reports describe a poor prognosis for small intestinal surgery in the horse, there is growing evidence that the short-term survival rate can exceed 80%. In addition to advancements in surgery and aftercare, early referral contributes considerably to the improved prognosis. Surgical procedures that restore anatomic and physiologic continuity to close to normal can minimize postoperative complications. Jejunojejunostomy carries a better prognosis than jejunocecostomy, probably because the latter involves anastomosis between two intestinal segments with dissimilar functions. Careful technique can reduce the prevalence of complications, such as postoperative ileus and serosal adhesions.     

Perforations of the small intestine

Six cases of perforation of the small intestine, one secondary to anaphylactoid purpura and five spontaneous, are reported. Ingestion of an iced drink acted as a trigger in two cases. A vascular genesis is put forward to explain the aetiopathogenesis of two cases and it is noted that perforation of this type is present in the final ileal ansa, at the mesenterial margin. In three cases, histology revealed the presence of double refraction crystal. These came from vegetal residues and are probably capable of penetrating from the lumen into the mucosa causing a foreign body reaction, abscess and subsequent perforation. In these cases, perforation occurred in an ansa located further away than the last ileal ansa (about 3 m) and on the mesenterial margin. Intestinal resection and subsequent end-to-end, single layer anastomosis were performed in all cases.     

Defining the critical limit of oxygen extraction in the human small intestine

Although animal models have been used to characterize the relation between oxygen consumption and blood flow, reliable data have not been generated in the human small intestine. We perfused segments of human small intestine by using an ex vivo perfusion circuit that allowed precise manipulation of blood flow and perfusion pressure. Our goal was to define the critical level of intestinal blood flow necessary to maintain the metabolic needs of the tissue. Human small intestine (n = 5) tissue obtained at transplantation harvest was transported on ice to the laboratory. A 40-cm mid-jejunal segment was selected for perfusion, and appropriate inflow and outflow vessels were identified and cannulated. Perfusion with an autologous blood solution was initiated through an extracorporeal membrane oxygenation circuit. After a 30-minute equilibration period, arterial and venous blood gases were measured at varying flow rates while maintaining a constant hematocrit level. Arterial and venous oxygen content, arteriovenous oxygen difference (A-VO2 diff), and oxygen consumption (VO2) were then calculated. Our results demonstrated that at blood flows > 30 ml/min/100 g, VO2 is independent of blood flow (1.6 +/- 0.06 ml/min/100 g), and oxygen extraction is inversely related to flow. Below this blood flow rate of 30 ml/min/100 g, oxygen extraction does not increase further (6.3 +/- 0.3 vol%), and VO2 becomes flow dependent. This ex vivo preparation defines for the first time a threshold value of blood flow for small intestine below which oxygen consumption decreases (30 ml/min/100 g). Previous animal studies have correlated such a decrease in oxygen consumption with functional and histologic evidence of tissue injury. This "critical" flow rate in human intestine is similar to that found previously in canine and feline intestine, but lower than that of rodent species.     

Acute and chronic effects of ethanol on fluid transport in the human small intestine

The effect of acute and chronic administration of ethanol on jejunal and ileal water and electrolyte transport was studied in healthy volunteers by the triple lumen intestinal perfusion technique. The acute perfusion of a glucose-free electrolyte solution containing 2 to 10 g per 100 ml of ethanol in the jejunum or ileum did not cause any significant alterations of sodium or water transport. In contrast, the administration of a folate-deficient diet and ethanol for 2 weeks produced a marked reduction in sodium and water absorption or a small net secretion (control, mean +/-SE: H2O = 0.91 +/- 0.06 ml per min, Na = 130 +/- 8 micronEq per min per 30 cm of intestine versus H2O = -0.13 +/- 0.14 ml per min, Na = -20 +/- 29 micronEq per min per 30 cm, P less than 0.001). These changes were not accompanied by a reduction in serum folate levels. The administration of ethanol with a folate-supplemented diet also produced significant but less pronounced changes in sodium and water transport control: H2O = 1.33 +/- 0.2 ml per min, Na = 185 +/- 34 micronEq per min per 30 cm of intestine versus H2O = 0.48 +/- 0.17 ml per min, Na =65 +/- 16 micronEq per min per 30 cm of intestine, P less than 0.05). From this study it appears that the diarrhea seen in chronic alcoholics can be explained in part by the effect of ethanol on intestinal sodium transport, without any accompanying changes in serum folate levels.     

Primary adenocarcinoma of the small intestine

Eighteen cases of primary adenocarcinoma of the small intestine have been reviewed, which demonstrated the relative frequency of symptoms common to this disease. The clinical features, pathology, and treatment of small bowel adenocarcinoma have been presented and the literature reviewed.