Different responses of apolipoprotein A-I, A-IV, and B gene expression during intestinal adaptation to a massive small bowel resection in rats

Gene expression of apolipoproteins (apo) A-I, A-IV, and B, the predominant protein components of chylomicrons, was investigated in the residual ileum after a massive small bowel resection in rats. A Northern blot analysis showed that the apo A-IV mRNA level, but not the apo A-I and B mRNA levels, in the ileum was significantly higher in the resected rats than in the sham-operated rats 24 h and 2 wk post-surgery. RT-PCR coupled with a primer extension assay revealed that the apo B-48 mRNA/apo B-100 mRNA ratio, i.e., apo B mRNA editing, in the ileum was unchanged by the resection. It is thus concluded that, among the major intestinal apolipoproteins, apo A-IV is the only one whose gene expression is influenced by loss of the proximal intestine.     

A cross-sectional study into the prevalence of root caries in periodontal maintenance patients

BACKGROUND: Epidermal growth factor (EGF) has been shown to increase intestinal absorptive surface area and transport function in normal animals. AIMS: To examine the effect of EGF on absorptive surface area and brush border membrane function in a model of massive small bowel resection. METHODS: New Zealand white rabbits were randomised into two groups: a resected group (60% proximal small bowel resection); and an unmanipulated control group. Distal remnant tissue was examined 10 and 21 days postsurgery. In separate experiments oral EGF (40 g/kg/day) was administered to resected animals from days 3 to 8 and animals were studied on day 10. RESULTS: Ten days postsurgery brush border surface area and total absorptive surface area were significantly increased in remnant tissue while brush border membrane vesicle (BBMV) glucose uptake was significantly decreased compared with controls. By 21 days brush border surface area returned to control levels though BBMV glucose uptake remained depressed. EGF treatment induced a further increase in brush border surface area in remnant intestine but did not alter BBMV glucose uptake. CONCLUSIONS: Surgical resection results in significant elevations in absorptive surface area coupled with a decrease in brush border membrane transport function distal to the site of anastomosis. EGF enhances glucose uptake in remnant intestine via recruitment of additional microvillus membrane into the brush border.     

Short-bowel syndrome in children and adults

Short-bowel syndrome is the malabsorptive state that follows extensive resection of the small intestine. Potential long-term survival without parenteral nutrition heavily depends on stimulation of the process of intestinal adaptation, through which the remaining small intestine gradually increases its absorptive capacity. This process is heavily nutrient dependent, and aggressive use of enteral nutrition is required to stimulate its completion. A combination of osmotic sensitivities, nutrient malabsorption, bowel dilatation and dysmotility, and changes in bacterial flora influence the symptoms and the management of this disorder. Chronic complications include parenteral nutrition-induced liver disease, nutrient deficiency states, and, frequently, small bowel bacterial overgrowth. Intestinal transplantation has been successfully developed in some centers in the United States, and preliminary experience suggest a long-term survival of 50%-75%, better in patients receiving an isolated intestinal transplant than a combined liver/bowel transplant. The ultimate role of intestinal transplantation is still undergoing evaluation.     

Short bowel syndrome in children

Short bowel syndrome is defined as malabsorption following small intestinal resection. There are many causes in children, most of whom present during infancy. The clinical presentation and physiologic consequences depend heavily on the segment of bowel removed and the extent of resection. The remaining intestine has the capacity to adapt anatomically and functionally, and stimulating the adaptation process is a major component of therapy. Clinical management of long-term complications, such as bacterial overgrowth, nutrient deficiency states, and parenteral nutrition-induced liver disease, are often key outcome determinants. The recent availability of intestinal transplantation now provides an additional therapeutic option for patients in whom all other forms of therapy fail.     

Qualitative changes in enteric flora and short-chain fatty acids after intestinal resection

Our aim was to determine the effect of intestinal transection and resection on the prevalence of enteric flora and evaluate whether any such changes alter luminal SCFA and lactic acid content. Dogs underwent either 50% proximal (PR, N = 6) or distal (DR, N = 7) resection, distal resection with bypass of the ileocecal junction (DRBP, N = 9) or midpoint transection alone performed to serve as the appropriate control for luminal sampling for either proximal (PTC, N = 6) or distal (DTC, N = 7) resection. Studies were performed every four weeks for 12 weeks. Both jejunum and ileum had >10(5)/ml aerobic bacteria, most commonly E. coli. Streptococcal species were more common in the normal jejunum than ileum but were found in the ileal remnant after PR. Significant (>10(5)) anaerobic growth occurred infrequently in the jejunum, and DR did not increase anaerobic growth in jejunum unless DRBP was performed (93% vs 62% DR, 45% DTC, 20% normal jejunum, P < 0.05). Clostridium species increased significantly in the jejunal remnant after DRBP. Significant anaerobic growth occurred infrequently in normal ileum but increased after PR (89% vs 50% PTC, P < 0.05). Flora normally found in the jejunum tended to increase in the ileum after PR. Jejunal SCFA increased after DRBP (3126 +/- 577 microg/ml vs 1600 +/- 301 DTC, P < 0.05) but not DR (1791 +/- 321 microg/ml). Significant (>10(5)) anaerobic bacterial growth was associated with increased SCFA content (2717 +/- 381 vs 1029 +/- 170 microg/ml, P < 0.05) and the presence of lactic acid (30% vs 5%, P < 0.05), but there was no correlation between the presence of specific bacteria and SCFA and lactic acid. Following resection of the proximal small intestine, the intestinal remnant tends to assume the bacteriologic characteristics of the resected segment. Following a distal resection, the presence of an intact ICJ protects against the proliferation of a flora characteristic of the distal intestine; resection with bypass of the ICJ results in the appearance of coliforms in the jejunal remnant. These changes in enteric flora do not correlate with content of specific SCFA and lactic acid in the small intestine.     

The use of benevolent power in nursing care

In response to estrogen the rat cervical epithelium undergoes squamous metaplastic changes, progressing from a resting state through a proliferating, secretory stage and finally to a cornified stage before sloughing or being reabsorbed. The transition from a secretory to a cornified epithelium is preceded by a dramatic reduction in the expression of the cellular retinol binding protein (CRBP). The associations among retinoids (retinol and retinoic acid), CRBP expression, and estrogen-induced keratinocyte differentiation were explored in cultured cervical epithelial cells. Retinoids supported proliferation of cervical epithelial cells expressing basal keratins. Alone, estrogen had no effect on proliferation and enhanced expression of keratins characteristic of stratified cervical epithelial cells. When added together, estrogen prevented retinoid effects on proliferation, whereas retinoids prevented the estrogen-enhanced expression of differentiation-associated cytokeratins. When CRBP expression was repressed by elevating intracellular cyclic AMP levels, the ability of retinol, but not retinoic acid, to block estrogen-induced changes in keratin expression was severely compromised. These results support a critical role for CRBP in cervical cell responsiveness to circulating retinoids (primarily retinol). We hypothesize that retinol inhibits estrogen-induced keratinization of the cervical epithelium, and the drop in CRBP level results in transient vitamin A deficiency within cervical epithelial cells, permitting the orderly transition from the secretory to the cornified stage.     

Comparative effect of growth hormone and plerocercoid growth factor in the intestinal resection in rat

OBJECTIVE: After massive bowel resection, absorption depends on how fast the mucosal adaptation takes place. This work aims at assessing the trophic effect of growth hormone (GH) and its analogue, the plerocercoid growth factor (PGF), on the intestinal mucosa after 90% small bowel resection. EXPERIMENTAL DESIGN: 24 male Wistar rats were divided into four groups of 6: Control (laparotomy), 90% small bowel resection (RID), resection and treatment with GH during 14 days (RID + GH) and resection and PGF treatment (RID + PGF). Intestinal mucosal adaptation was assessed by measuring mucosal weight and height, and evaluating the regenerative activity by measuring proliferation cell nuclear antigen (PCNA) labelling index. RESULTS: Bowel resection itself caused a significant increment of jejunal and ileal mucosal height in comparison with the control group. GH and PGF did not change this increase. Jejunal and ileal proliferation indexes were significantly higher than those in controls and they were significantly higher in both RID + GH and RID + PGF groups. CONCLUSIONS: GH and PGF cause a proliferative effect on the intestinal mucosa, even in hyperproliferative states such as the small bowel resection. This finding might have a clinic application.     

Short bowel syndrome--surgical aspects

INTRODUCTION: Long-term survival after massive intestinal resection is now possible with parenteral nutritional support. The expense, morbidity, and inconvenience of this therapy, however, have led to continued interest in alternatives for the treatment of the short bowel syndrome. Patients with short bowel require a multi disciplinary approach over a prolonged period. HISTORICAL CONSIDERATIONS: The history of small bowel transplantation started in 1959 when Lillehei showed that autotransplantation of the small intestine in a dog was feasible. From 1964 to 1971, 7 attempts of small bowel allotransplantations in humans have been reported. All 7 patients died. DEFINITION: Short gut syndrome is a malabsorptive condition occurring after significant loss of intestinal absorptive capacity. The clinical syndrome is manifested by malnutrition, steatorrhea, weight loss, and diarrhea due to decreased absorptive capacity. ETIOLOGY: Etiologic factors leading to the short gut state include necrotizing enterocolitis, midgut volvulus, trauma, embolic phenomenon, and Crohn's disease. PATHOPHYSIOLOGY: Intestinal failure is the end result of several complex interacting mechanisms related to: reduced enterocyte mass, short small bowel length with consequent reduced mucosal contact time for absorption, massive proximal loop dilatation with poor propulsion, and intraluminal stasis and bacterial overgrowth lead to bacterial translocation to the liver systemically. MANAGEMENT: Patients with short bowel must be totally or partly supported with intravenous nutrition until enteral absorption can sustain survival and growth. Autologous bowel reconstruction attempts to reconfigure the residual bowel to eliminate negative factors of bowel dilatation and stasis, and redistribute the absorptive mucosa to enhance the adaptation response. Several procedures have been suggested to: prolong transmitting time and increase mucosal contact time, enhance absorption by bowel tailoring and bowel lengthening, and increasing the Enterocyte mass. CONCLUSION: Autologous gastro-intestinal reconstruction is still in its infacny with prospect of new and different concepts for the future.     

Jejunal brake: inhibition of intestinal transit by fat in the proximal small intestine

Optimal absorption of fat requires adequate time of contact with the absorptive sites of the small intestine. In order to prevent steatorrhea, intestinal transit must be slowed in response to the fat that has emptied into the small intestine. Intestinal transit is known to be inhibited by fat in the ileum via the ileal brake. This response has suggested that the regulation of intestinal transit is a function of the distal small intestine. However, clinical observations suggest that the ileal brake is not the only control mechanism for intestinal transit. In short bowel patients with resection of the ileum, the proportion of fecal fat recovery remained constant even after the fat intake was increased threefold. In these patients, optimal fat absorption based on the slowing of intestinal transit must have been triggered by an inhibitory mechanism located outside of the distal small intestine. To test the hypothesis that fat in the proximal small intestine inhibited intestinal transit, we compared intestinal transit during perfusion of the proximal half of the small intestine with 0 (buffer only), 15, 30, or 60 mM oleate in dogs equipped with duodenal and mid-intestinal fistula. Intestinal transit across a 150-cm test segment (between fistulas) was measured by counting for the recovery of a radioactive marker in the output of the mid-intestinal fistula during the last 30 min of a 90-min perfusion. We found that oleate inhibited intestinal transit in a load-dependent fashion (P < 0.005). Specifically, while the mean cumulative recovery of the transit marker was 95.5% during buffer perfusion, the recovery decreased when 15 mM (64.3%), 30 mM o(54.7%), or 60 mM oleate (38.7%) was perfused into the proximal half of the small intestine. We conclude that fat in the proximal small intestine inhibits intestinal transit as the jejunal brake.     

Dramatically decreased high density lipoprotein cholesterol, increased remnant clearance, and insulin hypersensitivity in apolipoprotein A-II knockout mice suggest a complex role for apolipoprotein A-II in atherosclerosis susceptibility

Apolipoprotein (apo) A-II is the second most abundant apolipoprotein in high density lipoprotein (HDL). To study its role in lipoprotein metabolism and atherosclerosis susceptibility, apo A-II knockout mice were created. Homozygous knockout mice had 67% and 52% reductions in HDL cholesterol levels in the fasted and fed states, respectively, and HDL particle size was reduced. Metabolic turnover studies revealed the HDL decrease to be due to both decreased HDL cholesterol ester and apo A-I transport rate and increased HDL cholesterol ester and apo A-I fractional catabolic rate. The apo A-II deficiency trait was bred onto the atherosclerosis-prone apo E-deficient background, which resulted in a surprising 66% decrease in cholesterol levels due primarily to decreased atherogenic lipoprotein remnant particles. Metabolic turnover studies indicated increased remnant clearance in the absence of apo A-II. Finally, apo A-II deficiency was associated with lower free fatty acid, glucose, and insulin levels, suggesting an insulin hypersensitivity state. In summary, apo A-II plays a complex role in lipoprotein metabolism, with some antiatherogenic properties such as the maintenance of a stable HDL pool, and other proatherogenic properties such as decreasing clearance of atherogenic lipoprotein remnants and promotion of insulin resistance.     

Suppressed anti-aggregating and cGMP-elevating effects of sodium nitroprusside in platelets from patients with stable angina pectoris

Short bowel syndrome (SBS) in the newborn results in limited intestinal absorptive capacity, leading especially to fatty acid (FA) malabsorption. It is unknown whether adaptation occurs in time in FA absorption, and whether this adaptation is chain-length dependent. The aid of the present study was to prospectively evaluate FA absorption and excretion during SBS in the newborn. Twenty-one neonates who underwent small bowel resection (of variable length) for various reasons (necrotizing enterocolitis, intestinal atresia, meconium peritonitis, cloacal extrophy, etc) were studied. Eight neonates had SBS, defined as a small bowel remnant of less than 50% of the original small bowel length related to gestational age. The mean remaining small bowel length in the SBS group was 34% (24% to 42%). The non-SBS control group consisted of 13 neonates who had only minor small bowel resections. The mean remaining bowel length for the non-SBS group was 95% (70% to 100%). The results show that the total fractional excretion of FA (FE-FA) at 2 weeks and 1, 2, 3, and 4 months postsurgery was 51% +/- 37%, 33% +/- 24%, 51% +/- 65%, 53% +/- 27%, and 7% +/- 2% in patients with SBS, versus 12% +/- 8%, 24% +/- 10%, 9% +/- 3%, 8% +/- 3% and 17% +/- 14% in the non-SBS controls, respectively (P < .05 by ANOVA). There appeared to be an amelioration in time in FA absorption, especially in the SBS group, after 3 months. FE-FA was chain-length related, being considerably less for C10 and C12 than for C14 and longer amounts. An amelioration of absorption occurred in the SBS patients, especially with the longer-chain FA. On the basis of the study data, the authors conclude that in the initial adaptation phase shorter chain lengths are better absorbed than longer chain lengths; however, in the latter FA group, substantial adaptation occurs with time.     

Acid lipase inhibitor in chicken plasma identified as apolipoprotein A-I

We have reported a inhibitor of acid lipases in liver lysosomes and erythrocytes from chickens [M. Fujii et al., Int. J. Biochem., 22, 895-898 (1990)]. In this paper, the properties of the inhibitor were described in comparison with those of apo A-I of chicken. The purified inhibitor migrated with the same mobility on SDS-PAGE as apo A-I, and had a molecular weight of 27,000. The peptide map from the lipase inhibitor was similar to that of apo A-I. Antibodies to the acid lipase inhibitor also reacted with apo A-I. Apo A-I inhibited the acid lipase activities of liver lysosomes and erythrocytes from chickens as strongly as the lipase inhibitor. The N-terminal amino acid sequence of lipase inhibitor was identical to that of apo A-I as far as residue 20. The amino acid sequence of peptides obtained from the inhibitor by cleavage with CNBr corresponded to internal sequence of apo A-I, and so the CNBr-peptides were derived by cleavage after the methionine residues in apo A-I. The findings showed that the inhibitor of the acid lipases in liver lysosomes and erythrocytes from chickens was identical to apo A-I.     

Solution structure of synthetic peptide inhibitor and substrate of cAMP-dependent protein kinase. A study by 2D H NMR and molecular dynamics

Altered hepatic expression of apolipoproteins occurs during the acute phase response. Here we examined whether the acute phase response alters extra hepatic expression of apolipoproteins. Syrian hamsters were injected with endotoxin (LPS), tumor necrosis factor (TNF), interleukin (IL)-1, or the combination of TNF + IL-1 and mRNAs for serum amyloid A (apoSAA), apolipoprotein (apo) J, apo E. apo A-I, and apo D, were analyzed. LPS increased mRNA levels for apoSAA in all tissues examined. LPS and TNF + IL-1 increased mRNA levels for apo J in kidney, heart, stomach, intestine, and muscle. Individually, TNF and IL-1 were less potent than the combination of the two cytokines. LPS decreased mRNA levels for apo E in all tissues, except for mid and distal intestine. TNF and IL-1 were less effective than LPS. LPS, TNF + IL-1 and TNF decreased mRNA levels for apo A-I in duodenum. mRNA for apo D decreased in heart, were unchanged in brain and increased in muscle, following LPS. The widespread extra hepatic regulation of the apolipoproteins during the acute phase response may be important for the alterations in lipid metabolism that occur during infection and inflammation as well as the immune response.     

Differential Hsp70 plasma-membrane expression on primary human tumors and metastases in mice with severe combined immunodeficiency

Fibrates are used to lower plasma triglycerides and cholesterol levels in hyperlipidemic patients. In addition, fibrates have been found to alter the plasma concentrations of fibrinogen, plasminogen activator inhibitor-1 (PAI-1) and apolipoprotein A-I (apo A-I). We have investigated the in vitro effects of fibrates on fibrinogen, PAI-1 and apo A-I synthesis and the underlying regulatory mechanisms in primary monkey hepatocytes. We show that fibrates time- and dose-dependently increase fibrinogen and apo A-I expression and decrease PAI-1 expression in cultured cynomolgus monkey hepatocytes, the effects demonstrating different potency for different fibrates. After three consecutive periods of 24 h the most effective fibrate. ciprofibrate (at 1 mmol/l), increased fibrinogen and apo A-I synthesis to 356% and 322% of control levels, respectively. Maximum inhibition of PAI-1 synthesis was about 50% of control levels and was reached by 1 mmol/l gemfibrozil or ciprofibrate after 48 h. A ligand for the retinoid-X-receptor (RXR), 9-cis retinoic acid, and specific activators of the peroxisome proliferator-activated receptor-alpha (PPARalpha), Wy14,643 and ETYA, influenced fibrinogen, PAI-1 and apo A-I expression in a similar fashion, suggesting a role for the PPARalpha/RXRalpha heterodimer in the regulation of these genes. When comparing the effects of the various compounds on PPARalpha transactivation activity as determined in a PPARalpha-sensitive reporter gene system and the ability of the compounds to affect fibrinogen, PAI-1 and apo A-I antigen production, a good correlation (r=0.80; p <0.01) between PPARalpha transactivation and fibrinogen expression was found. Apo A-I expression correlated only weakly with PPARalpha transactivation activity (r=0.47; p=0.24), whereas such a correlation was absent for PAI-1 (r=0.03; p=0.95). These results strongly suggest an involvement of PPARalpha in the regulation of fibrinogen gene expression.     

Lipids and lipoproteins of malnourished children during early renutrition: apolipoprotein A-IV as a potential index of recovery

Twenty-six children with marasmus and 27 with kwashiorkor were compared with 23 control children of matching ages. Kwashiorkor was characterized by increased phospholipids (NS), low (P < 0.01) apolipoprotein (apo) B-rich LDL, and near normal apo A-I and HDL-C. In children with marasmus apo B (P < 0.02) LDL-C (NS), apo A-I (P < 0.01), and HDL-C (P < 0.001) decreased. Fifteen children in each group were followed for 2 wk. Control values were progressively reached after 2 wk. In the younger children final apo B was higher than in control subjects (P < 0.03) but apo A-I was identical. Apo A-IV, assayed because it correlates with the functional state of intestine, was near normal in children with kwashiorkor and decreased with treatment. In children with marasmus apo A-IV decreased by 50%, increased with treatment in older children, but further diminished in younger children. After 2 wk apo A-IV was significantly lower in all patients than in control subjects. Apo A-IV, by remaining depressed after other variables normalized, seems a good index of nutritional status.     

Intestinal adaptation is enhanced by epidermal growth factor independent of increased ileal epidermal growth factor receptor expression

BACKGROUND/PURPOSE: Intestinal adaptation after massive small bowel resection (SBR) is augmented by epidermal growth factor (EGF) via an unknown mechanism. We recently have observed that EGF increases the expression of EGF receptor mRNA and protein content in the remnant ileum after SBR. The purpose of this study was to determine whether the magnitude of EGF-induced receptor expression correlates with intestinal adaptation. METHODS: A 50% proximal SBR or sham operation (bowel transection with reanastomosis) was performed on male ICR mice. Animals from each group were then selected randomly to receive either human recombinant EGF (150 microg/kg/d) or saline by twice daily intraperitoneal injections. The remnant ileum was harvested at 1 week, and parameters of adaptation measured as changes in protein content. Ileal EGF receptor mRNA was quantitated using a ribonuclease protection assay. Changes in the expression ileal EGF receptor protein were determined by Western blot after immunoprecipitation. Comparisons of mean values between groups was performed using analysis of variance (ANOVA) and a P value of less than .05 was considered significant. Values are presented as mean +/- SEM. RESULTS: EGF was mitogenic to the ileum after sham operation as monitored by increases in ileal protein content (2.21 +/- 0.002 mg/cm Sham v 2.97 +/- 0.25 mg/cm Sham +/- EGF; P < .05). After SBR, adaptation resulted in increased ileal protein content (4.45 +/- 0.27 mg/cm), which was substantially boosted by EGF (5.98 +/- 0.39 mg/cm; P < .05). No differences were detected in ileal EGF receptor mRNA or protein expression between Sham or SBR groups that did not receive EGF. However, EGF significantly enhanced the expression of ileal EGF receptor mRNA to an equal extent after both sham and SBR (approximately threefold). The magnitude of this increase in EGF receptor protein (four- to sixfold) was similar in both EGF groups as shown by Western blotting. CONCLUSIONS: Changes in ileal EGF receptor expression are not mandatory for adaptation to occur. EGF upregulates the expression of mRNA and protein for its own intestinal receptor in vivo. Because EGF-induced receptor expression was comparable after both SBR and Sham operation, the beneficial effect of EGF during adaptation is likely caused by other factors in addition to increased receptor expression.