Interferon-α activates cytotoxic function but inhibits interleukin-2-mediated proliferation and tumor necrosis factor-α secretion by immature human natural killer cells

Natural killer (NK) cells play an important role in host defense mechanisms against infection and neoplasia. Interferon- (IFN-) has been shown to activate NK cells and to augment their cytotoxic activity, albeit its role in the maturation pathway of NK cells has not been elucidated. The present study examined whether IFN- activates the immature NK subset (Free cells) to become cytotoxic and also ascertained whether IFN- uses the same pathway of activation as that mediated by interleukin-2 (IL-2). Incubation of sorted Free cells overnight with IFN- resulted in augmentation of their cytotoxic function against NK sensitive target cells. The enhanced cytotoxic activity was not accompanied by a new recruitment of NK-target binder cells but by an increase in the frequency of killer cells in the conjugate fraction. Activation of the Free subset by IFN- resulted in upregulation of CD69, CD11b, and CD2 surface expression and stimulated secretion of IFN-. Unlike IL-2, IFN- did not stimulate the Free cells to proliferate or secrete TNF- and activation of cytotoxicity and modulation of surface antigens by IFN- were independent of TNF-. The failure of IFN- to stimulate secretion and proliferation by Free cells appeared to be mediated by negative signals. This was corroborated in experiments demonstrating that when Free cells were cultured with both IFN- and IL-2, a significant inhibition was observed for both the IL-2 dependent secretion of TNF- and proliferation. These results demonstrate that IFN- serves as both an activator and a regulator of NK function. Further, activation of the immature Free NK cells by IL-2 and IFN- proceeds by TNF--dependent and independent pathways, respectively. The findings also support our contention that the mechanism of activation of the cytotoxic machinery of NK cells is not linked to the mechanism of activation of cytokine secretion and/or proliferation.Abbreviations used IFN interferon - IL interleukin - PBL peripheral blood leukocytes - PE phycoerythrin - PE-GAM PE-conjugated Fab2 goat anti-mouse IgG - NK natural killer - NRS normal rabbit serum - TNF tumor necrosis factor - FCS fetal calf serum - FITC fluorescein isothiocyanate - PBS phosphate-buffered saline - MACS magnetic cell sorting - ELISA enzyme-linked immunosorbent assay - BSA bovine serum albumin - PKC protein kinase C - mAb monoclonal antibody - PBMC peripheral blood mononuclear cells - BCLL B-chronic lymphocytic leukemia - E effector - T target     

Neuronal nicotinic acetylcholine receptors expressed in Xenopus oocytes: role of the α subunit in agonist sensitivity and desensitization

Neuronal nicotinic acetylcholine receptors (nAChRs) were expressed in Xenopus laevis oocytes after nuclear injection of complementary deoxyribonucleic acid (cDNA) expression vectors. The two receptor subtypes 4/n1 and 3/n1 were readily distinguishable from one another by ACh sensitivity and desensitization. 3/n1 receptors showed lower ACh sensitivity and stronger desensitization than 4/n1 receptors. Furthermore, although the current/voltage relationship was very similar in both receptor subtypes, the voltage dependence of desensitization was found to be strikingly different. As the n1 subunit was unchanged, the subunits must be responsible for these functional differences. Symmetric hybrid cDNAs, 43 and 34, were constructed and functional receptors were obtained by co-injection with n1. These hybrid receptors displayed an ACh sensitivity that was mainly defined by the extracellular sequence of the subunit. In contrast, no part of the subunit was found fully to determine desensitization.     

Role of the adenylate cyclase system in inductive acetylcholinesterase synthesis in the brain

The increase in acetylcholinesterase (ACE) activity in the rat brain after intraventricular injection of adrenalin and the dibutyryl analog of cyclic AMP was shown to be the result of inductive synthesis of the enzyme. Induction of ACE is manifested to a greater degree in the white matter of the subcortex than in the cortex. Blocking -adrenergic receptors inhibits the stimulating action of adrenalin on ACE activity but does not alter the effect of cyclic AMP. Blocking of the -adrenergic receptors, on the other hand, potentiates induction of synthesis of the enzyme. The effects of adrenalin and of dibutyryl-cyclic AMP are similar in direction and are mediated through -adrenergic receptors. The increase in ACE activity after blocking of receptors can be explained by the elimination of their inhibitory effect on -adrenergic receptors.Department of Biochemistry, Tbilisi University. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Zakusov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 5, pp. 545–548, May, 1977.     

An α-mating-type-specific mutation causing specific defect in sexual agglutinability in the yeast Saccharomyces cerevisiae

We have identified a recessive -mating-type-specific gene agl causing agglutinability defect without significant effects on other sexual activities. a cells carrying agl showed sexual agglutination with cells but cells carrying agl showed sexual agglutination with neither cells nor a cells. cells carrying agl produced pheromone and responded to a pheromone just like wild cells. cells carrying agl showed a little decreased but significant mating ability when tested on solid media or membrane filter. The agl mutant is different from any -specific ste mutants found so far in many sexual activities. The agl gene is recessive, and unlinked to the mating type locus. Biological significance of the mating type agglutinability is discussed based on the results obtained with the mutant.     

Genetic characterization of an α-specific gene responsible for sexual agglutinability in Saccharomyces cerevisiae: mapping and gene dose effect

Summary A recessive ag1 mutation leads to specific defect in sexual agglutinability specifically in cells of the yeast Saccharomyces cerevisiae. The cryptopleurine resistance gene cry^R 1, closely linked to the mating type locus, was used to select / strains which emerged from / strains by mitotic nonreciprocal recombination, to genetically analyse ag1, since ag1 is expressed only in mating type. The ag1 gene was found to be linked to the centromere tightly, to met3 at 4.4 cM, and to ilv3 at 12 cM on chromosome X. Sexual agglutinability of cells was shown to be dependent on the dose of the AG1 gene, using / isogenic strains carrying AG1/AG1, AG1/ag1 or ag1/ag1. The sst2-1 mutation did not suppress the ag1 mutation. Based on these results, function of the AG1 gene is discussed.Abbreviations cM centimorgan - FDS first division segregation - NPD nonparental ditype - PD parental ditype - SDS second division segregation - TT tetratype     

A mutation affecting sexual agglutinability in MATα locus of Saccharomyces cerevisiae

Summary A temperature-sensitive non-agglutinative mutant of Saccharomyces cerevisiae was isolated and characterized. The mutation, sag2, affected sexual agglutination, conjugation and production of -mating pheromone at a restrictive temperature, but not the response to -mating pheromone. Genetic analyses showed that the mutation was recessive and in the MAT locus. The sag2 mutation complemented with mat2 but not with mat1 These results suggest that sag2 is in the MAT1 gene and that at a restrictive temperature the mutation, sag2, inactivated the MAT1 product, a positive regulator of -mating functions. The sag2 mutation is like mat1-5 in its retention of response to -mating pheromone. However, at 25 °C, sag2 cells were competent to mate, whereas mat1-5 cells were not. Hence, sag2 is regarded as a new allele in the MAT1 gene, which we designate mat1-11.     

Comparative evaluation of integrin α- and β-chain expression in colorectal carcinoma cell lines and in their tumours of origin

The integrin family consists of broadly expressed cell surface adhesion receptors, each member of which is composed of a non-covalently linked / heterodimer. Integrin receptors are involved in the interaction with matrix proteins and may contribute to invasion and metastasis of carcinomas. To examine the biological role integrins play in colorectal carcinoma we compared the expression of integrin - and -subunits in situ and in vitro. Eight newly established cell lines derived from immunohistochemically characterized colorectal carcinomas together with two sublines obtained after nude mouse passage and the commonly used colon carcinoma lines HT-29, SW480, SW620, and COLO 205 were investigated by immunocytochemistry and flow cytometry. The carcinomas in situ expressed 1-, 2-, 3-, 6-, v-and 1-subunits in variable amounts while being devoid of 4, 5 and 3. The individual integrin profile of the tumour in tissue was essentially maintained in vitro. However, a neo-expression of the 5 chain was found, together with an induction or increase in 1, 2, 3, v and 1 levels. No decrease in integrin subunit expression was observed. Standard-serum and serum-free medium revealed no striking differences in - and -chain expression in the cell lines HT-29 and COLO 205. In serum-free medium, SW480 showed a slight increase of 1 and 5 and a decrease of 3 and v while SW620 expressed more 1. We conclude that the great variability of adhesion receptor expression of the integrin family in colorectal carcinomas in situ is essentially maintained in vitro, although culture conditions which are only marginally influenced by serum factors unpredictably lead to some increase in expression or even induction of several integrin subunits.This work is dedicated to Prof. Wilhelm Doerr on the occasion of this 80th birthday     

Integrins and extracellular matrix-proteins in the different components of the Wilms' tumour

The Wilms' tumour (WT) is composed of blastema, epithelium and mesenchyme; the epithelium and possibly also the mesenchyme develop from the blastema, parallel to embryonal development. Since interactions between cell adhesion receptors and extracellular matrix (ECM) proteins play an important role in tissue maturation, we examined the expression of the integrin subunits 1–6, 1 and 4, and of the ECM proteins fibronectin, laminin and collagen I and IV, in 20 frozen WT samples and in 5 fetal and 2 adult kidneys. The integrin and ECM protein distribution in tumour epithelium and mesenchyme showed strong similarities to that in their fetal counterparts, whereas the tumour blastema differed strongly from the fetal blastema. In the WT blastema different components were recognized. Undifferentiated blastema, characterized by expression of 3 and 6 and the virtual absence of ECM proteins. Blastema with epithelial commitment, showing increased expression of 3 and 6 and the appearance of 2 and, as a very early phenomenon, production of laminin. Blastema with mesenchymal commitment, with loss of 3 and 6 and expression of 1, 4 and 5 and presence of ECM proteins. It is speculated that the inability of the (undifferentiated) blastema to produce ECM proteins is related to its relatively high metastatic potential when compared with epithelium and mesenchyme.     

Down-regulation of tumor necrosis factor α activity by acute ethanol treatment in human peripheral blood monocytes

As the most commonly used drug that can modulate both metabolic and immune pathways, ethanol is evaluated in this report as a regulator of tumor necrosis factor (TNF) production in human peripheral blood monocytes (M) in combination with a variety of stimuli. While acute ethanol treatment did not induce TNF in M, it was a potent down-regulator of M TNF production whether induced by the combination of interferon- plus muramyl dipeptide (MDP) (P<0.001), lipopolysaccharide (LPS) alone (P<0.01), or interferon- plus LPS. Down-regulation of M TNF by ethanol was dose dependent and statistically significant in the biologically relevant, 25–150 mM, ethanol concentration range. We also demonstrate that these ethanol concentrations did not affect M viability. TNF down-regulation by ethanol was most effective when ethanol was administered 4 hr prior to MDP stimulation; however, it was also effective—though to a lesser extent—if it was added at the time of MDP stimulation. Furthermore, ethanol also down-regulated TNF production of thein vivo preactivated M of trauma patients, which produce hyperelevated levels of TNF. We have previously shown that the majority of posttrauma elevated M TNF is produced by the M subpopulation expressing high-affinity type I Fc receptors (FcRI). When the FcRI cross-linking-stimulated M subpopulation was treated with acute ethanol, TNF production was suppressed again both inin vivo preactivated M of trauma patients and in M of normal controls. In experiments utilizing cyclooxygenase inhibitor, we also demonstrate that ethanol has a direct, prostaglandin E₂-independent, effect on M TNF production. These results demonstrate that acute ethanol exposure has the potential to down-regulate M production of TNF significantly regardless of the TNF-inducing stimulus. Decreased capacity of M to produce TNF might, therefore, contribute to the immunological and metabolic abnormalities described after ethanol uptake.     

Molecular and cytogenetic organization of the 5S ribosomal DNA array in chicken (Gallus gallus)

The 5S ribosomal (r) RNA genes encode a small (120-bp) highly-conserved component of the large ribosomal subunit. The objective of the present research was to study the molecular and cytogenetic organization of the chicken 5S rDNA. A predominant 2.2-kb gene (5S) consisting of a coding and intergenic spacer (IGS) region was identified in ten research and commercial populations. A variant gene repeat of 0.6kb (5S) was observed in some of the populations. Genetic linkage analysis and cytogenetic localization by fluorescence in-situ hybridization assigned the 5S rDNA to chromosome 9. The 5S rDNA array was determined to be 80.2±7.0kb upon electrophoretic sizing following EcoRV digestion. Sequence analysis of 5S IGS regions revealed considerable conservation between chicken subspecies (98.4% identity) as well as homology with vertebrate Pol III promoter and regulatory sequence motifs. Minor intraindividual sequence variation within 1000bp of IGS was observed in four cloned Red Jungle Fowl (Gallus gallus gallus) 5S repeats (95.5% identity in this region). Sequence comparisons between IGS regions of 5S and 5S genes indicated two short continuous (>20bp) and many short non-continuous homologous regions as well as other conserved features such as promoter and termination motifs.     

Ribonuclease activity of the “myofibrillary” fraction of normal and autolyzed muscle tissue

The separation in a sucrose gradient of the myofibrillary fraction of normal and autolyzed muscle tissue gave 4 components. During post-mortem destruction of the tissue there was observed a slight decrease of the myofibrillary fraction yield and also certain changes in the distribution of protein between different components. Under the selected conditions RNase activity was found in all 4 components. During the course of autolysis enzymatic activity increased in the whole myofibrillary fraction, as well as in the lysosomal-mitochondrial components of myofibrils.Research Laboratory, Ministry of Health of the USSR, Moscow. Translated from Buylleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 5, pp. 533–537, May, 1978.     

α 1- and β-adrenergic interactions on L-type calcium current in cardiac myocytes

We investigated the mechanism by which ₁-adrenergic activation regulates basal and stimulated whole cell L-type Ca current (I_Ca) in rat ventricular myocytes using the physiological neurotransmitter, norepinephrine (NE, 10M). Stimulation of ₁-adrenoceptors, achieved by NE+10M esmolol (a -receptor antagonist), had no significant effect on basal I_Ca. ₁-adrenergic activation had a marked inhibitory effect on I_Ca elevated by activation (NE+1M) prazosin, an ₁-receptor antagonist) or activation of adenylyl cyclase by forskolin (25M); the inhibitory effect was reversible upon washout. However, ₁-adrenergic stimulation had no significant effect on I_Ca previously increased by intracellular application of cAMP (25M). The inhibitory effect seen on I_Ca elevated by NE showed no significant shift of either I–V or inactivation curves. It is unlikely that the inhibitory effect of ₁-adrenergic stimulation on NE or forskolin-elevated I_Ca is mediated through activation of Ca-dependent protein kinase C or changes in intracellular free Ca (pCa=8.5, EGTA 5 mM) or cAMP-dependent phosphodiesterase. We conclude that ₁-adrenergic inhibition of -adrenergic stimulated-I_Ca is probably mediated through an as yet unknown G-protein. This inhibitory effect could serve as a regulatory feedback mechanism in physiological and pathophysiological settings.     

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.     

Erythromycin and cycloheximide sensitivities of protein and RNA Synthesis in sporulating cells of Saccharomyces cerevisiae: Environmentally induced modifications controlled by chromosomal and mitochondrial genes

Summary The purpose of the experiments reported below was to examine the response in sporulation medium of the three diploid cell types MAT MAT, MAT MAT (asporogenic diploids) and MAT MAT (sporogenic diploid) to erythromycin, a specific inhibitor of mitochondrial protein synthesis (MPS) in vegetative cultures, and cycloheximide, a specific inhibitor of cytosol protein synthesis (CPS) in vegetative cultures. When MAT MAT diploids are transferred to sporulation medium a significant fraction of total protein synthesis (CPS + MPS) becomes sensitive to erythromycin in contrast to the behavior of MATa MATa and MAT MAT diploids in which the resistance of CPS to erythromycin is maintained. The decompartmentalization of erythromycin sensitivity is thus cell type specific. Erythromycin stimulates total RNA synthesis of MAT MAT cells in sporulation medium but not of MAT MAT and MAT MAT cells. Cycloheximide inhibits protein synthesis and stimulates RNA synthesis in all three diploid cell types. An erythromycin resistant mutant, shown to be due to a mutation of the mitochondrial genome, exhibited only partial resistance of CPS to erythromycin in sporulation medium in the background of the MAT MAT mating type genotype. Total RNA synthesis in this mutant was not stimulated. The results reported indicate that mitochondrial functions during sporulation are not restricted to those involving respiratory metabolism.     

Transient expression of myosin heavy chain MHCIα in rabbit muscle during fast-to-slow transition

The expression of an -cardiac-like myosin heavy chain, MHCI, was investigated at both the mRNA and protein levels in rabbit tibialis anterior muscle undergoing fast-to-slow transition by continuous chronic low-frequency stimulation (CLFS). According to sequence analyses of the PCR product, the MHCI isoform was found to be identical to the -cardiac MHC expressed in rabbit atrium. In muscles at different degrees of transformation, the upregulation of MHCI mRNA preceded that of the MHCI mRNA. At more advanced stages of the transformation, MHCI mRNA decayed while MHCI mRNA persisted at high levels. The expression of MHCI, therefore, was transitory. Studies at the protein level were based on immunoblotting using a monoclonal antibody (F88 12F8,1), characterized to be specific to MHCI in rabbit muscle. These studies revealed a similar relationship between initial increase and successive decline of the MHCI protein as seen at themRNA level. Immunohistochemistry of 30-day stimulated muscle revealed that up to 65% of the fibres expressed the MHCI isoform in combination with other adult MHC isoforms. The most frequent patterns of coexistence were MHCIIa+MHCI + MHCI (28%), MHCI+MHCI (18%), and MHCIIa + MHCI (11%). According to these combinations, the upregulation of MHCI may be assigned as an intermediate step in the transformation of existing fibres during theMHCIIa MHCI transition. A small fraction of fibres contained, in addition to the MHCI + MHCI and MHCIIa + MHCI combinations, developmental myosin, suggesting that MHCI was also expressed in regenerating fibres originating from satellite cell-derived myotubes.     

Phenotypic and epistatic grouping of hypo- and hyper-rec mus mutants in Aspergillus

The mutants musK to musS of Aspergillus nidulans are sensitive to methyl-methanesulfonate (MMS) and several of them are meiotic-defective and alter mitotic recombination frequencies. All were found to be cross-sensitive to 4-nitro-quinoline-N-oxide (4-NQO) but unexpectedly none of them was hypersensitive to -rays and few to UV light. Double mus;uvs mutants were constructed to test for interactions with uvs mutations of the four epistatic groups of Aspergillus, UvsF, UvsC, UvsI, and UvsB. All meiotic-defective mus mutations caused some lethal interactions, usually with uvsF. None of them showed epistasis with UvsF or UvsB group mutants and one, musO, may represent a new group. Three mus mutations that affect recombination were assigned to the UvsC group, namely musN and K, and also musL which is recombination-defective and closely resembles uvsC. While uvsC mutants are mutators and lack UV-mutagenesis, most mus mutants had no effects on mutation. Only musR, which appeared epistatic with uvsI, showed reduced UV-reversion frequencies similar to uvsI. The recombination-proficient mus mutants appeared to be epistatic with more than one group, but in several cases sensitivities were slight and overlaps insufficient to obtain corroborating results with MMS and 4-NQO.     

A comparative study of skeletal and cardiac tropomyosins

Summary The subunit composition, the thiol group content and the biological activities of cardiac tropomyosin (TM) of various animal species were compared. Cardiac TM from small animals such as rabbit, guinea-pig, rat and dog contain 2 SH/mole and were resolved into one band on SDS and acid urea electrophoresis and into two bands on alkaline urea electrophoresis. Chicken cardiac TM likewise gave one band and it contains 4 SH/mole. In contrast pig, sheep and human cardiac TM contain respectively 2.6, 2.4, and 2.4 SH/mole and were resolved into two bands and on the different electrophoresis systems used, with a : ratio respectively of I:4.2, I:4.6, I:4.8. The -TM components from sheep skeletal and pig and sheep cardiac muscles were more positively charged than the rabbit skeletal -TM component, as shown in alkaline urea electrophoresis system. The and combinations of dimers found for skeletal muscle by other authors, were also found for cardiac pig TM.All the TM have the same effect on the Ca²⁺-stimulated ATPase activity of desensitized actomyosin (DAM) and on the Mg²⁺-stimulated ATPase activity of DAM with troponin-complex.This work suggests that the subunits of the TM from skeletal and cardiac muscles are heterogenous in their M.W. and their charges and that in the heart as well as in skeletal muscle a relationship seems to exist between the amount of the component and the speed of contraction of the muscle: a higher amount of this component was found in the bulky hearts which are also those which contract slower.     

The release of intracellular Ca2+ in lacrimal acinar cells by α-, β-adrenergic and muscarinic cholinergic stimulation: the roles of inositol trisphosphate and cyclic ADP-ribose

Stimulation of rat lacrimal acinar cells with acetylcholine (ACh) and the -adrenergic agonist isoprenaline causes a rapid increase in inositol phosphates with 1–4 phosphate groups, resulting in release of Ca²⁺ from intracellular stores. Stimulation with the -adrenergic agonist phenylephrine, however, causes a release of Ca²⁺ from internal stores which is 36% of that observed with ACh stimulation, but without inositol phosphate production. This Ca²⁺ rise was completely inhibited by 100 M ryanodine. Adrenaline (causing activation of both - and -adrenergic receptors) induces a Ca²⁺ release with inositol phosphate synthesis identical to that occuring in the -adrenergic response. Thus, the signalling pathway for -adrenergic stimulation occurs via a path different from that which releases Ca²⁺ via muscarinic cholinergic and -adrenergic stimulation. In permeabilized lacrimal acinar cells cyclic adenosine 5-diphosphoribose (cADP-ribose) and inositol 1,4,5-trisphosphate [Ins(1,4,5)P ₃] cause release of Ca²⁺ from intracellular stores. The Ca²⁺ release evoked by cADP-ribose, but not by Ins(1,4,5)P ₃, was abolished by 100 M ryanodine, implicating a possible involvement of cADP-ribose in phenylephrine-induced Ca²⁺ signalling. When the intracellular free Ca²⁺ concentration ([Ca²⁺]_i) is raised by application of ionomycin, inositol phosphates are synthesized with a half-maximal effect seen at 425 nM. In contrast, loading cells with the Ca²⁺ chelator 1,2-bis(2-aminophenoxy) ethane-N,N,N,N-tetraacetic acid (BAPTA) reduced the adrenaline-induced inositol phosphate synthesis by 27%. The stimulation-induced rise in [Ca²⁺]_i, therefore, appears to cause further synthesis of inositol phosphates, thereby amplifying the receptor-mediated response.     

Expression of transforming growth factor alpha in human tissues: Immunohistochemical study and Northern blot analysis

Summary The expression of transforming growth factor alpha (TGF-) was examined in various human tissues and the fetus, using immunohistochemistry and Northern blot analysis. TGF- immunoreactivity was detected mainly in the epithelial cells of the digestive tract, liver, pancreas, kidney, thyroid, adrenal, skin, mammary gland and genital organs. In the digestive tract, epithelial cells with regenerative change or hyperplastic change showed strong immunoreactivity to TGF-. Peripheral nerve, vessels, megakaryocytes and macrophages in the lung and spleen were also positive for TGF-. By Northern blot analysis the expression of TGF- mRNA was confirmed in the digestive tract, salivary gland, thyroid, kidney and mammary gland. In the human fetus, the nerve tissues, liver, adrenal and kidney were positive for TGF-. Strong immunoreactivity to TGF- was observed in the hepatocytes of the fetus. These findings indicate that TGF- is produced by a variety of nonneoplastic cells in both adult and fetal tissues.     

A comparative immunohistological study of cerebellar enolases

Summary A comparative immunohistological study of the neurone-specific enolase and enolase, demonstrates the exclusive neuronal localization of enolase and its absence from glial cells. In contrast, enolase is located in astroglial cells. The validity of enolase as a neuronal marker and enolase as an astrocytic marker, is confirmed both by a double labelling technique, using antibodies to and to revealed with fluorescence or peroxidase in the same tissue sections, and by immunoelectronmicroscopy.