The effect of epidermal growth factor on the incremental Young's moduli in the rat small intestine

Biomechanical remodelling of the rat small intestine after treatment with epidermal growth factor (EGF) subcutaneously for 2 days (n=6), 4 days (n=6), 7 days (n=6), and 14 days (n=4) was studied. The incremental circumferential, longitudinal and cross moduli close to the in vivo state were computed from bi-axial test data (combined inflation and axial stretching) by a least square method. The moduli in the circumferential direction and the longitudinal direction differed in all groups, i.e. the mechanical properties were anisotropic in both normal and EGF-treated rats. Time-dependent variation existed for the Young's moduli in all directions during EGF treatment (P<0.05). The circumferential modulus decreased during the first 7 days of EGF treatment and it almost remodelled back to that of the control group after 14 days treatment. The incremental modulus in the circumferential direction ranged between 17.4 and 24.2 kPa. The modulus in the longitudinal direction ranged between 22.9 and 32.4 kPa. The longitudinal modulus after 4 days EGF treatment was significantly larger than that of control group (P<0.02). The cross modulus decreased during the first 4 days of EGF treatment thereafter it increased to a maximum at 7 days. The values for the cross moduli were between 4.7 and 6.6 kPa. In conclusion, the mechanical properties in the intestinal wall are anisotropic and remodel during treatment with EGF.

Inverted Meckel's diverticulum masquerading Crohn disease in the small intestine

We describe a case of Meckel's diverticulum containing ectopic gastric epithelium being the leading point in an ileoileal intussusception. This is usually an acute or subacute condition, but in this case the course was protracted and the case was misdiagnosed and treated as Crohn disease.

Systemic administration of epidermal growth factor increases UCP3 mRNA levels in skeletal muscle and adipose tissue in rats

We have previously reported that systemic epidermal growth factor (EGF) treatment in rats reduces the amount of adipose tissue despite an unaltered food intake. The mitochondrial uncoupling proteins (UCP2 and UCP3) are thought to uncouple the respiratory chain and thus to increase energy expenditure. In order to find out whether the UCP system was involved in the EGF-induced weight loss, the effects of EGF on UCP2 and UCP3 in adipose tissue and skeletal muscle were investigated in the present study. Eight rats were treated with placebo or EGF (150 microg/kg/day) for seven days via mini-osmotic pumps. The EGF-treated rats gained significantly less body weight during the study period than the placebo-treated animals and had significantly less adipose tissue despite a similar food intake. The placebo group and the EGF group had similar UCP2 mRNA expression (in both adipose tissue and skeletal muscle), whereas the EGF-treated group compared to the placebo group had significantly higher UCP3 mRNA expression in both skeletal muscle (3.76 +/- 0.90 vs 8.41 +/- 0.87, P < 0.05) and in adipose tissue (6.38 +/- 0.71 vs 12.48 +/- 1.79, P < 0.05). In vitro studies with adipose tissue fragments indicated that the EGF effect probably is mediated indirectly as incubations with EGF (10 microM) were unable to affect adipose tissue UCP expression, whereas incubations with bromopalmitate stimulated both UCP2 and UCP3 mRNA expression twofold. Thus, EGF treatment in vivo was found to enhance UCP3 mRNA expression in both adipose tissue and skeletal muscle, which may indicate that the EGF effect on body composition might involve up-regulation of UCP3 in skeletal muscle and adipose tissue.

Systemic administration of epidermal growth factor reduces fat mass in rats: effects on the hormone-sensitive-lipase, lipoprotein lipase and leptin

We examined whether the reduction in fat mass induced by EGF treatment in mature animals was via activation of hormone-sensitive lipase (HSL) and thereby the induction of lipolysis, or through inhibition of lipoprotein lipase activity thus reducing fat uptake in adipose tissue. Sixteen male rats were treated with placebo or EGF 150 microg/kg/day for 7 days via mini-osmotic pumps. The results demonstrate that systemic EGF treatment reduces the amount of adipose tissue, most likely due to increased lipolysis as HSL activity as well as HSL mRNA were increased. The circulating levels of free fatty acids were slightly increased and leptin levels reflected the decrease in adipose tissue mass.

Epidermal growth factor and insulin-like growth factor I upregulate the expression of the epidermal growth factor system in rat liver

BACKGROUND/AIM

Both epidermal growth factor and insulin-like growth factor I play a role in connection with the liver. In the present study, the possible interaction of these two growth factor systems was studied by investigating the effect of epidermal growth factor or insulin-like growth factor I treatment on the expression of the epidermal growth factor receptor, and its activating ligands, transforming growth factor-alpha and epidermal growth factor.

METHODS

Fifty-five male rats received no treatment, human recombinant epidermal growth factor or human recombinant insulin-like growth factor I for either 3 or 7 days. The amount of epidermal growth factor receptor, transforming growth factor-alpha, and epidermal growth factor mRNA was quantitated by a calibrated user-friendly RT-PCR assay (CURT-PCR), and the expression of transforming growth factor-alpha and epidermal growth factor peptides was quantitated by ELISA.

RESULTS

Control liver (n=16) contained a mean (+/-SD) value of 12.7+/-7.4x10(-18) mol epidermal growth factor receptor mRNA, 3.8+/-2.0x10(-18) mol transforming growth factor-alpha mRNA and 0.8+/-0.4x10(-18) mol epidermal growth factor mRNA per microg total RNA and 9.8+/-1.6 fmol/mg protein epidermal growth factor and 144+/-22 fmol/mg protein transforming growth factor-alpha. Both epidermal growth factor and insulin-like growth factor I treatment increased the expression of mRNA for transforming growth factor-alpha and epidermal growth factor receptor, as well as the expression of transforming growth factor-alpha peptide. The level of epidermal growth factor receptor and transforming growth factor-alpha mRNA expression was found to correlate both in control and growth factor-treated animals, whereas the expression of epidermal growth factor receptor and epidermal growth factor showed no correlation. Marked differences were seen upon activation of the two growth factor systems, as epidermal growth factor, but not insulin-like growth factor I treatment, increased the plasma concentration of urea and decreased the concentration of insulin-like growth factor I and the liver enzymes, alanine aminotransferase and alkaline phosphatase.

CONCLUSION

Our results show that epidermal growth factor and insulin-like growth factor I, which belong to two different growth factor systems, both induce a correlated upregulation of transforming growth factor-alpha and epidermal growth factor receptor mRNA in rat liver. Although marked differences were observed after treatment with either epidermal growth factor or insulin-like growth factor I on the liver as reflected in the plasma concentrations of e.g. liver enzymes, a common motif in their action involves an upregulation of the expression of the epidermal growth factor system.

Systemic treatment with epidermal growth factor but not insulin-like growth factor I decreases the involution of the prostate in castrated rats

Epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I) are strong inducers of proliferation to prostate cells cultured in serum-free medium. Accordingly we wanted to study the growth of the prostate gland in castrated rats after treatment with EGF, IGF-I and testosterone. Castrated Wistar rats were treated with growth factors (EGF 35 microg/rat per day; IGF-I 350 microg/rat per day) or testosterone (2 mg/rat per day) for 3 days either immediately after or 10 days after castration. Prostate tissue was examined by stereological and immunohistochemical techniques and by enzyme-linked immunosorbent assay (ELISA). Treatment with EGF inhibited the involution of the prostate (P < 0.05), whereas treatment with IGF-I did not affect the prostate involution as compared to castrated controls. EGF treatment significantly increased the endogenous rat EGF in the ventral prostate, but cellular proliferation was not affected. Testosterone treatment increased the weight of the prostate, by increase of all tissue components of the prostate, and significantly increased cellular proliferation. Systemic administration of EGF but not IGF-I decreased the involution of the rat prostate induced by castration. Compared with testosterone, the effects of EGF treatment on the prostate involution were moderate, and the effects of EGF were not related to cellular proliferation.

The effect of epidermal growth factor and IGF-I infusion on hepatic and renal expression of the IGF-system in adult female rats

Systemic administration of epidermal growth factor (EGF) in neonatal rats results in reduced body weight gain and decreased circulating levels of IGF-I, suggesting its involvement in EGF-induced growth retardation. We investigated the effect of EGF and/or IGF-I administration for 7 days on circulating IGF-I and IGFBP levels and hepatic and renal IGF-system mRNA expression profiles in adult female rats. EGF administration (30 microg/rat/day) did not influence body weight, liver or kidney weight. In contrast, IGF-I (400 microg/rat/day) and EGF/IGF-I administration increased both body weight and kidney weight. Also, serum IGF-I and the 30 kDa IGFBPs (IGFBP-1 and -2) were significantly increased in these groups. Serum IGFBP-3 levels increased in the IGF-I group along with increased hepatic IGFBP-1 and -3 mRNA levels. In contrast, in the EGF administration group serum IGFBP-3 levels were significantly decreased; however, the mRNA levels remained unchanged. In the EGF/IGF-I administration group, serum IGF-I and IGFBP-3 levels were significantly lowered when compared with the IGF-I administration group. This was in contrast to the effect on kidney weight increase that was identical for the IGF-I and EGF/IGF-I groups. The decrease in serum IGFBP-3 was not reflected at the hepatic IGFBP-3 mRNA level. IGFBP-3 expression might be regulated at a post-transcriptional level although EGF induced IGFBP-3 proteolysis could not be demonstrated in vitro. We conclude that EGF administration reduced serum IGFBP-3 whereas IGF-I administration increased the level of IGFBP-3 and IGF-I and resulted in an increased body and kidney weight in adult female rats.

Time-dependent changes in the luminal surface and mass of the rat colon during prolonged systemic treatment with epidermal growth factor

BACKGROUND

Systemic treatment with epidermal growth factor (EGF) for 4 weeks increases the colonic mucosal weight and surface area. The present study was initiated to describe the time-dependent colonic changes during prolonged treatment with EGF.

METHODS

Forty-eight female Wistar rats were allocated into five groups receiving subcutaneous EGF treatment (150 microg/kg/day) for 0 (controls), 1, 2, 3, or 4 weeks. EGF was administered in the weeks before they were killed. By means of modern stereologic techniques (point counting and vertical sections), the weights of the colonic wall layers and the luminal surface area were measured on histologic sections. The colon was subdivided into proximal and distal parts.

RESULTS

The weight of the total colon increased relatively more than the total body weight. After 1 week of treatment with EGF the surface area and wet weight of the total colon increased by 47% and 10%, and after 4 weeks by 62% and 37%, respectively. After 4 weeks the weight increase was mainly due to increased mucosal weight (by 65%, P < 0.01) and less prominently the submucosa (by 45%, P < 0.01) and the muscularis propria (by 32%, P < 0.01). On the basis of the wet weight increase, the proximal colon was more responsive to EGF treatment than the distal colon.

CONCLUSIONS

Systemic treatment with EGF for 1 week increased the luminal surface area relatively more than the mass of the colon. Treatment with EGF for more than 1 week caused only a minor further surface area increase, whereas the colonic mass continued to increase in a time-dependent manner.

Pharmacological effects of epidermal growth factor (EGF) with focus on the urinary and gastrointestinal tracts

Epidermal growth factor (EGF) belongs to a family of growth factor ligands and receptors. At present, five ligands have been recognized which as EGF exert their effects via binding to the same EGF receptor. The family has three other receptors erbB2, erbB3, and erbB4, which have their own ligands (the heregulins). The system is ubiquitously distributed in mammals, and has important roles in normal development, and in regenerative and neoplastic growth. Mouse and human EGF were discovered in 1962 and 1975 by Stanley Cohen and Harry Gregory, respectively, due to EGFs potent systemic effects. EGF accelerated eyelid opening in newborn mice and inhibited gastric acid secretion in humans. Already in the late thirties, a factor in human urine was recognized which prevented or accelerated healing of experimental damage in the gastrointestinal tract. This factor appeared to be EGF. Around 1980, an effect of commercial interest was described-EGF caused shedding of the fleece in sheep. In line with the original observations, several studies have examined effects of EGF on developmental processes. Amongst other effects, EGF accelerates lung and intestinal maturation before birth and in newborn mammals. Due to the possible use of EGF in the wool industry, it was mandatory to know more about EGF. Amongst other effects in mature sheep and other animals are haemodynamic changes, changes in electrolyte homeostasis, and endocrinological changes. In relation to experimental damage, the therapeutic potential of systemic EGF has been demonstrated in all parts of the gastrointestinal tract, in the kidneys, in the liver and in the trachea. EGF has even been tried in humans in gastric ulcer healing and in necrotising enterocolitis. Studies on prolonged treatment with EGF have first recently appeared. We described effects of 4-5 weeks of treatment in Goettingen minipigs and in rats, and two other groups described effects in monkeys and in rats. In summary, species differences were observed. The species of higher order were most sensitive to treatment with EGF. EGF did not consistently change the total body weight despite EGF consistently reduced circulating levels of insulin-like growth factor I (IGF-I) in Goettingen minipigs as well as in rats. Low circulating levels of IGF-I are usually associated with retarded growth. This review mostly focuses on the organs which appeared to be most sensitive to EGF, the urinary and gastrointestinal tracts including the liver and the pancreas. The histopathological changes consisted mainly of epithelial proliferations in the gastrointestinal, urinary and respiratory tracts. These findings match the knowledge obtained from animals overexpressing the EGF agonist, transforming growth factor alpha (TGF alpha), and the mice with a knock out of the gene encoding for the EGF receptor. EGF receptor hyperstimulation (TGF alpha overexpression) in the context of the whole animal leads to epithelial proliferations whereas hypostimulation (EGF receptor knock out) leads to epithelial immaturities. In the minipigs, the epithelia of the oesophagus, ducts of the pancreas, and the urothelium were hyperplastic, the latter two epithelia with accumulation of glycoconjugates. In the rats, the epithelial hyperplasias in these tissues and in the small and large intestines were without glycoconjugate accumulations. In rats, the mucosal proliferations in the intestines resulted in increased mucosal surface area. Mesenchymal growth effects were also noted. In the ureters of the minipigs, smooth muscle cell hyperplasia and hypertrophia were found. The heart of the minipigs was also enlarged, an interesting finding regarding interactions between the different parts of the EGF system, as knock out mice of the receptors erbB2 and erbB4 die due to maldevelopments in the heart. Measurements in blood and serum also revealed consistent changes. (ABSTRACT TRUNCATED)

Time-dependent changes of levels of endogenous epidermal growth factor in submandibular glands, in kidneys, and in urine in rats during systemic treatment with EGF

BACKGROUND

Exogenous EGF influences the levels of endogenous EGF differently in the submandibular glands (SMG) and the kidneys. The aim of the present study was to examine the time-dependent changes in levels of endogenous EGF during 1-4 weeks of EGF treatment.

METHODS

Female rats were allocated into five groups receiving EGF subcutaneously (150 microg/kg/day) for 0 (controls), 1, 2, 3 and 4 weeks prior to sacrifice at an age of 12 weeks. At the end of the study period, 24-h urine samples were collected.

RESULTS

The weight of the SMG increased during EGF treatment (303+/-33 (controls), 359+/-37 (1 week EGF, P < 0.01), 390+/-30 (4 weeks EGF, P < 0.001) (mg mean+/-S.D.)). The EGF content of the SMG was unchanged after 1 week but threefold decreased after 4 weeks of treatment, respectively. The expression of EGF mRNA was decreased after 1 and 4 weeks as assessed with in situ hybridization. The weight of the kidneys was unchanged after 1 week and increased after 4 weeks of treatment (828+/-105 mg (controls) vs. 935+/-44 mg (4 weeks EGF, P < 0.005)). The renal content and the urinary excretion of EGF were significantly increased by 20-30% only in the group treated for 4 weeks.

CONCLUSION

EGF treatment induces a time-dependent decrease in the EGF content in the SMG most likely by reducing the biosynthesis of endogenous EGF. In contrast, the EGF content in kidneys and in urine was unchanged after 1 week and increased after prolonged treatment.

Systemic treatment with epidermal growth factor causes organ growth concomitant with reduced circulating levels of IGF-I and IGFBP-3: time-dependent changes in female rats

Systemic treatment with epidermal growth factor (EGF) in neonatal rats reduces circulating levels of insulin-like growth factor I (IGF-I) and causes somatic growth retardation. In this study, we investigated the effects of EGF treatment on the IGF system and on visceral organ growth and longitudinal growth in mature rats. We treated female Wistar rats for 0 (n = 16), 1 (n = 8), 2 (n = 8), 3 (n = 8), or 4 (n = 8) weeks with subcutaneous EGF (150 microg/kg/day). The animals were weighed once a week. At sacrifice, various viscera were removed and weighed. Blood and serum samples obtained at sacrifice were analysed for growth hormone (GH), IGF-I, IGF binding proteins (IGFBPs) and various routine parameters. EGF treatment increased the total body weight. All parts of the gastrointestinal tract, the liver, the pancreas, the spleen, the bladder, the suprarenal glands and the ovaries increased proportionately more in weight than the increase in total body weight; the heart and the kidneys increased proportionately in weight whereas the weight of the perirenal fat was reduced. There were no changes in tail length but the mean length of the tibia was slightly increased in the group treated for 4 weeks with EGF. Circulating GH was unchanged but IGF-I and IGFBP-3 were reduced approximately 25 and 45%, respectively, in all EGF treated groups. There were no changes in the hepatic content of IGF-I and IGFBPs. In conclusion, systemic EGF treatment causes visceral growth concomitant with reduced circulating levels of IGF-I and IGFBP-3 in mature female rats.

Glycoproteins in the urothelium and in the urine of the epidermal growth factor induced growing urinary tract in rats

Systemic treatment with epidermal growth factor (EGF) induces growth of all wall layers of the urinary tract in pigs and rats. We have previously described that the EGF stimulated urothelium in Goettingen minipigs accumulates glycoproteins. The aim of the present study was to examine and partly characterize glycoproteins in the urothelium and in the urine from rats treated with EGF. Seventy-two female Wistar rats were allocated into five groups receiving EGF treatment (150 microg/kg per day) for 0 (controls), 1, 2, 3 and 4 weeks before being killed. Glycoconjugates were characterized by means of lectins on tissue sections, and using Western blotting, in bladder extracts and in urine. The characterization mostly focused on the expression of the mucin-type core structures T and Tn using the lectins peanut agglutinin (PNA) and Vicia villosa (VVA) and specific monoclonal antibodies. The thickened EGF-stimulated urothelium retained the normal differentiation pattern as judged from the appearance on electron microscopy and from the expression of carbohydrate structures. Within the urothelium and in the urine there was increased expression of mucin-type glycoproteins suggesting increased urothelial production and excretion of mucin-type glycoproteins. In conclusion, the EGF stimulated hyperplastic urothelium most probably excretes increased amounts of mucin-type glycoproteins to the urine but it retains the normal pattern of differentiation as assessed by lectin characterization.

The effects of exogenous epidermal growth factor on the developing urinary tract in rats: a stereological description

Systemic treatment with epidermal growth factor (EGF) induces growth of all wall layers of the urinary tract in pigs and rats. In this study, we describe the time-dependent growth of the ureter and bladder. Forty-eight female Wistar rats were allocated into five groups receiving EGF treatment (150 microg/kg per day) for 0 (controls), 1, 2, 3 or 4 weeks before being killed. The 24-h urine excretion was increased only in the group treated for 4 weeks with EGF. Measured by a simple infusion device, EGF significantly increased the bladder capacity by more than 50% in all the EGF-treated groups. The volumes of the wall layers of the ureter and bladder were quantified using stereology. After 4 weeks of treatment with EGF, the total volumes of the ureter and bladder were 1.8- and 2.1-fold larger than in the control group (the urothelium was 2.8- and 3.5-fold larger and the muscular coat 1.6- and 1.6-fold larger in the ureter and bladder, respectively). In conclusion, the EGF-induced growth of the urinary tract is characterized by increased bladder capacity, and increased volume of all wall layers --most prominently the urothelium.

Endoscopic sclerotherapy in porcine esophagus changes luminal cross-sectional area and wall distensibility dose- and time-dependently

The dose- and time-dependent effects of endoscopic sclerotherapy on luminal cross-sectional area and wall distensibility were studied in pigs at 5 and 12 cm proximal to the gastroesophageal junction by means of impedance planimetry. Sixteen healthy animals underwent two sessions of endoscopic sclerotherapy two weeks apart with injections of either 5 or 10 ml of 1% Polidocanol in the distal 7 cm of the esophagus each time. The animals were investigated before sclerotherapy, two weeks after each session, and finally six weeks after the last session. Six healthy animals were studied as controls. Endoscopic sclerotherapy caused luminal narrowing in the sclerosed zone followed by normalization six weeks after the last treatment (P < 0.05 in both groups). Wall distensibility decreased in the sclerosed zone after treatment with 10 ml sclerosant (P < 0.05) followed by partial normalization, while no effect was found after 5 ml sclerosant (P > 0.2). Progressive dilations were observed in the proximal esophagus in both groups and were most pronounced in the 10 ml group (P < 0.05). Wall distensibility did not change proximal to the site of sclerotherapy in either group (P > 0.1).

Systemic treatment with epidermal growth factor in pigs induces ductal proliferations in the pancreas

BACKGROUND & AIMS

Epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha), and the EGF receptor are often overexpressed in chronic pancreatitis and in malignant pancreatic growth. Transgenic mice overexpressing TGF-alpha develop tissue changes in the pancrease resembling changes found in chronic pancreatitis. The effects of systemic treatment with EGF on the porcine pancrease were investigated in this study.

METHODS

Mature Goettingen minipigs were treated with solvent (n = 5), EGF (30 micrograms.kg-1.day-1; n = 6) for 4 weeks, or EGF (30 micrograms.kg-1.day-1; n = 5) for 5 weeks followed by 3 weeks of recovery. Pancreata were studied by routine histological examination and electron microscopy and were immunostained for proliferating cell nuclear antigen (PCNA).

RESULTS

In the EGF-treated animals, mainly larger interlobular ducts of the pancreas appeared to be considerably hyperplastic, with an increased number of nuclei that stained for PCNA. The epithelia of these ducts were increased in height, with accumulations of glycoconjugates in the columnar cells and in an increased number of goblet cells.

CONCLUSIONS

A new approach to experimentally induced hyperplastic changes of the excretory ducts of the pancreas is presented. Because ductal changes with glycoconjugate accumulations are common features of chronic pancreatitis and pancreatic cancer, the findings may be relevant to the pathogeneses of these conditions.

Systemic administration of insulin-like growth factor I (IGF-I) causes growth of the rat prostate

PURPOSE

To investigate the effects of insulin-like growth factor I (IGF-I) and epidermal growth factor (EGF) on the rat prostate. In addition, we investigated the effect of ornithine decarboxylase (ODC) inhibition with alpha-diflouromethylornitine (DFMO) on the expected growth of the prostate.

MATERIALS AND METHODS

Eight week old Wistar rats were allocated into groups of eight, receiving systemic treatment for 3 and 7 days with either IGF-I (400 micrograms/rat/day) or EGF (30 micrograms/rat/day) alone or in combination with DFMO.

RESULTS

Systemic treatment with IGF-I for 7 days resulted in a 29% (p < 0.01) increase in the mean wet weight of the ventral prostate. The mean weight of the dorsolateral lobe of the prostate increased by 39% (p < 0.05), and the seminal vesicle and coagulating gland increased 69% (p < 0.05) compared to controls. The ODC-activity in the prostate was significantly increased by IGF-I after 3 days of treatment, and administration of IGF-I concomitantly with DFMO significantly inhibited ODC activity and the weight increase of the prostate. Stereological examination of the prostate in the IGF-I-treated animals showed growth of the epithelial component of the gland. Systemic treatment with EGF did not affect the mean weight of the prostate or the seminal vesicle compared to controls.

CONCLUSION

The results demonstrate that treatment with IGF-I but not EGF for 7 days induces profound growth of the rat prostate and the seminal vesicle, and that the growth is dependent on an intact ODC-activity.

Acute contractile effects of epidermal growth factor on bladder smooth muscles. An in vivo and in vitro study in rats

Chronic treatment with epidermal growth factor (EGF) stimulates growth of all wall layers of the urinary tract in pigs and rats. Herein, we investigated the acute effects of EGF on detrusor smooth muscle activity. For in vivo examination, awake rats received EGF (75 micrograms/kg) intravenously and detrusor smooth muscle activity was monitored cystometrically. The EGF bolus caused no alteration in diuresis but a doubling of the micturition frequency, a 25% increase in micturition pressures, and increased irregular baseline contractile activity. For in vitro examination detrusor smooth muscle strips were exposed to EGF (1 microgram/ml). EGF caused contraction and increase in the spontaneous activity. In conclusion, EGF increases rat detrusor smooth muscle contractile activity in vivo and in vitro. The finding suggests that a direct effect of EGF on bladder smooth muscles is part of the genesis to the growth of the detrusor smooth muscle observed after chronic EGF treatment.

Chronic systemic treatment with epidermal growth factor induces smooth muscle cell hyperplasia and hypertrophy in the urinary tract of mature Goettingen minipigs

OBJECTIVE

To determine the effect of systemic treatment with epidermal growth factor (EGF) on the induction of growth in the urinary tract.

MATERIALS AND METHODS

Mature Goettingen minipigs were treated daily with vehicle (Tris-HCl; n = 5) or EGF (30 micrograms/kg) (n = 6) for 4 weeks. The total number of smooth muscle cells was counted using an optical disector in a 20 microns thick cross-section of the ureter and the mean smooth muscle cell volume estimated. Cell proliferation was detected by immunostaining for the marker Ki67.

RESULTS

The ureters of the animals treated with EGF were longer and thicker than those of the controls and the median cross-sectional area of the ureter was 3.3-fold larger; the growth involved all wall layers. The median (range) number of smooth muscle cells in a 20 microns thick cross-section of the ureter was 11 (9-12) x 10(3) in the pigs treated with placebo and 55 (19-80) x 10(3) in those treated with EGF, and the median (range) volume of the smooth muscle cells was 2.3 (2.2-2.4) x 10(3) and 4.0 (3.0-4.5) x 10(3) mm3, respectively.

CONCLUSIONS

There were two likely mechanisms contributing to smooth muscle cell hyperplasia, the division of fully differentiated smooth muscle cells and division of fibroblasts in the borderline between the submucosal layer and muscular coat, with ensuing differentiation into smooth muscle cells. Treatment with EGF induces the growth of all wall layers in the urinary tract with remarkable hyperplastic and hypertrophic changes of the smooth muscle cells in the muscular coat.

Epidermal growth factor and acute radiation damage in CDF1 mice in vivo

The aim was to investigate if extent and time course of acute radiation damage to epidermis and intestine could be moderated by epidermal growth factor (EGF). Twelve-to-sixteen weeks old female CDF1 mice were treated either by single dose local irradiation to the right hind leg or total body irradiation (TBI). The endpoints were skin score and lethality, respectively. Human recombinant EGF was given s.c. or i.p. at a dose of 5-10 microg/day either before or after irradiation. Body weight was significantly higher for EGF treated animals compared with controls treated with saline. However, EGF did not reduce the median skin score following local irradiation and did not increase LD50 (days 1-6) following TBI. Further studies using more specific assays are necessary to determine if radiation damage to less toxic levels can be ameliorated by EGF.

The effects of chronic administration of epidermal growth factor (EGF) to rats on the levels of endogenous EGF in the submandibular glands and kidneys

Epidermal growth factor (EGF) is mainly produced in the submandibular glands (SMG) and in the kidneys. It has recently been reported that EGF-related ligands may induce their own biosynthesis (autoinduction) in vitro. In the present paper, we investigated whether chronic systemic treatment with EGF influenced the amount of endogenous EGF in the SMG and kidneys. Eight-week-old female Wistar rats were treated with subcutaneous injections of placebo (n = 16) or human recombinant EGF (150 micrograms/kg per day, n = 8) for 4 weeks. Urine was sampled the last 24 h of the study period. At the time of killing, the SMG and the kidneys were removed. The SMG was larger in the EGF-treated animals, 229.8 +/- 35.5 (mean +/- SD) mg than in the control animals, 181.7 +/- 18.1 mg (P < 0.01). The total EGF content was smaller (0.51 +/- 0.15 vs. 1.12 +/- 0.40 nmol EGF/SMG, P < 0.001). The kidneys were larger in the EGF-treated animals (1.38 +/- 0.08 vs. 1.28 +/- 0.08 g, P < 0.05), but the EGF content and urinary excretions were not changed. In conclusion, chronic systemic treatment with EGF causes growth of the SMG with concomitantly reduced contents of EGF, and growth of the kidneys with unchanged content and excretion of EGF. These findings suggest that EGF may play a part in the regulation of the growth of the SMG and in EGF biosynthesis.

The effect of epidermal growth factor on circulating levels of IGF and IGF-binding proteins in adult Goettingen minipigs

It has recently been demonstrated that epidermal growth factor (EGF) administration to neonatal rodents causes growth retardation with concomitant reductions in circulation levels of IGF-I. We describe the effects of systemic EGF administration for 4 weeks on circulating levels of IGF-I and IGF-binding proteins (IGFBPs) and on thyroid hormones (tri-iodothyronine, T3; thyroxine, T4) in sexually mature pigs. Goettingen minipigs of either sex were treated with placebo (n = 5) or EGF (30 micrograms/kg per day, n = 6) s.c. for 4 weeks (in relation to an oesophageal sclerotherapy regimen). Blood samples were taken under anaesthesia before and after 1, 2, 3 and 4 weeks of treatment. Circulating levels of IGF-I, insulin, glucose, T3 and T4 were analysed every week and IGFBPs every second week. IGF-I was not reduced significantly after 1 week but significantly reduced after 2 and 3 weeks of EGF treatment. A similar decline was observed for the major IGFBP, IGFBP-3, which was reduced after 2 and 4 weeks. IGFBP-1, IGFBP-2 and IGFBP-4 increased throughout the treatment period (all significantly at week 4). EGF treatment induced increased circulating T3 after 2, 3 and 4 weeks of EGF treatment. In conclusion, we report that EGF treatment for 4 weeks in Goettingen minipigs reduces circulating IGF-I and IGFBP-3, increases circulating IGFBP-1, IGFBP-2 and IGFBP-4, and induces a slight hyperthyroidism as judged from increased circulating levels of T3.

Elastic properties in the circumferential direction in isolated rat small intestine

The aim was to study the passive biomechanical wall properties in the isolated duodenum, jejunum and ileum of the rat. The organ bath contained a Krebs-Ringer solution with 10(-2) M MgCl2 to abolish smooth muscle contractile activity. Stepwise inflation of an intraluminal balloon, in which the cross-sectional area (CSA) was measured, provided the distension stimulus. The circumferential wall stress-strain distributions were computed from steady-state values of these measurements and the unstressed wall thickness was measured in order to evaluate the passive elastic properties. The CSAs measured increased from duodenum to jejunum and to ileum (P < 0.001). At the highest applied pressure load the CSA was 16.64 +/- 0.46 mm2 for the duodenum, 18.70 +/- 0.53 mm2 for the jejunum and 21.73 +/- 0.49 mm2 for the ileum. The wall thickness was 0.19 +/- 0.01, 0.25 +/- 0.01 and 0.28 +/- 0.02 mm, in duodenum, jejunum and ileum, respectively (P < 0.01). All segments showed stress-strain distributions that were exponential by nature. Applying the function Y = exp (a + bX) gave a median determination coefficient of 0.98 (quartiles 0.96-0.99). The duodenum was significantly stiffer than the two other segments. The values of a and b were 2.03 +/- 0.11 and 14.82 +/- 1.81, 1.39 +/- 0.20 and 13.15 +/- 1.42, and 1.13 +/- 0.13 and 10.69 +/- 0.65 for the duodenum, jejunum and ileum, respectively. The a differed between the duodenum and the other segments (P < 0.001). whereas the b differed only between the duodenum and ileum (P < 0.005). In conclusion, differences in the luminal CSA, wall thickness and elastic properties were found between the duodenum, jejunum and ileum.

Effects of longterm epidermal growth factor treatment on the normal rat colon

BACKGROUND

Epidermal growth factor (EGF) exerts trophic effects on the mucosa of damaged and defunctioned colon, but the effects on the normal large bowel wall are not known.

AIMS

To investigate the effect of systemic EGF treatment on growth and morphology of normal rat colon.

METHODS

Rats were treated with subcutaneous biosynthetic EGF injections of 150 micrograms/kg/day for 28 days. The weight of the histological colonic wall layers and the luminal surface area were measured using quantitative morphometric analysis (stereology). The colon was subdivided into proximal and distal parts.

RESULTS

EGF treatment increased the total colon wet weight by 23% compared with controls (p < 0.005). The weight increase occurred in the mucosal (33%) and the submucosal layers of the bowel wall (36%) and there was a 69% increase of the total luminal surface area (p = 0.001). In the proximal part of colon of EGF rats there was a 68% increase in mucosal weight (p < 0.005) accompanied by a 79% increase in the mucosal surface area compared with controls (p < 0.005), whereas submucosal and muscularis propria weights were identical. In distal colon, the mucosal weight increased 28% in the EGF group (p < 0.005), the mucosal surface area increased by 72% after treatment (p < 0.01). Furthermore there was a 34% increase in the weight of submucosa (p < 0.001) in the distal colon among EGF rats.

CONCLUSIONS

Treatment of rats with EGF has a stimulating role on the mucosa and luminal surface area of the entire functioning colon and a trophic effect on the submucosa of the distal colon.

The effect of epidermal growth factor on circulating levels of free and total IGF-I and IGF-binding proteins in adult rats

In neonatal rats, systemic administration of epidermal growth factor (EGF) results in reduced body weight gain and decreased levels of circulating IGF-I, which suggests that it be involved in the EGF-induced growth retardation. We investigated the effect of 4 weeks of EGF administration on circulating free and total IGF-I and IGF-binding proteins (IGFBPs) in adult rats treated with saline (controls), 30 (low dose group) and 150 (high dose group) microgram/kg/day EGF. Serum IGF-I was determined in ultrafiltrates (free) and acid-ethanol extracts (total), and serum IGFBPs using Western ligand blotting, which yielded four distinct molecular bands. The IGFBPs were tentatively identified as IGFBP-3 (a double band at 42 and 38 kDa), IGFBP-1 and/or IGFBP-2 (a single band at 30 kDa) and IGFBP-4 (a single band at 24 kDa). EGF administration did not change the body weight, tibia length, or liver, heart and lung weight. In contrast, serum total IGF-I and IGFBP-3 decreased dose-dependently: total IGF-I averaged 1470 +/- 100 micrograms/l (controls; mean +/- SEM), 1030 +/- 60 micrograms/l (low dose group; P < 0.005) and 760 +/- 40 micrograms/l (high dose group; P < 0.005), whereas differences between IGFBP-3 levels reached significance (P < 0.05) between controls and high dose rats, only. When compared to controls, levels of IGFBP-1 and/or IGFBP-2 were increased in the low dose group (P < 0.05), but unchanged in the high dose group. IGFBP-4 was unaffected by EGF. Free IGF-I averaged 74 +/- 6 micrograms/l in controls, and was reduced to 35 +/- 6 micrograms/l (low dose group; P < 0.005) and 57 +/- 5 micrograms/l (high dose group; P < 0.05). Free IGF-I was inversely correlated (r = -0.49, P < 0.05) with IGFBP-1 and/or IGFBP-2. We conclude that in adult rats prolonged EGF administration has a marked depressing effect on circulating total and free IGF-I. Nevertheless, we did not observe any somatic growth retardation.

Systemic treatment with epidermal growth factor in the rat. Biomechanical properties of the growing small intestine

Prolonged treatment with epidermal growth factor (EGF) in the rat provides an experimental model to growth of the gastrointestinal tract. We treated female Wistar rats for 0 (n = 15), 1 (n = 8), 2 (n = 8), and 4 (n = 8) weeks with subcutaneous EGF (i50 micrograms.kg-1.day-1). Segments were taken from locations at 10, 50 and 90% along the length of the small intestine, weighed, the wall thickness was measured and the luminal cross-sectional area and passive biomechanical properties were assessed using impedance planimetry. In addition, the wall composition was evaluated on histological sections. The weight of the total small intestine and of the three segments (measured in mg.cm-1) increased with the duration of the EGF treatment due to mucosal and muscular growth. After 1 week of treatment the wall thickness increased. After 2 weeks of treatment the cross-sectional area began to increase. The circumferential stress-strain distributions revealed translation of the curves to the right in the graphs implying reduced wall stiffness during EGF treatment. In conclusion EGF treatment for 1 to 4 weeks caused a time-dependent increase in intestinal weight. The growth was characterized by increased wall thickness, increased cross-sectional area and reduced wall stiffness.

Systemic treatment in the rat with epidermal growth factor causes polycystic growth of the ovaries

BACKGROUND

It has previously been suggested that epidermal growth factor (EGF) plays a role in the function of the ovary. We administered systemic EGF to assess the influence of EGF receptor stimulation on the morphology of the ovaries.

METHODS

Forty-eight female Wistar rats were allocated to five groups receiving EGF treatment (150 microgram/kg/day) for 0 (controls), 1, 2, 3 and 4 weeks. All rats were exactly 8 weeks at the start of the experiment and 12 weeks at sacrifice. The EGF was administered in the weeks prior to sacrifice. At sacrifice, the perfusion-fixed ovaries were removed and weighed, and the volumes of tissue components were quantified using stereology.

RESULTS

EGF administration increased the total weight of the ovaries from 129 +/- 18 mg in the controls to 158 +/- 29 mg (p<0.05) after one week. In subsequent weeks the total weight increased to 230 +/- 73 mg (p<0.001). The weight gain after one week of treatment was exclusively due to a fourfold increase in follicular cyst volume (p<0.01). In subsequent weeks the cyst volume was increased up to eightfold. After 2, 3 and 4 weeks of treatment the quantity of luteinizing cells was likewise increased by 70% (p<0.01).

CONCLUSION

EGF administration causes the follicular cells to produce cysts and increases the quantity of luteinizing cells.

Chronic treatment with epidermal growth factor stimulates growth of the urinary tract in the rat

Twenty-four male Wistar rats, 8 weeks old, were allocated into three groups and treated with human recombinant epidermal growth factor (EGF) administered subcutaneously in doses of 0, 30, and 150 micrograms/kg per day for 4 weeks. Blood sampling was done every 2nd week and urine sampling was done for 2 consecutive days every week. The most striking finding was that the ureters were dose dependently enlarged, due to growth of all layers of the ureteric wall. The urothelium of the bladder showed considerable hyperplasticity with a widening of the basal proliferative compartment and a normal differentiation pattern as observed by the expression of carbohydrate epitopes, characterized with lectinohistochemistry. Blood examination revealed a decrease in blood haemoglobin concentration and a slight increase in serum creatinine concentration in the high-dose group. There were no effects of EGF on the urinary excretion of electrolytes, proteins, and endogenous EGF.

An immunoassay designed to quantitate different molecular forms of rat urinary epidermal growth factor with equimolar potency: application on fresh rat urine

Different molecular weight forms of epidermal growth factor (EGF) are present in vivo and this makes quantitation of EGF difficult. Most immunoassays employ antibodies against 6-kDa EGF, and such assays are likely to underestimate the amount of high molecular weight forms of EGF. The purpose of the present study was to develop a processing-independent ELISA which is able to quantitate different molecular forms of rat EGF with equimolar potency. Our "old ELISA" used two polyclonal antibodies against rat submandibular gland EGF as catching and detecting antibodies, and 6-kDa EGF purified from rat urine as calibrator. This assay was modified to a processing-independent ELISA by converting the different forms of EGF in the samples as well as the calibrator to the same immunoreactive form of EGF prior to analysis. This could be achieved by trypsinization because trypsin cleaved the different molecular forms of rat urinary EGF to a single immunoreactive form. We applied both the "old ELISA" and the processing-independent ELISA on different molecular forms of EGF and demonstrated that the "old ELISA" underestimated high molecular weight forms by two thirds. The relative amounts of high and low molecular weight forms of EGF in urine have been debated, since different results have been obtained by different techniques. In order to address the problem it is important to quantitate the different molecular forms with equimolar potency. Employing the processing-independent ELISA we find that high molecular weight forms of EGF constitute 40% and 6-kDa EGF 60% of EGF in fresh rat urine.

Impedance planimetric characterization of the distal oesophagus in the Goettingen minipig

Regional differences in biomechanical properties of the oesophagus were studied in 15 healthy Goettingen minipigs by means of impedance planimetry. The investigation was performed during anaesthesia by stepwise pressure-induced balloon distensions with concomitant measurement of pressure and luminal cross-sectional area (CSA) in the oesophagus 5 and 10 cm above the gastro-oesophageal junction. The circumferential wall tension, circumferential strain and incremental elastic modulus were computed from the measurements of pressure and CSA at steady-state conditions. Probably due to the anaesthesia, only scant peristalsis was recorded and the CSA always reached steady state during the balloon distensions. The CSAs were highest in the distal oesophagus (P < 0.001). At the highest induced pressure, the CSAs were 605 +/- 32 and 453 +/- 29 mm2 (mean +/- SEM) for the locations 5 and 10 cm from the gastro-oesophageal junction. The tension-strain distributions were non-linear and the curve obtained 5 cm above the gastro-oesophageal junction was shifted to the right when compared with the curve obtained from 10 cm above this junction. Fitting of the function tension = exp(a+b strain) to the data gave determination coefficients higher than 0.97 and P values lower than 0.001 for both measuring points. The constant a differed between the two locations in the oesophagus (P < 0.05). In conclusion, the pressure-CSA and the tension-strain distributions differed between the two measuring points suggesting that the elastic properties are different.

Chronic systemic treatment with epidermal growth factor in the rat increases the mucosal surface of the small intestine

We examined the effects of treatment with human recombinant epidermal growth factor (EGF) on the functioning small intestine in the rat. Male Wistar rats, 7-8 weeks old, were treated with EGF administered subcutaneously in doses of 0 (n = 7) or 150 micrograms/kg/day (n = 8) for 4 weeks. The histological composition and mucosal surface area of the perfusion-fixed small intestine was quantified with stereological principles. The length of the gut remained unchanged. The amount of tissue and surface area per length of gut (median (ranges)) were increased from 117 (101-131) mg/cm and 2.6 (2.1-3.5) cm2/cm in the controls to 146 (138-152) mg/cm and 3.5 (2.5-3.8) cm2/cm for the complete small intestine (both comparisons P < 0.02). The weight increase was due to mucosal growth in all parts of the intestine, whereas the surface area was only increased in proximal and middle parts. It is concluded that EGF treatment in rats increases the mucosal weight and surface area of the functioning small intestine.

Chronic administration of epidermal growth factor to pigs induces growth, especially of the urinary tract with accumulation of epithelial glycoconjugates

BACKGROUND

Epidermal growth factor (EGF) receptor hyperstimulation induced by systemically administered EGF or by the development of transgenic mice overexpressing transforming growth factor alpha (TGF alpha) or other EGF-related ligands is known to induce various effects, such as acceleration of developmental processes like incisor eruption, inhibition of gastric acid secretion, morphologic changes in the pancreas resembling pancreatitis, and malignancies in mammary glands and the liver. The present investigation was initiated to explore the effects of systemic EGF administration to the mature organism in a species with greater anatomic resemblance to humans than rodents.

EXPERIMENTAL DESIGN

Eleven Goettingen Minipigs underwent 4 weeks of treatment either with placebo (n = 5) or human recombinant EGF 30 micrograms/kg/day (n = 6) administered subcutaneously. At the end of Week 4, the animals were sacrificed, autopsy was performed, and tissue samples were collected for histologic examination.

RESULTS

EGF treatment caused macroscopic enlargement of the ureters, kidney, and heart. The ureters increased 4-fold in cross sectional area due to growth of all wall layers. The urothelium was hyperplastic with intracellular accumulations of material staining with Periodic acid-Schiff. Similar but less pronounced changes were found in the pancreas, lungs, salivary glands and esophagus.

CONCLUSIONS

The most important observation of the present study is that systemic treatment with EGF for 4 weeks induces considerable growth to the urinary tract. We suggest new biologic effects of the EGF family in promoting growth of the urinary tract and in stimulating epithelial glycoconjugate biosynthesis in the urothelium and excretory ducts of the pancreas.

Chronic treatment with epidermal growth factor causes esophageal epithelial hyperplasia in pigs and rats

Epidermal growth factor (EGF) is an important factor for maintaining the esophageal functional integrity. Goettingen minipigs were treated with either placebo or subcutaneous EGF (30 micrograms/kg/day) for four weeks. Wistar rats were treated with either placebo or subcutaneous EGF (150 micrograms/kg/day) for four weeks. At sacrifice, esophageal samples were obtained for histology, immunochemistry, and lectin characterization. In pigs, the thickness of the esophageal epithelium was almost doubled in the EGF-treated animals. Characterization with lectins revealed a normal pattern of differentiation. Subcutaneously administered EGF was visualized on cells located basally in the esophageal epithelium. In rats, EGF-treatment increased the esophageal volume of the epithelium, the lamina propria of the mucosa, and the submucosa. In conclusion, systemic EGF challenge induces growth of the esophageal epithelium with an unaltered pattern of differentiation. This supports previous studies demonstrating a beneficial effects of systemic EGF-treatment on sclerotherapy-induced esophageal damage.

Chronic systemic treatment with epidermal growth factor in pigs causes pronounced urothelial growth with accumulation of glycoconjugates

Epidermal growth factor (EGF) is present in large amounts in the urine, but the effects of systemically administered EGF on the urinary tract have not been described previously. In the present paper, we describe a potent growth induction of EGF on the urinary tract. Goettingen minipigs were treated with solvent (n = 5), EGF 30 micrograms/kg/day (n = 6) for 4 weeks, or EGF 30 micrograms/kg/day for 5 weeks followed by 3 weeks of recovery (n = 5). The ureters and bladders were examined by routine histology and electron microscopy and were immunostained for proliferating cell nuclear antigen. Four weeks of EGF treatment increased the median cross sectional area of the ureter fourfold with growth of all wall layers. The urothelium was widened from 5 cell layers in the controls to 10 in the EGF-treated animals. Proliferating cell nuclear antigen immunostaining revealed an increased mitotic activity in the basal zone of the urothelium. In the luminal zone, glycoconjugates accumulated in goblet cells, in cells with intracytoplasmic lumina, and beneath the luminal cell membrane in the umbrella cells. Our studies present a new experimental approach to growth induction of the urinary tract. The findings implicate the EGF system in regulating urothelial growth and glycoconjugate biosynthesis.

Systemic treatment with epidermal growth factor induces anaemia in Goettingen minipigs

1. From two independent experimental studies conducted in 48 minipigs with oesophageal sclerotherapy and concomitant treatment with epidermal growth factor, blood samples together with bone marrow biopsies were analysed for safety data. 2. Four to five weeks of systemic treatment with epidermal growth factor induced a decline in blood haemoglobin concentration in a time- and dose-dependent and reversible manner but without an effect on leucocyte or platelet counts. 3. The bone marrow expressed decreased amounts of haematopoietic tissue and reduced numbers of erythropoietic cells. 4. Four to five weeks of systemic treatment with epidermal growth factor induced reversible increases in serum concentrations of creatinine and urea, most likely reflecting renal impairment. 5. Groups in which creatinine and urea were not increased also had reduced blood haemoglobin concentrations. 6. These findings suggest that epidermal growth factor selectively impaired the erythropoiesis and stress the importance of risk-benefit analysis concerning the potential therapeutic applications of epidermal growth factor.

Preventive effects of recombinant human epidermal growth factor on the oesophageal epithelium in pigs subjected to sclerotherapy

OBJECTIVE

To investigate the role of epidermal growth factor (EGF), a small (relative molecular mass 6000) polypeptide with mitogenic properties in the protection of gastrointestinal mucosal integrity.

DESIGN

A prospective, randomized and blinded study.

METHODS

Twenty-four minipigs with surgically induced portal hypertension underwent four consecutive weekly sessions of oesophageal sclerotherapy with 5 ml 1% polidocanol and were concomitantly treated with either a placebo or human recombinant EGF administered subcutaneously. Mucosal damage was evaluated on a weekly basis by endoscopic estimation of the size of the ulcerated area and by post-mortem morphometry. The EGF-induced morphological changes in the oesophageal epithelium were also evaluated histologically.

RESULTS

In sclerosed and non-sclerosed parts of the oesophagus EGF significantly increased the thickness of the oesophageal epithelium (P < 0.03), but failed to reduce significantly the degree of oesophageal damage associated with sclerotherapy (P = 0.11).

CONCLUSIONS

Systemic EGF treatment induces proliferation of the oesophageal mucosa, and EGF may therefore have the potential to reduce sclerotherapy-induced oesophageal damage.

Epidermal growth factor attenuates the sclerotherapy-induced biomechanical properties of the oesophagus. An experimental study in minipigs

BACKGROUND

The effect of epidermal growth factor (EGF) on the biomechanical properties of the oesophagus subjected to sclerotherapy was studied in Goettingen minipigs by means of impedance planimetry.

METHODS

Seventeen animals underwent three sessions of weekly endoscopic sclerotherapy. During these 3 weeks and for the subsequent 2 weeks they were treated with either EGF or placebo. After another 3 weeks an impedance planimetric study was done. Ten healthy non-sclerosed pigs were studied as controls. Impedance planimetry was performed by stepwise pressure-induced balloon inflation for analysis of oesophageal cross-sectional area 5 and 10 cm above the gastro-oesophageal junction (GEJ).

RESULTS

Systemic treatment with EGF (total daily dose of 30 micrograms/kg/day, administered subcutaneously) for 3 to 7 days per week combined with a weekly paravenous injection of 20-40 micrograms/kg attenuated the oesophageal damage caused by sclerotherapy, implying less pronounced narrowing 5 cm above and less dilation 10 cm above the GEJ.

CONCLUSION

These observations suggest a potential therapeutic role for EGF in attenuating sclerotherapy-induced oesophageal injury.

Chronic systemic treatment with epidermal growth factor induces hypergastrinaemia in Goettingen minipigs

BACKGROUND

Epidermal growth factor (EGF) is an inhibitor of gastric acid secretion. The impact of chronic systemic treatment with EGF on intragastric pH and serum gastrin concentrations has not been investigated previously.

METHODS

Goettingen minipigs were treated with human recombinant EGF (hEGF) or placebo for 4 weeks. Once a week the acidity and protein concentration of gastric juice were determined, and serum gastrin concentrations measured. After 4 weeks, tissue specimens were obtained from the gastric antrum and immunostained for gastrin- and somatostatin-producing G- and D-cells. Furthermore, the development of antibodies against hEGF was evaluated.

RESULTS AND CONCLUSION

Subcutaneously administered hEGF, 30 micrograms/kg/day for 4 weeks, included a fourfold increase in basal serum gastrin concentration, increased the number of antral G-cells, and decreased the density of antral D-cells. The acidity of gastric fluid was reduced, and the protein concentration increased. All animals developed low-titred antibodies towards hEGF. The antibodies did not influence the extent to which the individual animal responded to the EGF treatment.

Tissue distribution of 131I-labelled epidermal growth factor in the pig visualized by dynamic scintigraphy

We visualized the metabolism of intravenously injected 131I-labelled epidermal growth factor in the pig using dynamic scintigraphy combined with repetitive samplings of blood, urine and bile. The labelled peptide was recognized in the samples by means of immunoprecipitation and high pressure liquid chromatography. The plasma elimination was extremely rapid, and it was described with a triexponential equation, C(t) = A*e -alpha*t+B*e-beta*t+C*e-gamma*t. The first two exponentials denoted the distribution phase, and the third the elimination phase. T1/2 alpha ranged from 0.4-0.7 min, T1/2 beta from 2.0-2.2 min and T1/2 gamma from 53.3-97.6 min. Concomitant with the rapidly declining plasma concentration, the gamma camera visualized the uptake by the liver and the kidneys. The liver was the principal organ for clearance and degradation of the labelled peptide, but only 0.12-0.30% of the injected dose was excreted into the bile. The renal uptake and the urinary excretion accounted for 6.6-13.0 and 2.5-4.9% of the given dose, respectively.

Systemic treatment with recombinant human epidermal growth factor accelerates healing of sclerotherapy-induced esophageal ulcers and prevents esophageal stricture formations in pigs

Human epidermal growth factor (EGF), a small polypeptide (6 kDa) with mitogenic properties, has been implicated in the protection of gastrointestinal mucosal integrity. The efficacy of EGF in the prevention and healing of sclerotherapy-induced esophageal lesions was investigated in 24 minipigs with surgically induced portal hypertension. In addition, the effect of EGF on intragastric acidity and pharmacokinetics was investigated as possible means to explain its protective mechanism of action. The animals underwent three weekly sessions of sclerotherapy with polidocanol 2% and were concomitantly and for an additional three weeks treated with either placebo or EGF administered paravenously in the esophagus and/or subcutaneously. The subcutaneous treatment with EGF significantly (P < 0.05) reduced esophageal stricture and scar formations associated with sclerotherapy. Gastric pH values were significantly (P < 0.01) elevated only in animals receiving subcutaneous injections of EGF. Furthermore, the subcutaneous administration of EGF was associated with unexpected prolonged plasma concentration of the peptide. These results suggest a possible clinical value of EGF as an adjunctive treatment with the sclerotherapy.

Biomechanical properties of the oesophagus damaged by endoscopic sclerotherapy. An impedance planimetric study in minipigs

BACKGROUND

The aims of the present study were to evaluate, by means of impedance plainmetry, regional differences in biomechanical properties in the normal oesophagus and the oesophagus damaged by sclerotherapy.

METHODS

Four minipigs underwent a weekly session of sclerotherapy for 4 weeks. Impedance planimetry was performed before the first session of sclerotherapy and 1 week after the last session of sclerotherapy. Investigations were performed by stepwise pressure-induced balloon distensions with concomitant measurements of pressure and luminal cross-sectional area (CSA) in the oesophagus 5 and 10 cm above the gastro-oesophageal junction (GEJ).

RESULTS

The normal oesophagus had significantly larger CSAs 5 cm than 10 cm above the GEJ (P < 0.05). Endoscopic sclerotherapy entailed an inversion (P < 0.05) of the normal oesophageal configuration, with narrowing 5 cm above the GEJ (P < 0.05) and increased CSAs 10 cm above the GEJ (P < 0.05).

CONCLUSIONS

Regional differences in CSA occur in the normal oesophagus, and sclerotherapy produces profound changes in the oesophageal configuration.