Transport and utilization of α-ketoglutarate by the rat kidney in vivo

In order to establish the characteristics of net renal transport and utilization of -ketoglutarate (-KG) in the rat, we have precisely quantified the renal blood flow, the urinary flow and the rates of -KG delivery, filtration, reabsorption or secretion, excretion, uptake or production by an in vivo rat kidney preparation. In normal rats, -KG uptake was higher than -KG reabsorption at both endogenous and elevated plasma -KG concentrations; thus, a net peritubular transport, which was the main supplier of -KG to the renal cells, took place. Saturation of reabsorption and peritubular transport of -KG occurred at blood -KG concentrations about 30 and 150 times above normal, respectively. Acute metabolic acidosis was found to have no effect on renal handling of -KG. At endogenous plasma -KG concentrations, alkalosis converted net renal uptake into net renal production of -KG resulting in addition of -KG by the renal cells both to blood and to the luminal fluid. Elevation of blood -KG concentration restored the renal uptake of -KG. This uptake, which was entirely accounted for by the peritubular transport of -KG, reached a maximum which was lower than that observed in normal and acidotic rats.     

Endogenous α-melanotropin and central dopamine systems in physical and psychological stress

Summary The response of central dopamine (DA) systems to physical stress (10 s footshock, 0.5 mA, to naive rats) or psychological stress (10 s stay in experimental chamber 1 day after footshock) was studied in male rats in view of possible interactions between these neuron groups and endogenous -MSH. Three hours before stress, part of the animals were injected i.v. or intraventricularly with antiserum against -MSH or with inactivated normal rabbit serum (NRS).Characteristic response patterns were observed in different DA neuron groups by histochemical microfluorimetry: In substantia nigra, increased fluorescence intensity of DA neurons indicating increased neuronal activity, was seen on the first day (1) 5 min after physical stress or (2) 30 min after a first transfer to the experimental chamber without footshock, and on the second day (3) immediately after the psychological stress in rats given a footshock on the previous day, or (4) 5 min after the second stay in the experimental chamber in animals previously exposed to the chamber without shock. Hence, the reaction appears to occur faster the second day. No significant intensity changes were detected in the ventromedial tegmental DA neurons (A10). The arcuate DA neurons which i.a. control -MSH secretion, responded to physical stress or control manipulations in a complex way, while no significant reaction was seen after psychological stress. Differences between physical and psychological stress were also seen in serum levels of -MSH (determined by RIA).Intravenous antiserum against -MSH enhanced the response of nigral DA neurons to physical stress and led to elevated intensity levels 5 min after psychological stress when values were again decreasing in uninjected rats. Moreover, a marked rise in intensity was elicited after psychological stress in the A10 DA neurons where no change was detected in the absence of antiserum. Anti--MSH also affected the arcuate DA neurons in psychological stress. Intraventricular antiserum did not display any specific effects.These data point to a modulatory influence of circulating -MSH on the functional state of central DA systems. They further reveal different temporal response patterns of nigral and also arcuate DA neurons in relation to the two stress situations and to other types of manipulations considered to be less stressful.The investigation was supported by grants from the Swiss National Science Foundation (3.231-0.77 and 3.547-0.79), the Hartmann-Müller Stiftung and the Jubiläumsspende of the University of Zürich     

alpha1-acid glycoprotein possesses in vitro pro- and antiinflammatory activities

We studied the effects of ₁-acid glycoprotein on tumor necrosis factor- (TNF-) and interleukin-10 (IL-10) production and lymphocyte response to phytohemagglutinin in cultured peripheral blood mononuclear leukocytes from 6 healthy donors. We observed 2 opposite responses to ₁-acid glycoprotein: first, stimulation of TNF- and IL-10 production and inhibition of lymphocyte proliferation, and second, suppression of cytokine production and stimulation of lymphocyte proliferation. In cell cultures isolated from 4 of 6 donors, the TNF-/IL-10 ratio remained unchanged after addition of native ₁-acid glycoprotein, but some fractions isolated by chromatography on concanavalin A-Sepharose changed this parameter. These changes were most pronounced after treatment with fraction C enriched with molecules with incomplete (biantennary) carbohydrate chains. The mechanisms of ₁-acid glycoprotein-induced effects on peripheral blood mononuclear leukocytes are discussed.     

Synchronous appearance of fibronectin,integrin α5β1, vinculin and actin in epithelial cells and fibroblasts during rat tracheal wound healing

The distribution of integrin 51 (51) and associated components during wound healing was investigated in the rat trachea following mechanical injury. Under anesthesia, the ventral surface of the trachea was scratched, and tissue specimens were obtained from 6 h to 3 weeks after injury and studied using light and electron microscopy and immunohistochemistry. 51, vinculin and actin in regenerating epithelial cells and extracellular fibronectin appear virtually simultaneously after injury (from 12 h to 7 days) as do 51, vinculin and -smooth muscle actin in fibroblasts and cellular fibronectin in granulation tissue (from 3 to 10 days). Immunoelectron microscopy 2 days after injury showed that 51 and vinculin were localized on the basal and lateral surfaces of regenerating epithelial cells and fibroblast surfaces, and fibronectin was localized just under the regenerating epithelial cells, around collagen fibrils and sporadically around fibroblasts. Bromodeoxyuridine labeling showed that the appearance of these components was associated with the period of cell proliferation. The appearances of fibronectin, 51, vinculin and actin in regenerating epithelial cells and fibroblasts during tracheal wound healing are well coordinated. During the initial cell migration phase, plasma fibronectin may stimulate cell migration before cellular fibronectin is produced in situ, and regenerating epithelial cells appear to begin to migrate into the wound before cell proliferation starts.     

Increase in TCRγδ T lymphocytes in synovia from rheumatoid arthritis patients with active synovitis

To determine the relative presence of TCR+ and TCR+ T cells in synovial tissue from patients with various types of inflammatory synovitis and in tissues from patients with a number of chronic T cell-mediated conditions, we stained frozen tissue sections with monoclonal antibodies in indirect immunofluorescence assays. In tissues obtained from patients with chronic T cell-mediated granulomatous conditions (Wegener's granulomatosis, lymphomatoid granulomatosis, granuloma annulare, Langerhan's cells granulomatosis, pigmented villonodular synovitis, Takayasu's arteritis, and talc granulomatosis), the T cells present were predominantly TCR+, without an increased presence of TCR+ cells. In contrast, 6 of 14 (43%) synovia from patients with rheumatoid arthritis (RA) showed increased TCR+ T cells (3–10 cells/hpf). The RA synovia with increased TCR+ cells present had an increased tissue inflammation score compared to RA synovia with few TCR+ cells [18.6±5.8 versus 11.6±4.2 (mean±SE),P<0.05]. In contrast, synovia from patients with osteoarthritis, systemic lupus erythematosus, and trauma did not show an increased presence of TCR+ T cells. Thus, in cellular inflammatory infiltrates the presence of increased TCR cells is not a component of noninfectious granulomatous inflammation but is found in approximately 40% of RA synovia with high levels of inflammation.     

An improved method for the quantitation of cellular migration: Role of αvβ3 integrin in endothelial and smooth muscle cell migration

The present study was undertaken to develop a simple and improvedmethod for the accurate quantitation of cellular migration and to examinethe role of v3 integrins in different cellular migration. Usingour newly developed micro-volume chemotaxis assay, we developed an improvedquantitative method to measure in vitro chemotaxis of smooth muscle orendothelial cells toward different extracellular matrix proteins. Theconvenience in setup and counting of migrated cells using this methodallows for large capacity screening and for various research applicationswith other cells as well. The signal. to noise ratios were in the range of10/1, along with about 10–20% intra- or inter-assayvariabilities. Using this method, we have determined that eithervitronectin at 0.4 µg/well or osteopontin at 0.4 µg/well areselective v3 chemoattractants for endothelial or smooth musclecells (0.5 × 105 cells/well). Additionally, a selective v3small molecule peptiddomimetic, monoclonal antibody LM609, or an anti-3 (v3/II3) anti-body, c7E3 demonstratedmaximal inhibition of cellular migration toward vitronectin or osteopontin.These data suggest the potential utility of this method in assessing therole of various mechanisms in cellular migration and also suggests the potential implication of an v3 antagonist in blocking pathologicalprocesses involving endothelial or smooth muscle cell adhesion/migration.     

Comparison of the eIF-2α Homologous Proteins of Seven Ranaviruses (Iridoviridae)

The -subunit of the eukaryotic initiation factor 2 (eIF-2) is a key component of the translation machinery of the cell. In response to cellular stress such as viral infections, eIF-2 is phosphorylated by double-stranded RNA-dependent protein kinase (PKR) leading to the inhibition of cellular protein synthesis. The importance of eIF-2 as a regulatory mechanism for protein synthesis is illustrated by the wide variety of strategies employed by viruses to down-regulate PKR. Thus, Vaccinia virus encodes K3L protein, which resembles eIF-2 and acts as a pseudo-substrate inhibitor of PKR. Nucleotide sequencing of the genome of epizootic haematopoietic necrosis virus (EHNV), a member of the genus ranavirus of Iridoviridae, has revealed an eIF-2 equivalent gene. We have cloned and sequenced eIF-2 genes of several iridoviruses of fishes and frogs. The eIF-2 open reading frames and deduced proteins of the iridoviruses investigated exhibit a high degree of homology of both nucleotide and amino acid sequences. At the N-terminus, the iridoviral eIF-2 shows significant homology to the N-termini of cellular initiation factor 2- of various species, to full-length poxviral eIF-2 proteins, and to the S1 domain of ribosomal proteins. Comparison of amino acid sequences of corresponding iridoviral proteins with eIF-2 homologous proteins of poxviruses and eukaryotes has revealed a high conservation of motifs. A phylogenetic analysis of eukaryotic eIF-2 and poxvirus and iridovirus eIF-2 sequences has demonstrated the relationship of these iridoviruses. In order to investigate the role of the eIF-2 equivalent, respective genes have been expressed in prokaryotic and eukaryotic (insect, fish and chicken cell) systems. The iridoviral eIF-2 protein has a molecular weight of 31 kDa and is cytoplasmic. The cellular and viral protein synthesis of iridoviruses is probably regulated by a mechanism similar to that of Vaccinia virus. Frog-virus 3, the type species of the genus ranavirus of Iridoviridae, has a unique translational efficiency and, moreover, down-regulates the cellular protein synthesis of infected cells.     

Pregnancy specific β1-glycoprotein and α2-pregnancy associated globulin in tumours of the female genital tract

Summary Tumour tissues obtained from 35 patients with malignancies of the female genital tract were investigated for production of pregnancy specific ₁-glycoprotein (PS₁G) and ₂-pregnancy associated globulin (₂-PAG). PS₁G was found in all five trophoblastic tumours studied and in 10 of the 30 non-trophoblastic cancers. ₂-PAG was not detected in any of the neoplastic tissues.In 18 of the patients with non-trophoblastic tumours PS₁G and ₂-PAG serum concentrations were also determined. No correlation between serum and tissue findings were noted. Thus, PS₁G does not seem to be a valuable serum indicator for monitoring the extent or variation of tumour mass in non-trophoblastic gynecological malignancies. Likewise, ₂-PAG is unlikely to serve as a clinical useful tumour marker in various gynecological cancers.     

The role ofγδ T cells in the normal and disordered immune system

Summary A small population of T cells does not express the conventional T cell receptor characterized by the and polypeptide chains (TCR) but instead, two polypeptides termed and (TCR). This alternative receptor is able to recognize antigen. It appears early in T cell ontogeny, but its role in the thymus prior to the availability of TCR remains unclear. In selected sites such as skin or gut TCR predominates in mice which might suggest a role of T cells in the first line of defense against infection, T cells secrete lymphokines and display cytotoxic activity. However, their activation requirements may differ from what is known for T cells since MHC-nonrestricted and also CD4 and CD8 negative T cells have been described. Preferential activation by mycobacterial antigens possibly indicates a special repertoire of the T cells. In various diseases slightly increased numbers of T cells were found, but these preliminary studies have not yet provided evidence for a major pathogenetic role of T cells.List of abbreviations C constant region (immunoglobulin or TCR gene segment) - CD4 cluster of differentiation 4 (mainly on helper cells) - CD8 cluster of differentiation 8 (mainly on cytotoxic cells) - D diversity region (immunoglobulin or TCR gene segment) - DNA desoxyribonucleic acid - IL2 interleukin 2 - J joining region (immunoglobulin or TCR gene segment) - kD kiloDalton - MHC major histocompatibility complex - NK natural killer (cells) - RA rheumatoid arthritis - TCR T cell receptor - V variable region (immunoglobulin or TCR gene segment)     

α 2-Adrenoceptors activate dihydropyridine-sensitive calcium channels via Gi-proteins and protein kinase C in rat portal vein myocytes

The presence of functional ₂-adrenoceptors was investigated in isolated smooth muscle cells from rat portal vein using the nystatin-perforated patch-clamp technique. The free cytoplasmic calcium concentration ([Ca²⁺]_i) was estimated using emission from the dye Fura-2. Activation of ₂-adrenoceptors by clonidine (an ₂-adrenoceptor agonist) or noradrenaline (a non-selective -adrenoceptor agonist), both in the presence of 0.1 M prazosin to block ₁-adrenoceptors, caused a slow and sustained increase in [Ca²⁺]_i which was inhibited by 0.1 M rauwolscine (an ₂-adrenoceptor antagonist). A similar Ca²⁺ response was obtained with oxymetazoline (a selective _2A-adrenoceptor agonist) suggesting that the increase in [Ca²⁺]_i resulted from activation of the _2A-adrenoceptor subtype. The increase in [Ca²⁺]_i did not occur in calcium-free solution or in the presence of oxodipine (a voltage-dependent calcium channel blocker), indicating that it depended on a calcium influx. The _2A-adrenoceptor-activated calcium influx was unchanged after complete release of the stored calcium induced by applications of ryanodine and caffeine. In addition, no accumulation of inositol trisphosphate was detected in the presence of 0.1 M prazosin. Taken together, these results indicate that _2A-adrenoceptor activation does not stimulate phosphoinositide turnover and subsequent calcium release from intracellular stores. Wholecell patch-clamp experiments showed that _2A-adrenoceptor activation promoted calcium influx through voltage-dependent L-type channels. Concomitant with calcium influx, _2A-adrenoceptor activation induced a 10- to 15-mV depolarization. Similar effects on both calcium channel current and [Ca²⁺]_i were obtained with mastoparan, an activator of Gi-proteins. Activation of calcium influx by both _2A-adrenoceptors and mastoparan was reduced by treatment with pertussis toxin and GF 109203X (a protein kinase C inhibitor). These data suggest that activation of protein kinase C through a transduction pathway involving Gi-proteins phosphorylates voltage-activated L-type calcium channels and thus, increases their opening probability.     

Mechanism of modulation of single sodium channels from skeletal muscle by the β 1-subunit from rat brain

We studied the molecular mechanism of the rat skeletal muscle -subunit (_I) gating kinetics modulation by the brain ₁-subunit by heterologous expression of single sodium channels from _I and ₁ in Xenopus laevis oocytes. Coexpression of ₁ reduced mean open time at –10 mV to 21% when compared to channels expressed by _I alone. Channels formed by _I exerted multiple openings per depolarization, which occurred in bursts, in contrast to the channels formed by the _I/₁ complex that opened in average only once per depolarizing voltage pulse. Macroscopic current decay (mcd), as evidenced by reconstructed open probability vs. time , was greatly accelerated by ₁, closely resembling mcd of sodium currents from native skeletal muscle. Generally was larger for channels expressed from the pure _I subunit.From our single channel data we conclude that ₁ accelerates the inactivation process of the sodium channel complex.     

Synoviocytes in chronic synovitis in situ and cytokine stimulated synovial cells in vitro neo-express α1, α3 and α5 chains of β1 integrins

The expression of the 1 integrins was examined immunohistochemically in synoviocytes from normal synovial membrane and from chronic synovitis of different aetiology and intensity. Normal synoviocytes were 61-positive but lacked 1 through 5. In mild inflammation type A synoviocytes neo-expressed 1, 3, and 5 chains. In severe inflammation both type A and B synoviocytes expressed 3, 4, 5, and 6 chains. The effects of inflammatory cytokines, as single agents or in combination, on the 1 integrin expression in cultured normal synoviocytes was determined by immunocytochemistry and flow cytometry. The 1 chain, while absent in unstimulated synoviocytes, was induced by interleukin-1 (IL-1), tumour necrosis factor- (TNF-), and interferon- (INF-). This effect was enhanced by combining IL-1 and TNF-. Expression of the 3 chain was up-regulated by IL-1 and, more intensely, by IFN-. Transforming growth factor (TGF-) inhibited the up-regulating effect of IL-1 and antagonized the effect of IFN- on 3 chain expression. Expression of the 5 chain was up-regulated significantly by co-stimulation through IL-1 together with TGF- or TNF-. Thus, the 1 integrin profile of cytokine activated synoviocytes in vitro resembled that of synoviocytes in synovitis in situ. These data suggest that IL-1, TNF-, IFN-, and TGF- are likely to be among the effectors regulating 1 integrin expression in synoviocytes in vivo.     

Defective NF-κB Signaling in Dedifferentiated Hepatoma Cells

Dedifferentiated rat hepatoma cells contain defects that result in the loss of hepatic gene expression, including the liver-enriched HNF4/HNF1 pathway. We examined induction of NF-B, a key mediator of the inflammatory response, in hepatoma and dedifferentiated hepatoma cells. We show that exposure of dedifferentiated hepatoma cells, but not rat and human hepatoma cell lines, to proinflammatory cytokines or lipopolysaccharide resulted in rapid and sustained NF-B induction. IB- levels, but not NF-B subunit p65 or IB- levels, were elevated compared with those for parental hepatoma cells. Interestingly, LPS-mediated activation of NF-B was found to be independent of degradation of IB- or IB-. Thus, these results suggest that loci responsible for maintaining hepatic gene expression also influence cellular responses to inflammatory agents.     

The effect of an α-ketoglutarate-pyridoxine complex on human maximal aerobic and anaerobic performance

Summary The administration of 30 mg/kg of body weight of an -ketoglutarate-pyridoxine complex (-KG compl; stoichiometric ratio -KG: pyridoxine 46.35 to 53.65) to trained non-athletic individuals increases max by 6% (p<0.005). The kinetics of the on- and off-responses at the onset and offset of a rectangular work load is not affected by the drug. Peak blood lactate concentration [La_b] following two supramaximal running work loads lasting 60 s and 132±4 s, respectively is significantly (p<0.05 and p<0.005) less after the -KG compl treatment (La_b=–1.1 and –2.7 mmol·1^–1, respectively) than in a control group. The half time (t1/2) of La disappearance from blood during recovery is unaffected by the -KG compl treatment (19.7 min vs 19.5 min). The increase in max and the corresponding decrease of [La_b] are not found after separate administration of either of the components of the complex. It is concluded that -KG complex stimulates aerobic metabolism, probably prompting mitochondrial reabsorption of -KG, which activates the malate-oxalacetate shuttle and the generation of high energy phosphates at the substrate level.     

Transient Exposure of Human Bronchial Epithelial Cells to Cytokines Leads to Persistent Increased Expression of ICAM-1

Effects of several cytokines on kinetics of Intercellular Adhesion Molecule-1 (ICAM-1) and Vascular Cell Adhesion Molecule-1 (VCAM-1) expression were studied on a bronchial epithelial cell line (BEAS-2B). VCAM-1 was neither constitutively expressed on BEAS-2B cells nor induced by Interferon-gamma (IFN-), Tumor Necrosis Factor-alpha (TNF-), Interleukin-1beta (IL-1), IFN-, IL-4, IL-6, IL-8 or Granulocyte Macrophage-Colony Stimulating Factor (GM-CSF). ICAM-1 was constitutively expressed on BEAS-2B cells. IFN- and TNF- upregulated ICAM-1 expression on these cells. The functional importance of IFN- plus TNF- upregulation of ICAM-1 expression on BEAS-2B cells was demonstrated by neutrophil-BEAS-2B cell adhesion assays. Cytokines are rapidly released and cleared in animals. Therefore, transient cytokine(s) exposure might occur on the bronchial mucosa. Brief incubation of BEAS-2B cells with IFN- plus TNF- led initial upregulation of ICAM-1 expression followed by a protracted downregulation. Our findings stress the importance of studying the mechanism(s) controlling the persistent increased expression of ICAM-1 after brief cytokine(s) exposure.     

Neutrophil elastase α1-proteinase inhibitor complexes in pleural effusions

Summary Polymorphonuclear (PMN) granulocyte derived neutrophil elastase (NE) is rapidly antagonized by ₁-proteinase inhibitor (₁ PI) in vivo. To determine the clinical value of elastase ₁-proteinase inhibitor complexes (E-₁ PI) in pleural effusions, fluid samples of 99 patients were examined. Fifty-six had malignant effusions, 30 had nonmalignant exudates (pleural protein above 3 g/dl) mainly of inflammatory origin, and 13 patients had low protein transudates (below 3 g/dl) due to congestive heart failure. Nonmalignant exudates showed significantly higher (P<0.001) concentrations of E-₁ PI compared with malignant effusions or low protein transudates (P<0.001). Malignant exudates secondary to lung cancer were characterized by higher (P<0.001) median pleural E-₁ PI concentrations compared to malignant exudates due to primarily extrathoracic malignancies. Total pleural leukocyte counts and pleural neutrophil counts were performed in 68 effusions. By this means no clear-cut differentiation between malignant and nonmalignant exudates seems possible except for marked empyema. In conclusion, E-₁ PI complexes in pleural fluid may better reflect the stage of inflammation of pleural effusions rather than mere pleural leukocyte counts. Low levels of E-₁ PI complexes (<75 ng/ml) in pleural exudates with protein values above 3 g/dl are characteristic of malignant exudates. Determination of E-₁ PI in pleural exudates may serve as a sensitive marker of inflammation and useful adjunct to pleural cytology in aspects of differential diagnosis of pleural effusions.Abbreviations E-₁ PI elastase ₁ proteinase inhibitor complexes - NE neutrophil elastase - PMN polymorphonuclear     

Ion-induced release of LHRH,TRH and α-MSH from hypothalamic synaptosomes and its inhibition by vinblastine

Homogenates of rat hypothalamic tissue were fractionated by means of discontinuous sucrose density gradient centrifugation. Immunoreactive luteinizing hormone releasing hormone (LHRH), thyrotropin releasing hormone (TRH), and -melanocyte stimulating hormone (-MSH) were found to be concentrated in the synaptosome-enriched fraction. This fraction was suspended in 0.32 M sucrose and the release of the three peptides was investigated. After incubation, the synaptosomes were re-isolated by ultrafiltration, and the concentration of each peptide in the ultrafiltrate was determined by radioimmunoassay. When the synaptosomal fraction was incubated at 30° C in 0.32 M sucrose containing either 60 mM K⁺-2 mM Ca²⁺ or 140 mM Na⁺ alone a release of LHRH, TRH, and -MSH occurred. Of the total content 30–50% of LHRH but only about 10% of TRH and -MSH was releasable. When the synaptosome preparation was preincubated for 30 min at 30°C with 10^–4 M vinblastine. K⁺- as well as Na⁺-induced release of LHRH, THR, and -MSH was inhibited, and the stimulatory effect of each cation was almost totally blocked by preincubation with 5×10^–4 and 10^–3 M vinblastine. The inhibitory action of vinblastine (5×10^–4 M) did not affect the oxidation of glucose to CO₂ by the synaptosomes. The results of the present investigation demonstrate that synaptosome-enriched fractions of hypothalamic origin are more stable with respect to LHRH, TRH, and -MSH release during incubation in isotonic sucrose than they are in ionic solutions, and that the peptides are released by a vinblastine-sensitive mechanism.Supported by grants from the National Institute of Arthritis, Metabolism, and Digestive Diseases (AMO 1237), the National Institute of Child Health and Human Development (HDO8672), and the National Institutes of Health contract (5-P17-HL1487-06)Supported by Grant No. 512-6951 from the Danish Medical Research Council     

Structure of the liver as a possible factor in the regulation of α-fetoprotein synthesis

During regeneration of the mouse liver after poisoning with CCl₄ and paracetamol, hepatocytes containing -fetoprotein (FP) lose their membrane antigen that served as marker for biliary capilaries. Both during regeneration and in early postnatal development, cessation of FP synthesis by the cells coincides with the appearance of an antigen marking the biliary capillaries on their surface. It is suggested that cessation of FP synthesis is the result of establishment of a system of contacts characteristic of the definitive hepatic column.Laboratory of Immunochemistry and Diagnosis of Tumors, Oncologic Scientific Center, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR L. M. Shabad.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 87, No. 6, pp. 576–579, June, 1979.     

Epidermal growth factor,transforming growth factor-α, and epidermal growth factor receptor content in normal and carcinomatous gastric and colonic tissue

Summary Epidermal growth factor (EGF) and transforming growth factor- (TGF-) are polypeptides which bind to the EGF receptor (EGFr) and may play a role in cell growth and carcinogenesis. Our study investigated the content of EGF, TGF-, and EGFr in tumors of the stomach and the colon in comparison with the sourrounding mucosa. EGF was detected in half of the stomach specimens with concentrations between 1 and 9 ng/g weight irrespective of histology. In the colon no EGF was found in the tumor or normal mucosa. In the stomach normal mucosa contained higher TGF- concentrations (mean 22.4 ng/g) than the tumors (mean 11.8 ng/g), but the difference was not statistically significant because of a wide variation in mucosal values. By contrast, the colon mucosa displayed significantly higher TGF- concentrations than the tumor tissues (33 ng/g versus 12 ng/g; P < 0.01). EGFr content in the gastric mucosa was lower compared to gastric carcinoma (48 fmol/g versus 75 fmol/g) yet not significantly different. In contrast, colorectal tumor specimens disclosed significantly higher concentrations than the mucosal tissues (mean of 155 fmol/g versus 80 fmol/g; P < 0.01). In conclusion, TGF- should not be considered a tumorigenic but a physiological growth factor in the stomach and colon. An elevated EGFr content in colorectal tumors in comparison with the normal mucosa could lead to a growth advantage by an autostimulating mechanism.Abbreviations EGF epidermal growth factor - EGFr epidermal growth factor receptor - TGF- transforming growth factor - ROC receiver operating characteristic Dedicated to Prof. Dr. G. Paumgartner on the occasion of his 60th birthday     

Regulation of oxygen consumption in perfused rat liver: decrease by α-sympathetic nerve stimulation and increase by the α-agonist phenylephrine

In livers perfused with Krebs-Henseleit bicarbonate buffer containing bovine red cells, 5 mM glucose and 2 mM lactate, electrical stimulation round the hepatic artery and the portal vein caused via -receptors a decrease in oxygen consumption and portal flow, an increase in glucose output and a switch from lactate uptake to output.In livers perfused with erythrocyte- and substrate-free buffer both in a volume- or pressure-constant system stimulation of the liver nerves resulted in similar changes. Infusion of the -agonist phenylephrine mimicked the metabolic and hemodynamic nerve effects, but led to an increase in oxygen uptake. The converse effects of -sympathetic nerve stimulation and -agonist infusion on oxygen consumption indicate either a different mode of action or a complex mechanism with opposing metabolic and hemodynamic components.