Effect of surgical alteration of the rat gastrointestinal tract on the growth and development of Hymenolepis diminuta

Eight groups of rats were used to study the involvement of the enteric (ENS) and central (CNS) nervous systems in the development of Hymenolepis diminuta using surgical intestinal transection, or CNS denervation, or both procedures. The transection procedure was used to isolate the ENS of the small intestine from either orad and/or caudal portions of the alimentary system, while the CNS denervation was used to eliminate direct visceral efferent inputs from the CNS. Nine days after the surgical procedures, all rats were infected with 35 cysticercoids of H. diminuta. On 20 days postinfection, the infection intensity, tapeworm dry weight, tapeworm morphology, intestine length, and intestinal wet weight were recorded. Only the combination of the duodenal and ileal transections with a CNS denervation reduced infection intensity and prevented the increased intestinal length normally observed in infected rats. In contrast, none of the various intestinal transection procedures alone or CNS denervation alone had any effect on the survival, ability to produce oncospheres or morphology of the tapeworms. In conclusion, tapeworm survival is decreased when both CNS and ENS inputs into the small intestine are altered or absent.

Effects of intestinal transplantation on postprandial motility and regulation of intestinal transit

BACKGROUND

The effects of intestinal transplantation on gut motility have not been completely defined. In this study we examine the effects of ileal transplantation on ileal smooth muscle contractility, together with gastroduodenal emptying, intestinal flow, and transit rates in a canine model of short-gut syndrome.

METHODS

Animals (n = 22) were instrumented with strain gauge transducers, collection cannulae, and infusion catheters to assess motility, intestinal flow and transit rates, and gastroduodenal emptying. Ten animals served to define normal parameters. Six animals underwent a 70% resection of the proximal small intestine to serve as short-gut controls. Six animals underwent removal of a 100-cm segment of the ileum, with cold storage, and autotransplantation the following day combined with a 70% resection of proximal bowel.

RESULTS

Transplant animals exhibited delayed gastroduodenal emptying, reduced intestinal flow rates, and postprandial phasic contractions that were similar to short-gut controls. However, transplant animals experienced rapid intestinal transit compared with short-gut controls (4.8 +/- 0.4 cm/min vs 2.0 +/- 0.3 cm/min; mean +/- SEM; P <.05).

CONCLUSIONS

The transplanted intestine, even with 18 hours of cold storage, exhibits a relatively normal postprandial motor response. However, adaptive responses of the transplanted intestine, such as regulation of intestine transit, may be impaired by neuromuscular injury associated with denervation or ischemia.

Deficient iNOS in inflammatory bowel disease intestinal microvascular endothelial cells results in increased leukocyte adhesion

Microvascular endothelial cells play a key role in inflammation by undergoing activation and recruiting circulating immune cells into tissues and foci of inflammation, an early and rate-limiting step in the inflammatory process. We have previously [Binion et al., Gastroenterology112:1898-1907, 1997] shown that human intestinal microvascular endothelial cells (HIMEC) isolated from surgically resected inflammatory bowel disease (IBD) patient tissue demonstrate significantly increased leukocyte binding in vitro compared to normal HIMEC. Our studies [Binion et al., Am. J. Physiol.275 (Gastrointest. Liver Physiol. 38):G592-G603, 1998] have also demonstrated that nitric oxide (NO) production by inducible nitric oxide synthase (iNOS) normally plays a key role in downregulating HIMEC activation and leukocyte adhesion. Using primary cultures of HIMEC derived from normal and IBD patient tissues, we sought to determine whether alterations in iNOS-derived NO production underlies leukocyte hyperadhesion in IBD. Both nonselective (N(G)-monomethyl-L-arginine) and specific (N-Iminoethyl-L-lysine) inhibitors of iNOS significantly increased leukocyte binding by normal HIMEC activated with cytokines and lipopolysaccharide (LPS), but had no effect on leukocyte adhesion by similarly activated IBD HIMEC. When compared to normal HIMEC, IBD endothelial cells had significantly decreased levels of iNOS mRNA, protein, and NO production following activation. Addition of exogenous NO by co-culture with normal HIMEC or by pharmacologic delivery with the long-acting NO donor detaNONOate restored a normal leukocyte binding pattern in the IBD HIMEC. These data suggest that loss of iNOS expression is a feature of chronically inflamed microvascular endothelial cells, which leads to enhanced leukocyte binding, potentially contributing to chronic, destructive inflammation in IBD.

Total antioxidant capacity of colon in patients with chronic ulcerative colitis

It has been proposed that oxidative stress is involved in the pathophysiology of ulcerative colitis. We have reported the depletion of the nonenzymatic antioxidant, glutathione, in colon from active and inactive ulcerative colitis. The colon contains several biochemically linked antioxidant systems. We hypothesized that diminished total antioxidant capacity in active ulcerative colitis would be associated with increased colonic lipid peroxidation. This study was designed to determine total antioxidant capacity and lipid hydroperoxide levels using colon obtained at surgery from controls (N = 16; 4 females, 12 males; mean age 70 years), and active and inactive ulcerative colitis (N = 15; 3 females, 12 males; mean age 39). Total antioxidant capacity of control colon was higher in muscularis externa compared to the mucosal-submucosal layer (P < 0.05). There were no differences in colonic total antioxidant capacity or lipid hydroperoxide levels comparing control colon to inactive and active ulcerative colitis. The results did not support depletion of tissue total antioxidant capacity by free radicals. Depletion of glutathione in ulcerative colitis may be a specific disorder rather than a secondary defect attributable to global oxidative stress. Nonspecific antioxidant supplements appear unlikely to be beneficial in the treatment of ulcerative colitis.

Nitric oxide production is diminished in colonic circular muscle from acquired megacolon

PURPOSE

Nitric oxide modulates human colonic smooth muscle function. To determine whether nitric oxide production is altered in colon from acquired megacolon, we measured cholinergic nerve-mediated contractions in vitro before and after inhibition of nitric oxide synthase.

METHODS

Intramural nerves in circular smooth muscle from histologically normal colon (n = 12) and acquired megacolon (n = 3) were activated by electrical field stimulation.

RESULTS

In controls blockade of nitric oxide synthase by N(G)-Nitro-L-Arginine induced increases (P < 0.05) in amplitude of contractions; these increases in amplitudes were blocked by L-Arginine (analysis of variance; P < 0.05). By contrast, blockade of nitric oxide synthase did not increase amplitudes of contractions with circular smooth muscle from acquired megacolon. An immediate phasic contraction was blocked by atropine sulfate.

CONCLUSIONS

The results support the concept that nitric oxide production modulates cholinergic nerve-mediated contractions in normal colonic circular muscle, whereas acquired megacolon is associated with altered release of this inhibitory neurochemical. Potential explanations include depletion of tissue L-Arginine, decreased capacity to recycle citrulline to arginine, or decreased release of vasoactive intestinal peptide from circular smooth muscle in acquired megacolon.

Effect of barium sulfate on wound healing in the gastrointestinal tract of the rat

PURPOSE

To study the effect of barium sulfate on wound healing in the gastrointestinal tract of the rat.

MATERIALS AND METHODS

Sixty rats weighing approximately 320 g were divided into four groups: Fifteen control rats had gastric, small-bowel, and colonic incisions; 15 rats had gastric incision; 15 rats had small-bowel incision; and 15 rats had colonic incision. Barium sulfate was placed into the incision before closure in all rats except those in the control group, and the effects were documented clinically and histopathologically for 3 months. Autopsy was performed in five rats from each group at 1, 4, and 12 weeks. The incisions in the rats receiving barium sulfate were compared with those in the control rats.

RESULTS

There was no difference in the clinical course (weight gain, activity, and viability) between the control and experimental groups. Early and late autopsy findings and histopathologic grading of healing and inflammatory response were similar for both the control and experimental groups.

CONCLUSION

Under the conditions of this study, the effect of barium sulfate on visceral transmural wound healing in the gastrointestinal tract of the rat was minimal.

Nitric oxide synthase is increased following small intestinal transplantation in the rat

Transplantation of the small intestine is a neural model that could include extrinsic denervation, loss of intrinsic enteric neurons, or loss of intrinsic neural pathways. Nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase activity was measured in normal rat ileum, ileum 3 months after resection of the jejunum, and ileum 3 months after isotransplantation of the ileum. The distribution of NADPH diaphorase activity and immunoreactive neuronal nitric oxide synthase were examined. Nicotinamide adenine dinucleotide phosphate diaphorase activity was increased in transplanted ileum (16.5+/-3.5 mU/mg protein) compared to normal controls (6.6+/-0.7) and resection controls (6.8+/-0.6) (P < 0.05, ANOVA). Histologically, NADPH diaphorase activity and immunoreactive nitric oxide synthase appeared increased within nerve cell bodies following transplantation. These findings may represent an adaptive response of the enteric nervous system to extrinsic denervation. Loss of intrinsic neural pathways was not supported as a mechanism.

Distribution of muscarinic receptor subtypes in rat small intestine

Despite its great promise, small intestinal transplantation in some patients is complicated by difficult postoperative management. The reasons for this are complex. In a rat model of small intestinal transplantation, frequencies of migrating myoelectric complexes during fasting are reduced in ileal isografts and muscarinic receptor density is decreased. We hypothesized that the distribution of muscarinic 1 receptors localized to enteric neurons is altered after small intestinal transplantation. Distal small intestine was orthotopically transplanted in Lewis-to-Lewis donor-recipient combinations. At 3 months, transplanted and normal ileum was obtained to prepare membrane fractions. [N-methyl-3H]Scopolamine served as ligand, while scopolamine methylbromide, pirenzepine, and methoctramine were used in competitive homologous and heterologous displacement experiments. Receptor subtype models were examined by nonlinear regression analysis. In normal and transplanted ileum, heterologous displacement was consistent with three site models (P < 0.05). In normals, the muscarinic 1 receptor subtype was most abundant, with a relative distribution of 69 to 78%. There was a relative distribution of 13 to 16% for muscarinic 3 receptor subtype. After transplantation, the muscarinic 1 subtype decreased to a mean of 45% but the muscarinic 3 subtype increased to a mean of 42%. Using pirenzepine, mean pKD values were not different between the two groups. It is concluded that the decrease in muscarinic 1 receptor subtype after transplantation could be related to neuronal cell loss or to downregulation of the expression of muscarinic 1 receptors. The results did not support defective posttranslational processing of receptor proteins.

Inflammation modulates in vitro colonic myoelectric and contractile activity and interstitial cells of Cajal

Inflammation suppresses phasic contractile activity in vivo. We investigated whether inflammation also suppresses in vitro phasic contractile activity and, if so, whether this could in part be due to the alteration of specific slow wave characteristics and morphology of the interstitial cells of Cajal (ICC). Circular muscle strips were obtained from normal and inflamed distal canine colon. Inflammation was induced by mucosal exposure to ethanol and acetic acid. The amplitudes of spontaneous, methacholine-induced, substance P-induced, and electrical field stimulation-induced contractions were smaller in inflamed muscle strips than in normal muscle strips. Inflammation reduced the resting membrane potential and the amplitude and duration of slow waves in circular muscle cells. Inflammation did not affect the amplitude of inhibitory junction potentials but did decrease their duration. Ultrastructural studies showed expansion of the extracellular space between circular muscle cells, reduction in the density of ICC and associated neural structures, damage to ICC processes, vacuolization of their cytoplasm, and blebbings of the plasma membrane. We conclude that inflammation-induced alterations of slow wave characteristics contribute to the suppression of phasic contractions. These alterations may, in part, be due to the damage to ICC. Inflammation impairs both the myogenic and neural regulation of phasic contractions.

Postprandial motor activity and its relationship to transit in the canine ileum

BACKGROUND

The purpose of this study was to elucidate the mechanism of reduced intestinal transit rate in the ileum as compared with the jejunum.

METHODS

Twenty-one dogs were each instrumented with 12 strain gauge transducers, 2 collection cannulas, and an infusion catheter defining a 100 cm study in the midjejunum (n = 11) and midileum (n = 10). Postprandial motor activity and intestinal transit were measured 1 hour after ingestion of a 650 kcal solid meal. Contractile activity was analyzed by means of computer programs that determine frequency, amplitude, and propagation behavior of circular smooth muscle contractions.

RESULTS

Postprandial ileal contractions occurred with greater frequency (13.7 +/- 2.5 versus 11.5 +/- 0.4; p = 0.04) and displayed a higher incidence of propagation (61% +/- 2% versus 44% +/- 3%; p = 0.0001) than jejunal contractions, but traveled at significantly slower rates (1.0 +/- 0.7 cm/sec vs 3.7 +/- 0.9 cm/sec; p = 0.0001). The net result was significantly slower transit in the ileum compared with the jejunum (4.7 +/- 0.7 cm/min versus 13.1 +/- 1.5 cm/min; p = 0.0006). Within each region, transit correlated with parameters of propagating contractions. Stepwise regression of the combined data revealed that contraction velocity was the most important variable determining intestinal transit rate (r = 0.64; p < 0.001).

CONCLUSIONS

Contrary to previous thinking, postprandial ileal contractions display a high degree of temporal and spatial organization. Slow ileal transit is mainly due to reduced propagation velocity, which is intrinsic to the circular smooth muscle.

Decreased vasoactive intestinal peptide levels and glutathione depletion in acquired megacolon

We reported decreased vasoactive intestinal peptide levels in acquired megacolon. The origin of altered neuropeptide levels is unknown, but recent work suggested that tissue antioxidants may function as neuroprotectants. Our hypothesis was that altered levels of inhibitory neurotransmitters in human colon are associated with depletion of the tripeptide thiol, glutathione. Normal colon samples (N = 10; from patients 41-80 years old) and acquired megacolon samples (N = 10; from patients 31-98 years old) were obtained at surgery. Vasoactive intestinal peptide levels were decreased in muscularis externa from acquired megacolon (P = 0.01), while there was a modest increase in NADPH diaphorase activity in muscularis externa from megacolon (P = 0.10). Glutathione in acquired megacolon was detectable in muscularis externa from only five specimens (P < 0.05), but was not significantly different (P > 0.05) in the mucosal-submucosal layer. The results supported the presence of vasoactive intestinal peptide and NADPH diaphorase in distinct subpopulations of nerves in human colon. The results also supported the hypothesis that glutathione functions as a neuroprotectant in a subset of patients with acquired megacolon.

Myoelectric activity and absorptive capacity of rat small intestinal isografts

The effect of transplantation on small intestinal absorption, digestive capacity, myoelectric activity, and morphology was assessed in inbred Lewis rats. Electrodes were sutured to the duodenum and isografted jejunoileum or to the native jejunoileum in controls. The frequency of migrating myoelectric complexes (MMCs) in the duodenum was 3.3 +/- 0.3/hr in controls and 1.8 +/- 0.4/hr in transplants (P < 0.05). MMC frequency in the jejunoileum was 5.1 +/- 1.3/hr in controls and 3.2 +/- 0.9/hr in transplants (P > 0.05). MMCs appeared to migrate from the duodenum to the jejunoileum 80 +/- 3% of the time in controls and 59 +/- 7% of the time in transplant rats (P < 0.05). Absorption in the transplanted jejunoileum demonstrated a 35-40% decrease in glucose and electrolytes absorption. Villus height and number of nuclei per villus was reduced. Intestinal length (dry) was 103 +/- 6 cm for controls and 51 +/- 3 cm for transplant rats (P < 0.05). Brush border sucrase activity was unchanged. We conclude that small intestinal isografts display similar myoelectric activity as controls, but the decreased absorptive capacity and villus height may require longer segments of intestine to be transplanted in order to support normal nutrition.

Expression of mRNA for vasoactive intestinal peptide in rat small intestine

Transplantation of small intestine is a neural model that permits studies of expression of the neuropeptide, vasoactive intestinal peptide, following extrinsic denervation, transection of intrinsic neural pathways, and an ischemic interval. Tissue levels of vasoactive intestinal peptide were examined at 3 months in ileum from a sham operation, in ileum after resection of proximal small intestine, in ileum after resection of proximal small intestine and extrinsic denervation, in ileum after resection of proximal small intestine and 30 min of ischemia, and in ileum obtained 3 months after ileal isografting in Lewis-to-Lewis combinations. Vasoactive intestinal peptide levels were increased in transplanted rat ileum, resection controls, denervation controls, and ischemic controls compared to sham-operated ileum (pANOVA < 0.01). The increased levels of this peptide were highest in denervation controls and lowest in ischemic controls. Northern blot analysis using rat vasoactive intestinal peptide cDNA identified a single 1.7-kb transcript in normal and transplanted rat ileum. The density of vasoactive intestinal peptide transcripts was increased in transplanted ileum (8450 +/- 540) compared to normal ileum (5790 +/- 620) (P < 0.01), and the ratio of this transcript to glyceraldehyde-3-phosphate dehydrogenase density units was also increased in transplanted ileum (0.81 +/- 0.08) compared to normal ileum (0.40 +/- 0.07; P < 0.01). Enhanced transcriptional regulation was the likely mechanism for increased tissue vasoactive intestinal peptide. The increased tissue levels appeared to be a response to extrinsic denervation and transection of intrinsic neural pathways, while an ischemic interval appeared to decrease tissue levels of the peptide.

Delayed gastroduodenal emptying is an important mechanism for control of intestinal transit in short-gut syndrome

PURPOSE

To understand the relative importance of changes in ileal smooth muscle contractility versus alteration of intestinal flow rate as control mechanisms for regulating intestinal transit in a surgical model of short-gut syndrome.

METHODS

A model of short-gut syndrome was created by performing a 70% proximal small-bowel resection in dogs. Ten control and 6 animals with short-gut syndrome were instrumented with strain gauge transducers, steel collection cannulas, and a Silastic intraluminal infusion catheter in the midileum. Motor activity was analyzed by computer programs that determine frequency, amplitude, and propagation behavior of postprandial contractions. Perfusions of 14C-polyethylene glycol and bolus injection of 3H-polyethylene glycol were used to determine intestinal flow and transit rates. Total gastroduodenal emptying was determined using a 14C-polyethylene glycol-labelled meal.

RESULTS

Postprandial contraction frequency was decreased in animals with short-gut syndrome, but other significant changes in amplitude, mean area, and propagation behavior of postprandial ileal contractions were not seen. Gastroduodenal emptying and mean intestinal flow rates were markedly slower in animals with short-gut syndrome, as were intestinal transit rates.

CONCLUSIONS

In this model of short-gut syndrome, the major adaptive change is decreased intestinal flow rate, related to delayed gastroduodenal emptying. The spatial organization of ileal contractions does not change substantially aside from a change in frequency which can be accounted for by transection of the intestinal wall.

Prevention of blood exposure. Body and facial protection

Regardless of the specific clinical setting in the operating room, it is clear that better protection of all personnel is an appropriate objective in the current environment. Better protection through improved PPE and modification of operational practices is essential. A prompt response to blood contact when it does occur is likewise appropriate. With conscientious applications of methods to reduce blood exposure, it is hoped that the operating room can become a safer place with respect to occupational infections from bloodborne pathogens.

Immunocytes and abnormal gastrointestinal motor activity during ileitis in dogs

Infiltration of specific immunocytes and stimulation of abnormal gastrointestinal motor activity during ileal inflammation induced by mucosal exposure to ethanol and acetic acid were investigated in 17 dogs. Ileal inflammation significantly increased the frequency of giant migrating contractions (GMCs) and decreased the frequency of migrating motor complexes (MMCs). The frequency of retrograde giant contractions (RGCs) increased only on the day of ethanol and acetic acid treatment. Diarrhea, urgency of defecation, and apparent abdominal discomfort were related to the increased frequency of GMCs. Ileal inflammation also prolonged the duration of postprandial MMC disruption. Histological and immunohistochemical findings indicated transmural inflammation with marked increase in polymorphonuclear cells in the lamina propria and muscularis externa layers. Myeloperoxidase activity increased severalfold in both layers. Cells containing interleukin-2 receptor (IL-2R) increased in the lamina propria. Other immunocytes, such as B and T lymphocytes, dendritic cells, and human leukocyte antigen DR-1 (HLADR)-positive cells, did not exhibit a significant increase in the inflamed ileum compared with the normal proximal jejunum. We conclude that stimulation of GMCs may be the major motility marker of intestinal inflammation.

Bloodborne pathogen transmission from healthcare worker to patients. Legal issues and provider perspectives

Health-care providers have an obvious, primary obligation to patients. Yet providers also have obligations to the public health (society), their institutional or individual self-interests, and their employees (fellow health-care workers). These obligations contain inherent conflicts, and attempts to reconcile the conflicts often perpetuate contradictions. This article identifies and discusses some of the moral and legal bases of these conflicts.

Multidisciplinary management of altered body image in the patient with an ostomy

Many clinical studies have found patients with ostomies to be a group facing multiple adjustment demands. One of these demands is coping with a significant change in body image. At the Medical College of Wisconsin, a team approach has been initiated; the ET nurse, the psychologist, and the surgeon deal with body image concerns together. Problems requiring counseling have included difficulty with personal acceptance, personal and social body-image disruption, sexual concerns, reduced self-care skills, and the management of surgical complications. This article represents a study employing a methology of selected case presentations. Cases were chosen to outline the types of problems encountered and were selected from referrals made for psychologic intervention by the surgeon and ET nurse. The patients included four women and three men, ranging in age from 22 to 79 years. Data were compiled by examining the records of the surgeon, ET nurse, and psychologist. The primary needs revolved around personal or social acceptance of altered body image. By addressing these needs in a straightforward, time-limited manner, postsurgical counseling was delivered effectively for these patients. In conclusion, we have demonstrated the multidisciplinary approach to be successful in facilitating adaptation to an altered body image.

Expression of mRNA for vasoactive intestinal peptide in normal human colon and during inflammation

The availability of colon provides a ready source of human neurons. Among the products of nerve cell bodies, vasoactive intestinal peptide is a neuropeptide that serves as a marker of non-adrenergic, non-cholinergic inhibitory nerves in colon. These nerves have been proposed to be involved in regulation of immune function, secretion, and smooth muscle function. In previous work, we identified decreased tissue levels of vasoactive intestinal peptide in a disorder of chronic colonic mucosal inflammation, ulcerative colitis. We hypothesized that diminished gene expression of vasoactive intestinal peptide could result in decreased tissue levels of this neuropeptide. Sigmoid colon was obtained at surgery from controls (n = 6) and patients with ulcerative colitis (n = 6). Vasoactive intestinal peptide mRNA was quantified by Northern blot hybridization and tissue levels of vasoactive intestinal peptide were determined by radioimmunoassay. Tissue vasoactive intestinal peptide was decreased only in the mucosal-submucosal layer of ulcerative colitis (p = .02). There was a single 1.7 kbase vasoactive intestinal peptide transcript identified in both control colon and ulcerative colitis. Normalized vasoactive intestinal peptide mRNA levels were increased by 260% in ulcerative colitis compared to controls (p < .01). These observations suggest that decreased vasoactive intestinal peptide gene expression or abnormal post-transcriptional processing are not primary defects in this disorder of chronic inflammation. The findings support the alternative hypothesis that axonal degeneration in ulcerative colitis could result in increased expression of neuronal vasoactive intestinal peptide mRNA.

Motor activity and transit in the autonomically denervated jejunum

The role of extrinsic (autonomic) innervation in postprandial contractile activity of the small intestine is unknown. Using a canine model, we investigated the effects of complete extrinsic denervation on the parameters of fasting and postprandial jejunal contractions and their relationship to intestinal transit. Individual contractions were recorded using strain gauge transducers. Spatial and temporal parameters of contractions were analyzed by computer methods. Bolus injection of 14C-polyethylene glycol was used to calculate intestinal transit rates. Statistical comparisons of control and denervated animals were made by nonparametric tests. Extrinsic denervation did not abolish fasting or fed motor activity, but the following effects were observed: (1) the frequency of migrating motor complexes (MMCs) increased; (2) the onset of fed motor activity was delayed, and the duration of fed activity was shortened; (3) frequency, mean amplitude, and mean area of postprandial contractions were decreased; (4) fewer contractions propagated distally, and mean propagation distance was shortened; and (5) intestinal transit was slower for solids, but not for liquids. In the small intestine, extrinsic nerves modulate motor activity, which is under primary control of the intrinsic (enteric) nervous system.

Gene expression and transcript size of the prepro-peptide VIP/PHM-27 in normal human tissue

The transcript size of VIP/PHM-27 mRNA (vasoactive intestinal peptide/peptide histidine methionine) and the relative distribution of VIP/PHM-27 gene expression in 10 normal human tissues was examined. After mRNA extraction from tissue, VIP/PHM-27 transcript size and relative abundance of mRNA was determined by Northern blot analysis and densitometry of the autoradiograms. VIP/PHM-27 mRNA was detectable in brain, pancreas, colon, ileum and striated muscle while no hybridization signal was observed in liver, kidney, lung, heart, prostate and placental tissue. VIP/PHM-27 transcript in human brain and gut was a single band of 1.7 kb; by contrast, a 7.0-kb transcript was detected in striated skeletal muscle. The highest relative levels of mRNA were observed in brain and pancreas.

Muscarinic cholinergic receptor density following small intestinal transplantation in rats

After small intestinal transplantation, intestinal isografts can organize migrating myoelectric complexes, and we have shown that migrating myoelectric complex frequency in the fasted state was reduced compared with controls after transplantation of the distal 50% of small intestine. We hypothesized that changes in motor activity after transplantation were related to alteration of cholinergic nerve activity or receptor density. With use of standard microsurgical techniques, the distal 50% of small intestine was orthotopically transplanted in a Lewis-to-Lewis donor-recipient combination. Resection controls were prepared by resecting the proximal 50% of small intestine, and sham controls were prepared by performing a sham laparotomy. Two months after surgery, small intestine was harvested. Choline acetyltransferase activity among the three groups was similar, suggesting that intrinsic cholinergic nerves remained intact. There was a strong trend toward decreased acetylcholinesterase activity [analysis of variance (ANOVA), P = 0.16] after transplantation, consistent with loss of extrinsic vagal nerve fibers. There were no differences in histochemical distribution of acetylcholinesterase among these groups. Muscarinic receptor density, as determined by binding to [N-methyl-3H]scopolamine, was decreased after transplantation (ANOVA, P = 0.02). There was a trend toward decreased receptor density in animals with resected small intestine. Surgical interruption of intrinsic nerve pathways rather than ischemia or extrinsic denervation might be the mechanism for diminished receptor density after transplantation, and reduced small bowel motor activity may be related to decreased density of muscarinic cholinergic receptors.

Assessing the risk of blood exposure in the operating room

During the past 3 years, a great deal of new information has been published on the risk of blood exposure and injury in the operating room. In addition, detailed information about the effectiveness of barrier materials, operating room garments, and gloves has also become available. On the basis of this information, it has become possible to recommend strategies, barrier materials, and garments that should reduce the risk of contracting a blood-borne infection in the operating room. Further attempts to decrease the risk of blood exposure and injury require thorough evaluation of all risk-reduction strategies and careful selection of protective apparel and barriers on the basis of well-designed studies performed in the operating room environment.

Pathophysiology of small intestinal motility

Only in the last few years have we begun to understand the effects of surgical procedures on contractile activity of the small intestine. Although most patients readily adapt to the procedures that are performed, operations such as small intestinal transplantation make it imperative that we pursue a more thorough understanding of the effects of surgery on the motility of the small intestine.

Acquired megacolon is associated with alteration of vasoactive intestinal peptide levels and acetylcholinesterase activity

Based upon previous morphologic studies, we hypothesized that the development of acquired megacolon was associated with abnormalities of enteric neurotransmitter concentrations and enzymatic activities. Specimens were obtained at surgery from patients with normal descending-sigmoid colon (n = 13) and patients with sigmoid megacolon (n = 6; defined by radiologic measurement). Radioimmunoassays were used to measure the non-adrenergic, non-cholinergic inhibitory neuropeptide, vasoactive intestinal peptide, and the non-adrenergic, non-cholinergic excitatory neuropeptide, substance P, while spectrophotometric assays were used to quantitate acetylcholinesterase activity and choline acetyltransferase activity. There were significantly decreased concentrations of vasoactive intestinal peptide and decreased acetylcholinesterase activity in muscularis externa from patients with acquired megacolon. In megacolon, vasoactive intestinal peptide-containing nerve fibers appeared to be diminished in circular and longitudinal smooth muscle, and immunostaining of nerve cell bodies in the plexus submucosus externus appeared diminished. These results suggest the hypothesis that production of vasoactive intestinal peptide is altered allowing secondary colonic hypertrophy to develop from prolonged cholinergic nerve-mediated contractions of circular smooth muscle. As a corollary to this hypothesis, colonic dilatation might result from prolonged contraction of longitudinal smooth muscle.

In-use evaluation of surgical gowns

Surgical gowns must protect patients from the bacteria of operating room personnel and also protect staff members from the lethal viruses in the blood of patients. The current study was done to evaluate the barrier function of several surgical types of gowns during use in surgical procedures and identify the frequency of failure of the gowns and some causes for this failure. We performed direct observation of 234 operations during which the surgeon and the first assistant wore 535 gowns. Blood strikethrough occurred most often when contamination on the outside of the gown was heavy (20 per cent), but still occurred after medium (7 per cent) and small (1 per cent) contamination. We found significant differences between gowns based on the material used and the design of the gowns. Gowns reinforced with a second layer of material or a layer of plastic material were more effective at preventing strikethrough than a single layer of material. One gown was identified that was unacceptable for any use in the operating room. Gowns of different designs and degrees of protection should be chosen based on the body area likely to be exposed to blood and the amount of predicted blood contamination. Further improvement in gown materials and design are required, since surgeons cannot consider any of these gowns protective during strenuous use.

Double gloving. Protecting surgeons from blood contamination in the operating room

Health care workers, particularly surgeons, understand the importance of preventing contamination from blood of patients infected with deadly viruses. One of the most common areas of contamination is the hands and fingers due to the failure of glove protection. There are varying opinions regarding the frequency of glove failure, the necessity of wearing two gloves for added protection, and the ability to operate when wearing two gloves. We performed a prospective, randomized, trial of 143 procedures involving 284 persons to answer these questions for surgeons and first assistants. Overall, the glove failure rate (blood contamination of the fingers) was 51% when one glove was worn and 7% when two gloves were worn. Acceptability was 88% in the group who agreed to wear two gloves, and 88% of these did not perceive that tactile sense was significantly impaired. We believe that double gloving should be, and can be, used routinely during major surgical procedures to protect surgeons from blood contamination.

Small bowel transplantation promotes bacterial overgrowth and translocation

Alterations in the symbiotic relationship between immunocompromised hosts and their resident gut microflora may lead to serious complications following small bowel transplantation (SBT). This study examined the effects of SBT and cyclosporine (CsA) immunosuppression on gut bacterial populations and translocation to the mesenteric lymph nodes. Sixty adult male meat-fed Lewis rats were divided into six groups: normal controls, CsA alone (24 mg/kg im qod), CsA carrier vehicle alone, isografts, isografts given CsA, and allografts given CsA. Rats were killed after 3 weeks and segments of small bowel and colon were harvested for quantitative tissue culture. Mesenteric lymph nodes and blood were cultured to identify translocation. Transplantation alone led to an increase in gram-negative aerobes from 2.6 to 4.6 colony forming units/100 mg tissue (P less than 0.05) in the distal ileum (transplanted segment). Eighty-four percent of transplanted animals receiving CsA had bacteria recovered from their mesenteric lymph nodes compared to none in controls (P less than 0.001) and 20% in isografts not receiving CsA (P less than 0.02). Intestinal transplantation alone appears to promote gram-negative overgrowth while the addition of CsA therapy facilitates translocation to the mesenteric lymph nodes and may predispose to gut-associated sepsis following SBT.

Risk of blood contamination and injury to operating room personnel

The potential for transmission of deadly viral diseases to health care workers exists when contaminated blood is inoculated through injury or when blood comes in contact with nonintact skin. Operating room personnel are at particularly high risk for injury and blood contamination, but data on the specifics of which personnel are at greater risk and which practices change risk in this environment are almost nonexistent. To define these risk factors, experienced operating room nurses were employed solely to observe and record the injuries and blood contaminations that occurred during 234 operations involving 1763 personnel. Overall 118 of the operations (50%) resulted in at least one person becoming contaminated with blood. Cuts or needlestick injuries occurred in 15% of the operations. Several factors were found to significantly alter the risk of blood contamination or injury: surgical specialty, role of each person, duration of the procedure, amount of blood loss, number of needles used, and volume of irrigation fluid used. Risk calculations that use average values to include all personnel in the operating room or all operations performed substantially underestimate risk for surgeons and first assistants, who accounted for 81% of all body contamination and 65% of the injuries. The area of the body contaminated also changed with the surgical specialty. These data should help define more appropriate protection for individuals in the operating room and should allow refinements of practices and techniques to decrease injury.

Small bowel transplantation in the rat with immediate restoration of intestinal continuity

Compared with other rat transplant models, small bowel transplantation (SBT) is associated with higher peritransplant morbidity and mortality. We describe a two-stage technique of SBT in the rat that minimizes perioperative complications and also allows immediate restoration of intestinal continuity. Inbred Lewis strain rats were used as donors and recipients. A one-stage technique was originally adopted whereby the distal 50% of the jejunoileum was transplanted followed by near-total resection of the native small intestine and restoration of intestinal continuity. Among 20 rats transplanted with this technique, only one survived longer than 30 days. With the two-stage technique, transplantation of the donor jejunoileum in continuity was performed, followed by native enterectomy 7 days later. With the two-stage technique 17 of 20 rats survived indefinitely (greater than 50 days). Other important technical modifications are described. In the hands of a skilled microvascular surgeon, the two-stage SBT technique results in consistently improved survival and minimal morbidity.

Great expectations: stress and the medical family. 1987 Committee on Issues, Association for Academic Surgery

The high divorce rate and significant stress experienced by families of academic surgeons stimulated the Committee on Issues of the Association of Academic Surgery to choose medical family stress as the topic for the 1987 Committee presentation at the annual meeting. The Committee hoped to provide insight into the cause of this stress and new strategies for coping with this pervasive problem. Forty-three percent of the 505 surgeons who entered the Association from 1981 through 1984 and 38% of their spouses responded to a questionnaire covering issues of time management, response to stress, child rearing, financial security, and spouse career. A panel consisting of Shirley P. Levine, M.D., Hiram C. Polk, Jr., M.D., and Lane A. Gerber, Ph.D., after discussing the questionnaire results, recommended realistic goal setting, specific prioritization of activities, recognition of the considerable contributions of the spouse, and insight into personal limitations as mechanisms for improving family function.

The efficacy of oral antimicrobials in reducing aerobic and anaerobic colonic mucosal flora

We investigated the impact of intestinal antisepsis on the colonic mucosa-associated flora. Four groups of dogs were studied: group A received no bowel preparation, group B received a three-day clear-liquid diet, group C underwent mechanical cleansing of the bowel, and group D had mechanical cleansing followed by oral neomycin and erythromycin. Mucosal biopsy specimens were obtained for bacteriologic and scanning electron microscopic (SEM) studies. No significant difference in recovery of mucosal bacteria was observed between groups A and B. A significant decrease in recovery of aerobes was observed in group C, and a significant decrease in both aerobes and anaerobes was observed in group D compared with group A; Enterobacteriaceae and Bacteroides were either eliminated or greatly reduced. The SEM analysis of group D revealed a marked decrease in mucosa-associated microflora compared with groups B and C. Oral neomycin-erythromycin produced a significant quantitative reduction in the colonic mucosa-associated bacterial population, including the potentially pathogenic Escherichia coli and Bacteroides fragilis group isolates. These mucosa-associated bacteria are a likely source of contamination of the abdominal cavity and wound at the time of colon surgery.

Opioid receptors and the initiation of migrating myoelectric complexes in dogs

The role of endogenous opioids and opioid receptors in the control of migrating myoelectric complexes (MMCs) was studied in conscious dogs implanted with silver-silver chloride electrodes. In normal fasted dogs, MMC cycle times were 103 +/- 7 min in the duodenum. During naloxone infusion (1-2 mg/kg iv, then 0.2-1.0 mg.kg-1.h-1 iv) cycle times increased to 219 +/- 29 min (P less than 0.01). Naloxone (2 mg/kg iv, then 1 mg.kg-1.h-1 iv) had no effect on the response of the small intestine to bethanecol (5 mg sc) or to feeding. Pretreatment with naloxone (2 mg/kg iv) 5 min before the administration of motilin (400-500 micrograms/kg iv) did not block the initiation of MMCs by motilin. In separate experiments, animals were pretreated with the positive or negative isomer of the opioid receptor antagonist WIN-44,441 (0.2 mg/kg iv) 5 min before morphine administration. The negative isomer binds to opioid receptors whereas the positive isomer does not. The negative but not the positive isomer antagonized all effects of morphine on intestinal myoelectric activity. These studies suggest that endogenous opioids and opioid receptors may play a role in control of the initiation of MMCs and that motilin and exogenous opioids act via different mechanisms to initiate MMCs.

Ketocyclazocine, a kappa-opioid receptor agonist, and control of intestinal myoelectric activity in dogs

The role of kappa-opioid receptors in the control of fed and fasted myoelectrical activity of the stomach and small intestine was studied in conscious dogs implanted with bipolar silver electrodes. In fasted dogs, migrating myoelectric complex (MMC) cycle times were 105 +/- 14 min in the duodenum. Administration of ketocyclazocine (1 mg/kg iv) inhibited contractile activity, blocked migration of distally propagating MMCs, and increased the MMC cycle time to 246 +/- 56 min (P less than 0.0005). Pretreatment with naloxone (2 mg/kg iv) 5 min before administration of ketocyclazocine (1 mg/kg iv) prevented the disruption by ketocyclazocine of the distally propagating MMC but did not completely antagonize the effect of ketocyclazocine on MMC cycle time. MMC cycle time was 102 +/- 14 min before naloxone plus ketocyclazocine administration and 138 +/- 22 min after administration (P less than 0.005). Although MMC cycle times were still significantly prolonged over control after naloxone plus ketocyclazocine, cycle times were significantly decreased compared with ketocyclazocine administration alone (P less than 0.005). Ketocyclazocine (1 mg/kg iv) completely inhibited the fed pattern of myoelectric activity for 74 +/- 26 min when administered 15 min after feeding. Bethanecol (2 mg sc)-initiated spike activity was not blocked by ketocyclazocine. These studies suggest that endogenous opioids and kappa-opioid receptors may play a role in the inhibition of gastric action potentials and small intestinal spiking activity.

Primary adenocarcinoma of the ileostomy after colectomy for ulcerative colitis

A fifth case of adenocarcinoma arising at an ileostomy site many years after total colectomy for ulcerative colitis is reported with a review of the literature. The patient is a 79-year-old white man who presented with a bleeding, locally invasive exophytic mass at his ileostomy site 36 years after total colectomy for ulcerative colitis; he is the oldest patient, with the longest interval from creation of his ileostomy to diagnosis of adenocarcinoma. Careful gross and histopathologic examination of any mass arising at an ileostomy site is recommended. Early detection of such a slowly growing malignancy arising in a long-standing ileostomy may result in cure.

Effect of central sympathectomy on gastric and small intestinal myoelectric activity and plasma motilin concentrations in the dog

Using a canine model, we studied fed and fasting gastric and small intestinal myoelectric activity and plasma motilin concentrations before and after transection of the spinal cord between the second and third thoracic segments. In sham-operated dogs, migrating complexes returned to normal by the second day after operation. Immediately after spinal cord transection, migrating complexes cycled in jejunum and ileum but not in the stomach and duodenum. After 11 and 15 days, migrating complexes returned to the duodenum and stomach, respectively. Plasma motilin concentrations did not cycle in animals without duodenal migrating complexes but returned to a normal cyclical pattern when duodenal migrating complexes returned. Feeding interrupted migrating complexes after cord transection and sham operation. The data observed in animals after 15 days suggest that myoelectric activity in fasted dogs and conversion of the fasted to the fed state of myoelectric activity are not under the control of supraspinal, sympathetic pathways.

Morphine initiates migrating myoelectric complexes by acting on peripheral opioid receptors

The role of peripheral and central opioid receptors in morphine-induced migrating myoelectric complexes (MMECs) was studied in conscious dogs implanted with silver-silver chloride electrodes. In normal fasted dogs morphine (100-200 micrograms/kg iv) initiated phase III of the MMEC in the duodenum. Once initiated the MMEC propagated distally. This effect of morphine was blocked by the opioid receptor antagonists naloxone (2 mg/kg iv) and N,N-diallylnormorphinium bromide (4 mg/kg iv). Higher doses of morphine (300-600 micrograms/kg iv) initiated phase III activity in fed dogs as early as 20 min after feeding, while lower doses (150 micrograms/kg iv) initiated phase III activity routinely when administered 100 min after feeding. In dogs with bilateral vagotomies and bilateral thoracolumbar sympathetic chain ganglionectomies, morphine (150 micrograms/kg iv) initiated phase III activity in the duodenum, which then migrated distally. This study demonstrates that morphine initiates phase III of the MMEC by acting through peripheral opioid receptors.

Pancreaticogastrostomy: clinical experience with a direct pancreatic-duct-to-gastric-mucosa anastomosis

The propensity for leakage and disruption at the site of the pancreaticojejunostomy is a major reason for morbidity and death after pancreaticoduodenal resection. Because it is less prone to leakage and disruption, pancreaticogastrostomy has been reintroduced as a possible alternative to pancreaticojejunostomy. Of four patients in whom the pancreas was simply implanted into the stomach and five patients in whom a direct pancreatic-duct-to-gastric-mucosa anastomosis was constructed, there was no morbidity or death related to the pancreatic anastomosis. Because of evidence that a direct pancreatic-duct-to-gastric-mucosa anastomosis has an increased incidence of patency and because it was successful in a clinical setting, it is recommended.

Mechanism of propagation of canine migrating motor complex--a reappraisal

This study quantitatively evaluated the characteristics of the aboral propagation of the canine migrating motor complex (MMC). Five conscious dogs were implanted with extraluminal force transducers along the small intestine. After constructing a 30-cm Thirty-Vella loop of jejunum, 56 of 91 activity fronts were outside the tolerance limits for propagation from the proximal intestine to the loop established in the same dogs before operation. Similarly, 44 of 109 activity fronts were outside the tolerance limits for propagation from the loop to the distal intestine. After surgery, the propagation time from the proximal jejunum to the loop was significantly increased, and activity fronts were observed to originate in the loop and in the intestine distal to the anastomosis. Our study indicates that the hypothesis that extrinsic nerves alone control the migration of the MMC is incomplete. We suggest that the extrinsic and the intrinsic innervation of the gastrointestinal tract are both required for the precise pattern of the migration of the MMC.