Quantitative analysis of protease recognition by inhibitors in plasma using microscale thermophoresis.

High abundance proteins like protease inhibitors of plasma display a multitude of interactions in natural environments. Quantitative analysis of such interactions in vivo is essential to study diseases, but have not been forthcoming, as most methods cannot be directly applied in a complex biological environment. Here, we report a quantitative microscale thermophoresis assay capable of deciphering functional deviations from in vitro inhibition data by combining concentration and affinity measurements. We obtained stable measurement signals for the substrate-like interaction of the disease relevant inhibitor α-1-antitrypsin (AAT) Z-variant with catalytically inactive elastase. The signal differentiates between healthy and sick AAT-deficient individuals suggesting that affinity between AAT and elastase is strongly modulated by so-far overlooked additional binding partners from the plasma.

Histopathologic changes during mesenteric ischaemia and reperfusion.

The basic electrical rhythm (BER) of the intestine is known to decrease during mesenteric ischaemia. Some studies have reported the relationship between the BER and the pathologic changes that occur in the bowel during vascular injury. However, these changes have not been completely elucidated. This study describes the histopathologic pattern when the rabbit small intestine was subjected to ischaemia of varying time lengths (30-150 minutes) and subsequent reperfusion for six hours. Intestinal biopsies were taken at baseline, at the end of ischaemia, and at hourly intervals during reperfusion. Microscopic examination of the biopsies revealed evidence of progressive infarction of the mucosa during ischaemia. There was an acute worsening of the pathology during reperfusion, the severity being greater when reperfusion was preceded by longer periods of ischaemia. These changes were statistically significant. The observed pattern in this study shows clearly that reperfusion injury is reflected in the histopathologic response and that this is worse in severity than the response to ischaemia. Studies of longer duration should further clarify the picture during recovery in ischaemia/reperfusion injuries of the bowel.

Ileoanal pouch versus ileostomy: is there a difference in quality of life?

Ileoanal pouch (IAP) construction is arguably the procedure of choice to follow proctocolectomy for ulcerative colitis (UC) or familial adenomatous polyposis (FAP). Patients with UC or FAP at our institution choose their operation after counseling with the surgeon, with an enterostomal therapist, and with patients who have undergone IAP and proctocolectomy with ileostomy (IL). We studied these patients who chose IAP and IL, to determine differences in outcome and quality of life (QOL) between those two groups. We assessed outcomes by evaluating clinic and hospital records and surveyed patients' QOL via a standardized questionnaire. During a retrospective 10-year study period, 86 patients underwent evaluation for IAP construction for UC (64) and FAP (22). Fifty-five patients underwent IAP construction, and 31 underwent IL. There were no operative deaths. Thirty-four patients sustained 69 early and late complications (40%). The IAP group experienced a higher complication rate, 53 per cent, compared with the IL group, 16 per cent. Forty-five patients (56%) have completed questionnaires. Eighty-seven per cent of IAP patients and 93 per cent of IL patients responded that their overall QOL is "always" better since their operation (P = not significant). Both groups reported very favorable responses to questions regarding work, social life, family life, sleep, and relationships without statistically significant differences between the two groups. Despite a high complication rate, IAP is an excellent operation for many patients with UC or FAP, but patients who choose IL after preoperative counseling can be expected to have similar improvement in quality of life.

Intestinal tachyarrhythmias during small bowel ischemia.

The electrical control activity (ECA) of the bowel is the omnipresent slow electrical wave of the intestinal tract. Characterization of small bowel electrical activity during ischemia may be used as a measure of intestinal viability. With the use of an animal model of mesenteric ischemia, serosal electrodes and a digital recording apparatus utilizing autoregressive spectral analysis were used to monitor the ECA of 20 New Zealand White rabbits during various lengths of ischemia. ECA frequency fell from 18.2 +/- 0.5 cycles per minute (cpm) at baseline to 12.2 +/- 0.9 cpm (P < 0.05) after 30 min of ischemia and was undetectable by 90 min of ischemia in all animals. Tachyarrhythmias of the ECA were recorded in 55% of the animals as early as 25 min after ischemia was induced and lasted from 1 to 48 min. Frequencies ranged from 25 to 50 cpm. These tachyarrhythmias were seen only during ischemia, suggesting that they are pathognomonic for intestinal ischemia. The use of the detection of ECA changes during intestinal ischemia may allow earlier diagnosis of mesenteric ischemia.

Noninvasive detection of ischemic bowel.

PURPOSE: Acute mesenteric arterial occlusion is an abdominal catastrophe that carries high morbidity and mortality rates. Current diagnostic methods, however, lack sensitivity and specificity and do not provide information about the viability of the affected bowel. Early diagnosis and intervention would improve patient outcomes and survival rates. The basic electrical rhythm (BER) is the omnipresent electrical slow wave of the gastrointestinal tract that characterizes the underlying electrical activity of the bowel. BER frequency is known to fall with ischemia. Superconducting quantum interference devices (SQUIDs) can detect BER by measuring the magnetic fields generated by the electrical activity of the smooth muscle of the small bowel. The purpose of this study was to determine the ability of a SQUID to detect mesenteric ischemia in a free-lying section of small bowel in an animal model of acute superior mesenteric artery occlusion. METHODS: Seven adult male rabbits (six experimental and one control) were studied with transabdominal SQUID and electrode recordings during baseline and after the induction of mesenteric ischemia with balloon occlusion of the superior mesenteric artery. Continuous recordings were taken for 120 minutes of ischemia and analyzed with autoregressive spectral analysis to determine the BER frequency during specific time points of the study. Two independent investigators blinded to the experimental preparation examined the results to determine whether there was decreased BER frequency and thus ischemia. The results are expressed as mean +/- SEM, and paired t tests were used to determine statistical significance. RESULTS: BER was detected in all seven animals and fell from 10.7 +/- 0.5 cpm to 7.0 +/- 1.8 cpm after 30 minutes of ischemia in the magnetic channels (P <.05, with t test). The fall in BER was detected by the SQUID in all six experimental animals. The blinded observers correctly identified healthy and ischemic magnetic data recording, with a sensitivity of 94% and specificity of 100%. CONCLUSION: SQUIDs can noninvasively detect bowel ischemia early in a free-lying segment of small bowel in this animal model with a high degree of sensitivity and specificity.

Ileoanal pouch procedures: clinical outcomes and quality-of-life assessment.

Ileoanal pouch (IAP) anastomosis following total colectomy for ulcerative colitis or familial adenomatous polyposis is performed with the goal of avoiding a permanent ileostomy and its effects on life satisfaction. During a retrospective 10-year study period, 55 patients underwent IAP construction for ulcerative colitis (36) and familial adenomatous polyposis (19). We assessed complications by chart review and surveyed patients regarding quality of life via a standardized questionnaire. There was no operative mortality, and there were three late deaths (6%). Twenty-nine patients (54%) sustained 68 early and late complications. Pouchitis was the most common complication (24%), and two patients required pouch excision (4%), one for pouchitis and one for rectovaginal fistula. Thirty-one patients (65%) have completed questionnaires. Forty-seven patients (87%) responded that their overall quality of life is "always" better since creation of the IAP, and only one patient in the IAP group has greater than ten bowel movements a day. Twenty-one patients (68%) never have interference with intimate relationships and 20 (65%) never have interference with physical activities. However, 20 patients (65%) sometimes have sleep interference, and 19 patients (61%) sometimes have fecal soilage. None of the patients continue to take steroids. We conclude that the complication rate following IAP construction is high, but pouch loss is infrequent. Despite a high complication rate, the majority of patients experience an improvement in quality of life.

Effects of mesenteric ischemia and reperfusion on small bowel electrical activity.

UNLABELLED: Previous studies involving basic electrical rhythm (BER) have not been carried out far enough to fully characterize the relationship between mesenteric ischemia and BER. The phenomenon of reperfusion injury has also not been correlated with BER activity. The goal of this study was to characterize changes in BER during mesenteric ischemia and reperfusion and to correlate them with changes in pathology. METHODS: Serosal electrodes were used to record the electrical activity of rabbit jejunum (n = 20) at baseline, during ischemia (90-210 min), and during reperfusion (120-240 min). BER frequency and amplitude were monitored, and biopsies were taken at the end of ischemia and reperfusion. A pathologist blinded to the specimen identity graded the histology on a scale of 0 (no changes) to 6 (transmural necrosis). Paired t test, the Kruskal-Wallis test of non-parametric ranks, and Fisher's r to z test were used for statistical significance where appropriate. RESULTS: BER frequency and amplitude fell significantly after 15 min of ischemia and became undetectable by 90 min of ischemia in all animals. The likelihood that BER would return during reperfusion was highly correlated with length of ischemia (r = 0.99). Longer periods of reperfusion were associated with increasing pathologic grade. CONCLUSIONS: BER frequency and amplitude are very sensitive to ischemia and their changes occur well before histopathologic changes. The variation in electrical activity of the small bowel during ischemia and reperfusion is a dynamic process that reflects the metabolic state of the smooth muscle. If electrical activity of the bowel is to be used for assessment of viability, continuous recordings more accurately reflect the metabolic state of the smooth muscle.