PubMed Health⌕ Search

Biomedical subjects

G S Schultz

Publications and source records attributed to G S Schultz.

At least 73 records · Page 4Linked to original sources
PubMed1989

Enhancement of wound healing by topical treatment with epidermal growth factor.

Experimental studies in animals have demonstrated that the topical application of epidermal growth factor accelerates the rate of epidermal regeneration of partial-thickness wounds and second-degree burns. We conducted a prospective, randomized, double-blind clinical trial using skin-graft-donor sites to determine whether epidermal growth factor would accelerate the rate of epidermal regeneration in humans. Paired donor sites were created in 12 patients who required skin grafting for either burns or reconstructive surgery. One donor site from each patient was treated topically with silver sulfadiazine cream, and one was treated with silver sulfadiazine cream containing epidermal growth factor (10 micrograms per milliliter). The donor sites were photographed daily, and healing was measured with the use of planimetric analysis. The donor sites treated with silver sulfadiazine containing epidermal growth factor had an accelerated rate of epidermal regeneration in all 12 patients as compared with that in the paired donor sites treated with silver sulfadiazine alone. Treatment with epidermal growth factor significantly decreased the average length of time to 25 percent and 50 percent healing by approximately one day and that to 75 percent and 100 percent healing by approximately 1.5 days (P less than 0.02). Histologic evaluation of punch-biopsy specimens taken from the centers of donor sites three days after the onset of healing supported these results. We conclude that epidermal growth factor accelerates the rate of healing of partial-thickness skin wounds. Further studies are required to determine the clinical importance of this finding.

Administration, Topical↗
PubMed1989

Increased binding of epidermal growth factor at preimplantation sites in mouse uteri.

The presence of receptors for epidermal growth factor (EGF) in nonpregnant uteri and the elevation of EGF levels in blood during early pregnancy suggest that EGF and its receptor may play important roles in the early stages of pregnancy. We determined the distribution of EGF receptors in uteri of nonpregnant and pregnant mice during the late preimplantation period (days 4.5-5.0 of pregnancy) using radioautograph and quantitative binding techniques. Radioautography of [125I]EGF binding to cornua from nonpregnant mice showed low levels of specific binding evenly distributed throughout the cornua. In contrast, radioautographs of cornua from pregnant mice showed bands of elevated binding encircling the lumen at sites of preimplantation. Results from radioautography were supported by quantitative analysis of [125I]EGF binding to uterine homogenates from nonpregnant and pregnant mice. Binding of [125I]EGF to uterine membranes was highly specific and time dependent. The average level of specific EGF binding calculated from Scatchard plots of nonpregnant uteri (27 +/- 13 fmol/mg protein) was significantly (P less than 0.05) lower than that in pregnant superovulated uteri (106 +/- 67 fmol/mg protein). Furthermore, specific binding of EGF was significantly (P less than 0.05) higher in preimplantation sites than in the intervening nonimplantation regions from the same uteri (42 +/- 6 vs. 29 +/- 4 fmol/mg protein, respectively). Differences in EGF binding appear to be due to changes in the number of EGF receptors, since half-displacement values (1 nM) were similar in all samples. These results demonstrate that alterations of EGF receptor levels occur at sites where implantation will occur in mouse uteri and support the concept that the transforming growth factor-alpha/EGF receptor and its ligands are involved in implantation of concepti.

Animals↗
PubMed1989

Reversal of Adriamycin-impaired wound healing by transforming growth factor-beta.

Impaired wound healing remains an important clinical problem. Treatment with systemic Adriamycin (doxorubicin) is known to impair wound healing in patients, and it has been used to produce animal models of impaired healing. The results of previous studies have shown that local treatment of incisions in normal rats with transforming growth factor beta (TGF-beta) or epidermal growth factor (EGF) stimulated early increases in tensile strength of surgical incisions in normal rats. We investigated the effects of locally applied, biosynthetic TGF-beta or EGF on the tensile strength of standardized incisions in rats treated with Adriamycin. Systemic Adriamycin treatment (8 milligrams per kilogram) produced significant decreases in wound tear strength (WTS) and wound tear energy (WTE) when compared with that of normal rats at seven and ten days (p less than 0.01). A single dose of TGF-beta (2 micrograms) in a collagen vehicle stimulated a reversal of this wound healing impairment at ten days (p less than 0.05), returning the WTS and WTE to near normal levels. A single dose of EGF (50 micrograms) in hyaluronic acid failed to increase tensile strength, probably because of formulation of EGF in a vehicle that does not prolong its release in incisions. These results suggest that exogenous growth factors may be clinically useful in stimulating healing in incisions in healing impaired conditions.

Animals↗
PubMed1989

Transforming growth factor alpha and its receptor in neural retina.

Transforming growth factor alpha (TGF-alpha) stimulates mitosis of many ectodermal cells but has not previously been studied for its role in neural tissues such as retina. We examined bovine retina for the presence of TGF-alpha mRNA, TGF-alpha protein and for the presence and location of the TGF-alpha/EGF receptor. Biochemical studies demonstrated a high level (770 fmol/mg protein) of specific, high affinity (Kd = 2 nM) TGF-alpha/EGF receptors in membrane homogenates of neural retina, but undetectable binding to homogenates of retinal pigment epithelium. Light microscopic autoradiograms of sections of neural retinal tissue incubated with 125I-EGF indicated that specific TGF-alpha/EGF receptors were present on one or more cell types of the retina with the exception of the outer segments of the photoreceptor cells. In addition, retinal cells appear to synthesize TGF-alpha since both mRNA for TGF-alpha and TGF-alpha protein (4.2 ng/mg protein) were detected in retinal extracts using cDNA hybridization and TGF-alpha RIA techniques. The role(s) of TGF-alpha and its receptor in retina is unknown, but it is possible that they interact via an autocrine/paracrine mechanism to influence retinal regeneration, proliferative retinopathies or neural transmission.

Animals↗
PubMed1988

Effects of long-term dietary choline and phosphatidylcholine administration on muscarinic receptors in aged mouse brain.

It has been suggested that choline and/or phosphatidylcholine may be beneficial in improving the memory deficits associated with aging and Alzheimer's disease. The effects of long-term choline or phosphatidylcholine treatment on cholinergic receptors in the brain have been investigated. Mice were maintained on one of four diets from 50 days of age until sacrificed at 20-24 months. [3H]-QNB binding in the cortex, hippocampus and striatum was specific, saturable and of high affinity. Animals treated with a phosphatidylcholine-enriched diet displayed a down-regulation of muscarinic receptors in the cortex and hippocampus, reflected by a decrease in Bmax. There were no significant differences in the binding affinities among the treatment groups. Choline levels were unaffected by the various diets, however phosphatidylcholine treatment resulted in an increase in phosphatidylcholine in the cortex and somewhat in the hippocampus. This study indicates that choline and phosphatidylcholine have different effects after long-term dietary administration. Phosphatidylcholine treatment results in a down-regulation of muscarinic receptors in certain brain areas which appears to be related to an increase in phosphatidylcholine concentration. Any potentially beneficial effects derived from chronic phosphatidylcholine treatment must overcome the apparent down-regulation of muscarinic receptors which may occur.

Aging↗
PubMed1988

Acceleration of tensile strength of incisions treated with EGF and TGF-beta.

The ability of surgeons to accelerate wound healing through pharmacologic intervention is limited. The effects of locally applied, biosynthetic human epidermal growth factor (EGF) and transforming growth factor-beta (TGF-beta) on tensile strength of experimental incisions were investigated. A single dose of EGF in saline failed to increase tensile strength over controls. Thus, EGF was incorporated into multilamellar liposomes, which prolonged the exposure of incisions to EGF (p less than 0.001). A single dose of EGF in multilamellar liposomes produced a 200% increase in wound tensile strength over controls between 7 and 14 days (p less than 0.05). Light and electron microscopy of the wounds revealed increased collagen formation and fibroblast proliferation. A single dose of TGB-beta in a collagen vehicle stimulated a 51% increase in wound tensile strength at 9 days (p less than 0.01). We conclude that addition of EGF and TGF-beta in appropriate vehicles stimulates early transient increases in wound tensile strength in normal rats.

Animals↗
PubMed1988

Epidermal growth factor in urine of nonpregnant women and pregnant women throughout pregnancy and at delivery.

Human epidermal growth factor (EGF) concentrations were measured by a specific solid phase RIA in random urine samples collected throughout the menstrual cycle of normal menstruating women (n = 8), women with tubal sterilization (n = 6), women taking a low dose oral contraceptive (n = 5), and women throughout pregnancy (n = 52) and delivery (n = 35). There were no differences in EGF concentrations between the proliferative and secretory phases of the menstrual cycle (P greater than 0.05). Normal menstruating women had higher urinary EGF concentrations [mean +/- SE, 37.2 +/- 6.0 micrograms/g creatinine (4.23 +/- 0.68 ng/mumol)] than women with tubal sterilization [32.7 +/- 4.0 (3.71 +/- 0.45)] or women taking a low dose oral contraceptive [19.5 +/- 6.0 (2.21 +/- 0.68)], but the differences were not significant (P greater than 0.05). During pregnancy, urinary EGF concentrations increased linearly from 6-20 weeks gestation (r = 0.76; P less than 0.001), then declined toward term (r = -0.71; P less than 0.001). EGF concentrations in early pregnancy (less than 12 weeks) or at term did not differ significantly from those in normal menstruating women (P greater than 0.05). For women delivering normal, appropriate for gestational age (AGA) infants, there was no correlation between urinary EGF concentrations and fetal weight or sex (P greater than 0.05). Urinary EGF concentrations in women delivering normal AGA infants [52.7 +/- 2.5 (5.98 +/- 0.28); n = 16] did not differ significantly (P greater than 0.05) from those in women with class A/B diabetes [41.9 +/- 2.8 (4.76 +/- 0.31); n = 6] or women delivering twins [45.6 +/- 2.6 (5.18 +/- 0.29); n = 8] with a greater fetoplacental mass. However, women delivering an intrauterine growth-retarded fetus with decreased fetoplacental mass had lower urinary EGF concentrations (24.9 +/- 2.2 (2.83 +/- 0.25); n = 5] than women with normal AGA infants (P less than 0.01). The significance of the rise in the urinary EGF concentration late in the second trimester and lower urinary EGF concentrations in women delivering intrauterine growth-retarded infants is not known, but may reflect an important physiological role for EGF in fetal-maternal hormonal interaction and development.

Adolescent↗
PubMed1988

Growth factors and corneal epithelium.

Regeneration of corneal epithelium following injury is essential for visual rehabilitation. A limited number of approaches are available for treating patients who fail to heal epithelial injuries adequately. The presence of specific receptors for epidermal growth factor (EGF) on epithelial cells suggests that this potent mitogen may play a role in normal epithelial wound healing. Topical application of biosynthetic human EGF significantly accelerated epithelial regeneration in primates following epikeratophakia surgery. Epidermal growth factor alone and with fibronectin accelerated epithelial regeneration of rabbits following mild alkali burns. Since prolonged exposure of cells to EGF is necessary to induce mitosis, the dynamics of EGF in the eye and with various lenses was studied. When applied in methylcellulose-based eye drops, 90% of the EGF was lost from tear film within 10 min, while a small amount (10%) remained associated with conjuctival tissue. Soft contact lenses or epikeratophakia lenticles took up substantial amounts of EGF (50 micrograms) and released 85% of the EGF within 24 h, with a half-life of 4 h in vitro. Epidermal growth factor did not diffuse through corneas or lenticles and did not promote epithelial downgrowth along sutures in primate corneas. These results suggest that biosynthetic growth factors may be useful in the treatment of some epithelial injuries.

Alkalies↗
PubMed1987

Epithelial wound healing enhanced by transforming growth factor-alpha and vaccinia growth factor.

Epidermal regeneration following middermal injuries to skin requires both proliferation and migration of keratinocytes. Epidermal growth factor (EGF) stimulates the proliferation of keratinocytes in culture, and topical administration of EGF accelerates epidermal regeneration of partial thickness burns or split-thickness incisions in vivo. Transforming growth factor-alpha (TGF-alpha) and vaccinia growth factor (VGF) have substantial sequence homology with EGF, and all appear to bind to the same receptor protein. Whether TGF-alpha or VGF can affect epidermal wound healing in vivo is not known. The present studies show that topical administration of TGF-alpha or VGF in antibiotic cream to partial thickness burns (second degree) accelerated epidermal regeneration in comparison with untreated or vehicle-treated burns. Low levels of both TGF-alpha and VGF (0.1 microgram per milliliter) appeared to be more effective than EGF in stimulating epidermal regeneration. Regenerated epithelium from burns treated with TGF-alpha or VGF appeared normal histologically. This finding suggests that topical application of selected growth factors may be useful in accelerating healing of partial thickness injuries.

Animals↗
PubMed1987

Levels of epidermal growth factor binding in third-trimester and term human placentas: elevated binding in term placentas of male fetuses.

Specific binding of iodine 125-labeled epidermal growth factor was measured in membrane homogenates of third-trimester and term human placentas of male and female fetuses. All placentas (n = 35) generated curvilinear Scatchard plots, and all placentas had similar equilibrium dissociation constants for both high-affinity (210 pmol/L) and low-affinity (830 pmol/L) binding sites. Mean maximum number of available binding sites of term placentas from male fetuses (330 +/- 110 fmol/mg protein; n = 11) was significantly higher (p less than 0.001) than that of female fetuses (170 +/- 80 fmol/mg protein, n = 13). Occupation of epidermal growth factor receptors by endogenous epidermal growth factor could not account for the difference in levels of epidermal growth factor binding. Kendall's rank order correlation test demonstrated a significant positive correlation of the gestational age in weeks with the maximum number of epidermal growth factor receptors in placentas from male fetuses (p less than 0.002; T = 0.527; n = 17) and female fetuses (p less than 0.01; T = 0.404; n = 18). These results indicate that there is a sexual dimorphism in the level of epidermal growth factor receptors in placentas of male and female fetuses during the third trimester and that the level of epidermal growth factor receptors increases during the third trimester for placentas of both male and female fetuses.

Epidermal Growth Factor↗
PubMed1986

Enhancement of epidermal regeneration by biosynthetic epidermal growth factor.

Epidermal regeneration depends on mitosis and migration of keratinocytes. Epidermal growth factor is known to stimulate growth of keratinocytes in vitro, thus it might be expected to promote wound healing. The results of this study show that topical application of biosynthetic human epidermal growth factor accelerates epidermal regeneration in split-thickness wounds and partial-thickness burns. The significant enhancement of epidermal regeneration suggests the potential for clinical use of epidermal growth factor for accelerating healing of burns, wounds from trauma, diabetic ulcers, skin graft donor sites, and others.

Animals↗
PubMed1986

The presence of epidermal growth factor binding sites in the intracellular organelles of term human placenta.

Highly purified lysosomes, rough and smooth endoplasmic reticulum, and Golgi apparatus, as well as microvillus plasma membranes, bound 125I-labelled epidermal growth factor ([125I]EGF) with similar affinity. Scatchard plots for all the organelles were curvilinear. The apparent number of available binding sites per mg protein of intracellular organelles was 27-71% of that found in microvillus plasma membranes. The bound and free [125I]EGF were not degraded by any of the organelles. Binding and dissociation of [125I]EGF in all organelles were dependent on the time and temperature of incubation. The specificity of [125I]EGF binding was similar in all organelles. The optimal pH for binding to lysosomes was 6.0, in contrast to 7.0 for all the other organelles. Exposure of different organelles to enzymes and protein-modifying reagents resulted in numerous binding differences between the intracellular organelles and microvillus plasma membranes. Covalent affinity labelling with [125I]EGF revealed two major proteins of 155 and 140(X10(3)) Mr in all the organelles. The 155 X 10(3) Mr protein was labelled predominantly in all organelles except rough endoplasmic reticulum, where both proteins were equally labelled. Addition of proteolytic inhibitors during isolation of organelles did not alter the pattern of [125I]EGF-labelled binding proteins found in the organelles. EGF also stimulated phosphorylation of the 155 and 140(X10(3)) Mr proteins in all the organelles. The 155 X 10(3) Mr protein was phosphorylated more than the 140 X 10(3) Mr protein in microvillus plasma membranes and smooth endoplasmic reticulum, whereas the 140 X 10(3) Mr protein was phosphorylated more than the 155 X 10(3) Mr protein in lysosomes and both proteins were equally phosphorylated in rough endoplasmic reticulum. Several organelles also contained minor [125I]EGF-binding proteins that did not show phosphorylation response and proteins that showed phosphorylation response but did not bind [125I]EGF. Thus, the present study demonstrates by a number of different criteria, that several intracellular organelles of term human placenta also contain EGF-binding and kinase activities.

Autoradiography↗
PubMed1985

Topography of human placental receptors for epidermal growth factor.

These studies were undertaken to determine whether term human placental microvillus plasma membranes, which are exposed to maternal blood, and basolateral plasma membranes, which are in close proximity to fetal blood capillaries, contain receptors for epidermal growth factor (EGF). These two highly purified membranes bound 125I-EGF with similar affinity (apparent dissociation constants, 0.07-0.12 nM, but the total number of available receptors was greater in microvillus (8.2 pmol/mg protein) compared to basolateral (4.9 pmol/mg protein) plasma membranes. Detailed characterization of 125I-EGF binding to these membranes revealed numerous similarities as well as differences. The two membranes contained two major (155 and 140 kDa) and at least three minor (115, 175, and 210 kDa) specific 125I-EGF binding proteins. The 115-kDa protein was only found in basolateral plasma membranes. The 155-kDa protein was predominantly labeled in microvillus, whereas the 140-kDa protein was labeled predominantly in basolateral plasma membranes. The addition of protease inhibitors did not alter the multiple 125I-EGF binding proteins pattern found in these membranes. EGF stimulated phosphorylation of 140- and 155-kDa proteins in both microvillus and basolateral plasma membranes. However, the 155-kDa protein was phosphorylated to a greater extent in microvillus, whereas both 140- and 155-kDa proteins were phosphorylated equally in basolateral plasma membranes. Light and electron microscope autoradiographic studies revealed that 125I-EGF preferentially associated with microvillus plasma membranes. The data demonstrates the presence of EGF receptors in outer cell membranes of syncytiotrophoblasts and suggests that maternal EGF may influence syncytiotrophoblast function by binding to receptors in microvillus plasma membranes, while fetal EGF may also influence syncytiotrophoblast function but via receptors in basolateral plasma membranes.

Cell Membrane↗
PubMed1985

Effect of growth factors with dexamethasone on healing of rabbit corneal stromal incisions.

Treatment of rabbit corneal wounds with topical corticosteroid retards both epithelial regeneration and healing of penetrating stromal wounds. Currently, no clinical agent is available which accelerates the rate of stromal wound healing. Epidermal growth factor (EGF, 0.5 mg ml-1), fibroblast growth factor (FGF, 20 micrograms ml-1), and insulin (0.5 mg ml-1) were tested for their ability to accelerate healing of totally penetrating wounds in rabbit corneas when the hormones were administered alone or in combination with dexamethasone (1 mg ml-1). After 5 days of treatment with eye drops, the tensile strengths of corneal wounds treated with EGF (54 +/- 4 g mm-1) or treated with EGF and dexamethasone (32 +/- 9 g mm-1) were significantly higher than the tensile strengths of corneal wounds treated with only saline vehicle (3 +/- 1 g mm-1) or dexamethasone (1 +/ 0 g mm-1) (P less than 0.001). The combination of dexamethasone with EGF significantly (P less than 0.025) reduced the strength of corneal wounds compared to treatment with EGF alone. Similarly, the tensile strength of corneal wounds after 5 days of insulin treatment alone (28 +/- 8 g mm-1) or in combination with dexamethasone (25 +/- 7 g mm-1) was significantly increased compared with saline- or dexamethasone-treated corneas (P less than 0.001). In the absence of dexamethasone, EGF increased the tensile strength of corneal wounds significantly better than insulin (P less than 0.01). However, when EGF or insulin were given in combination with dexamethasone there was no significant difference between the tensile strength produced by the peptide hormones. In comparison to the tensile strength of corneal wounds treated by EGF or insulin, treatment with FGF alone (5 +/- 4 g mm-1) or in combination with dexamethasone (2 +/- 1 g mm-1) produced poor wound healing. The in vitro actions of EGF or FGF alone or in combination with dexamethasone were tested for ability to stimulate [3H]-thymidine incorporation into pure cultures of human corneal fibroblasts (HCF) in defined culture medium. EGF (5 mM) or FGF (100 ng ml-1) alone stimulated [3H]-thymidine incorporation approximately 2.5-fold compared to control cultures, whereas in combination with dexamethasone (10 nM), the stimulatory action of FGF, but not EGF, was abolished. Dose-response curves indicated that HCF in culture were very sensitive to EGF, insulin, and FGF with maximum stimulation of [3H]-thymidine incorporation occurring at approximately 1 nM for EGF and insulin and at 100 micrograms ml-1 for FGF. Binding of 125I-EGF to HCF reached maximum after 2 hr at 37 degrees C and was specific, saturable, and of high affinity (half saturation at 1 nM). (ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1985

Biosynthetic human EGF accelerates healing of Neodecadron-treated primate corneas.

Topical administration of biosynthetic human epidermal growth factor (h-EGF), given in combination with an antibiotic and synthetic steroid (Neodecadron) accelerated the rate of corneal epithelial regeneration and significantly increased the strength of full-thickness stromal incisions in primates. The regenerated epithelial cells of EGF-Neodecadron-treated corneas appeared normal on histologic examination and showed no evidence of hypertrophy or hyperplasia. The EGF-Neodecadron-treated stromal incisions were characterized by new collagen formation and a smaller epithelial cell plug than Neodecadron-treated control corneas. These results suggest that biosynthetic h-EGF, which lacks the immunologic potential of nonhuman proteins, may be effective in accelerating healing of corneal epithelial defects and stromal incisions in patients whose healing is suppressed by treatment with steroids.

Animals↗
PubMed1984

Rapid purification of radioiodinated peptides with Sep-Pak reversed phase cartridges and HPLC.

A simple, rapid method is described for the purification of radioiodinated peptides for use in radioimmuno- and in radioreceptor assays. Iodinated reaction mixtures are applied directly onto Sep-Pak disposable, reversed phase cartridges equilibrated with phosphate buffer. Unreacted 125-iodide and other non-peptide reaction components are eluted with buffer. The peptide fraction is then eluted with 70% buffer: 30% acetonitrile. The peptide fraction is further purified by reversed phase high pressure liquid chromatography to separate the native peptide and the mono- and diiodo-derivatives. In this study the method is used to prepare 125-iodide-labeled monoiodo-leucine enkephalin and monoiodo-angiotensin II, which are free of the parent peptides and diiodo-derivatives and are of maximum obtainable specific radioactivity. The usefulness of these labeled peptides in radioimmuno- and radioreceptor assays is demonstrated by their binding to specific antibodies and receptors, respectively.

Chromatography, High Pressure Liquid↗