Skeletal muscle tissue engineering approaches to abdominal wall hernia repair

Abdominal wall hernias resulting from prior incisions are a common surgical complication affecting hundreds of thousands of Americans each year. The negative consequences associated with abdominal hernias may be considerable, including pain, bowel incarceration, vascular disruption, organ loss, and death. Current clinical approaches for the treatment of abdominal wall hernias focus on the implantation of permanent biomaterial meshes or acellular xenografts. However, these approaches are not infrequently associated with postoperative infections, chronic sinuses, or small bowel obstruction. Furthermore, the most critical complication, hernia recurrence, has been well described and may occur in a large percentage of patients. Despite many advances in repair techniques, wound healing and skeletal muscle regeneration is limited in many cases, resulting in a decrease in abdominal wall tissue function and contributing to the high hernia recurrence rate. This review will give an overview of skeletal muscle anatomy, skeletal muscle regeneration, and herniation mechanisms, as well as discuss the current and future clinical solutions for abdominal wall hernia repair. Birth Defects Research (Part C) 84:315–321, 2008. © 2008 Wiley‐Liss, Inc.     

The effects of phorbol esters on fluid transport and blood flow in the small intestine

Studies were designed to examine the effects of phorbol esters on intestinal fluid transport and blood flow in the anesthetized cat and enteropooling in the conscious rat. Intraluminal administration of phorbol ester into a segment of isolated small bowel produced a copious intestinal secretion and a concomitant mesenteric hyperemia in the cat. Net fluid movement in the intestine was converted from absorption in the control state to secretion following phorbol ester administration. Intravenous atropine reduced the phorbol ester-induced secretion by 56%; clonidine abolished the remaining secretory response. In the rat, intragastric administration of phorbol ester produced enteropooling comparable to that of other potent intestinal secretagogues. Since phorbol esters are known to activate protein kinase C, these studies suggest that activation of protein kinase C in the small intestine may lead to a full secretory response. The evidence suggests that this secretion is accompanied by a metabolic hyperemia. These results suggest that protein kinase C plays an important role in the regulation of intestinal fluid transport.     

Location and Pathogenic Potential of Blastocystis in the Porcine Intestine

Blastocystis is an ubiquitous, enteric protozoan of humans and many other species. Human infection has been associated with gastrointestinal disease such as irritable bowel syndrome, however, this remains unproven. A relevant animal model is needed to investigate the pathogenesis/pathogenicity of Blastocystis. We concluded previously that pigs are likely natural hosts of Blastocystis with a potentially zoonotic, host-adapted subtype (ST), ST5, and may make suitable animal models. In this study, we aimed to characterise the host-agent interaction of Blastocystis and the pig, including localising Blastocystis in porcine intestine using microscopy, PCR and histopathological examination of tissues. Intestines from pigs in three different management systems, i.e., a commercial piggery, a small family farm and a research herd (where the animals were immunosuppressed) were examined. This design was used to determine if environment or immune status influences intestinal colonisation of Blastocystis as immunocompromised individuals may potentially be more susceptible to blastocystosis and development of associated clinical signs. Intestines from all 28 pigs were positive for Blastocystis with all pigs harbouring ST5. In addition, the farm pigs had mixed infections with STs 1 and/or 3. Blastocystis organisms/DNA were predominantly found in the large intestine but were also detected in the small intestine of the immunosuppressed and some of the farm pigs, suggesting that immunosuppression and/or husbandry factors may influence Blastocystis colonisation of the small intestine. No obvious pathology was observed in the histological sections. Blastocystis was present as vacuolar/granular forms and these were found within luminal material or in close proximity to epithelial cells, with no evidence of attachment or invasion. These results concur with most human studies, in which Blastocystis is predominantly found in the large intestine in the absence of significant organic pathology. Our findings also support the use of pigs as animal models and may have implications for blastocystosis diagnosis/treatment.     

Failure to find a humoral factor which influences the compensatory response after resection of the rat small bowel

Small bowel resection was performed in one parabiont of a parabiotic rat pair to determine whether there was a "humoral" or other circulating factor present which could influence the compensatory response seen in the remainder of the small bowel. Following intestinal resection in one parabiont, there was an increase in DNA synthesis in the intestine of that member provided at least 40% of the small intestine was removed. The compensatory response seen in a resected animal was not observed in its parabiotic partner, even though an attempt was made to make the potentially responding animal more sensitive to the influence of any circulating "factors" by resecting its intestine as well. The results obtained are in disagreement with the one closely related report in the literature; it is suggested that there is no good evidence for the existence of a resection-induced circulating factor with the capability of crossing a vascular anastomosis and controlling proliferation of small intestinal epithelium.     

FAILURE TO FIND A HUMORAL FACTOR WHICH INFLUENCES THE COMPENSATORY RESPONSE AFTER RESECTION OF THE RAT SMALL BOWEL

Small bowel resection was performed in one parabiont of a parabiotic rat pair to determine whether there was a ‘humoral’ or other circulating factor present which could influence the compensatory response seen in the remainder of the small bowel. Following intestinal resection in one parabiont, there was an increase in DNA synthesis in the intestine of that member provided at least 40% of the small intestine was removed. the compensatory response seen in a resected animal was not observed in its parabiotic partner, even though an attempt was made to make the potentially responding animal more sensitive to the influence of any circulating ‘factors’ by resecting its intestine as well. The results obtained are in disagreement with the one closely related report in the literature; it is suggested that there is no good evidence for the existence of a resection-induced circulating factor with the capability of crossing a vascular anastomosis and controlling proliferation of small intestinal epithelium.     

A growth-stimulating activity derived from the proximal small intestine is associated with an adaptive response

Luminal nutrition is important for the maintenance of small intestinal structure and function. The equilibrium between crypt cell production and villous cell loss in the mucosal epithelium of the small intestine is altered under certain conditions such as after a small bowel resection. Immediately after resection, there is a marked increase in crypt cell proliferation giving rise to an adaptive hyperplasia in the remnant intestine and for this response luminal nutrition is a critical factor. We have previously demonstrated the presence of a growth-stimulating (GS) activity in a heat-stable acidic extract of the rat proximal intestine 24, 48, and 96 h after resection, which is coincidental with an increase in crypt cell proliferation as measured by thymidine kinase activity. Eight days after resection when the GS activity is no longer detectable, the thymidine kinase activity returns to control values. The molecular weights of the peptides associated with this GS activity are 4500 and 1500, as determined by Sephadex gel filtration. Of note is that the oral intake of food is necessary for the appearance of the GS activity postoperatively. The presence of the GS activity has also been demonstrated upon refeeding after a fast, as well as at weaning in the rat, two physiological situations known to be associated with increased proliferation in the small intestine. This GS activity in the proximal intestine first detected in the resection model may represent a general mechanism by which food controls the cell renewal pattern of the small intestine.     

Genital oedema in patients treated by continuous ambulatory peritoneal dialysis: an unusual presentation of inguinal hernia.

Four patients receiving continuous ambulatory peritoneal dialysis presented with scrotal or labial oedema but no detectable cough impulse. Two of the patients later developed clinical evidence of inguinal hernia, and in the other two inguinal hernias were found at operation. These cases suggest that genital oedema occurring in a patient receiving continuous ambulatory peritoneal dialysis is a sign of a small inguinal hernia which may not be detectable clinically.     

NUTRITIONAL ASPECTS OF ANASTOMOTIC OPERATIONS—With Special Reference to the Sprue Syndrome

Necessary but radical operation which results in short-circuits between various levels of the digestive tract, with or without resections of portions of the esophagus, stomach or intestine, frequently cures the condition for which the operation was done, but leaves the patient with difficult nutritional problems. These nutritional disturbances are usually associated with inability to maintain or gain weight as a result of badly regulated movement of food material through the altered digestive tract, and by the removal or diversion of important digestive secretions, such as those elaborated by the stomach, pancreas, duodenum and small bowel.Increased intestinal rate and diminished specific gastrointestinal secretions reduce the ability of the small bowel to properly absorb food, with resulting malnutrition, deficiency disease, and at times specific avitaminosis. Inability to absorb fat and fat-soluble substances is a constant feature of these conditions. Successful treatment of the nutritional problems involves constant, prolonged overfeeding of nonbulky foods, usually given in regular, frequently administered meals of small volume. Vitamin concentrates may occasionally be of some temporary assistance but are not needed if a balanced diet is given and may cause undesirable and sometimes dangerous symptoms. The use of supplemental substances, such as liver extract and a wetting agent, such as “Tween 80,” to improve fat absorption have been demonstrated to be of value.The postoperative conditions described are fairly similar to the condition known as sprue, and it is possible that the general principles underlying the treatment of this disease apply to the entire group of post-operative nutritional disturbances alluded to.     

Nutritional aspects of anastomotic operations with special reference to the sprue syndrome

Necessary but radical operation which results in short-circuits between various levels of the digestive tract, with or without resections of portions of the esophagus, stomach or intestine, frequently cures the condition for which the operation was done, but leaves the patient with difficult nutritional problems. These nutritional disturbances are usually associated with inability to maintain or gain weight as a result of badly regulated movement of food material through the altered digestive tract, and by the removal or diversion of important digestive secretions, such as those elaborated by the stomach, pancreas, duodenum and small bowel. Increased intestinal rate and diminished specific gastrointestinal secretions reduce the ability of the small bowel to properly absorb food, with resulting malnutrition, deficiency disease, and at times specific avitaminosis. Inability to absorb fat and fat-soluble substances is a constant feature of these conditions. Successful treatment of the nutritional problems involves constant, prolonged overfeeding of nonbulky foods, usually given in regular, frequently administered meals of small volume. Vitamin concentrates may occasionally be of some temporary assistance but are not needed if a balanced diet is given and may cause undesirable and sometimes dangerous symptoms. The use of supplemental substances, such as liver extract and a wetting agent, such as "Tween 80," to improve fat absorption have been demonstrated to be of value.The postoperative conditions described are fairly similar to the condition known as sprue, and it is possible that the general principles underlying the treatment of this disease apply to the entire group of post-operative nutritional disturbances alluded to.     

MATING FREQUENCY AND FECUNDITY IN INSECTS

1. The paper summarizes the published evidence on the relation between mating frequency and fecundity in insects. There is experimental evidence of varying quality for 63 species and non-experimental evidence for about 60.
2. Repeated mating may be universally necessary for full fecundity and fertility in female insects (in species in which the females normally mate more than once).
3. The evidence is remarkably poor. We need more properly designed experiments (and not just observations of natural variation), with sufficient sample sizes and statistics, and measurements of the fecundities and fertilities of singly and multiply mated females, when the multiple matings are separated by many days or weeks. Most of the existing experiments of this sort are defective in some way.
4. In species with greater total fecundity and longevity, multiple mating may be more likely to enhance fertility than in species with small fecundity and short life span.
5. Females in naturally monandrous species do not show increased fecundity or fertility with repeated mating, whereas females of polyandrous species do.
6. There is no obvious connexion between paternal investment, in so far as we know about it, and the increase of fecundity by repeated mating.
7. There is a small tendency for females to breed more quickly and be shorter lived if they mate repeatedly.     

Obstruction of Bowel due to Lesion in the Myenteric Plexus

Two patients are described who were found to have a destructive lesion of the myenteric plexus. In one the upper small intestine was involved and the clinical picture was of recurrent pseudo-obstruction; in the other the lesion was in the distal colon and resulted in intractable constipation. The lesion cannot be demonstrated by conventional histological techniques, being seen only in silver preparations cut parallel to the bowel wall, and may have been overlooked in the past. The aetiology is unknown.     

Platelet-activating factor: an endogenous mediator for bowel necrosis in endotoxemia

We have developed a model of isochemic bowel necrosis in the rat by injecting platelet-activating factor (PAF) or PAF in combination with bacterial endotoxin. PAF causes profound hypotension, and it has been suggested that it is released during endotoxin shock. Because ischemic bowel necrosis is often associated with shock or infection, it is possible that PAF is the endogenous mediator that causes shock and bowel necrosis during sepsis. In this study, we have demonstrated that: 1) normal intestine contained a small amount of PAF; 2) necrotic lesions of the intestine could be induced by endotoxin injection; 3) PAF production in the bowel is markedly increased in animals treated with endotoxin; 4) pretreatment of the animal with PAF antagonists prevent endotoxin-induced necrosis; 5) isolated, buffer-perfused small intestine produced a small quantity of PAF in response to endotoxin injection. Therefore, we conclude that PAF is a likely endogenous mediator in endotoxemia, which causes bowel necrosis and shock.     

EARLY DIAGNOSIS OF STRANGULATION OBSTRUCTION OF THE SMALL INTESTINE

Early recognition of strangulation obstruction of the small intestine is important in order that surgical relief may be undertaken before the bowel has been irreversibly damaged or the condition of the patient has so deteriorated as to make immediate operation unreasonably hazardous.In the presence of other symptoms, an operative scar, particularly on the lower abdomen, should alert the examining physician to the possibility of strangulation obstruction. (In a series of 100 cases, the greatest single cause of strangulation was adhesive bands subsequent to abdominal operation.)Other hallmarks of aid in diagnosis and in distinguishing early from advanced strangulation are discussed.X-ray evidence varies in accord with the rapidity of development and the stage of strangulation.Abdominal puncture may be utilized as a means of diagnosis with little risk.     

In vivo evidence for interferon-gamma-mediated homeostatic mechanisms in small intestine of the NHE3 Na+/H+ exchanger knockout model of congenital diarrhea

Mice lacking NHE3, the major absorptive Na(+)/H(+) exchanger in the intestine, are the only animal model of congenital diarrhea. To identify molecular changes underlying compensatory mechanisms activated in chronic diarrheas, cDNA microarrays and Northern blot analyses were used to compare global mRNA expression patterns in small intestine of NHE3-deficient and wild-type mice. Among the genes identified were members of the RegIII family of growth factors, which may contribute to the increased absorptive area, and a large number of interferon-gamma-responsive genes. The latter finding is of particular interest, since interferon-gamma has been shown to regulate ion transporter activities in intestinal epithelial cells. Serum interferon-gamma was elevated 5-fold in NHE3-deficient mice; however, there was no evidence of inflammation, and unlike conditions such as inflammatory bowel disease, levels of other cytokines were unchanged. In addition, quantitative PCR analysis showed that up-regulation of interferon-gamma mRNA was localized to the small intestine and did not occur in the colon, spleen, or kidney. These in vivo data suggest that elevated interferon-gamma, produced by gut-associated lymphoid tissue in the small intestine, is part of a homeostatic mechanism that is activated in response to the intestinal absorptive defect in order to regulate the fluidity of the intestinal tract.     

Adenosine 3' , 5'-cyclic monophsphate phosphodiesterase activities in the x-irradiation induced rat small bowel adenocarcinoma.

The adenosine 3′, 5′-cyclic monophosphate phosphodiesterase (PDE) activities were evaluated in X-irradiation induced Holtzman rat small bowell adenocarcinoma and age-matched normal small intestine. Within normal small intestine, PDE activity was optimal at pH 7.4, and highly dependent upon the addition of Mg²⁺ or Mn²⁺. Analyses of the rat small bowel adenocarcinoma revealed significantly elevated PDE activities above the normal small bowel which were found to be relatively constant throughout the length of the ileum and jejunum. These findings suggest that the diminished intracellular adenosine 3′, 5′-cyclic monophosphate levels observed in this lesion (1) may be the consequence of elevated PDE activities.     

Modulation of Salmonella infection by the lectins of Canavalia ensiformis (Con A) and Galanthus nivalis (GNA) in a rat model in vivo

The plant lectins, Concanavalin A (Con A) and Galanthus nivalis agglutinin (GNA) have been prefed to rats for 3 d pre- and 6 d postinfection with Salmonella typhimurium S986 or Salm. enteritidis 857. Con A significantly increased numbers of Salm. typhimurium S986 in the large intestine and in faeces, and severely impaired growth of the rats, more severely than is the case of infection with Salmonella typhimurium alone. Con A had much less effect on rats infected with Salm. enteritidis 857 only showing a significant increase in numbers in the colon, accompanied by intermittent increases of Salmonella in the faeces during the study. GNA significantly reduced pathogen numbers in the lower part of the small bowel and the large intestine of rats infected with Salm. typhimurium S986 and significantly improved rat growth. GNA had little effect on infection by Salm. enteritidis 857 with slight decreases in Salmonella numbers in the small intestine and large intestine and transient increases in the faeces.     

Inter-organ communication between intestine and liver in vivo and in vitro

The maintenance of body homeostrasis requires a finely tuned system of interorgan communication. The intimate metabolic interrelation between intestine and liver is characterized by the unique anatomic position of both tissues using the portal vein as a private channel with the pancreas in optimal position to modulate hepatic metabolism.Gut-derived peptides (such as glucagon-like peptide-1) appear to be involved in the process of liver regeneration by regulating the release of pancreatic hormones (e.g. insulin). Extensive bowel resection or functional exclusion of small intestine may lead to severe liver dysfunction and even cirrhosis, which may be due to the lack of some intestine-derived and as yet unknown factor(s). Here a close cooperation between small intestinal mucosa and hepatocytes is demonstrated leading to the concept of a metabolic gut-liver unit. This metabolic interaction forms a wide spectrum ranging from the secretion of peptide hormones to changes in (portal-venous) substrate availability or hepatocyte cell volume. Further investigation and identification of the mechanisms of such regulatory processes may be facilitated by combined perfusion of isolated rat intestine and liver. Using this in vitro approach we could demonstrate the presence of metabolic interorgan communication between isolated perfused tissues independent of plasma borne hormones or extrinsic neural control.     

An ultra-low-power image compressor for capsule endoscope

Background  

Gastrointestinal (GI) endoscopy has been popularly applied for the diagnosis of diseases of the alimentary canal including Crohn's Disease, Celiac disease and other malabsorption disorders, benign and malignant tumors of the small intestine, vascular disorders and medication related small bowel injury. The wireless capsule endoscope has been successfully utilized to diagnose diseases of the small intestine and alleviate the discomfort and pain of patients. However, the resolution of demosaicked image is still low, and some interesting spots may be unintentionally omitted. Especially, the images will be severely distorted when physicians zoom images in for detailed diagnosis. Increasing resolution may cause significant power consumption in RF transmitter; hence, image compression is necessary for saving the power dissipation of RF transmitter. To overcome this drawback, we have been developing a new capsule endoscope, called GICam.     

Symposium on diarrhea. 5. Postoperative diarrhea.

Under normal circumstances many physiologic mechanisms prevent diarrhea. The most important are the normal processes of gastric emptying, digestion and absorption, the functioning of the ileocecal valve and elimination of bacteria from the small bowel. A surgical procedure may disrupt any of these mechanisms or may unmask a previously asymptomatic disorder that now requires appropriate treatment. Treatment of diarrhea related to surgery may be directed toward the diarrhea itself with such agents as tranquilizers and opiates but if these are not soon effective any disrupted functions must be analysed and specific measures taken to correct or compensate for these disruptions. The most useful measures in appropriate cases are the prevention of the dumping syndrome and the administration of pancreatic enzymes, cholestyramine, hydrophilic stool thickeners and broad-spectrum antibiotics. These measures may be ineffective or inadequate and surgical revision may be necessary.     

Malignant Carcinoid Tumour with Gangrene of the Small Intestine

Four patients with a malignant carcinoid tumour of the small bowel (three had the carcinoid syndrome) developed gangrene of the small intestine. Attention is drawn to this seldom recognized complication, as early surgery may be life saving.