Characterization of coagulase-negative staphylococci and macrococci isolated from cheese in Germany

Cheese, especially ripened varieties, harbor a very complex and heterogeneous microbiota. In addition to the desired microorganisms (starter cultures) added during cheese production, potentially harmful bacteria may also enter the production chain. Regarding the latter, the focus of this study was on coagulase-negative staphylococci (CNS) and Macrococcus caseolyticus. Both are known to harbor a variety of genes coding for antibiotic resistance, including mecA, mecB, mecC, and mecD. Coagulase-negative staphylococci or macrococci carrying such genes or other virulence factors should not be present in cheese. Cheese samples (101 in total) were collected from retail sources. Coagulase-negative staphylococci and M. caseolyticus were isolated utilizing selective agars, and species were identified by phenotypical tests and partial sequencing of the sodA gene. The results allowed identification of 53 CNS strains and 19 M. caseolyticus strains. Among the CNS, 11 isolates of Staphylococcus saprophyticus and one Staphylococcus epidermidis isolate were obtained. Both species are potential human pathogens and may thus adversely affect the safety of these food products. Screening for antimicrobial resistance was performed by application of disc diffusion tests, a gradient strip-test, and 14 different PCR tests. Evidence for methicillin resistance (by either positive disc diffusion assay for cefoxitin or by mec PCR) was found in CNS isolates and M. caseolyticus (9 isolates each). Regarding other virulence factors, no genetic determinants for coagulase or the most common staphylococcal enterotoxins sea, seb, sec, sed, and see were detected in any of the CNS or M. caseolyticus isolates by PCR testing. In conclusion, the presence of facultatively pathogenic CNS and carriers of genes for antibiotic resistance in both groups of microorganisms, especially mec genes, and the respective food safety issues need further evaluation and surveillance.

Characterization of coagulase-negative staphylococci from brining baths in Germany

Brining is an important step in cheese making, and using brine baths for this purpose is common practice in German dairies. Time of brining, brine concentration, and composition of the complex and heterogeneous microbiota, including coagulase-negative staphylococci (CNS), contribute to the ripening and taste of cheese. As well as producing staphylococcal enterotoxins, some CNS show antibiotic resistance; therefore, we isolated 52 strains of presumptive CNS from cheese brines from 13 factories in Germany. Species identification by sodA gene sequencing revealed that 50 isolates were CNS: 31 Staphylococcus saprophyticus, 4 Staphylococcus carnosus, 4 Staphylococcus equorum, 3 Staphylococcus sciuri, 2 Staphylococcus hominis, and 2 Staphylococcus warneri. One isolate each was identified as Staphylococcus epidermidis, Staphylococcus pasteurii, Staphylococcus succinus, and Staphylococcus xylosus. Further subtyping of the Staph. saprophyticus isolates to the subspecies level revealed the presence of 6 Staph. saprophyticus ssp. saprophyticus. Using pulsed-field gel electrophoresis with the identified Staph. saprophyticus strains, 12 independent clones were identified, resulting in the exclusion of 18 strains from further testing. In 19 of the remaining 32 CNS isolates, resistance to antibiotics was observed. Resistance was found against oxacillin (17), penicillin (5), and cefoxitin (1). Four isolates expressed resistance to both oxacillin and penicillin. No resistance was found to enrofloxacin, tetracycline, gentamicin, or erythromycin. Then, PCR analysis for antibiotic resistance genes was performed for 22 different genes. Only genes blaZ and bla_TEM were found in 7 isolates. These isolates were selected for challenge tests with different concentrations of lactic acid and NaCl to examine whether expression of antibiotic resistance was influenced by these stressors. An increase in the minimal inhibitory concentration from 0 to 2.0 µg/mL was seen for trimethoprim/sulfamethoxazole only in one isolate of Staph. saprophyticus at an increased lactic acid concentration. Finally, all isolates were tested for genetic determinants (entA, entB, entC, entD, and entE) of the most common staphylococcal enterotoxins; none of these genes were detected. We found no indication for unacceptable risks originating from the isolated CNS.

Short communication: Tryptic β-casein hydrolysate modulates enteric nervous system development in primary culture

The intestinal tract of the newborn is particularly sensitive to gastrointestinal disorders, such as infantile diarrhea or necrotizing colitis. Perinatal development of the gut also encompasses the maturation of the enteric nervous system (ENS), a main regulator of intestinal motility and barrier functions. It was recently shown that ENS maturation can be enhanced by nutritional factors to improve intestinal maturation. Bioactivity of milk proteins is often latent, requiring the release of bioactive peptides from inactive native proteins. Several casein-derived hydrolysates presenting immunomodulatory properties have been described recently. Furthermore, accumulating data indicate that milk-derived hydrolysate can enhance gut maturation and enrichment of milk formula with such hydrolysates has recently been proposed. However, the capability of milk-derived bioactive hydrolysate to target ENS maturation has not been analyzed so far. We, therefore, investigated the potential of a recently described tryptic β-casein hydrolysate to modulate ENS growth parameters in an in vitro model of rat primary culture of ENS. Rat primary cultures of ENS were incubated with a bioactive tryptic β-casein hydrolysate and compared with untreated controls or to cultures treated with native β-casein or a Prolyve β-casein hydrolysate (Lyven, Colombelles, France). Differentiation of enteric neurons and enteric glial cells, and establishment of enteric neural network were analyzed using immunohistochemistry and quantitative PCR. Effect of tryptic β-casein hydrolysate on bone morphogenetic proteins (BMP)/Smad pathway, an essential regulator of ENS development, was further assessed using quantitative PCR and immunochemistry. Tryptic β-casein hydrolysate stimulated neurite outgrowth and simultaneously modulated the formation of enteric ganglia-like structures, whereas native β-casein or Prolyve β-casein hydrolysate did not. Additionally, treatment with tryptic bioactive β-casein hydrolysate increased the expression of the glial marker glial fibrillary acidic protein and induced profound modifications of enteric glial cells morphology. Finally, expression of BMP2 and BMP4 and activation of Smad1/5 was altered after treatment with tryptic bioactive β-casein hydrolysate. Our data suggests that this milk-derived bioactive hydrolysate modulates ENS maturation through the regulation of BMP/Smad-signaling pathway. This study supports the need for further investigation on the influence of milk-derived bioactive peptides on ENS and intestinal maturation in vivo.

276 IN VITRO FERTILIZATION PROCEDURES AFFECT THE HEPATIC GENOMIC CYTOSINE METHYLATION LEVEL AND THE PHENOTYPE OF BOVINE FETUSES

Epigenetic perturbations are assumed to be responsible for phenotypic abnormalities of fetuses and offspring originating from in vitro embryo techniques. We studied 29 viable bovine Day 80 fetuses to assess the effects of different in vitro fertilization (IVF) protocols on hepatic genomic cytosine methylation levels and on fetal phenotype. Two groups of IVF-fetuses (IVF1, n = 5 and IVF2, n = 10) were compared with control fetuses generated by artificial insemination (AI, n = 14). Both IVF protocols were previously employed to generate live offspring but differed with respect to gonadotropins in the oocyte maturation medium (0.01 units/mL b-FSH and b-LH for IVF1 versus 0.2 units/mL o-FSH for IVF2) and serum concentrations in the embryo culture media (5% estrous cow serum in IVF1 versus 10% estrous cow serum in IVF2). Analysis of variance (General Linear Model Procedure, SPSS for Windows version 12.0; SPSS GmbH Software, Munich, Germany) showed that fetus group significantly affected fetus weight and length (P < 0.01), heart (P < 0.05) and liver (P < 0.01) weight, and 5-methylcytosine (5 mC) content of liver DNA (P < 0.001). Comparison of group means (t-test) showed that methylation levels in both groups of IVF fetuses differed significantly from AI controls. We observed hepatic DNA hypomethylation (-15.4% vs. AI control, P < 0.01) in IVF1 fetuses, and hypermethylation (+11.6% vs. AI control, P < 0.001) in IVF2 fetuses, but only IVF2 fetuses showed phenotypic abnormalities. The IVF2 fetuses were significantly heavier (18.6%, P < 0.01) and longer (4.3%, P < 0.05) than AI fetuses, with increased heart (21.8%, P < 0.05) and liver (25%, P < 0.001) weights, and thus displayed an overgrowth phenotype. A clinical-chemical screen of 18 plasma parameters failed to detect abnormalities in IVF1 fetuses but revealed significantly increased levels of insulin-like growth factor 1 (40.8%, P < 0.001) and creatinine (28.5%, P < 0.05) in IVF2 fetuses. Our data indicate that bovine IVF-procedures can induce protocol-specific and persistent changes in hepatic cytosine methylation level with or without obvious concomitant changes in fetal phenotype. This suggests that epigenetic change after bovine IVF could be more widespread than previously thought and highlights the value of epigenetic diagnostic screening.

Detection of a promoter polymorphism in the gene of intestinal fatty acid binding protein (I-FABP)

Postprandial fat absorption is supposed to be a major factor in the development of the metabolic syndrome. In recent years, the assimilation of plasma triglycerides has been the focus of several groups, revealing a number of specific fat or fatty acid transporters. The intestinal fatty acid binding protein, I-FABP-2, participates in the absorption of nutritional fats. The influence of a coding polymorphism has been investigated intensively. However, it remains still unclear whether this polymorphism has a major impact on postprandial TG levels in humans. We found a polymorphism in the promoter of FABP-2, which might involve the retinoid receptor in the transcriptional activity. In functional analysis, we have been able to demonstrate that the various promoter alleles develop different activities in the human intestinal epithelial cells and that the postprandial appearance of plasma TGs in healthy subjects also depends on their genotype. Since the distribution of the identified promoter polymorphism does not differ in subjects suffering from type 2 diabetes, the overall influence on the development of the metabolic syndrome seems to be minor.

Transendothelial migration of 27E10+ human monocytes

The myeloid-related proteins MRP8 (S100A8) and MRP14 (S100A9), two members of the S100 family of calcium-binding proteins, are co-expressed and form a cell-surface and cytoskeleton-associated heterodimer upon calcium mobilization which is recognized by the mAb 27E10. The heterodimer is abundantly expressed in the cytoplasm of granulocytes and a subpopulation of blood monocytes. Previously, we and others demonstrated endothelium-associated MRP8/14 in inflamed tissues in the vicinity of transmigrating leukocytes, suggesting a function of the proteins in this process. Here, we demonstrate that 27E10(+) cells represent a fast-migrating monocyte subpopulation which preferentially utilizes an ICAM-1-dependent mechanism. The following observations imply a function of MRP8/14 in the transmigration process: (i) higher secretion of MRP8/14 from 27E10(+) monocytes compared to 27E10(-) monocytes after interaction with activated endothelium, (ii) higher expression of CD11b on 27E10(+) compared to 27E10(-) monocytes, (iii) up-regulation of CD11b on 27E10(-) monocytes in the presence of MRP14 or MRP8/14 heterodimers but not MRP8 and (iv) active participation of MRP14 but not of MRP8 in transmigration as shown by blocking with respective antibodies. We show that the interaction of 27E10(+) monocytes with activated endothelium leads to MRP8/14 release which may account for the high MRP8/14 concentrations in body fluids of patients with acute or chronic inflammatory diseases. Released MRP8/14 may serve a function by enhancing CD11b expression and/or affinity in human monocytes and by participating in the transendothelial migration mechanism. Thus, MRP8/14 substantially contributes to the recruitment of monocytes to an inflammatory site.

The two calcium-binding proteins, S100A8 and S100A9, are involved in the metabolism of arachidonic acid in human neutrophils

Recently, we identified the two myeloid related protein-8 (MRP8) (S100A8) and MRP14 (S100A9) as fatty acid-binding proteins (Klempt, M., Melkonyan, H., Nacken, W., Wiesmann, D., Holtkemper, U., and Sorg, C. (1997) FEBS Lett. 408, 81-84). Here we present data that the S100A8/A9 protein complex represents the exclusive arachidonic acid-binding proteins in human neutrophils. Binding and competition studies revealed evidence that (i) fatty acid binding was dependent on the calcium concentration; (ii) fatty acid binding was specific for the protein complex formed by S100A8 and S100A9, whereas the individual components were unable to bind fatty acids; (iii) exclusively polyunsaturated fatty acids were bound by S100A8/A9, whereas saturated (palmitic acid, stearic acid) and monounsaturated fatty acids (oleic acid) as well as arachidonic acid-derived eicosanoids (15-hydroxyeicosatetraenoic acid, prostaglandin E(2), thromboxane B(2), leukotriene B(4)) were poor competitors. Stimulation of neutrophil-like HL-60 cells with phorbol 12-myristate 13-acetate led to the secretion of S100A8/A9 protein complex, which carried the released arachidonic acid. When elevation of intracellular calcium level was induced by A23187, release of arachidonic acid occurred without secretion of S100A8/A9. In view of the unusual abundance in neutrophilic cytosol (approximately 40% of cytosolic protein) our findings assign an important role for S100A8/A9 as mediator between calcium signaling and arachidonic acid effects. Further investigations have to explore the exact function of the S100A8/A9-arachidonic acid complex both inside and outside of neutrophils.

Identification of epithelial and myeloid-specific DNA elements regulating MRP14 gene transcription

Macrophage migration inhibition factor-related protein 14 (MRP14) is a Ca2+-binding protein of the S-100 family highly abundant in myelomonocytic and epithelial cells. The expression pattern is restricted to myeloid and epithelial cells and therefore the MRP14 gene is ideally suited to study the regulation of gene expression in these cells. We characterized the human MRP14 promoter by using the chloramphenicol acetyltransferase reporter assay system. The analysis was performed in epithelial (TR146) and myeloid (HL-60) cells, and we were successful in mapping positive and negative regulatory elements. The region -114/-419 contains strong myeloid-specific regulatory elements, whereas the domain -600/-1000 enhances the MRP14 transcription in epithelial cells. The sequence -462/-600 accommodates a regulatory element that enhances the promoter activity in both myeloid and epithelial cells. Regions -114/-419 and -1000/-4500 reduce the expression of MRP14 only in epithelial cells, whereas the domains -419/-462 and -4500/-6500 contain down-regulating elements in both, epithelial and myeloid cells. The presented data demonstrate that transcription of the human MRP14 gene is regulated in a complex manner enabling the precise control of the MRP14 level in epithelial and myeloid cells.

Novel insights into structure and function of MRP8 (S100A8) and MRP14 (S100A9)

The two migration inhibitory factor- (MIF)-related protein-8 (MRP8; S100A8) and MRP14 (S100A9) are two calcium-binding proteins of the S100 family. These proteins are expressed during myeloid differentiation, are abundant in granulocytes and monocytes, and form a heterodimeric complex in a Ca2+-dependent manner. Phagocytes expressing MRP8 and MRP14 belong to the early infiltrating cells and dominate acute inflammatory lesions. In addition, elevated serum levels of MRP8 and MRP14 have been found in patients suffering from a number of inflammatory disorders including cystic fibrosis, rheumatoid arthritis, and chronic bronchitis, suggesting conceivable extracellular roles for these proteins. Although a number of possible functions for MRP8/14 have been proposed, the biological function still remains unclear. This review addresses recent developments regarding the MRP14-mediated promotion of leukocyte-endothelial cell-interactions and the characterization of MRP8/14 heterodimers as a fatty acid binding protein complex. In view of the current knowledge, the authors will hypothesize that MRP8 and MRP14 play an important role in leukocyte trafficking, but do not affect neutrophil effector functions.

The effects of ovine placental lactogen and bovine growth hormone on hepatic and mammary gene expression in lactating sheep

The ability of ovine placental lactogen (oPL) to bind to the growth hormone receptor (GHR) raises the possibility that oPL may exert a growth hormone (GH)-like action on galactopoiesis. We have compared the effects of treating lactating ewes for 5 days with an equimolar dose (0.1 mg/kg/day, administered as two equal doses 12 hourly) of either bovine growth hormone (bGH) (n = 10), oPL (n = 10) or saline (n = 9) on hepatic and mammary GHR, insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 (IGFBP-3) gene expression and hepatic GHR number. Hepatic GHR and IGFBP-3 mRNA were unaltered by bGH or oPL treatment. Hepatic IGF-I mRNAs increased following bGH (P < 0.05) but not oPL treatment. GHR gene expression was greater in liver compared to mammary gland extracts. There was no effect of either bGH or oPL treatment on mammary GHR, IGF-I or IGFBP-3 mRNA or hepatic GHR number. These studies confirm the galactopoietic effects of bGH in lactating ruminants and suggest that the mechanism of this action is not via increased hepatic GHR number or gene expression. In addition, the increase in hepatic but not mammary IGF-I mRNA with bGH treatment suggests an endocrine action of IGF-I on milk synthesis. These studies also demonstrate that an equimolar dose of oPL is not galactopoietic or somatogenic in the lactating ewe.

The gene encoding the myeloid-related protein 14 (MRP14), a calcium-binding protein expressed in granulocytes and monocytes, contains a potent enhancer element in the first intron

Myeloid-related proteins 8 and 14 (MRP8 and MRP14) are two Ca2+-binding proteins of the S-100 family highly abundant in myelomonocytic cells. The expression is not only dependent on the developmental status of the cell but also on the inflammatory situation in the tissue. In order to identify regulatory elements responsible for the high expression of MRP14 in myeloid cells, reporter gene constructs have been transfected into HL-60 cells, Mono Mac 6 cells, and L132 cells. We demonstrated that a DNA element in the first intron (positions 153-361) enhances the transcriptional activity of the homologous promoter and of the heterologous herpes simplex virus thymidine kinase promoter up to 37-fold. To further identify the functional site, the region between positions 153 and 192 was analyzed functionally using the thymidine kinase promoter. The region increased the expression in the same magnitude as the complete intron. This enhancer is highly conserved in the human and murine MRP genes, indicative of its involvement in the transcription of MRPs. Protein binding to the region is demonstrated using EMSA, DNA cross-linking, Southwestern blotting, and affinity purification. Affinity purification confirms that four proteins bind to the enhancer element.

The transcription factors c-myb and C/EBP alpha regulate the monocytic/myeloic gene MRP14

The entry of microorganisms into the body induces inflammatory processes. During this process a sequence of cellular, humoral, non-specific and specific actions are evoked to combat the infection. Macrophages and granulocytes, which are developed from a common progenitor cell, are the cellular components of the specific and non-specific immunoreaction. MRP14 (Macrophage migration inhibitory related protein) and MRP8, two S-100 proteins contained in high concentrations in these cells are obviously essential for adhesion and migration of monocytes and granulocytes. To investigate the transcriptional regulation of these genes we cotransfected constructs expressing CAT under control of the MRP14 promoter and expression constructs of C/EBP alpha and v-myb, two transcription factors involved in myeloid/monocytic differentiation. Transfection with C/EBP alpha revealed a massive enhancement of the MRP14 promoter in both, HL 60 cells (granulocytic differentiated) and L132 fibroblasts. In contrast, v-myb reduces MRP14 promoter activity. Northern blot analysis of L132 cells transfected with the C/EBP alpha expression vector demonstrate that C/EBP alpha is sufficient to enhance MRP14 expression in the context of the whole genome.

The heterodimer of the Ca2+-binding proteins MRP8 and MRP14 binds to arachidonic acid

The S100 proteins MRP8 and MRP14 have been shown to be expressed by myeloid cells during inflammatory reactions. Since the majority of S100 proteins exhibit their biological activity when associated as complex it was investigated whether murine MRP8 and MRP14 form heterodimers and whether this complex may bind lipids of the cell membrane. This is of particular importance since their anchoring into the plasma membrane is unclear although upon calcium binding the proteins translocate from the cytoplasma to the cytoskeleton and the plasma membrane. Using recombinant proteins we could show that not the monomers but only the heterodimers specifically bind arachidonic acid. This finding opens new perspectives for the role of MRP8 and MRP14 in acute and chronic inflammatory processes.

Myeloid-related protein (MRP) 8 and MRP14, calcium-binding proteins of the S100 family, are secreted by activated monocytes via a novel, tubulin-dependent pathway

Myeloid-related protein (MRP) 8 and MRP14, two members of the S100 family expressed in myelomonocytic cells, have been ascribed some extracellular functions, e.g. antimicrobial, cytostatic, and chemotactic activities. Since S100 proteins lack structural requirements for secretion via the classical endoplasmic reticulum/Golgi route, the process of secretion is unclear. We now demonstrate the specific, energy-dependent release of MRP8 and MRP14 by human monocytes after activation of protein kinase C. This secretory process is not blocked by inhibitors of vesicular traffic through the endoplasmic reticulum and Golgi, and comparative studies on tumor necrosis factor-alpha and interleukin-1beta indicate that MRP8 and MRP14 follow neither the classical nor the interleukin-1-like alternative route of secretion. Inhibition by microtubule-depolymerizing agents revealed that MRP8/MRP14 secretion requires an intact tubulin network. Accordingly, upon initiation of MRP8/MRP14 secretion, immunofluorescence microscopy showed a co-localization of both proteins with tubulin filaments. Release of MRP8 and MRP14 is associated with down-regulation of their de novo synthesis, suggesting that extracellular signaling via MRP8/MRP14 is restricted to distinct differentiation stages of monocytes. Our data provide evidence that the S100 proteins MRP8 and MRP14 are secreted after activation of protein kinase C via a novel pathway requiring an intact microtubule network.

Electroporation efficiency in mammalian cells is increased by dimethyl sulfoxide (DMSO)

Electroporation is one of the most common methods used transform mammalian cells with plasmids. This method is versatile and can be adapted to meet the requirements of many cell lines. However, sometimes the efficiency of this method is low. We demonstrate that dimethyl sulfoxide (DMSO) facilitated a better DNA uptake in four different cell lines (HL60, TR146, Cos-7 and L132). The cells were electroporated with a beta-Gal expression plasmid in a medium containing DMSO (1.25%) during, and for 24 h after the pulse. In all these cells a dramatic (up to 8-fold) increase in transfection efficiency occurred after this treatment. This method opens up the possibility of using electroporation even in cells which are difficult to transfect.

Differential effects of maternal ovine placental lactogen and growth hormone (GH) administration on GH receptor, insulin-like growth factor (IGF)-1 and IGF binding protein-3 gene expression in the pregnant and fetal sheep

The role of placental lactogen (PL) in the regulation of maternal metabolism and fetal growth is not understood. Both PL and growth hormone (GH) have been suggested as possible regulators of mammogenesis. Our aim was to compare the effects of recombinant ovine placental lactogen (oPL) and bovine growth hormone (bGH) on maternal mammary gland development and fetal growth. Pregnant ewes were treated from day 101 to 107 of gestation with twice daily subcutaneous injections of recombinant oPL (n = 7), bGH (n = 8) (0.15 mg/kg live weight/day) or saline (n = 8). On day 108 of gestation, fetal and maternal tissues were collected. The relative abundance of growth hormone receptor (GHR), insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein-3 (IGFBP-3) mRNA was assessed in mammary gland, maternal liver and heart, and in fetal and placental tissues. There was no detectable change in mammary tissue GHR, IGF-1 or IGFBP-3 gene expression with either bGH or oPL treatment. Maternal administration of bGH, but not oPL, during pregnancy caused an increase in maternal hepatic IGF-1 gene expression (P < 0.005). Treatment with oPL, but not bGH, resulted in a significant increase (P < 0.025) in the relative abundance of fetal hepatic IGFBP-3 mRNA. Maternal hepatic GHR gene expression was not affected by treatment. This study suggests that while bGH treatment of pregnant ewes induces characteristic somatogenic responses, oPL treatment does not have comparable effects. However, oPL may indirectly influence the fetal somatotropic axis by altering fetal hepatic IGFBP-3 production.

Developmental changes in the expression patterns of IGFs, type 1 IGF receptor and IGF-binding proteins-2 and -4 in perinatal rat lung

The insulin-like growth factors (IGF-I and IGF-II), their receptors and binding proteins (IGFBPs) are endogenously expressed in a number of tissues including the lung during fetal and neonatal development. This endogenous autocrine/paracrine IGF 'system', together with endocrine sources, contributes to the regulation of lung cell proliferation. We investigated the expression of the mRNAs encoding IGF-I, IGF-II, the type 1 IGF receptor (IGF-T1R) and two IGF-binding proteins (IGFBP-2 and IGFBP-4) in rat lung during the perinatum. These were compared in lung with surfactant apoprotein A (Sp-A) mRNA levels. mRNA in extracts of fetal tissues collected between day 17 of gestation (17f) and day 9 after birth (9d) was estimated by Northern blot or RNase protection analysis. At day 20 of gestation IGF-I, IGF-T1R and IGFBP-4 mRNA levels were higher in lung than liver (all P < 0.01), whereas IGF-II and IGFBP-2 mRNA levels were higher in liver than lung (each P < 0.02). The expression of IGF-1, IGFBP-2 and IGFBP-4 in lung was high before birth (days 17-20f) but decreased to low levels at days 21f, 22f or at birth (1d) but increased in the neonatal lung. IGF-II expression in lung was high at 17f but decreased before birth and remained low after birth. The IGF-T1R was expressed at moderate levels before birth, decrease before birth but peaked at days 2-5 after birth. The decrease in expression of these growth regulators before birth expression of these growth regulators before birth was matched by an increased in Sp-A expression which was clearly seen at day 20f, peaked at 1d and then was clearly seen at day 20f, peaked at 1d and then was maintained at high levels after birth. Primary cell cultures of 18f lung epithelia express IGFBP-2 while fibroblasts from the same animals express only IGFBP-4. Cells grown from 22f lung tissue express IGFBP-2 and IGFBP-4 at lower levels, behaving in vitro as they do in vivo. The contrasting levels of expression of different components of the IGF system in the fetal lung and liver indicate organ-specific regulation. IGFBP-2 and IGFBP-4 expression in different cell types within lung but with similar temporal changes suggests cell-specific regulation, perhaps by a common agent. The patterns by a common agent. The patterns of expression of IGF-I, IGF-T1R, IGFBP-2 and IGFBP-4, but not IGF-II, in developing lung correspond to previously described phasic changes in lung cell proliferation rates. The nadir in expression of these four major components of the lung IGF system occurs in the saccular phase when the lung begins to differentiate, probably under the influence of certain endocrine agents.

The mouse homologue of the HTLV-I tax responsive element binding protein TAXREB107 is a highly conserved gene which may regulate some basal cellular functions

We report the cDNA sequence of a mouse gene homologous to the HTLV-I tax responsive element binding protein TAXREB107 (M-TAXREB107). This gene is constitutively and ubiquitously expressed indicating a conserved biological function. We present evidence that its transcription is under strict control of a regulatory factor, which is rapidly metabolized.

[Somatomedins and their binding proteins are involved in wound healing after hypoxia of the central nervous system]

Insulin-like growth factors (IGFs) are involved in cell growth and differentiation. In muscle tissue they regulate axonal in growth and maintain the connection. They also play a role in regeneration of the peripheral nerve system. We hypothesized that IGFs might also be important factors in the recovery of central nervous tissue after traumatic damage such as perinatal asphyxia. Our group developed a rat model to mimic the resulting damage and test the changes of expression of IGF-1, -2 and several of their binding proteins. We also examined the influence of exogenous IGF-1 and -2 after asphyxia in the same model. Rats underwent a unilateral ligation of the A. carotis followed by a 15 or 90 min inhalational hypoxia (8% O2). The treatment resulted in a mild or severe damage in the ligated hemisphere with either selective neuronal loss or complete infarction of the volume, respectively. The treatment induced expression of both IGFs and binding protein 2, 3 and 5. Binding protein 1 is not expressed and binding protein 4 is suppressed soon after hypoxia-ischemia. We conclude that both IGFs and several of their binding proteins are involved in response and wound healing after hypoxic brain damage. This was further tested in a second experiment. Rats were injected with IGF-1 or IGF-2 intra-ventricular soon after the hypoxic damage. IGF-1 treatment significantly reduced neuronal loss, IGF-2 had no effect. Behaviour tests, however, showed no difference between IGF-1 treated rats and controls. Our studies show interesting aspects for further investigation and a possible treatment of perinatal asphyxia and traumatic damage of nerve tissue.

IGFBP-2 expression in liver and mammary tissue in lactating and pregnant ewes

Binding proteins for the insulin-like growth factors (IGFBPs) modulate the actions of IGF I and IGF II. IGFBP-2 is particularly high in plasma of pregnant and fetal animals and in milk. We investigated the peri-lactational control of IGFBP-2 expression and secretion. Fifteen singleton-bearing pregnant ewes at day 101 of gestation were injected sc twice daily for 8 days with bovine growth hormone (bGH) or ovine placental lactogen (oPL) both at 0.15 mg.kg-1.d-1 or saline. A further fifteen ewes at day 17 of lactation were injected sc twice daily for 5 days with bGH or oPL at 0.1 mg.kg-1.d-1 or saline. On the last day of injection blood samples were taken and the animals were sacrificed. Liver and mammary tissue samples were immediately frozen and subsequently extracted to provide total RNA for evaluation by Northern blot analysis using a rat IGFBP-2 cDNA probe. Plasma samples were analysed by Western ligand blotting for IGFBP-2. The comparison of the two saline-treated groups (pregnant vs lactating ewe) revealed no difference in the plasma concentrations of IGFBP-2. IGFBP-2 mRNA expression in the liver of the lactating ewes was markedly increased compared to that in the pregnant ewes. In contrast, in mammary tissue the expression was significantly lower in lactating than in pregnant sheep. In pregnant animals treatment with bGH, but not oPL, decreased the expression of IGFBP-2 in liver. There was a similar trend in the lactating ewe.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential expression of insulin-like growth factor binding proteins (IGFBP) 4 and 5 mRNA in the rat brain after transient hypoxic-ischemic injury

Recent studies suggest a role for the insulin-like growth factor (IGF) system in the repair of damaged tissue following hypoxic-ischemic injury in the infant rat brain. We have used a unilateral model of hypoxic-ischemic injury to assess the possible involvement of two IGF binding proteins (IGFBPs), IGFBP-4 and IGFBP-5, in the post-asphyxial response. Ligation of the right carotid artery of 21-day-old rats was followed by either 15 min or 60 min exposure to 8% oxygen to produce moderate and severe damage respectively. Using in situ hybridization, the distribution of IGFBP-4 and IGFBP-5 mRNA was determined in brains collected over 10 days following the insult. In the control brains (no damage), both IGFBPs were expressed in distinct regions. IGFBP-4 mRNA was detected in limited areas of the hippocampus and in several cortical layers, while IGFBP-5 mRNA was found primarily in the thalamus. In response to hypoxic-ischemic injury, IGFBP-4 mRNA expression was reduced in regions of neuronal loss, suggesting a neuronal origin for IGFBP-4. The expression of IGFBP-5 mRNA was not altered by the 15 min insult, but was heavily induced from 3 days following the 60 min insult, particularly in the subependymal layer and adjacent white matter on the ligated hemisphere. This suggests that IGFBP-5 may be involved in recovery from severe hypoxic-ischemic injury and may be important in the regeneration of oligodendrocytes.

Tissue distribution and ontogeny of growth hormone receptor messenger ribonucleic acid and ligand binding to hepatic tissue in the midgestation sheep fetus

While circulating GH concentrations are high in fetal life, skeletal growth is only slightly reduced by GH deficiency in utero. This has been explained by the relatively low binding of GH to fetal hepatic tissue, suggesting a lack of GH receptors (GHR). The GHR also recognizes ovine placental lactogen (oPL), which may have a specific role either as a fetal growth-promoting hormone or in regulating fetal metabolism. We investigated GHR expression and membrane binding of ovine (o) GH and oPL in various ovine fetal tissues and in maternal liver at different gestational stages. Singleton-bearing ewes at 51, 95, and 120 days gestation were killed. Liver, muscle, kidney, and brain samples were taken from the fetuses as well as placentas and livers from the ewes (n = 3/gestational age). GHR mRNA measured by Northern blot analysis was expressed at high levels in maternal liver at all gestational stages. A major band was observed at 4.4 kilobases (kb), and three minor bands were observed at 2.5, 1.7, and 8.1 kb. In fetal and placental tissue, only the 4.4-kb band was detected. This was present as early as day 51 of gestation in liver, kidney, lung, heart, and placenta and increased slightly with advancing gestation. On day 51, the expression of GHR mRNA in muscle was negligible, but by day 95, muscle expressed higher concentrations than fetal liver. Placental samples showed only a slight signal, with no change over the gestational range studied. In situ hybridization revealed the placental mRNA to be primarily associated with the decidua. Hepatic tissue showed specific binding to [125I]oGH and [125I]oPL from 51 days gestation. [125I]oPL showed a higher [51 days, 17.9 +/- 1.9% (mean +/- SEM); 95 days, 11.5 +/- 1.6%; 120 days, 16.3 +/- 0.9%] specific binding to the liver membranes than [125I]oGH (51 days, 2.1 +/- 0.7%; 95 days, 2.6 +/- 0.3%; 120 days, 3.5 +/- 0.4%). We conclude that oGHR are present as early as day 51 of gestation in various tissues, including liver. The message appears later in skeletal muscle than in liver. As the GH receptor binds oPL with higher potency than oGH, the parallel ontogenic changes in [125]oGH and [125]oPL binding in the liver do not support the presence of a PL receptor under independent developmental regulation.

Hypoxia and hypoxia/ischemia affect the expression of insulin-like growth factor binding protein 2 in the developing rat brain

Brain halves were collected at various time points from 21-day-old Wistar rats exposed to either a short or prolonged period of inhalational hypoxia following unilateral carotid ligation post-insult. Neuronal loss was restricted to the side of the carotid ligation. Northern blot analysis was performed for IGFBP-2 mRNA. The prolonged hypoxia decreased the expression of IGFBP-2 five hours post insult, whereas the shorter insult level showed an (P < 0.05) increase above control. In both groups IGFBP-2 mRNA increased to peak 3-5 days post insult. After a decline at day 6, expression was again high 7-10 days after HI. In the short hypoxia group, where there was little neuronal loss, the expression of IGFBP-2 in both hemispheres followed the same pattern over time. However prolonged hypoxia induced higher IGFBP-2 expression in the ligated hemisphere where there was extensive neuronal loss. At day 5 post-insult 5/9 rats showed an additional, slightly smaller (1.4 kb vs 1.7 kb) second transcript. The different pattern of expression associated with different degrees of injury suggest that IGFBP-2 is involved in the post asphyxial response. Hypoxia itself leads to alterations in IGFBP-2 expression. Greater expression is associated with neuronal loss. These observations suggest that the IGF system contributes to neuronal rescue and/or brain repair processes.

Expression of insulin-like growth factor-binding protein 2 (IGF-BP 2) following transient hypoxia-ischemia in the infant rat brain

Hypoxia-ischemia induced by unilateral carotid ligation followed by either 15 (moderate) or 90 (severe) min exposure to 8% oxygen was associated with induction of IGF-BP 2 mRNA expression. A specific rat IGF-BP 2 cDNA probe was used to determine the IGF-BP 2 mRNA distribution in brain sections using in situ hybridization. Untreated control rats and the non-ligated hemisphere in experimental rats expressed IGF-BP 2 mRNA in the choroid plexus, meninges and more weakly in the thalamus, hippocampus and cortical layer 5. Increased expression in experimental rats was limited to regions known to have neuronal damage. Three days after the moderate insult the signal was increased in the CA1/2 region of the hippocampus and thalamus of the ligated side. Three days after the severe insult IGF-BP 2 expression was found surrounding the infarcted regions while by 5 days after severe insult the whole infarcted volume showed induction. The results suggest a role for the IGFs in the post-asphyxial response. IGF-BP 2 may alter the bio-availability of IGF 1 or 2 or modulate their actions in the area of infarction, and thus promote cerebral repair and recovery.

IGF binding protein-2 gene expression and the location of IGF-I and IGF-II in fetal rat lung

Binding proteins for the insulin-like growth factors (IGF-BPs) are important modulators of the biological actions of IGF-I and IGF-II. The generation of IGFBPs within developing organs, and their spatial arrangement, may similarly determine IGF action at specific microanatomical sites. In situ hybridization studies with late gestation (days 16, 18 and 20) fetal rat lung using a cDNA probe for IGFBP-2 showed strong gene expression in the fetal lung epithelial structures (alveoli and airways). The sites of IGFBP-2 gene expression were associated with immunoreactive IGF-II at the apical surface of the epithelium. By day 20, there was also some IGFBP-2 gene expression and immunoreactive IGF-II at discrete sites in the mesenchyme. In contrast, immunoreactive IGF-I was found predominantly distributed in a punctate pattern, consistent with its presence in the lumen or walls of small vessels or capillaries, and in a granular, intracellular form in both epithelial and mesenchymal cells. These studies suggest that endogenously generated IGFBP-2 may determine the distribution of IGF-II, principally at the apical surface of lung epithelia. IGF-I does not colocalise with IGF-II peptide or the sites of IGFBP-2 gene expression. We conclude that the spatial distributions of these two related growth factors are separately controlled, to some extent by endogenously generated binding proteins.

Ovine placental lactogen is a potent somatogen in the growth hormone (GH)-deficient rat: comparison of somatogenic activity with bovine GH

The somatogenic effects of recombinant ovine placental lactogen (oPL) were investigated in the GH-deficient dwarf rat and compared to those of identical doses of recombinant bovine GH (bGH) in three independent studies. Both oPL and bGH treatments resulted in an increase (P less than 0.05) in body weight gain compared to that in saline controls, with oPL treatment being more potent than bGH (P less than 0.05). In promoting linear growth, oPL was more potent (P less than 0.05) than bGH in some instances. The nitrogen content of dry carcass matter was increased with oPL treatment compared to saline (P less than 0.05), with a nonsignificant increase in bGH-treated animals. Carcass fat was similarly reduced by both oPL and bGH treatment (P less than 0.05) compared to saline. Serum insulin-like growth factor-I (IGF-I) concentrations were increased significantly (P less than 0.05) by both oPL and bGH treatments, with a significantly greater effect of oPL suggested in one study. No increase in hepatic IGF-I mRNA was evident with either treatment, suggesting that the increase in serum IGF-I is due to posttranscriptional mechanisms. The expression of IGF-binding protein-3 hepatic mRNA was increased (P less than 0.05) with bGH treatment compared to that after saline treatment, but was unaffected by oPL treatment, indicating regulation by GH at the transcriptional level. The binding of [125I]bGH to hepatic membrane preparations demonstrated no difference in specific binding compared to that in saline controls. However, [125I]oPL specific binding was greater in oPL-treated animals (P less than 0.05). Animals treated with bGH had reduced (P less than 0.05) hepatic GH receptor mRNA compared to saline controls, but oPL treatment had no effect. Thus, oPL is a potent anabolic and lipolytic agent in the dwarf rat, exerting greater somatogenic effects on some parameters than bGH. Our data suggest differences in receptor binding and effects on GH receptor and IGF-binding protein-3 expression with these two treatments, raising the possibility of actions through different pathways or differential effects at the GH receptor level.

Functional maturation of arginine vasotocin secretory responses to osmotic stimulation in the chick embryo and the newborn chicken

The time-course of appearance of plasma vasotocin and the ontogeny of the vasotocin response to osmotic stimulation during embryonic development was examined in the chicken. In the first experiment, blood was obtained by heart puncture of chicken embryos on embryonic days (E) 15-20, and by decapitation of chickens on the day of hatching (D1 = E21). Plasma was separated for measurement of osmolality and vasotocin. Basal plasma osmolality remained constant until E20 (285-291 mosmol/kg) and was significantly increased at D1 (304 +/- 2 mosmol/kg). Plasma vasotocin was first detectable at E16 (5.5 +/- 0.8 (S.E.M.) pmol/l) and increased thereafter with a peak at E18 (21.8 +/- 2.3 pmol/l). The concentration decreased again at D1 (9.0 +/- 1.7 pmol/l). Osmotic stimulation with hypertonic NaCl 60 min before the animals were killed in the second experiment increased plasma osmolality, at all time points, by 9 +/- 0.2 mosmol/kg in all animals, but increased vasotocin in an age-dependent manner. The vasotocin response was greatest in D1 chickens, and the increase in vasotocin concentration relative to the control group value was 61 pmol/l, whereas the corresponding value in young (E15-E18) and older (E19-E20) embryos was only approximately 9 and 18 pmol/l respectively. In a third experiment the time-course of vasotocin secretion after osmotic stimuli in catheterized chickens (E18 and D1) was established. The basal plasma osmolality was significantly increased after 15 min in both groups. Vasotocin levels were significantly raised after 15 min in E18 and after 30 min in D1 chickens and further increased thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypoxia-ischemia induces transforming growth factor beta 1 mRNA in the infant rat brain

Transforming growth factor beta 1 (TGF beta 1) mRNA expression was examined after hypoxia-ischemia in rat brains using in situ hybridization. Twenty-one-day-old Wistar rats had unilateral ligation of the right carotid artery followed by either 15 or 90 min inhalational hypoxia. Fifteen min of hypoxia resulted in moderate damage with selective neuronal loss in cortical layer 3 and in the hippocampus of the ligated hemisphere. Seventy-two hours after hypoxia TGF beta 1 expression was markedly increased above control levels in those sites. Levels were normal after 120 h. Ninety min of hypoxia led to an infarction of the lateral cerebral cortex and hippocampus of the ligated hemisphere. One hour after hypoxia TGF beta 1 mRNA was expressed in the hippocampus of the damaged side. Seventy-two and 120 h after hypoxia, expressing cells were found throughout the cerebral cortex, piriform cortex, striatum, thalamus and hippocampus of the infarcted side. These data show that TGF beta 1 mRNA expression is induced after a hypoxic-ischemic insult in the brain. TGF beta 1 may be involved in post-asphyxial repair mechanisms.

A role for IGF-1 in the rescue of CNS neurons following hypoxic-ischemic injury

Three days after unilateral hypoxic-ischemic injury in infant rats insulin-like growth factor 1 (IGF-1) production by astrocytes was enhanced in the injured region. This was associated with increased expression of mRNA for IGF binding protein-3 but not for binding protein-1. In adult rats a single lateral cerebroventricular injection of IGF-1 two hours following a similar injury markedly reduced neuronal loss. It is suggested that endogenous IGF-1 is neurotrophic and that centrally administered IGF-1 may have therapeutic potential for brain injury.