Size heterogeneity of epidermal growth factor in human body fluids

The Significance of Epidermal Growth Factor in Noninvasively Obtained Amniotic Fluid Predicting Respiratory Outcomes of Preterm Neonates

Preterm premature rupture of membranes (PPROM) interrupts normal lung development, resulting in neonatal respiratory morbidity. Although post-PPROM risks have been researched, only a few studies have investigated noninvasively obtained amniotic fluid (AF) to predict neonatal outcomes. In this study, we aimed to determine whether epidermal growth factor (EGF) in vaginally-collected AF is a significant predictor of neonatal respiratory outcomes after PPROM. We analyzed EGF in vaginally-obtained AF from 145 women with PPROM at 22−34 weeks of gestation. The following neonatal outcomes were included: respiratory distress syndrome, surfactant need, duration and type of respiratory support, and bronchopulmonary dysplasia. We found that EGF concentration was associated with gestational age, and its medians were lower in neonates with respiratory morbidities than unaffected ones. EGF concentrations gradually declined, the lowest being in the most clinically ill patients. EGF < 35 pg/mL significantly predicted the odds of severe respiratory outcomes. EGF in noninvasively collected AF may be a reliable predictor for respiratory outcomes of preterm neonates with PPROM before 34 weeks of gestation. The results of our study may have implications for further research both in noninvasive amniotic fluid analysis and the management of patients after PPROM.

Characterization of human epidermal growth factor in human serum and urine under native conditions

The objective of this study was to investigate the molecular nature of the human epidermal growth factor (EGF) in serum and urine samples of normal subjects. Recombinant EGF emerged as a single peak and did not interact with human IgG1 and albumin up to the concentration of 12 microg/ml. Freshly separated human serum contained only trace amounts of EGF. However, EGF appeared and increased in serum separated from blood after spontaneous overnight clotting. The authentic 6 kDa form of EGF made up nearly 40% of the total EGF in serum and revealed relatively homogeneous feature. The remaining immunoreactive fractions corresponded to 160 kDa proEGF. Immunoreactive EGF in blood seemed to be associated with the EGF release from platelets. TSKgel G3000SW chromatography of freshly-voided morning and day urines revealed that urine samples mainly contained two major form of EGF; a high-molecular-weight (HMW) and low-molecular-weight (LMW) forms. In the sense of molecular nature of EGF contents, morning urine was more heterogeneous than day urine of the same individuals. The LMW form of EGF in morning urine, in which its proportion was more than 90% of the total EGF, revealed further heterogeneous feature generally containing three to four different components.

Structure and function of human sweat glands studied with histochemistry and cytochemistry

The basic structure and the physiological function of human sweat glands were reviewed. Histochemical and cytochemical techniques greatly contributed the elucidation of the ionic mechanism of sweat secretion. X-ray microanalysis using freeze-dried cryosections clarified the level of Na, K, and Cl in each secretory cell of the human sweat gland. Enzyme cytochemistry, immunohistochemistry and autoradiography elucidated the localization of Na,K-ATPase. These data supported the idea that human eccrine sweat is produced by the model of N-K-2Cl cotransport. Cationic colloidal gold localizes anionic sites on histological sections. Human eccrine and apocrine sweat glands showed completely different localization and enzyme sensitivity of anionic sites studied with cationic gold. Human sweat glands have many immunohistochemical markers. Some of them are specific to apocrine sweat glands, although many of them stain both eccrine and apocrine sweat glands. Histochemical techniques, especially immunohistochemistry using a confocal laser scanning microscope and in situ hybridization, will further clarify the relationship of the structure and function in human sweat glands.

Histochemical and immunohistochemical markers for human eccrine and apocrine sweat glands: an aid for histopathologic differentiation of sweat gland tumors

Apocrine and eccrine sweat glands are distinct in function, although they are closely related to each other developmentally and morphologically. In certain sweat gland tumors, it is difficult to differentiate between eccrine or apocrine sweat glands. Therefore, this paper reviews histochemical and immunohistochemical markers to differentiate apocrine and eccrine sweat glands with the aim of better understanding the structural and functional characteristics of these sweat glands. Specific markers for apocrine sweat glands are as follows: neuraminidase sensitive anionic sites detected by cationic colloidal gold at pH 2.0, and mitochondrion-like secretory granules that have epidermal growth factor-like antigenicity. The following antibodies react with apocrine sweat glands but not with eccrine sweat glands; the antibodies raised against 70 kDa glycoprotein purified from human milk fat globule membranes, and HMFG-1 (1.10.F3) monoclonal antibody produced by immunizing mice with defatted human milk fat globule membranes. Markers for eccrine sweat glands are as follows: dark cell granules that have chondroitinase ABC sensitive anionic sites detected by cationic gold at pH 2.0 after pretreatment with EGTA, and intercellular canaliculi with high activity of alkaline phosphatase. CEA and GCDFP-15 are expressed in both eccrine and apocrine sweat glands. Anti-EMA monoclonal antibody (E29) stains both eccrine and apocrine sweat glands.

Role of growth factors and their receptors in gastric ulcer healing

The repair of gastric ulcers requires the reconstitution of epithelial structures and the underlying connective tissue, including vessels and muscle layers. Several growth factors have been implicated in this process, since they are able to regulate important cell functions, such as cell proliferation, migration, differentiation, secretion, and degradation of extracellular matrix, all of which are essential during tissue healing. Epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), hepatocyte growth factor (HGF), and trefoil factors (TFFs) are mainly involved in the reconstitution of the epithelial structures. Platelet derived growth factor (PDGF), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and transforming growth factor-beta (TGF-beta) play a major role in the reconstitution of connective tissue, including vessels and smooth muscle cells, and provide the extracellular matrix substrate for cell migration and differentiation. The expression of these growth factors and their receptors is increased during ulcer healing and, in some cases, intracellular signaling related to receptor binding and transduction has been demonstrated. EGF, TGF-alpha and TFFs are normally present either in the gastric juice or in the mucosa, and may exert their effects immediately after damage, before newly synthesized EGF and TFFs are released from the ulcer margin. The inhibition of their effects by neutralizing antibodies may result in delayed ulcer healing, while the administration of recombinant or natural analogues may improve ulcer repair. In this review, we will summarize the basic molecular characteristics of some of these growth factors, and will discuss available evidence supporting their role in the ulcer repair process.

Immunohistochemical localization of activated EGF receptor in human eccrine and apocrine sweat glands

Epidermal growth factor (EGF) is secreted into sweat from secretory cells of human sweat glands. The function of EGF in sweat is poorly understood. The biological function of EGF is exerted by the binding of EGF to the receptor (EGFR) and its activation. Therefore, we immunohistochemically localized the activated form of EGFR in human eccrine and apocrine sweat glands to assess the functional importance of the EGF-EGFR system in human sweat glands. Frozen sections of human skin were stained with a monoclonal antibody (MAb) specific for tyrosine-phosphorylated (activated) EGFR and with an MAb that stains both activated and non-activated EGFR. In the secretory portion of eccrine sweat glands, nuclei of the secretory cells were stained with the anti-activated EGFR MAb. In coiled and straight portions of eccrine sweat ducts, nuclei of luminal and peripheral cells were stained with the antibody specific for activated EGFR. Luminal cell membranes and luminal cytoplasm of inner ductal cells possessed non-activated EGFR. In the secretory portion of apocrine sweat glands, activated EGFRs were present in cytoplasm and nuclei of secretory cells. These data suggest that EGF, already known to be present in the cytoplasm of secretory cells in eccrine and apocrine sweat glands, activates EGFR in the nuclei of secretory cells themselves in an intracrine manner. Because ductal cells do not express EGF, EGF in the sweat secreted from the secretory cells should activate EGFR in the ductal cells in a paracrine manner. (J Histochem Cytochem 49:597-601, 2001)

Course of epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I) in mammary secretions of the goat during end-pregnancy and early lactation

The epidermal growth factor (EGF) plays a crucial role in mammogenesis in many species. In ruminants, studies are limited, as EGF does not occur in peripheral plasma and specific analytical systems do not exist. Therefore a heterologous radioimmunoassay based on rhEGF was set up to monitor EGF in mammary gland secretions from goats during end-pregnancy and early lactation. IGF-I was measured with an established radioimmunoassay. Samples were collected from 13 goats for 25 days ante-partum and 25 days post-partum. Mammary gland secretions were obtained ante-partum by removing a small amount of the udder secretions (control half) or milking (stimulated half). Post-partum normal milk samples were collected. Blood samples were drawn by jugular venipuncture for the same period. EGF was found to occur in different molecular weight forms in the mammary glands. For routine measurements these proteins were extracted with acetone and not further separated. IGF-I and EGF concentrations in mammary secretions and similarly IGF-I in blood were high ante-partum and decreased slightly towards birth. IGF-I but not EGF is found in the peripheral plasma. Whereas IGF-I concentrations in blood were quite constant post-partum, IGF-I and EGF dropped in mammary secretions close to the detection limits. The decrease was more pronounced in the stimulated half than in the control half. The data support a synergistic role for EGF and IGF-I for mammogenesis. Both factors are further influenced by the milking stimulus and thus the functional state of the udder.

Immunohistochemical localization of epidermal growth factor in cat paradental tissues during tooth movement

Epidermal growth factor enhances proliferation and differentiation of cells during growth, maturation, and tissue healing. The objectives were to localize the epidermal growth factor in paradental cells and to determine the effect of orthodontic treatment on its concentrations in periodontal ligament fibroblasts, alveolar bone surface lining cells, and epithelial rests of Malassez. Sixty male cats, 1 year old, were divided into 2 groups: active and sham, and further divided into 10 time groups. In the active group, 1 maxillary canine was retracted by 80 g force; in the sham group, the animals received an inactive appliance. Sagittal sections of each half maxilla were stained for epidermal growth factor; staining intensity was measured microphotometrically in 10 periodontal ligament fibroblasts, alveolar bone surface lining cells, and epithelial rests of Malassez cells in sites of periodontal ligament tension and compression, and in corresponding sites near control and sham canines. The overall mean staining intensity of the cells of the active group animals was 30.47%, whereas that of the sham group was 21.78% (P <.0001). In all 3 types, cells near the actively treated canines stained significantly darker (P <.0001) than cells near the sham or control canines, particularly between 12 hours and 7 days. These results demonstrate that orthodontic forces increase epidermal growth factor concentrations in paradental cells, suggesting that epidermal growth factor participates in the tissue remodeling that facilitates tooth movement.

Transforming growth factor-alpha and other growth factors stimulate cell division in olfactory epithelium in vitro

The rate of cell division in olfactory epithelium (OE) is upregulated by ablation of the olfactory bulb (Carr and Farbman, 1992), or downregulated by occlusion of a naris. We used an organ culture assay of fetal rat olfactory mucosa to study regulation of the mitotic rate. Addition of any one of three members of the epidermal growth factor (EGF) family-EGF, transforming growth factor-alpha (TGF-alpha), or amphiregulin (AR)-to a serum-free culture medium resulted in a two- to threefold increase in the number of dividing OE cells. TGF-alpha elicited a maximal response in a dose of 100-200 pM culture medium and was 2 orders of magnitude more potent than the other EGF family members. Addition of TGF-beta 1, TGF-beta 2, insulinlike growth factor-1 or platelet-derived growth factor to the culture medium had slightly less effect than EGF or AR, in about the same molar dose range; addition of nerve growth factor had virtually no net effect on cell division. Immunohistochemistry on adult rat OE showed that basal cells, supporting cells, and acinar cells of Bowman's glands were immunoreactive with antibody to TGF-alpha but not with antibody to EGF. Most growth factors upregulated division of both olfactory neuron progenitors and supporting cells. The data suggest that several growth factors, most prominently TGF-alpha 1, may participate in the mitotic regulation of OE.

Role of epidermal growth factor in peptic ulcer healing

In recent years, increasing interest has been focused on peptide growth factors, and impressive progress has been made in the understanding of their role in tumor development and progression. However, evidence is mounting that peptides such as epidermal growth factor and transforming growth factor-alpha may be of much more physiological than pathological importance. This brief article is intended to give a rapid overview of the available data supporting a role for epidermal growth factor and its human homologue urogastrone in peptic ulcer healing.

Effect of Epidermal Growth Factor on Tympanic Membranes with Chronic Perforations: A Clinical Trial

Epidermal growth factor is an important modulator of cell growth, and its role in normal wound healing is well documented. Epidermal growth factor receptors have been identified in tympanic membranes of different animals. The ability of epidermal growth factor to promote healing of tympanic membrane perforations has recently been shown in experimental animals. We performed a double-blind, placebo-controlled study of the effect of epidermal growth factor applied locally on the tympanic membrane for 1 week in patients with chronic perforations. Seventeen adult patients took part in the study, eight in the epidermal growth factor group and nine in the placebo group. Three placebo-treated patients were later treated with epidermal growth factor, and five patients received repeated epidermal growth factor treatment. Perforation size was measured as a percentage of the tympanic membrane area before and at least 1 month (mean, 2.6 months) after treatment. One perforation in the placebo group healed completely, but none of the epidermal growth factor-treated perforations closed. Perforations became slightly smaller in both groups (mean decrease, 0.3% and 2.7% for epidermal growth factor and placebo, respectively), but these changes in size were not statistically significant for either group. At otomicroscopy, a proliferation reaction with thickening of the tympanic membrane and pseudomembrane formation at the perforation edge could be seen in some ears. Histologically, a sample from one epidermal growth factor-treated ear demonstrated signs of hypertrophic epithelium when compared with the morphology of a placebo-treated tympanic membrane. The only complications were two mild infections in the placebo group. Hearing remained stable after epidermal growth factor treatment.

Thyroid hormone upregulates gene expression, synthesis and release of pro-epidermal growth factor in adult rat kidney

Attempts were made to elucidate whether thyroid hormone upregulates renal pro-epidermal growth factor (pro-EGF) gene expression, biosynthesis and release in adult rats which were rendered hypothyroid. Predominantly pro-EGF was detected in renal cortex, whereas pro-EGF and its degraded species were found in urine. We demonstrated that T3 increased pro-EGF levels in renal cortex to 2.2 +/- 0.17, 2.37 +/- 0.19, 2.73 +/- 0.25, and 3.10 +/- 0.45 fold within day 1, 2, 4 and 8, respectively following treatment. Immunoreactive EGF, assessed by immunohistochemical methods, was confined in the distal convoluted tubule and thick ascending limb of Henle. T3 markedly enhanced the density of irEGF in these nephrons. T3 augmented the concentration of urinary irEGF to 2.1, 2.2, 2.8 and 3.6 fold within day 1, 2, 4 and 8 and the abundance of urine pro-EGF to 2.53 +/- 1.39, 3.8 +/- 0.70, 3.59 +/- 1.48 fold within day 1, 2, 4, respectively. Moreover, we employed reverse transcriptase/polymerase chain reaction method to analyze relative abundance of pro-EGF mRNA in kidneys of various thyroid states and found T3 markedly increased pro-EGF mRNA levels after treatment of 1, 2 and 4 days. These results indicated that thyroid hormone augmented the gene expression, biosynthesis and excretion of pro-EGF in adult rat kidney.

Epidermal growth factor is digested to smaller, less active forms in acidic gastric juice

BACKGROUND/AIMS

Epidermal growth factor (EGF) is present in gastric juice and has potent mitogenic properties. The stability of EGF in gastric juice under various physiological and pathophysiological conditions was examined.

METHODS

Recombinant human EGF1-53 was incubated with HCl containing pepsin. We also determined the forms of EGF present in the gastric juice of patients under basal conditions, patients taking the acid suppressant omeprazole, patients with achlorhydria, and volunteers undergoing intragastric neutralization with NaHCO3 (n = 6 per group). Samples were analyzed using mass spectroscopy and/or high-pressure liquid chromatography followed by radioimmunoassay. The effect of acid and pepsin digestion on EGF bioactivity was determined using an in vitro hepatocyte bioassay and an in vivo cytoprotection assay in the rat stomach.

RESULTS

EGF1-53 was digested to the EGF1-49 and EGF1-46 forms in all samples containing pepsin when the pH was < 4. In gastric juice samples with pH > 4, the proportion of intact EGF increased to about 60%. For both methods of bioassay, intact EGF1-53 was about 3-4 times as potent as acid and pepsin-treated EGF.

CONCLUSIONS

EGF is produced in the 1-53 form but is rapidly cleaved to smaller, less active forms in acidic gastric juice. In contrast, only a small proportion of the EGF is cleaved if the pH is maintained above 4. This mechanism may be relevant to the healing process of acid suppressants.

Urinary excretion of growth factors in patients with ovarian cancer

The levels of epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) were analysed in 24-h urine samples from patients with ovarian malignancies, benign ovarian tumours, and healthy controls by specific radioimmunoassays. No significant difference in total urinary immunoreactive EGF excretion between the groups was detected. However, 79% (23/29) of the patients with ovarian carcinomas excreted TGF-alpha (median 12.6 pmol/24 h), whereas only 17% (2/12) of the patients with benign ovarian tumours and 23% (3/13) of the controls did so. The difference between cancer patients and controls was highly significant (P < 0.001). Analyses of the urine samples separated by gel filtration revealed a greater molecular heterogeneity of EGF and TGF-alpha in cancer patients than in controls. High and low molecular weight forms of EGF were able to bind to the EGF receptor and to induce anchorage-independent growth. After surgical reduction of the tumour, a distinct decrease of urinary high molecular weight forms was observed. Thus, some macromolecular growth factors seem to be associated with epithelial ovarian carcinomas.

Relationship between epidermal growth factor and its receptor in human benign prostatic hyperplasia

Human benign prostatic hyperplasia (BPH) samples were analyzed to evaluate the presence of immunoreactive epidermal growth factor (irEGF) and EGF receptor (EGFR). In all BPH samples examined both peptide and its receptor were present. Scatchard analysis of binding data of [125I]EGF showed two classes of binding sites with high and low affinity. Intratissular irEGF concentrations showed a significant inverse linear correlation with EGFR levels. Two groups of samples can be identified: the first showing high irEGF concentrations and low levels of EGF binding sites; the second low irEGF and high concentrations of EGFR. The simultaneous presence of EGF and its receptor in BPH samples indicates that this growth factor may act in an autocrine/paracrine manner in human prostatic tissue. The inverse relationship between EGF and the two sites of EGFR lead one to hypothesize that EGF itself could play a central role in determining receptor cell surface availability.

Human epidermal growth factor-on molecular forms present in urine and blood

A sensitive enzyme-linked immunosorbent assay (ELISA) for quantitation of human epidermal growth factor (EGF) was employed to study EGF in urine and blood. The EGF/creatinine ratio in urine was significantly higher for women (range and (median); 0.20-0.83 (0.50) nmol EGF/mmol creatinine) than for men (0.17-0.63 (0.30) nmol EGF/mmol creatinine). We were not able to demonstrate EGF in plasma (median plasma EGF < 0.01 nmol/l) whereas serum contained a range and (median) of 0.02-0.31 (0.12) nmol EGF/l. The amount of EGF in serum showed a weak correlation to the platelet count (r = 0.327). EGF was partly purified by affinity chromatography from urine (urine EGF) and from activated platelets in platelet rich plasma (blood EGF). Both blood and urine contained a high molecular weight form of EGF (HMW EGF) as well as 6 kDa EGF. HMW EGF from blood was similar to HMW EGF from urine concerning behaviour upon gel filtration, pI and apparent affinity constant for binding to the EGF receptor. However, HMW EGF constituted approx. 40% of blood EGF but only 10% of urinary EGF. The 6 kDa EGF from both blood and urine contained two isopeptides with pI around 4.40 and 4.15 but in various proportions. The apparent affinity constant for binding to the EGF receptor for blood 6 kDa EGF was 1.8 x 10(10) l/mol compared to 1.0 x 10(10) l/mol for urinary 6 kDa EGF and 0.8 x 10(10) l/mol for HMW EGF from both blood and urine. The present study suggests that the processing of the EGF precursor differs in the blood and in the kidneys and that 6 kDa EGF from blood and urine binds to the EGF receptor with a higher apparent affinity constant than does HMW EGF.

Modulation of epidermal growth factor receptors in psoriatic lesions during treatment with topical EGF

Active psoriatic lesions have increased EGF/TGF alpha receptors, historically known as the EGF-R. This increase is due to their persistence into the outer parakeratotic layers as measured by autoradiography, immunohistochemistry, and mRNA assays. When psoriatic lesions in patients resolve due to therapy with different modalities, the EGF-R persistently expressed in the outer layers of the epidermis either disappear or resume a basal location presumably due to receptor downregulation. To test whether EGF could downregulate EGF-R and biologically affect psoriatic epidermis, split-thickness skin grafts of active psoriatic lesions were sutured onto the dorsal surface of nude mice. After 3 weeks, the mice were treated daily for a 6-week period with placebo, or 10 or 50 micrograms/ml EGF. Immunostaining showed persistent EGF-R in all epidermal layers in the untreated, placebo-, and 10 micrograms/ml EGF-treated groups. Those grafts receiving a high dose of EGF (50 micrograms/ml) showed either no immunoreactive EGF-R or faint basilar staining. As an additional check for functional activity of the EGF-R, an abundant substrate for this receptor, PLC-gamma 1 was also evaluated following EGF treatment. A similar distribution and modulation pattern following treatment were observed in the grafts immunostained for PLC-gamma 1, suggesting that exogenous EGF treatment affected metabolic pathways subsequent to ligand receptor binding. Morphologic alterations characteristic of a regressing psoriatic phenotype (a decrease in acanthosis, thickness, and the resumption of the orthokeratotic mode of differentiation) were noted in those lesions receiving the 50 micrograms/ml EGF treatment. This study indicates that persistent EGF-R in psoriasis vulgaris are biologically active in vivo and may serve a pivotal role in the regulation of psoriatic lesions.

Immunoreactive EGF in human benign prostatic hyperplasia: relationships with androgen and estrogen receptors

Benign prostatic hyperplasia (BPH) is a sex steroid dependent disease. Estrogens and androgens can modulate in different mammalian tissues epidermal growth factor (EGF) production and/or secretion. In order to clarify the relationships between estrogen and androgen receptor concentrations and those of immunoreactive EGF (irEGF), we have evaluated these parameters in 14 human BPH samples, by means of a dextran-coated charcoal method and radioimmunoassay, respectively. Cytosolic steroid receptors did not seem to correlate with irEGF. A linear significative relationship was evident between nuclear androgen receptor (ARn) levels and endogenous irEGF but not between nuclear estrogen receptors and irEGF: in ARn negative BPH samples, irEGF levels were lower than in ARn positive ones. Therefore, it is possible that androgens act at prostatic tissue level, through their own receptors, by modulating EGF production and/or secretion.

Wound healing of the ocular surface

Wound healing is a complex, long-lasting regulatory sequence that involves expression of a number of genes, which are active during the individual's development. Some of the phenomena differ from normal tissue turnover and growth only quantitatively. This article reviews the current data on corneal wound healing, with particular reference to mesenchymal matrix proteins and their integrin receptors, to growth factors and to proteolytic enzymes. Some inflammatory mediators are also discussed. The theoretical basis for therapeutic interventions is also discussed briefly, in the light of present knowledge.

Release of different fractions of epidermal growth factor from human platelets in vitro: preferential release of 140 kDa fraction

Platelet-rich plasma in acidic-citrate-dextrose anticoagulant was kept for 5 days in an oxygen-permeable bag at 22 degrees C in an incubator/rotator. Platelet count remained stable throughout the experiment. On days 0, 3 and 5, aliquots were removed; platelets were isolated by centrifugation at 22 degrees C, 1500 g for 20 min, reconstituted to the original volume with PBS buffer, and the contents of alpha-granules were released by repeated freezing and thawing. Epidermal growth factor (EGF) and beta-thromboglobulin (beta-TG) in the platelet-poor plasma and platelet lysates were determined by radioimmunoassays. Results indicated that in platelet-free plasma, both total EGF and beta-TG increased 3-5-fold after 5 days; this amount represented 10-20% of the factors stored in the platelets. Correspondingly, the EGF and beta-TG contents of the platelet lysates exhibited accompanying decreases. HPLC fractionation showed that the main EGF fraction which progressively decreased in the lysates and increased in plasma had a molecular mass of 140 kDa. The contents of the 67 kDa and 6 kDa fractions did not change substantially. We conclude that under these conditions, the 140 kDa fraction was released preferentially. In view of these and previous experiments, it seems likely that different organs contribute to plasma EGF fractions.

Localization of Epidermal Growth Factor Immunoreactivity in Sheep Skin During Wool Follicle Development

Interactions among the cells and matrices of the epidermis and mesenchyme of skin are essential for hair follicle initiation and development. The identification of receptors for epidermal growth factor (EGF) on epithelial components of the follicle during growth has suggested that the ligand participates in some of these events. We have used affinity-purified antibodies together with an alkaline phosphatase detection procedure to investigate the distribution of EGF in the skin of the sheep during wool follicle formation. Immunoreactivity was restricted to the periderm and intermediate layers of fetal epidermis at 55 d of gestation, when the first wave of wool follicles are initiated. This particular distribution persisted during subsequent development but never became associated with the basal cells of the epidermis. The activity was lost around 118 d, coinciding with sloughing of the periderm. No immunoreactivity was found in the plugs or the dermal condensations of the developing follicles. At approximately 105 d of gestation, however, reactions were detected in the outer root sheath as the follicles matured and in the differentiating cells of the sebaceous glands. A similar distribution pattern was also noted at 140 d, just prior to birth, and in adult animals, indicating that EGF was sequestered and perhaps synthesized within the follicle. The presence of immunoreactive material was also associated with the pilary canals and the skin surface, suggesting that this may have had its origin in the sebaceous glands. We examined this using a radioreceptor assay for EGF. Material washed from the skin surface and sebaceous gland extracts were found to displace 125I-EGF from rat liver membranes, in parallel with mouse EGF.

Epidermal growth factor in human tear fluid: a minireview

This minireview deals with the presence of epidermal growth factor (EGF) in human tear fluid. It explains the occurrence of EGF in tear fluid, the origin of EGF and its dependency on tear fluid dynamics. The alterations in tear fluid EGF concentrations that occur during diseases of the ocular surface are described and discussed in the context of the current knowledge about the interaction between EGF and EGF receptors. The possible clinical implications of topical treatment with EGF are considered.

Variation of hydrophobicity of human urinary epidermal growth factor

Epidermal growth factor is present in human urine in large amounts, but its biological significance is not known. The results of this study indicate that the predominant 6000-dalton form of epidermal growth factor in human urine is divided by hydrophobic interaction chromatography into four fractions; only 3% of the total 6000-dalton epidermal growth factor coeluted with the biosynthetic epidermal growth factor and the rest was separated into three different peaks. These different forms may lack one or two amino or carboxy terminal amino acids from the 53 amino acids present in epidermal growth factor, or they may be products of deamidation or oxidation of amino acid(s). Further knowledge of these micromodifications of epidermal growth factor secreted in urine may reveal the origin and function of epidermal growth factor in humans.

Ocular disease leads to decreased concentrations of epidermal growth factor in the tear fluid

The concentration of epidermal growth factor (EGF) in tear fluid (TF) was recently shown to decrease with increasing tear fluid flow (TFF). The purpose of the present study was to clarify the effects of ocular surface disease on the TF EGF concentrations. Tear fluid samples (n = 243) were collected from diseased eyes by means of blunted glass capillaries. The time of collection was measured for each sample, and the tear fluid flow in the capillaries (TFFc) was calculated. The concentration of human EGF (hEGF) was determined using a time-resolved immunofluorometric assay (TR-IFMA). For statistical analysis diagnosis-dependent multigrouping was performed and the data of the patient groups were compared to the data for a control group. The control material consisted of 271 TF samples collected from healthy eyes before (n = 59) and after stimulation of reflex tearing (n = 212). It was shown that TF specimens of patients (n = 243) contained significantly (p less than 0.001) less EGF (mean 952 pg/ml) than the TF of healthy control individuals before (n = 59 samples; mean 6589 pg/ml) or after stimulation of reflex tearing (n = 212 samples; mean 2762 pg/ml). The EGF concentration of every patient group was significantly lower than that found in the TF of control individuals both before and during reflex tearing (p less than 0.001). The rate of EGF released with TF during collection did not differ significantly between the various groups of patients or from that released with the TF of normal individuals before induction of reflex tearing.(ABSTRACT TRUNCATED AT 250 WORDS)

Radioimmunoassay of epidermal growth factor in human saliva and gastric juice

A sensitive radioimmunoassay was developed for human epidermal growth factor (hEGF) in saliva and gastric juice. This method was sufficiently sensitive for an accurate measurement of hEGF in these biological fluids. The minimal detectable concentration of EGF was 30 ng/L. The imprecision profile of EGF standard curve had a CV less than 10% in the range of 0.1-3.0 micrograms/L. Serial dilution curves of saliva and gastric juice paralleled that of standard EGF. The antibody to hEGF showed no cross-reactivity with a large excess of growth factors, such as human transforming growth factor alpha, human insulin-like growth factor I, and platelet-derived growth factor (c-sis). No detectable cross-reactivity was observed with some biological gut peptides: somatostatin, gastrin, secretin or pancreatic polypeptide. The intra-assay CV for saliva and gastric juice was less than 10%, and the recoveries were 93.9 +/- 8.7% and 93.7 +/- 11.3%, respectively for saliva and gastric juice. Gel exclusion chromatography revealed hEGF-like substances, heterogeneous in size in saliva and gastric juice, the origins and physiological functions of which are unknown.

Expression of epidermal growth factor in human tissues. Immunohistochemical and biochemical analysis

The expression of epidermal growth factor (EGF) was examined on various human tissues by radioimmunoassay, immunohistochemistry and Northern blot analysis. Immunoreactive EGF was found in most of the human tissues by radioimmunoassay at various levels. Large quantities of EGF were detected in the kidney and thyroid gland. Immunohistochemically, EGF immunoreactivity was detected mainly in the epithelial cells of the lung, stomach, duodenum, pancreas, kidney, pituitary gland, thyroid gland, mammary gland, ovary, uterus and placenta. Weakly EGF-positive cells were also found in the adrenal gland. The results of EGF-immunostaining were not always consistent with the data from radioimmunoassay. We consider that the amount of EGF measured by radioimmunoassay reflects the density of EGF-positive cells in the tissues and the concentration of EGF in individual EGF-positive cells. Furthermore, EGF mRNA was expressed in the salivary gland, thyroid gland, mammary gland and kidney. It is thus evident that EGF is produced by a variety of human tissues. The kidney expressed exceptionally high levels of EGF mRNA which was about one-tenth of the expression in mouse submandibular gland, suggesting that most of EGF in the urine is produced and secreted by the epithelial cells of renal tubules.

Expression of epidermal growth factor mRNA in the developing mouse mandibular process

Reverse transcription and cDNA amplification (polymerase chain reaction) of total RNA preparations were used to characterize the expression of EGF mRNA in the mandibular arch of day 9-17 mouse embryos. EGF mRNA was present in mandibles at day 9 and 10 but not at days 11-17. Separate RNA preparations from epithelium and mesenchyme at day 10 revealed EGF mRNA in both components.

Immunohistochemical demonstration of epidermal growth factor in the lacrimal and submandibular glands of rats

The extraorbital and intraorbital lacrimal glands, the Harderian glands, and the submandibular glands of five rats were excised after ethanol perfusion under general anesthesia. Indirect immunohistochemistry with antibodies specific to epidermal growth factor (EGF) was performed. EGF-like immunofluorescence (EGF-LI) was shown to be present both in the lacrimal glands (extra- and intraorbital) and in the submaxillary gland. In the lacrimal glands the specific immunoreaction appeared within the lumen of the acini and the cells of the tubular ducts close to the acini. Only faint EGF-LI was observed within the acinar cells. The submandibular glands showed intense EGF-LI only in the cells of the granular convoluted tubules. The Harderian gland did not show any EGF-LI. The results strongly support the idea that the lacrimal gland is a source of EGF in tear fluid (TF). Diseases of the lacrimal gland therefore may lead to decreased concentrations of EGF in tears. This may account in part for the pathophysiology of tear deficiency syndromes and may serve as the basis of a new rationale for the external application of EGF.

Epidermal growth factor and haptocorrin in nasal secretion

We report that nasal secretion contains the growth-promoting peptide epidermal growth factor (EGF) and a cobalamin-binding protein. Based on its amino-terminal sequence the cobalamin binding protein is classified as haptocorrin (HC). We have investigated the concentration of these components, the volume secreted, and the concentration of total protein after nasal challenge with methacholine, methacholine + ephedrine, histamine and serotonin. The EGF and HC concentrations do not differ for the four challenge agents employed. Range and median for all values obtained are 0.1-2.5 (0.7) nmol/l (n = 49) for EGF and 50-405 (190) nmol/l (n = 63) for HC. After challenge with methacholine the amount of secretion (80-630 (200) mg (n = 14) and the protein concentration (1.5-7.8 (3.5) g/l (n = 14] are lower than for any other challenge. After challenge with serotonin or histamine the amount secreted is 60-1125 (480) mg (n = 39). The concentration of protein is significantly higher (p less than 0.01) after challenge with serotonin (1.4-56.0 (17.0) g/l (n = 18] than after challenge with histamine (2.0-25.0 (5.0) g/l (n = 20].

Epidermal growth factor in human tear fluid: increased release but decreased concentrations during reflex tearing

To further clarify the role of epidermal growth factor (EGF) in the physiology and pathophysiology of the ocular surface the effects of reflex tearing on concentrations of EGF in tear fluid were studied. Tear fluid samples were collected with glass capillaries before (basal samples, 59 eyes, 30 individuals) and during reflex tearing (stimulated samples, n = 212, 40 eyes, 20 individuals). The rate of tear fluid flow in the capillaries (TFFc) was measured. The concentrations of human EGF (hEGF) was determined by time-resolved immunofluorometric assay (TR-IFMA). The first basal samples contained higher concentrations of hEGF than the samples from the contralateral eyes (n = 28) collected thereafter (p less than 0.05). The basal samples from 40 eyes contained a significantly higher mean concentration of hEGF (8466 pg/ml) than did the stimulated samples (n = 212, 2763 pg/ml); p less than 0.001). The mean TFFc increased from 63 nl/s to 506 nl/s during reflex tearing (p less than 0.001) and the amount of hEGF released from 567 fg/s (n = 40) to 1400 fg/s (n = 212; p less than 0.001). Basal samples from females contained higher concentrations of hEGF than did those from males. The maintenance of the hEGF concentration at a certain level and the increased amount of hEGF released into the tear fluid during reflex tearing suggests continuous release of hEGF into tear fluid from the lacrimal gland.

Biology of sweat glands and their disorders. II. Disorders of sweat gland function

Part I of this article (J Am Acad Dermatol 1989; 20:537-63) focused on normal sweat gland function. Part II provides a discussion of hyperhidrosis and hypohidrosis. Hyperhidrotic disorders affect the palms and soles and the axillae and are associated with previous spinal cord injuries, peripheral neuropathies, brain lesions, intrathoracic neoplasms, systemic illness, and gustatory sweating. Hypohidrotic disorders include anhidrotic ectodermal dysplasia, hereditary sensory neuropathy, Holmes-Adie syndrome, and generalized anhidrosis.

Biology of sweat glands and their disorders. I. Normal sweat gland function

The basic mechanisms of sweat gland function and an updated review of some relatively common disorders of sweat secretion, are presented. Although sweat secretion and ductal absorption are basically biophysical and biologic cellular processes, a detailed description of the basic biophysical principles of membrane transport has been avoided to make the discussion more readable. The cited references will, however, help those readers primarily interested in the basic details of sweat gland function. Part I of this article includes a discussion of morphologic characteristics, central and peripheral nervous control of sweat secretion, neurotransmitters, intracellular mediators and stimulus secretion coupling, Na-K-Cl cotransport model for the ionic mechanism of sweat secretion, ingredients of sweat, ductal function, the pathogenesis of abnormal sweat gland function in cystic fibrosis, and the discovery of the apoeccrine sweat gland. Part II, to be published in the May issue of the Journal, reviews reports of all those major disorders of hyperhidrosis and hypohidrosis that have appeared in the literature during the past 10 years. It is hoped that this review will serve as a resource for clinicians who encounter puzzling disorders of sweating in their patients, as well as for investigators who wish to obtain a quick update on sweat gland function.

Epidermal growth factor is a constant component of normal human tear fluid

Epidermal growth factor (EGF) is a mitogenic polypeptide, which was first isolated from mouse submaxillary gland. Since EGF also stimulates the growth of corneal epithelial cells and only preliminary data exist on its presence in tear fluid, we studied the occurrence of human EGF (hEGF) in the tear fluid of 36 healthy persons (31 women and 5 men from 20 to 59 years of age; 60 eyes). hEGF, as measured by an immunofluorometric assay, was present in all tear fluid samples investigated. Its concentration varied from 200 to 2860 pg/ml (median, 705 pg/ml). The tear fluid hEGF concentrations differed less between the eyes of one individual than between individuals. The total amount of hEGF released to the tear fluid increased with fluid flow, but the higher the flow was, the lower the concentration of hEGF. We could not find any evidence of sex dependency in the hEGF concentrations. In demonstrating that hEGF is a normal component of human tear fluid, the results of this study suggest that hEGF may be important for conjunctival and corneal epithelial integrity.

Secretion of epidermal growth factor and related polypeptides by the DU 145 human prostate cancer cell line

Epidermal growth factor (EGF)-like proteins may be important in regulating the growth of human prostate cancer cells and in the development of hormone independence. In the present study, we demonstrated that the DU 145 human prostate cancer cell line secretes EGF-like polypeptides into serum-free culture medium. The production of both authentic EGF and transforming growth factor-alpha was demonstrated by specific radioimmunoassays. In addition to 6-7k monomers, immunoreactive higher molecular weight species were isolated by gel chromatography. The DU 145 cells also specifically bound human EGF, with both high- (Kd 1.8 x 10(-10) M) and low- (Kd 1.1 x 10(-9) M) affinity binding sites. Exogenous EGF stimulated 3H-thymidine incorporation when cells were plated at low density in serum-free culture medium, while at higher cell density neither cell division nor 3H-thymidine incorporation was significantly altered. We postulate that DU 145 cells may be autologously stimulated by endogenously produced EGF and related polypeptides, which, under normal culture conditions, precludes any further effect of exogenous EGF.

Biological effects of epidermal growth factor, with emphasis on the gastrointestinal tract and liver: an update

Epidermal growth factor (EGF) is a 6,000 Da polypeptide hormone produced by glands of the gastrointestinal tract, namely the salivary and Brunner's glands. It is found in a wide variety of external secretions as well as in blood and amniotic fluid. In fetal and neonatal life, EGF appears to play an important role in the development of the oral cavity, lungs, gastrointestinal tract and eyelids. Its presence in cells of the central nervous system suggests that it also plays a role in modulating the development of this system. In adult animals, the function of EGF is much less well understood. In rodents, it apparently modulates acid secretion from parietal cells in the stomach, and it undoubtedly plays an important role in wound healing, either through its localization within skin or by the licking of wounds with EGF-containing saliva. Considerable evidence now suggests that it may be one of the key factors in initiating liver regeneration after partial hepatectomy or chemical injury. The liver appears to be the principal organ which regulates the circulating level of EGF. In fact, EGF is cleared so efficiently by the liver that only the peripheral cells of the lobule (zone 1) sequester EGF, and little remains in the circulation for cells in the more distal zones (zones 2 and 3). In the liver, EGF normally binds to a plasma membrane receptor and is internalized within the liver cell, where the vast majority of EGF and its receptor are destroyed in lysosomes. A small but consistent quantity of EGF enters the bile intact. In the regenerating liver, however, the lysosomal pathway appears to be shut down, and the EGF is diverted to hepatocyte nuclei prior to the initiation of DNA synthesis. Nuclear EGF is found free as well as bound to a high-molecular-weight protein which has many characteristics identical to the plasma membrane EGF receptor. The plasma membrane receptor is a large transmembrane glycoprotein of 170,000 Da containing four domains: an extracellular EGF-binding portion, a hydrophobic membrane-spanning segment, a proximal cytoplasmic domain which binds ATP and protein substrates containing tyrosine for phosphorylation and a terminal cytoplasmic portion with 3 tyrosines which undergo autophosphorylation after EGF binding.(ABSTRACT TRUNCATED AT 400 WORDS)

Human epidermal growth factor: renal production and absence from plasma

Among the unsettled questions in the physiology of human epidermal growth factor (EGF) are (1) does EGF circulate in the blood and (2) what is the source of the abundant urinary immunoreactive EGF (irEGF). Therefore, we monitored the concentration of irEGF by an ultrasensitive assay in blood plasma from 5 healthy subjects every 20 min overnight carefully avoiding activation of platelets. Detectable levels (0.8-3.7 pM) were observed in only one of the subjects, in 5 of 29 samples. In random day-time plasma samples from 18 healthy adults, EGF was undetectable (less than 0.8 pM) in 13 subjects, and in 5 subjects EGF levels ranged from 2.2 to 4.9 pM. Furthermore, in 5 patients with a tumor in a functioning kidney we measured urinary relative irEGF concentration (nmol/mmol creatinine) before and after unilateral nephrectomy. The concentration fell by approximately 50%. Our findings are consistent with (1) blood irEGF residing exclusively in platelets, and (2) urinary irEGF originating from the kidneys.

The parotid gland is the main source of human salivary epidermal growth factor

To clarify the production of human epidermal growth factor (EGF) by different salivary glands, we measured its concentration by radioimmunoassay separately in whole saliva, in parotid gland (PG) saliva and in mixed submandibular (SMG) and sublingual gland (SLG) saliva. Also, we studied the presence of EGF in PG and SMG by immunohistochemistry. The mean (geometric) concentrations of EGF in PG saliva (2704 pg/ml, +/- SEM interval 2393-3056 pg/ml, n = 20) was higher (p less than 0.001) than in whole saliva (864 pg/ml, +/- 733-1019 pg/ml, n = 29), which in turn was higher (p less than 0.001) than in mixed SMG + SLG saliva (357 pg/ml, +/- 296-430 pg/ml, n = 16). No sex difference existed in any salivary gland EGF. Immunohistochemistry revealed EGF in the acinar cells of both PG and SMG, but only in PG there were prominent EGF deposits in luminal spaces. Our data suggest that EGF is produced by both PG and SMG, but that more of it is secreted from the PG. This result is new and challenges the general view that human salivary EGF is mainly from SMG. In mouse almost all salivary EGF comes from SMG and its amount is androgen dependent. Thus there are great differences in sources and regulation of salivary EGF between man and mouse.