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M J Waters

Publications and source records attributed to M J Waters.

At least 127 records · Page 7Linked to original sources
PubMed1990

Visual demonstration of growth hormone receptors on human growth plate chondrocytes.

The sites of action of GH in the human infant remain unclear; recent evidence in animals suggests direct actions on growth plate and other tissues. We have used a monoclonal antibody recognizing the human GH receptor to visually identify and localize GH receptors in the human infant growth plate. Sternochondral cartilage was obtained at postmortem from infants dying of sudden infant death (n = 20), and either decalcified, fixed, and cut into longitudinal sections or digested with collagenase for monolayer culture of chondrocytes. Sections of cultured chondrocytes were stained immunocytochemically with a monoclonal antibody recognizing human GH receptor (MAb 263), using an avidin-biotin system. Sternochondral cartilage was also obtained at operation from adolescents undergoing sternochondroplasty. In infant tissue, GH receptor was identified in sections in chondrocytes of the proliferative and hypertrophic layers, in perichondrium, in osteocytes in new bone, and in hemopoietic precursor cells in marrow. Cultured chondrocytes showed heterogeneous staining for GH receptor. With prolonged culture from 5-8 days, the pattern of staining changed from individual cells to groups of cells. [125I]Human (h)GH showed specific binding to chondrocyte monolayer (0.6 +/- 0.3%), confirmed visually on emulsion autoradiography. In support of specificity of MAb263, it was able to displace [125I]hGH from monolayers by 35%. Adolescent cultured chondrocytes failed to demonstrate specific binding of [125I]hGH. We conclude that GH receptors are widely distributed in a range of mesenchyme cells in the human infant growth plate, including bone and hemopoietic precursors. The expression of these receptors appears to be maturation dependent in both intact tissue and culture, while they may no longer be expressed after the peak growth phase of puberty.

Adolescent↗
PubMed1990

Effects of epidermal growth factor on gastrointestinal electromyographic activity of conscious sheep.

Adult sheep were infused with depilating doses of epidermal growth factor (EGF) at 4 micrograms/kg per h for 24 h. Food was available ad libitum during recording of integrated electromyographic (EMG) activity of the gastrointestinal tract. In comparison with control sheep infused with saline, EGF reduced the frequency of A and B sequences of contraction of the reticulum and rumen over the 24-h period, an effect attributable to the consumption of less food. During the 24-h infusion, EGF stimulated phase III migrating myoelectric complex (MMC)-like activity of the duodenum with an associated decline in the EMG of the abomasal antrum. Infusion of EGF for 1 h at 2.5 and 5.0 micrograms/kg per h in fasted animals produced inhibitory effects on the frequency of A sequences of contraction of the reticulum and rumen during the infusion, and on the amplitude of the ruminal EMG during, and in the hour following, infusion. Phase III MMC-like activity of the duodenum was stimulated by EGF in fasted animals. It is concluded that in fed sheep, depilating doses of EGF have inhibitory effects on the EMG activity of the reticulum and rumen through reductions in food consumption and by other undefined mechanisms. Additional effects of EGF on the gastrointestinal tract of sheep include stimulation of duodenal phase III MMC-like activity.

Abomasum↗
PubMed1990

Localization of the growth hormone receptor/binding protein in skin.

Acromegaly is characterized by coarsening of facial features, acanthosis nigricans, hypertrichosis and oily skin. To determine the site through which GH exerts these effects, we have used immunohistochemistry to localize the GH receptor/binding protein (BP) in rat, rabbit and human skin. Three monoclonal antibodies (MAb 1, 43, 263) were immunoreactive in identical locations, whereas no immunoreactivity was evident when control monoclonal antibodies (MAb 50.8 and MAb 7 (rat] were used. Skin from neonatal and adult animals was used to determine whether GH receptor/BP expression was developmentally regulated. Immunoreactivity of the GH receptor/BP in the three species was consistently localized in the stratum basale and stratum spinosum. Intermittent staining was observed in the stratum granulosum. Scattered basal epidermal cells often displayed more intense immunoreactivity. This distribution was observed at all maturational stages examined. Intense GH receptor/BP immunoreactivity was observed in all histological layers of the lower one-third of hair follicles and in hair matrix cells of the dermal papillae. Immunoreactivity was also detected in the outer epithelial root sheath of the upper two-thirds of hair follicles, in sebaceous glands and in fibroblasts of the connective tissue sheath surrounding the follicle. GH receptor/BP immunoreactivity was also present in the secretory duct and myoepithelial cells of human eccrine sweat glands. Fibroblasts, Schwann cells of peripheral nerve fascicles, skeletal muscle cells and adipocytes of the dermis were also immunoreactive as were medial smooth muscle and endothelial cells of arteries. These results provide evidence that GH acts locally on the epidermis and epidermal appendages concordant with our recent localization of GH receptor/BP to epithelial cell types of the gastrointestinal and reproductive systems.

Animals↗
PubMed1989

An electrostatic model for the interaction between growth hormone and its receptor involving chelation of Ca2+ to the human growth hormone molecule.

We previously postulated the local involvement of cations in the complex between human growth hormone and its receptors in the liver. The original electrostatic model involved convergence of unit negative charges on the hormone and receptor, towards an interposed Ca2+ ion. That model was consistent with (a) the Ca2+ dependence of human growth hormone binding, (b) the magnitude of the Ca2+ mediated increase in the affinity of human growth hormone binding, and (c) could also explain the relative affinities of human and non-primate growth hormones for growth hormone receptors. In the present report, the original electrostatic model is revised with the postulate that Ca2+ is chelated to the human growth hormone molecule. The consequences of this postulate are explored mathematically with the result that it becomes necessary to propose an additional unique hindrance determinant (positive residues in helices one and four are good candidates) to account for the lower affinity of non-primate growth hormones relative to human growth hormone. Predictions are made regarding the effect of a particular point mutation (at position 34) on the affinity of hormone binding.

Animals↗
PubMed1989

Characterization of the growth hormone-binding protein of human serum using a panel of monoclonal antibodies.

A panel of monoclonal antibodies (MAbs) reactive with distinct epitopes on the rabbit liver GH receptor and rabbit serum GH-binding protein (GHBP) were tested for cross-reactivity with the GHBP from human serum. Four of seven MAbs reacted with the human serum GHBP. Immunoprecipitation of the human binding protein enabled hormonal specificity identical to that previously reported for human GH receptors to be demonstrated. Scatchard analyses of 125I-labelled human GH binding to the serum GHBP were carried out with correction made for endogenous human GH which was measured by radioimmunoassay of each serum sample. This approach yielded the first reliable estimates of the affinity and capacity of the human GHBP. The binding capacity (mean +/- S.E.M.) of female sera (804 +/- 126 pmol/l; n = 6) was greater than that of male sera (505 +/- 36 pmol/l; n = 9; P less than 0.02). The affinity of the GHBP was 0.91 +/- 0.10 litres/nmol (n = 15). The presence of multiple epitopes common to the human serum GHBP and the rabbit liver GH receptor is consistent with identity between the extracellular domains of the human GHBP and the human GH receptor, as is the case for the rabbit GHBP and GH receptor.

Adult↗
PubMed1988

Rabbit liver growth hormone receptor and serum binding protein. Purification, characterization, and sequence.

A putative growth hormone receptor from detergent-solubilized rabbit liver membranes and the growth hormone binding protein from rabbit serum have been purified 59,000- and 400,000-fold, respectively, primarily by affinity chromatography. Both purified proteins exhibit high affinity binding for human growth hormone; K alpha = 9-30 x 10(9) M-1 for the liver receptor and K alpha = 6 x 10(9) M-1 for the binding protein. The apparent molecular weight of the liver receptor is 130,000 by reduced sodium dodecyl sulfate gel electrophoresis, while that of the binding protein is 51,000. Both contain N-linked carbohydrate. The amino-terminal sequences of the liver growth hormone receptor and the serum binding protein were found to be the same, indicating that the binding protein corresponds to the extracellular domain of the liver receptor. Ubiquitin was found covalently linked to the liver receptor but not to the serum binding protein. The amino acid sequences of several peptides from the liver receptor were also determined after tryptic and V8 protease digestion.

Animals↗
PubMed1988

Use of calcium dependence as a means to study the interaction between growth hormones and their binding proteins in rabbit liver.

The affinity of 22,000-Mr human growth hormone (22 K-hGH) for GH binding proteins in rabbit liver is increased approx. 19-fold by 25 mM-Ca2+. In contrast, ovine growth hormone (oGH) binding is Ca2+-independent up to 10 mM, and decreased by greater Ca2+ concentrations. The 20,000-Mr hGH variant (20K-hGH), lacking residues 32-46, exhibits intermediate behaviour. Without Ca2+ there is a residual 40% of maximum specific binding to liver microsomes, and this increases to 65% with liver cytosolic GH binding proteins. In contrast with 22K-hGH, Scatchard analysis of 20K-hGH binding to liver microsomes produces curvilinear plots in the presence of 25 mM-Ca2+. From these results and inhibition studies with monoclonal antibodies to the GH binding proteins, it is concluded that deletion of the region 32-46 from 22K-hGH has eliminated one component of high-affinity Ca2+-potentiable binding. The Ca2+-mediated increase in Ka for the 22K-hGH-binding protein interaction is consistent with convergence of unit negative charges on the hormone and binding protein towards an intercalated Ca2+ ion. A positive charge in the critical region of nonprimate GHs would render their interactions Ca2+-independent and of lower Ka compared with 22K-hGH. A likely candidate for the negatively charged interactive residue is glutamate-33, since it is unique to human GH and is replaced by a positively charged arginine in non-primate GHs. Its absence in 20K-hGH could explain the altered calcium-dependence of 20K-hGH binding to what is probably the type 2 binding protein [Barnard & Waters (1986) Biochem. J. 237, 885-892]. The Ca2+-dependence of 20K-hGH binding to a subset of GH binding proteins provides both a verification and a mechanistic basis for the proposal [Hughes, Tokuhiro, Simpson & Friesen (1983) Endocrinology (Baltimore) 113, 1904-1906] that 20K-hGH binds with high affinity to only a subset of binding proteins in rabbit liver membranes.

Animals↗
PubMed1988

Outbreak of enterovirus 71 infection in Victoria, Australia, with a high incidence of neurologic involvement.

An outbreak of infections caused by enterovirus 71 occurred in southeastern Australia during the winter of 1986. Infection was confirmed by virus isolation or serology in 114 patients, 65 of whom were admitted to hospital. Fifty-one percent of inpatients were infants younger than 12 months old and 85% were younger than 5 years old. Many cases of hand, foot and mouth disease occurred in the community during the epidemic, but 51% (33 of 65) of patients admitted to hospital had central nervous system involvement, often associated with severe symptoms. Six patients had encephalitis and one had a poliomyelitis-like paralytic illness. Various skin manifestations other than hand, foot and mouth disease occurred, especially in young children, and 25 patients had significant respiratory disease including at least 7 with pneumonia. Enterovirus 71 is one of very few viruses that cause hand, foot and mouth disease as well as a variety of other clinical manifestations. The most important of these is meningoencephalitis, which causes significant morbidity, especially in infants and young children.

Child↗
PubMed1988

Isolation of a chemotactic protein for neutrophils from human ovarian follicular fluid.

Human follicular fluid was found to contain a factor chemotactic for human neutrophils. This chemotactic activity was shown to be heat labile and trypsin sensitive. Gel permeation chromatography experiments indicate that the chemotactic protein has an approximate molecular weight of 100 kd. Isoelectric focussing suggests an isoelectric point for this protein of around 5.8. The biologic and clinical significance of this apparently unique chemotactic protein remains to be determined.

Body Fluids↗
PubMed1988

The ontogeny of growth hormone receptors in the rabbit tibia.

To address the question of the mode of action of GH in stimulating longitudinal bone growth, we have used a panel of anti-GH receptor monoclonal antibodies to demonstrate GH receptors in the rabbit tibia and have studied the ontogeny of these receptors. In the neonate, receptors were localized in the hypertrophic zone between the cartilage canals, a region that develops into a secondary ossification center. In support of this finding, receptors were also localized on monolayer cultures of human infant costal chondrocytes. In 20- and 50-day-old rabbits, receptors were localized on reserve and proliferative chondrocytes in the growth plate. In 50- and 130-day-old rabbits receptors were localized on proliferative chondrocytes in the condylar cartilage. In older (180-day-old) rabbits with closed growth plates, GH receptors could not be detected, even in condylar cartilage. These results support the case for revision of the somatomedin hypothesis to accommodate a direct interaction between GH and receptors on epiphyseal chondrocytes.

Aging↗
PubMed1987

Dedifferentiation of cultured thyroid cells by epidermal growth factor: some insights into the mechanism.

Epidermal growth factor (EGF) has been shown to enhance both the proliferation and dedifferentiation of thyroid cells in culture, leading to a maintained dedifferentiated state, even in the presence of thyrotropin (TSH). Since this maintained loss of differentiated function is not seen with other mitogens, it may relate to a regulatory role for EGF in thyroid function. Therefore, we have examined the loci affected by the dedifferentiative actions of EGF using porcine thyroid cells in culture. EGF (10 ng/ml) induces a loss of thyrotropin (TSH) receptors with a time course identical to the loss in ability to transport iodide. This could account for the difference in extent of iodide uptake and morphological dedifferentiation seen between TSH- and cAMP-supported cells, although the fact that cAMP-supported cells also dedifferentiate implies a lesion distal to the cyclase. Reciprocal plot analysis of iodide uptake in control and EGF-treated cells shows that EGF increases the Km for iodide transport, corresponding to a decreased affinity of iodide pump sites for iodide. These effects on iodide pump affinity and TSH receptor number may result from reversal of thyroid cell polarity in monolayer culture, or they may be the result of more specific actions of EGF at these loci. It has been possible to discriminate between the proliferative and dedifferentiating actions of EGF using amiloride, a non-specific inhibitor of the Na+/H+ antiporter. An optimum concentration of amiloride (0.1 mM) was able to block EGF-stimulated incorporation of [3H]thymidine into DNA without preventing the blockade of iodide uptake, which implies that dedifferentiation is not a consequence of proliferation.(ABSTRACT TRUNCATED AT 250 WORDS)

Amiloride↗
PubMed1986

The human growth hormone receptor of cultured human lymphocytes. Structural characteristics and glycosylation properties.

The structural characteristics and glycoprotein nature of the human growth hormone (hGH) receptor in cultured lymphocytes (IM-9 cell line) were studied with the use of a bifunctional reagent (disuccinimidyl suberate) to couple 125I-hGH covalently to intact cells. After cross-linking, the hormone-receptor complexes were analysed by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. A single band of Mr 140,000 was identified under reducing conditions. The labelling of this band was blocked by unlabelled hGH but not by insulin, ovine prolactin, bovine or ovine growth hormones. The Mr 140,000 band was immunoprecipitated by either anti-hGH antibody or by a monoclonal antibody against rat liver growth hormone receptor. In the absence of reductant two major bands of Mr 270,000 and 140,000 were found. On two-dimensional gel electrophoresis, with the first dimension in the absence of reductant and the second in its presence, the Mr 270,000 complex generated the Mr 140,000 band. The nature of the oligosaccharide chains of the receptor was studied by treatment with different glycosidases. The electrophoretic mobility of the Mr 140,000 receptor complex was markedly increased after digestion with endoglycosidase F but showed no or little change after digestion with endoglycosidase H. The Mr 140,000 band was also sensitive to neuraminidase treatment. In addition the 125I-hGH-receptor complex was adsorbed by immobilized wheat germ agglutinin and to a smaller extent by immobilized concanavalin A, lentil lectin, ricin I and ricin II. In conclusion, taking into account that hGH is a Mr 22,000 polypeptide, the binding subunit of the GH receptor in human IM-9 lymphocytes has an Mr of approx. 120,000. The native receptor may exist as a homodimer of the binding subunit formed by disulphide bonds. Furthermore, the GH receptor subunit contains asparagine N-linked type of oligosaccharide chains. Most, if not all, of these chains are of the complex type and appear to be sialylated whereas no high-mannose type chains are detectable in the mature form of the receptor.

Acetylglucosaminidase↗
PubMed1986

Serum and liver cytosolic growth-hormone-binding proteins are antigenically identical with liver membrane 'receptor' types 1 and 2.

Studies with a panel of monoclonal antibodies (MAbs) reactive towards the presumptive rabbit liver growth-hormone (GH) receptor show that the rabbit serum GH-binding proteins share seven antigenic determinants (three at the hormone-binding site and four located elsewhere) with the liver cytosolic GH-binding proteins and the putative GH 'receptors' associated with the hepatocyte membrane. The rabbit serum binding proteins have an affinity for GH similar to the membrane GH receptors [for human GH, Ka = 2.45 (+/- 0.15) X 10(9) M-1 (mean +/- S.E.M., n = 8)] and high capacity relative to membrane 'GH receptors'. Analogues of the postulated membrane 'receptor' subtypes 1 and 2 exist in the serum, but not subtype 3, which is also absent from liver cytosol. The serum and cytosolic binding proteins have identical cation-dependence properties; hGH binding is Ca2+-dependent, whereas oGH binding is Ca2+-independent. Affinity labelling of hGH-affinity-purified serum binding proteins with 125I-hGH demonstrated a major GH-binding subunit, of Mr 55,000, identical with the major component purified from membranes. In view of their high affinity and capacity, the serum binding proteins could control availability of GH to membrane receptors. It is suggested that the cytosolic binding proteins may be newly synthesized serum binding proteins. The existence of a close relationship between subsets of membrane-associated GH-binding sites, the serum GH-binding proteins and cytosolic GH-binding proteins dictates a reappraisal of earlier ligand-binding studies, which did not distinguish between binding-site subsets in the liver.

Animals↗
PubMed1986

Detection of IgM antibodies to delta antigen after coinfection and superinfection with the delta virus.

A sensitive microtitre radioimmunoassay was developed for detection of IgM antibodies to delta antigen. The assay was based on the selective binding of IgM from test sera to antihuman IgM (u-chain specific) fixed to wells of a microtitre plate, and utilized delta antigen extracted from the liver of an experimentally infected chimpanzee. This test proved to be useful in distinguishing between coinfection and superinfection with the hepatitis delta virus (HDV). Transient anti-delta IgM responses were observed in patients coinfected with HDV, while prolonged elevated IgM levels were found in HBsAg carriers with chronic liver disease superinfected with HDV. Two distinct serological patterns were observed in both coinfection and superinfection. In coinfection, only 50% of patients with detectable anti-delta IgM went on to develop a long-lasting antibody response. Following superinfection with HDV either stationary or fluctuating levels of IgM antibody were demonstrated. In patients with fluctuating antibody levels, the presence or absence of IgM antibody related to the level of viral replication.

Hepatitis Antibodies↗
PubMed1986

Epidermal growth factor: effect on circulating thyroid hormone levels in sheep.

Observations on the effect of thyroid hormones on mouse submaxillary gland epidermal growth factor (EGF) and on the complementary effect of EGF on cultured thyroid cells led us to examine the interaction between EGF and thyroid hormones in the whole animal, during and after 24 h of infusion of 3.3 micrograms/kg X h mouse EGF into 6 merino ewes. There was a profound depression of both circulating T4 and T3 levels, to less than 20% of saline-infused control values, extending beyond the end of infusion. Plasma TSH concentrations were unchanged during the first 8 h of the infusion, excluding the likelihood of a suppressive effect of EGF on the hypothalamic-pituitary axis. Serum rT3 and 3,3'-diiodothyronine, however, experienced a more transitory 6-fold increase. These findings are consistent with a dual inhibitory effect of EGF on both thyroid hormone secretion and peripheral metabolism.

Animals↗