ß2-Adrenergic receptor agonist induced hepatic steatosis in mice: modeling nonalcoholic fatty liver disease in hyperadrenergic states.

Nonalcoholic fatty liver disease (NAFLD) is a spectrum of disorders ranging from hepatic steatosis [excessive accumulation of triglycerides (TG)] to nonalcoholic steatohepatitis, which can progress to cirrhosis and hepatocellular carcinoma. The molecular pathogenesis of steatosis and progression to more severe NAFLD remains unclear. Obesity and aging, two principal risk factors for NAFLD, are associated with a hyperadrenergic state. ß-Adrenergic responsiveness in liver increases in animal models of obesity and aging, and in both is linked to increased hepatic expression of ß2-adrenergic receptors (ß2-ARs). We previously showed that in aging rodents intracellular signaling from elevated hepatic levels of ß2-ARs may contribute to liver steatosis. In this study we demonstrate that injection of formoterol, a highly selective ß2-AR agonist, to mice acutely results in hepatic TG accumulation. Further, we have sought to define the intrahepatic mechanisms underlying ß2-AR mediated steatosis by investigating changes in hepatic expression and cellular localization of enzymes, transcription factors, and coactivators involved in processes of lipid accrual and disposition-and also functional aspects thereof-in livers of formoterol-treated animals. Our results suggest that ß2-AR activation by formoterol leads to increased hepatic TG synthesis and de novo lipogenesis, increased but incomplete ß-oxidation of fatty acids with accumulation of potentially toxic long-chain acylcarnitine intermediates, and reduced TG secretion-all previously invoked as contributors to fatty liver disease. Experiments are ongoing to determine whether sustained activation of hepatic ß2-AR signaling by formoterol might be utilized to model fatty liver changes occurring in hyperadrenergic states of obesity and aging, and thereby identify novel molecular targets for the prevention or treatment of NAFLD.NEW & NOTEWORTHY Results of our study suggest that ß2-adrenergic receptor (ß2-AR) activation by agonist formoterol leads to increased hepatic TG synthesis and de novo lipogenesis, incomplete ß-oxidation of fatty acids with accumulation of long-chain acylcarnitine intermediates, and reduced TG secretion. These findings may, for the first time, implicate a role for ß2-AR responsive dysregulation of hepatic lipid metabolism in the pathogenetic processes underlying NAFLD in hyperadrenergic states such as obesity and aging.

Endocrine complications of celiac disease: a case report and review of the literature.

PURPOSE: The purpose of this article is to review recent literature regarding endocrine disorders related to celiac disease (CD). METHODS: We describe a case report and review existing literature on the endocrine manifestations of CD. RESULTS: CD is an autoimmune disorder characterized by intestinal inflammation in response to gluten. CD can cause a wide range of extra-intestinal complications, including endocrine manifestations. Metabolic bone disease including osteoporosis and osteopenia, vitamin D deficiency, secondary hyperparathyroidism and less frequently osteomalacia can be seen. In CD, fracture risk is increased by 30-40%, while risk for hip fracture is approximately doubled. The risk for other endocrine disorders, particularly autoimmune endocrinopathies, is also increased in those with CD compared to the general population. Epidemiologic data indicate the risk for hypothyroidism is 3-4 times higher among those with CD, while risk of type 1 diabetes is greater than double. Risk for primary adrenal insufficiency is a striking 11-fold higher in those with versus without CD, though the absolute risk is low. Fertility is reduced in women with CD before diagnosis by 37% while male fertility in the absence of hypogonadism does not appear to be affected. Other endocrine conditions including hyperthyroidism, ovarian failure, androgen insensitivity, impaired growth and growth hormone deficiency and autoimmune polyendocrine syndromes have also been associated with CD. CONCLUSIONS: CD is associated with a wide range of endocrine manifestations.

Altered expression of hepatic ß-adrenergic receptors in aging rats: implications for age-related metabolic dysfunction in liver.

Increased ß-adrenergic receptor (ß-AR)-mediated activation of adenylyl cyclase (AC) in rat liver during aging has been linked to age-related increases in hepatic glucose output and hepatosteatosis. In this study, we investigated the expression of ß-ARs, individual receptor subtypes, and G protein-coupled receptor (GPCR) regulatory proteins in livers from aging rats. Radioligand-binding studies demonstrated that ß-AR density increased by greater than threefold in hepatocyte membranes from senescent (24-mo-old) compared with young adult (7-mo-old) rats and that this phenomenon was blocked by food restriction, which is known to retard aging processes in rodents. Competition-binding studies revealed a mixed population of ß1- and ß2-AR subtypes in liver membranes over the adult life span, with a trend for greater ß2-AR density with age. Expression of both ß-AR subtype mRNAs in rat liver increased with age, whereas ß2- but not ß1-AR protein levels declined in livers of old animals. Immunoreactive ß2- but not ß1-ARs were preferentially distributed in pericentral hepatic regions. Levels of GRK2/3 and ß-arrestin 2 proteins, which are involved in downregulation of agonist-activated GPCRs, including ß-ARs, increased during aging. Insofar as sympathetic tone increases with age, our findings suggest that, despite enhanced agonist-mediated downregulation of hepatic ß-ARs preferentially affecting the ß2-AR subtype, increased generation of both receptor subtypes during aging augments the pool of plasma membrane-bound ß-ARs coupled to AC in hepatocytes. This study thus identifies one or both ß-AR subtypes as possible therapeutic targets involved in aberrant hepatic processes of glucose and lipid metabolism during aging.

ß2-Adrenergic receptor ablation modulates hepatic lipid accumulation and glucose tolerance in aging mice.

Catecholamines acting through ß-adrenergic receptors (ß(1)-, ß(2)-, ß(3)-AR subtypes) modulate important biological responses in various tissues. Our previous studies suggest a role for increased hepatic ß-AR-mediated signaling during aging as a mediator of hepatic steatosis, liver glucose output, and insulin resistance in rodents. In the current study, we have utilized ß(2)-AR knockout (KO) and wildtype (WT) control mice to define further the role of ß(2)-AR signaling during aging on lipid and glucose metabolism. Our results demonstrate for the first time that age-related increases in hepatic triglyceride accumulation and body weight are attenuated upon ß(2)-AR ablation. Although no differences in plasma triglyceride, non-esterified fatty acids or insulin levels were detected between old WT and KO animals, an age-associated increase in hepatic expression of lipid homeostasis regulator Cidea was significantly reduced in old KO mice. Interestingly, we also observed a shift from reduced glucose tolerance in young adult KO animals to significantly improved glucose tolerance in old KO when compared to age-matched WT mice. These results provide evidence for an important role played by ß(2)-ARs in the regulation of lipid and glucose metabolism during aging. The effect of ß(2)-AR ablation on caloric intake during aging is currently not known and requires investigation. Future studies are also warranted to delineate the ß(2)-AR-mediated mechanisms involved in the control of lipid and glucose homeostasis, especially in the context of a growing aging population.

Gene alterations and intestinal mucosal changes following growth factor and omega-3 exposure in a rat model of inflammatory bowel disease.

BACKGROUND: We have previously shown that there is synergism between Hepatocyte Growth Factor (HGF) and Omega-3 (OM-3) enriched feeds using an immunologic model of inflammatory bowel disease (IBD). This combination decreased inflammation and cytokine levels and increased microvascular density and mucosal mass. This study evaluates the gene alterations that occurred using this same model. METHODS: Twenty adult female transgenic HLA-B27 rats were divided into four groups: Group 1: (Regular feeds, IV saline); Group 2: (OM-3 feeds, IV saline); Group 3: (Regular feeds, IV HGF 150 µg/kg/day); Group 4: (OM-3 feeds, IV HGF 150 µg/kg/day). Rats were sacrificed 14 days after pump placement. Bowel was harvested and RNA extracted. Microarray gene chips were used. Statistical analysis was done by analysis of variance using Partek Genomics Suite. Results were significant if fold change was more than 2 or less than -2, with P<0.05. RESULTS: In the ileum, HGF up- or down-regulated 34 genes, while OM-3 affected 60 genes. Together 68 genes were affected. Families with a synergistic effect included Solute Carrier Proteins, ATP Binding Cassette Proteins, and Matrix Metalloproteinases. In the colon, 23 genes were affected by HGF, while 66 genes were affected with OM-3. Combined exposure affected 32 genes, including a synergistic effect on solute carrier proteins, aquaporins, and immunologic factors. CONCLUSIONS: There is a synergistic gene alteration effect of exposure of two (HGF and Omega-3 enriched feeds) agents on bowel mucosa. Of most interest was the synergistic effect on the solute carrier protein family, a previously identified gene family up-regulated in response to intestinal failure.

Role of ß-adrenergic receptors in regulation of hepatic fat accumulation during aging.

Excessive fat accumulation in liver (hepatic steatosis) predisposes to hepatic functional and structural impairment and overall metabolic risk. Previous studies noted an association between hepatic steatosis and age in humans and rodents. However, the mechanisms leading to age-associated hepatic fat accumulation remain unknown. Earlier work from our group showed that ß-adrenergic receptor (ß-AR) levels and ß-AR-stimulated adenylyl cyclase activity increase in rat liver during aging. Here we investigated whether age-associated increases in ß-AR signaling play a role in augmenting hepatic lipid accumulation. We demonstrate an increase in hepatic lipid content during senescence and a significant correlation between hepatic fat content and stimulation of adenylyl cyclase activity by the ß-AR agonist isoproterenol in rat liver. Isoproterenol administration to young and old rodents in vivo increased hepatic lipid accumulation. Furthermore, in vitro overexpression of ß1- and ß2-AR subtypes in hepatocytes from young rodents increased cellular lipid content, whereas inhibition of ß-ARs by receptor subtype-specific inhibitors reduced lipid levels in hepatocytes from senescent animals. Isoproterenol-induced hepatic lipid accumulation in vivo was prevented by the ß-AR nonselective blocker propranolol, suggesting a novel therapeutic effect of this class of drugs in hepatic steatosis. Acipimox, which inhibits adipose tissue lipolysis, did not alter isoproterenol-mediated hepatic fat accumulation; thus ß-AR responsive hepatic lipid accumulation does not appear to be related primarily to altered lipolysis. These findings suggest that augmented hepatic ß-AR signaling during aging may increase lipid accumulation in liver and advocate a possible role for ß-adrenergic blockers in preventing or retarding the development of hepatic steatosis.

Vacuum-assisted closure in the treatment of extensive lymphangiomas in children.

BACKGROUND: The management of lymphangiomas in children is a complex problem with frequent recurrence and infection. Vacuum-assisted closure (VAC) devices have been shown to accelerate the healing of open wounds. We hypothesized that VAC therapy might decrease complications after resection of lymphangiomas. METHODS: A retrospective review was performed on 13 children (August 2005 to April 2010) who were patients undergoing lymphangioma resection with postoperative VAC therapy. Patient demographics, size and location of the lymphangioma, VAC duration and number of changes, hospital stay, complications, need for further surgery, and length of follow-up were recorded. RESULTS: Thirteen children (mean age, 8 years; mean weight, 34 kg) underwent 15 operations for lymphangiomas followed by postoperative VAC therapy. Locations included the head and neck, thorax and abdomen, and lower extremity. The mean VAC duration was 19 days, and they underwent a mean of 2.6 VAC changes. Six children had operative closure of the wound at a mean of 15 days postoperative. The remaining patients underwent closure by secondary intention. There were no recurrences. Complications included VAC device malfunctions requiring intervention and wound infections. Mean follow-up was 289 days. CONCLUSION: Postoperative VAC therapy for the treatment of lymphangiomas can be an effective adjunct to surgical treatment by decreasing risks of recurrence and infection.

Hepatocyte growth factor and omega-3-enriched feeds have a synergistic effect on mucosal mass in an animal model of inflammatory bowel disease.

BACKGROUND: Hepatocyte growth factor (HGF) decreases intestinal inflammation and cytokine levels in an animal model of inflammatory bowel disease (IBD). Luminal omega-3 (OM-3) is anti-angiogenic, reduces inflammation, and may decrease symptoms in patients with Crohn's disease. This study evaluates the synergism of HGF and OM-3. METHODS: Twenty adult female transgenic HLA-B27 rats were divided into 4 groups: group 1: regular feeds, IV saline; group 2: OM-3-enriched feeds, IV saline; group 3: regular feeds, IV HGF (150 µg/kg per day); and group 4: OM-3-enriched feeds, IV HGF(150 µg/kg per day). Rats were killed at 14 days after pump placement. Small and large bowel mucosa was harvested, and DNA and protein were extracted and quantified. Statistical analysis was done by analysis of variance with post-hoc Tukey's HSD test. RESULTS: Content of protein and DNA in the ileum were significantly increased by supplementation of HGF (P < .001, P < .01, respectively) alone. OM-3 significantly increased protein content but not DNA (P = .02, P = 0.3, respectively). Combined, they had a synergistic effect greater than either supplement alone (P = .0001, P = .002, respectively). In the colon, HGF and OM-3 did not significantly increase protein or DNA content individually or together. CONCLUSIONS: This is the first demonstration of the synergistic effect of a growth factor (HGF) and a dietary supplement (OM-3) in an immunologic model of IBD.

Single-incision thoracoscopic surgery in children: equivalent results with fewer scars when compared with traditional multiple-incision thoracoscopy.

BACKGROUND: Single-incision pediatric endosurgery is gaining popularity, especially for abdominal operations. Several reports in the literature support the feasibility of the single-incision approach in pediatric laparoscopy. Here we compare our experience with single-incision thoracoscopic surgery (SITS) to traditional multiple-incision video-assisted thoracoscopic surgery (VATS) in children. METHODS: A chart review of all patients who underwent SITS at our institution was performed. The same number of demographically matched VATS case controls were selected from a pool of patients operated on during the same time period. Operative time, time until chest tube removal, length of stay, complications, and any need for further intervention were recorded. Statistical analysis was done by Student's t-test using Instat 3. RESULTS: Fourteen SITS procedures were performed during the study period. These patients were compared with 14 VATS case controls. Both groups were similar with regard to age, weight, sex, and procedures performed. The mean operative time in the SITS group was 84 ± 43 minutes versus 64 ± 30 in the VATS group (P=.18). Days until chest tube removal was 4 ± 2.2 in the SITS group and 2.8 ± 1.4 in the VATS group (P=.09). Length of hospital stay was 5.5 ± 4.4 days in the SITS group versus 7.2 ± 8.6 in the VATS group (P=.51). There were no intraoperative complications and no procedure conversions in either group. One SITS patient who underwent a wedge resection and mechanical pleurodesis for a spontaneous pneumothorax was readmitted for a recurrent pneumothorax and required a reoperation. CONCLUSIONS: Our experience demonstrates that there are no statistically significant differences in operative time, time until chest tube removal, and length of hospital stay when comparing SITS to VATS in children. We believe that SITS is an equivalent procedure that allows for fewer scars when compared with traditional multiple-incision VATS in children.

Prophylactic antibiotics do not decrease the incidence of wound infections after laparoscopic pyloromyotomy.

PURPOSE: Although laparoscopic pyloromyotomy is considered to be a clean case, many surgeons administer prophylactic preoperative antibiotics. The aim of this study was to evaluate the impact of prophylactic antibiotics on the wound infection rate after laparoscopic pyloromyotomy. METHODS: We conducted a retrospective review of all patients who underwent laparoscopic pyloromyotomy at our institution between August 2002 and December 2009. Data included patient age, sex, weight, serum HCO(3) at admission and at operation, and if the patient received prophylactic antibiotics. The rate of wound infection or other wound complications, including suture granuloma, umbilical granuloma, umbilical hernia, skin dehiscence, and omental evisceration, was determined. RESULTS: Two hundred ninety-nine patients underwent 301 consecutive laparoscopic pyloromyotomies. Sixty-four percent (n = 194) of patients returned for follow-up and were included in the study. Fifty-seven percent (group A, n = 111) received antibiotics, and 43% (group B, n = 84) did not. There were 3 wound infections in each of the equally matched groups (group A, 2.7%; group B, 3.5%; P = .73). Other wound complications occurred in 4.5% of patients (n = 5) in group A and 8.3% of patients (n = 7) in group B (P = .27). CONCLUSION: The use of prophylactic antibiotics does not significantly decrease the rate of wound infection or other wound complications after laparoscopic pyloromyotomy.

Chronology of the effect of massive small bowel resection and hepatocyte growth factor (HGF) on intestinal adaptation.

BACKGROUND: We previously demonstrated that hepatocyte growth factor (HGF) increases mucosal protein and DNA content at single time points during intestinal adaptation in rats. This study evaluates mucosal changes after massive small bowel resection (MSBR) and with the addition of IV HGF measured over the timeframe of intestinal adaptation. METHODS: Sixty adult female Sprague-Dawley rats were divided into three groups and underwent massive small bowel resection (MSBR), MSBR+HGF (intravenous 150 mg/kg/d), or sham operation (control). Five animals per group were sacrificed at 7, 14, 21, and 28 d. Ileal mucosa was harvested and DNA and protein extracted. DNA content (ug/mg mucosa) was measured at 260 nm and protein content (ug/mg mucosa) was measured using the Bradford assay. MIB-5 immunohistochemical staining was done to confirm that the increased DNA content was due to proliferation. Statistical analysis was by ANOVA with post-hoc Tukey's HSD test. RESULTS: At 7 and 14 d, protein concentration was increased following HGF administration in comparison to MSBR alone and in control rats (P<0.05 and P<0.03, respectively). Mucosal DNA content in the MSBR-HGF rats was significantly increased over MSBR and control groups at 21 and 28 d (P<0.02 and P<0.004, respectively). MIB-5 immunohistochemical staining correlated with mucosal DNA content at 21 and 28 d (P<0.0005 and P<0.002, respectively). CONCLUSIONS: The mucosal response to MSBR for the period 7-14 d after surgery demonstrates that protein content is increased due to an emphasis on hypertrophy, whereas at 21-28 d hyperplasia is the primary change as demonstrated by the increase in DNA content. This response was enhanced by HGF. This is the first demonstration correlating the bimodal gene response during intestinal adaptation to the bimodal mucosal response. Also, this is the first demonstration of a biphasic response by the mucosa to HGF during intestinal adaptation.

Impaired mitochondrial complex III and melatonin responsive reactive oxygen species generation in kidney mitochondria of db/db mice.

We have previously demonstrated that melatonin, at pharmacological concentrations, causes rapid reactive oxygen species (ROS) generation at the antimycin-A sensitive site of mitochondrial complex III (MC-3). In the current work, we used this melatonin response to investigate the role of mitochondrial dysfunction in the development of diabetic nephropathy. We find that the development of diabetic nephropathy, as indicated by hyperfiltration and histopathological lesions in the kidney of db/db mice, is associated with diminished melatonin-induced ROS generation and MC-3 activity, indicating impaired MC-3 at the antimycin-A site. The MC-3 protein level in the renal mitochondria was equivalent in db/db and the nondiabetic db/m mice, whereas mitochondrial complex I (MC-1) protein was dramatically upregulated in the db/db mice. This differential regulation in mitochondrial complexes may alter the equilibrium of the electron transport in renal mitochondria and contribute to ROS overproduction. The study provides one mechanism of enhanced oxidative stress that may be involved in the pathogenesis of diabetic nephropathy in db/db mice.

ß-Adrenergic Responsive Induction of Insulin Resistance in Liver of Aging Rats.

INTRODUCTION. We previously demonstrated increases in ß-adrenergic receptor (ß-AR) density in rat liver, in association with increased ß-AR-mediated stimulation of glucose output in rat hepatocytes, during senescent aging. We therefore hypothesized that pharmacologic ß-adrenergic stimulation might induce insulin resistance and glucose output in liver of aging rats in vivo. METHODS. In this study, pancreatic clamps were performed on young adult (4-month-old) and senescent (24-month-old) Fischer 344 male rats by infusing somatostatin (3 µg/kg/min) at time 0 to inhibit insulin secretion, and then infusing insulin (1 mU/kg/min) to replace basal insulin concentrations. At time 0 rats also received either the ß-AR agonist isoproterenol (100 ng/kg/min) or saline (control). After 120 min the insulin infusion rate was increased to 4 mU/kg/min for an additional 120 min. Tritiated glucose was infused throughout the study to measure glucose turnover rates. RESULTS AND CONCLUSION. The results of the pancreatic clamp studies demonstrated that under saline control conditions hepatic glucose production (HGP) was suppressed during hyperinsulinemia in both young and old rats, with a trend toward reduced insulin sensitivity in the older animals. Isoproterenol infusion impaired insulin-induced suppression of HGP in both age groups. The results suggest that ß-AR stimulation by isoproterenol increases HGP and acutely induces hepatic insulin resistance in both young and old rats. A similar role for ß-adrenergic-mediated hepatic insulin resistance in aging humans would suggest a novel therapeutic target for the treatment or prevention of glucose dysregulation and diabetes developing with advancing age.

The effect of hepatocyte growth factor on gene transcription during intestinal adaptation.

PURPOSE: Previously, we investigated the physiologic effects of hepatocyte growth factor (HGF) on intestinal adaptation using a massive small bowel resection (MSBR) rat model. To correlate these altered physiologic changes with gene alterations, we used microarray technology at 7, 14, and 21 days after MSBR. METHODS: Forty-five adult female rats were divided into 3 groups and underwent 70% MSBR, MSBR + HGF (intravenous 150 µg/kg per day), or sham operation (control). Five animals per group were killed at each time point. Ileal mucosa was harvested and RNA extracted. Rat Gene Chips and Expression Console software (Affymetrix, Santa Clara, CA) were used. Statistical analysis was done by analysis of variance using Partek Genomics Suite (Partek, Inc, St Louis, MO). Results were significant if fold change was more than 2 or less than -2, with P < .05. RESULTS: Compared with the control group, MSBR group had significant increases in up-regulated and down-regulated genes. The MSBR-HGF group had further increases in up-regulated and down-regulated genes compared with the MSBR group. At 7 days, 6 cellular hypertrophy families had 30 genes up-regulated, and HGF up-regulated an additional 14 genes. At 21 days, 5 hyperplasia gene families had 32 up-regulated genes. Hepatocyte growth factor up-regulated an additional 16 genes. CONCLUSIONS: Microarray analysis of intestinal adaptation identified an early emphasis on hypertrophy and later emphasis on hyperplasia. This is the first demonstration that the effect of HGF on intestinal adaptation is recruitment of more genes rather than an increase in the fold change of already up-regulated genes.

Dose variation of hepatocyte growth factor and its effects on an animal model of TPN-induced liver injury.

BACKGROUND: Total parenteral nutrition (TPN) induced liver failure is the leading indication for transplantation in children. Our previous research demonstrated the benefit of a specific intravenous dose of hepatocyte growth factor (HGF) in the amelioration of TPN-induced liver injury. This study was designed to ascertain the optimum concentration of HGF in an animal model of TPN-induced liver injury. MATERIALS AND METHODS: Twenty adult female Sprague-Dawley rats underwent 70% small bowel resection and placement of venous catheters connected to subcutaneous osmotic minipumps. Four groups (n=5 each) based on the contents of the osmotic pump were utilized as follows: group 1 (control): saline; group 2: HGF 75 mcg/kg/d; group 3: HGF 150 mcg/kg/d; and group 4: HGF 250 mcg/kg/d. Each rat received 14 d of TPN without enteral nutrition. After sacrifice, the liver was harvested. Hepatic inflammation was evaluated using antibodies for TNF-α and IL-6. Apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) technique. RESULTS: All concentrations induced statistically significantly less IL-6 and TNF- α expression compared to the control animals. Increased efficacy was demonstrated with increasing dose concentration up to 150 mcg/kg/d but not 250 mcg/kg/d. Apoptotic activity was decreased statistically significantly for all dose concentrations compared with the controls, as well as to increases in dose concentration. CONCLUSIONS: Increasing concentrations of HGF were directly correlated with increased modulation of inflammatory response and apoptotic index in this animal model for TPN-induced liver injury, up to 150 mcg/kg/d. Further increases were significant with respect to apoptotic index only. Further investigations are warranted to determine if HGF may be useful to minimize TPN-induced liver injury in children.

Growth factor modulation of hepatic inflammation: a novel approach to the management of total parenteral nutrition-associated liver disease.

PURPOSE: Dependence on total parenteral nutrition in intestinal failure or short bowel syndrome patients can lead to many complications. The most significant complication is progressive liver injury leading to liver failure. This study assesses the potential of hepatocyte growth factor (HGF) in modulating the hepatic response in a rat cholestatic liver injury model. METHODS: Female Sprague-Dawley rats were divided into 3 groups: control (n = 5), chronic liver injury (alpha-naphtylisocyocyanate [ANIT] every 3.5 days at 75 mg/kg; n = 5), and chronic liver injury plus HGF (ANIT + HGF at 250 microg kg(-1) d(-1); n = 5). The rats initially underwent massive (80%) small bowel resections. Seven days later, they were given intraperitoneal injections of saline (control) or ANIT and implantation of an osmotic minipump for continuous intravenous saline or HGF. Intraperitoneal saline or ANIT injections were subsequently administered every 3.5 days to create a chronic cholestatic model. After 14 days, the animals were euthanized, and liver biopsies were obtained. The liver biopsies were evaluated by histology, immunofluorescence staining for interleukin-6 and tumor necrosis factor alpha, and assessment of apoptosis by terminal dUTP-transferase-mediated nick end labeling (TUNEL) technique. RESULTS: In this chronic liver injury model, HGF did not effect the grade of inflammation. However, HGF did induce retention of the ductal structures and avoided ductal proliferation, damage, and evidence of primary sclerosing cholangitis (P < .05). Hepatocyte growth factor induced less interleukin-6 (P < .011) and tumor necrosis factor alpha (P < .01) expression. Apoptotic activity was also significantly less in the HGF group (P < .01). CONCLUSION: Hepatocyte growth factor preserved the hepatic ductal system, modulated the hepatic inflammatory response, and reduced the apoptotic index in this chronic cholestatic liver injury model. It may diminish or prevent liver damage in patients with total parenteral nutrition-induced liver injury.

Role for Notch signaling in salivary acinar cell growth and differentiation.

The Notch pathway is crucial for stem/progenitor cell maintenance, growth and differentiation in a variety of tissues. The Notch signaling is essential for Drosophila salivary gland development but its role in mammalian salivary gland remains unclear. The human salivary epithelial cell line, HSG, was studied to determine the role of Notch signaling in salivary epithelial cell differentiation. HSG expressed Notch 1 to 4, and the Notch ligands Jagged 1 and 2 and Delta 1. Treatment of HSG cells with inhibitors of gamma-secretase, which is required for Notch cleavage and activation, blocked vimentin and cystatin S expression, an indicator of HSG differentiation. HSG differentiation was also associated with Notch downstream signal Hes-1 expression, and Hes-1 expression was inhibited by gamma-secretase inhibitors. siRNA corresponding to Notch 1 to 4 was used to show that silencing of all four Notch receptors was required to inhibit HSG differentiation. Normal human submandibular gland expressed Notch 1 to 4, Jagged 1 and 2, and Delta 1, with nuclear localization indicating Notch signaling in vivo. Hes-1 was also expressed in the human tissue, with staining predominantly in the ductal cells. In salivary tissue from rats undergoing and recovering from ductal obstruction, we found that Notch receptors and ligands were expressed in the nucleus of the regenerating epithelial cells. Taken together, these data suggest that Notch signaling is critical for normal salivary gland cell growth and differentiation.

Reduced expression of epidermal growth factor receptors in rat liver during aging.

Proliferative responsiveness of hepatocytes to epidermal growth factor (EGF) declines during aging. The role of EGF receptors in mediating age-dependent changes of EGF-induced mitogenic signaling in liver remains incompletely understood. We assessed EGF receptor expression levels in whole liver specimens as well as in freshly isolated and cultured hepatocytes from young adult and senescent Fischer 344 male rats. Hepatic EGF receptor messenger RNA and protein levels, and the number of high- and low-affinity receptor binding sites, decreased with aging. Ligand-induced EGF receptor activation, determined by receptor dimerization and tyrosine phosphorylation, was reduced in old animals in parallel with the age-related decline in receptor expression. Stimulation of the extracellular signal-regulated kinase pathway by EGF was also attenuated in hepatocytes from old animals. Our results implicate decreased expression of EGF receptors as a key determinant of reduced mitogenic signaling responsive to EGF stimulation of liver during aging.