Budesonide, but not tacrolimus, affects the immune functions of normal human keratinocytes

Topical immunosuppressant therapy is widely used in the treatment of inflammatory skin diseases such as psoriasis and atopic dermatitis. Besides its beneficial therapeutic effects, application of topical anti-inflammatory drugs may render the epidermis more vulnerable to invading pathogens by suppressing innate immune responses in keratinocytes, such as cytokine production and Toll-like receptor (TLR) expression. In order to evaluate and compare the immunosuppressive effects of different immunosuppressant drugs on keratinocytes, we treated lipopolysaccharide (LPS)-stimulated and -unstimulated normal human keratinocytes with the synthetic corticosteroid budesonide and the macrolide tacrolimus. The expressions of the pattern recognition receptors (PRRs) TLR2 and TLR4 were measured by quantitative RT-PCR, pro-inflammatory cytokines IL-1alpha, IL-8 and TNF-alpha were monitored by quantitative RT-PCR and by ELISA, and alterations in TLR2 protein level were measured by flow cytometry. Budesonide had a suppressive effect on both constitutive and LPS-induced IL-8 gene expression. The amount of TNF-alpha mRNA was diminished in unstimulated keratinocytes, while TLR2 mRNA expression was markedly enhanced both in unstimulated and LPS-treated cells after incubation with budesonide. This increase in TLR2 mRNA expression was also detectable at the protein level in LPS-stimulated cells. Tacrolimus had no effect on any of the examined genes. Budesonide, but not tacrolimus, significantly inhibited the NF-kappaB-dependent luciferase reporter activity in HaCaT cells after induction with LPS or TNF-alpha. Although tacrolimus and budesonide are both effective treatments in some inflammatory skin diseases, the data provided here imply differences in local therapeutic and adverse effects of these two topical immunosuppressants.

Fate of cloned embryonic neuroectodermal cells implanted into the adult, newborn and embryonic forebrain

NE-4C, one-cell derived neuroectodermal stem cells expressing a reporter gene--green fluorescent protein (GFP) or heat-resistant alkaline phosphatase (PLAP)--or prelabeled with bromodeoxyuridine (BrdU) were implanted into the forebrain of adult, new-born and fetal mice and into the mid- and forebrain vesicles of early chick embryos. The fate of implanted cells in the mouse and chick hosts was followed up to 6 and 2 weeks, respectively. Neural differentiation was monitored by detecting the expression of neuron-specific markers and GFAP. NE-4C cells integrated into the early embryonic brain tissue and developed into morphologically differentiated neurons. The same cells produced expanding tumor-like aggregates in the newborn forebrain and were expelled from the adult forebrain parenchyma. In the adult brain, long-term survival and integration of stem cells were revealed only in neurogenic zones. The data suggest that noncommitted, proliferating neuroectodermal progenitors can integrate into the brain tissue at time and site of tissue genesis.

The role of the glucocorticoid-dependent mechanism in the progression of sodium taurocholate-induced acute pancreatitis in the rat

The effects of glucocorticoids on acute pancreatitis (AP) have remained contradictory. The aim of this study was to investigate the time courses of the effects of the exogenous glucocorticoid agonists dexamethasone (DEX) and hydrocortisone (HYD) and a glucocorticoid antagonist (RU-38486) and to characterize the local and systemic responses in AP in rats. The glucocorticoid antagonist and agonists were administered just before AP induction. Serum amylase activity determinations, IL-6 bioassays, pancreatic weight/body weight ratio measurements, and survival analysis were performed. Liver and lung injuries were assessed via neutrophil leukocyte infiltration in myeloperoxidase (MPO) assays, tissue adenosine triphosphate (ATP) level determinations, and histology. In the glucocorticoid agonist groups, the survival rate increased, while the serum amylase level, the IL-6 activity, and the pancreatic weight/body weight ratio decreased significantly as compared with the control and RU-treated groups. AP resulted in significant decreases in tissue ATP levels in both the liver and the lung. In the DEX- or HYD-treated groups, the liver ATP levels were significantly elevated, while both the liver and the lung MPO levels were attenuated as compared with the AP and RU-treated groups. These results suggest that glucocorticoids may play important roles in mitigating the progression of the inflammatory reaction during the early phases of AP.

Restraint stress and anti-tumor immune response in mice

Psychological stress modulates the immune system through the hypothalamic-pituitary-adrenal axis, the sympatho-adrenomedullary axis and the opioid system. According to literature data, restraint stress increases the immune cell apoptosis, decreases the spleen and thymus cell content, the natural killer (NK) activity in the spleen, and it compromises the anti-tumor immune response in mice. We immobilized mice in two consecutive nights, and then determined the cell number, apoptosis, NK cell content, NK activity and the level of cytokine mRNAs (TNF-beta, TNF-alpha, IL-4, IL-5, IL-1alpha, IFN-gamma, IL-2, IL-6, IL-1beta and IL-3) in the thymus and spleen. No consistent changes were detected in any of the immune parameters either in C57Bl/6 or in DBA/2 mice. Stressed or control B6 mice were injected with B16 melanoma cells immediately after the immobilization or one week later. No significant differences were found in the growth of primary tumors and lung metastases in stressed and control animals. Taken together, our mice, kept in a general-purpose non-SPF animal house, seemed to be refractory to the stress-induced immunomodulation. Our interpretation is that stress-induced immunomodulation can occur only in mice isolated from any background stressors, or rather natural stimuli, throughout their life.

Kupffer cell phagocytosis blockade decreases morbidity in endotoxemic rats with obstructive jaundice

OBJECTIVE AND DESIGN

The consequences of Kupffer cell phagocytosis blockade were studied in endotoxemic rats with obstructive jaundice.

MATERIAL OR SUBJECTS

159 male Wistar rats.

TREATMENT

Obstructive jaundice was induced by bile duct ligation (BDL). Gadolinium chloride (1 mg/100 g iv) was given 6 days after BDL to inhibit Kupffer cell activity and the animals were challenged with 1 microg/g endotoxin 24 h later.

METHODS

Endotoxin sensitivity, tumor necrosis factor-alpha and interleukin-6 production were studied, liver and lung injury were assessed by neutrophil infiltration assay, tissue adenosine triphosphate, aspartate aminotransferase, alanine aminotransferase level determinations and histology, respectively. For statistics non-parametric methods were used.

RESULTS

BDL sensitized the animals to endotoxin, increased endotoxin-induced tumor necrosis factor-alpha and interleukin-6 production and reduced ATP contents of the liver and the lung. Kupffer cell blockade significantly increased the resistance against endotoxin, diminished the inflammatory cytokine release and reduced endotoxin-induced tissue injury in BDL animals.

CONCLUSION

Attenuation of Kupffer cell function decreases endotoxin-induced lethality and morbidity in obstructive jaundice.

Receptor-like properties of the 26 kDa transmembrane form of TNF

Most members of the TNF family of proteins exist as transmembrane proteins with relatively long intracellular domains, and a number of them are involved in the ill-defined phenomenon of "reverse signaling". We have identified a putative nuclear localization signal in the cytoplasmic domain of TNF which proved to be functional in two assays. Western analysis identified an approximately 10 kDa peptide corresponding to the transmembrane and cytoplasmic domains of TNF after the proteolytic liberation of the 17 kDa, soluble form of TNF. This 10 kDa peptide was enriched in internal membranes and nuclear fractions of disrupted cells. Immune electron-microscopic studies proved its localization in transport vesicles and the nucleus. The nuclear transport of the intracellular segment of TNF resembles the signaling process through the Notch-type of receptors. Indeed, the presence of the 10 kDa peptide seems to influence the expression of another inflammatory cytokine, interleukin-1 beta. These findings suggest that the transmembrane form of TNF has receptor-like properties and its interaction with the receptors initiates a bidirectional signaling.

The effects of glucocorticoids and a glucocorticoid antagonist (RU 38486) on experimental acute pancreatitis in rat

The effects of glucocorticoids on acute pancreatitis are a matter of dispute. In animal experiments, dexamethasone and hydrocortisone significantly decreased the serum amylase activities 8 hours after the induction of pancreatitis. In the dexamethasone treated group, the serum IL-6 level was significantly decreased at 4 and 8 hours, while in the hydrocortisone treated group, all the IL-6 values were significantly diminished vs. the control group. As compared to the control, a glucocorticoid antagonist (RU 38486) did not influence the serum amylase activity, but significantly increased the serum IL-6 level. These results suggest that glucocorticoids may play a role in the control of pancreatitis caused by inhibition of cytokine production.

Pathophysiological effects of human TNF-alpha-producing tumor xenografts in immunosuppressed mice

Groups of CBA mice immunosuppressed with anti-thymocyte serum (ATS) treatment were xeno-transplanted with either HeLa human cervical carcinoma cells or genetically modified cells expressing the human tumor necrosis factor-alpha (TNF) gene (All cells). Both cell lines were highly resistant to the cytotoxic effects of TNF. If 3 x 10(6) tumor cells were inoculated s.c. into female mice, HeLa cells grew progressively into large tumors and killed 74% of the recipients, while TNF-expressing All cells caused fatal tumor growth only in 22% of the mice. 3 x 10(6) or 1.5 x 10(7). All cells produced progressive tumor growth and lethality in all male recipients. In sera of all the A11-cell-transplanted mice, biologically active TNF was detected shortly (4.5 h) after tumor inoculation (6 39 U/ml), decreasing to below detection level in the circulation by day 3. In recipients of 15 million A11 cells, circulating TNF reappeared and reached high levels (12-1000 U/ml) 3 to 7 weeks later, when the animals bore large tumors (14-23 mm). Generally, such mice became cachectic, severely anemic, hypothermic, and soon died. On account of calcium mobilization from bones, their serum Ca levels were high. Electron microscopy revealed severe liver damage, but there were no signs of chronic arthritis. These results suggest that ATS-treated mice xenotransplanted with TNF-gene-transfected A11 human tumor cells provide a new model for studying the pathophysiological and anti-tumor effects of TNF.

A genetically modified recombinant tumor necrosis factor-alpha conjugated to the distal terminals of liposomal surface grafted polyethyleneglycol chains

A genetically modified recombinant tumor necrosis factor (TNF)-alpha (rKRKTNF) was conjugated to the terminal carboxyl groups of liposome grafted polyethyleneglycol (PEG) chains. The long-circulating liposomes were composed of egg phosphatidylcholine, cholesterol (chol) and 7% carboxyl PEG-phosphatidylethanolamine. The conjugation efficiency of the genetically modified rKRKTNF under the conditions described in the text was approximately 55%. The biological activity of liposomal rKRKTNF, as tested with an in vitro cytotoxicity assay was reduced compared to the free, unconjugated rKRKTNF. In vivo biodistribution studies showed that conjugation of as little as 0. 13% of the grafted PEG chains resulted in a rapid elimination of the formulation from the blood stream. It is speculated that both non-selective conjugate chemistry and inherent recognition of the TNF by the components of the reticuloendothelial system (RES) are responsible for the short blood half life of the rKRKTNF-PEG-liposomes. The result suggest that conjugating a rapidly clearing recombinant cytokine to long-circulating liposomes provides little advantage in modifying the pharmacokinetic parameters of the cytokine.

45T-1, an established cell line with characteristics of Sertoli cells, forms organized aggregates in vitro after exposure to tumor necrosis factor alpha

In the testis TNF is produced by germinal cells. The putative role of tumor necrosis factor alpha (TNF) in development and differentiation was investigated in 45T-1 mouse cell cultures, a cell line with characteristic markers of Sertoli cells, established from transgenic mouse families expressing the polyoma large T antigen in their testes. Exposure to TNF elicited a gradual assembly of the cells of the monolayer into highly organized spheroids. The first morphological sign of the changes was detected one week after TNF treatment by anti-desmin immunostaining which showed the formation of foci in the culture consisting of several hundred cells connected by an increasing number of cell contacts. Between days 10-20 the cells formed large ovoid or vermiform aggregates covered by several layers of flat, elongated cells. These cells extended septae into the inner mass of the spheroids consisting of loosely arranged, large polygonal or palisadic cells. The spheroids were surrounded by radially arranged elongated cells covered by small blebs. TNF treatment upregulated laminin expression in 45T-1 cell cultures, which is known to induce formation of cord-like structures by Sertoli cells in vitro. Coculturing 45T-1 cells with immortalized germinal cells or TNF-producing HeLa cells also lead to the formation of spheroids. These observations suggest that TNF production of germinal cells might contribute to the organization/differentiation of Sertoli cells.

New picture archiving and communications system plus new facility equals critical path planning challenge

The architectural design and construction of a new imaging department is one of the most complex challenges in healthcare architecture. When a client also plans a simultaneous change in basic operating system technology from film-based to filmless imaging, the challenge for both hospital management and the facility/technology design team is even more complicated. A purposeful planning process plus a carefully composed team of internal and external experts are the two essentials for success in executing this difficult conversion of both facility and technology.

Highly increased TNF sensitivity of tumor cells expressing the yeast delta 9-desaturase gene

L929 and WEHI tumor cell lines were genetically modified to constitutively express the Saccharomyces cerevisiae Ole 1 gene, coding for the delta 9-desaturase enzyme. These cells exhibit an increased ratio of monounsaturated fatty acids in their membrane phospholipids paralleled by an overall decrease in the membrane molecular order and a highly increased tumor necrosis factor-alpha (TNF) sensitivity. The TNF-alpha signaling cascade involves events, like receptor clustering and cleavage of membrane constituent lipid molecules by phospholipases, which are influenced by the physical state of cellular membranes. We discuss the possible involvement of non-bilayer forming lipids in the control of signaling mechanisms leading to TNF cytotoxicity.

TNF inhibits myogenesis and downregulates the expression of myogenic regulatory factors myoD and myogenin

The presence of TNF and other inflammatory cytokines and their receptors is detected during embryonic development, but our knowledge about the role of these proteins in differentiation and development is very limited. TNF modulates the synthesis and activity of a number of transcriptional proteins that regulate the activity of tissue specific genes, therefore it may play a role in normal development. Since its synthesis is upregulated by stress and infections, it may also participate in the induction of pathological developmental processes and malformation. We investigated the effect of TNF in an in vitro differentiation system using C2 myoblasts. This inflammatory cytokine exerted a positive effect on the early steps of the process: it enhanced the proliferation and aggregation of myoblast cells. In contrast, TNF strongly inhibited the expression of those myogenic transcription factors (myoD and myogenin), which are known to be responsible for upregulated activity of muscle specific genes (like the genes of the myofilament proteins), and blocked the synthesis of mRNAs of myogenic differentiation markers (like skeletal alpha-actin, myosin heavy and light chains). As a result, these cells did not synthesize myofilament proteins and the organization of myofilaments did not take place in TNF-treated myoblasts.

Modulation of lipid unsaturation and membrane fluid state in mammalian cells by stable transformation with the delta9-desaturase gene of Saccharomyces cerevisiae

The composition and physical state of membrane lipids determine the dynamic nature of membranes, which in turn, could directly be linked to the activity of various membrane-associated cellular functions. To better understand the molecular basis of different membrane-related phenomena we established a novel strategy to alter unsaturation of mammalian cell membranes with an identical genetic background. We transfected L929 mouse fibroblastoid cells with DNA constructs containing the Delta9-fatty acid desaturase gene (Ole1) of S. cerevisiae under the control of desaturase promoters derived either from wild type or mutant strains of the dimorphic fungus H. capsulatum.

Cloning and characterization of the genes of the CeqI restriction-modification system

Two genes from Corynebacterium equii, a Gram-positive bacterium producing the CeqI restriction-modification enzymes were cloned and sequenced. In vivo restriction experiments, DNA and amino acid sequence data suggest that the two genes code for the endonuclease and the methyltransferase enzymes. However, when the two genes are expressed in E. coli, practically no enzyme activity can be detected in the supernatants of sonicated cells. Based on the DNA sequence data CeqI restriction endonuclease (an EcoRV izoschizomer) consists of 270 amino acid residues with a predicted molecular mass of 31.6 kDa, in good agreement with the previously measured 32 +/- 2 kDa. The methyltransferase is 517 residues long (approx. 60 kDa). The two genes are in opposite orientation and overlap by 37 base pairs on the chromosome. The deduced amino acid sequence of the putative endonuclease gene revealed long stretches of hydrophobic amino acids, that may form the structural basis of the unusual aggregation properties of the restriction endonuclease. The amino acid sequence of the methylase shows homologies with other type II methyltransferases.

Insoluble glycogen, a metabolizable internal adsorbent, decreases the lethality of endotoxin shock in rats

Insoluble glycogen is an enzymatically modified form of naturally occurring soluble glycogen with a great adsorbing capacity. It can be metabolized by phagocytes to glucose. In this study we used insoluble glycogen intravenously in the experimental endotoxin shock of rats. Wistar male rats were sensitized to endotoxin by Pb acetate. The survival of rats were compared in groups of animals endotoxin shock treated and non-treated with insoluble glycogen. Furthermore, we have determined in vitro the binding capacity of insoluble glycogen for endotoxin, tumour necrosis factor alpha, interleukin-1 and secretable phospholipase A₂. Use of 10 mg/kg dose of insoluble glycogen could completely prevent the lethality of shock induced by LD₅₀ quantity of endotoxin in rats. All animals treated survived. Insoluble glycogen is a form of ‘metabolizable internal adsorbents’. It can potentially be used for treatment of septic shock.

[Creation of monoclonal antibodies against tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor alpha (TFG-alpha), their definition and possible use]

These antibodies were characterised immunoserologically and immunohistochemically. The antibodies proved suitable in the detection of TNF-alpha and TGF-alpha production by different cells and tissues. These anti-TNF-alpha specific monoclonal antibodies were able to inhibit the cytotoxic effect of hrTNF-alpha in vitro. These monoclonal antibodies may potentially be useful in the future for determining TNF-alpha or TGF-alpha level by different immunodiagnostical assays (ELISA, RIA, FIA) in the medical practice.

Platelet-activating factor antagonists (BN 52021 and BN 50730) inhibit tumor necrosis factor-alfa-mediated cytotoxicity on murine L929 tumor cells

Tumor necrosis factor (TNF)-alfa has been described as a mononuclear phagocyte-produced cytotoxin that causes the necrosis and regression of some tumors. The mechanism of the cytotoxicity and the basis for the differential cytotoxic effects of TNF against cells of various origin remains unclear. It has also been reported, that murine TNF stimulates the production of platelet-activating factor (PAF) by cultured peritoneal macrophages, and that PAF enhances TNF production by alveolar macrophages. Furthermore, it is known that the synthesis and release of PAF are inhibited by plasma proteinase inhibitors. This study was devoted to investigate the effects of two specific PAF antagonists (BN 52021 and 50730), and a proteinase inhibitor (aprotinin; GordoxR) on the TNF-induced cytotoxicity in L929 murine fibroblasts. Our present findings indicate that TNF-induced cytotoxicity is inhibited in a dose-dependent manner by the PAF antagonists studied and by the kallikrein inhibitor aprotinin. These findings provide further evidence suggesting that PAF might be involved in the process of the TNF-alfa-induced cytotoxicity of L929 mouse fibroblasts.

Presynaptic inhibitory effect of TNF-alpha on the release of noradrenaline in isolated median eminence

The effect of tumor necrosis factor-alpha (TNF-alpha) on the stimulation-evoked release of noradrenaline (NA) from isolated rat median eminence (ME) was investigated, using a low-volume perfusion system. Median eminence, loaded with [3H]noradrenaline, was superfused with Krebs solution and stimulated electrically (2 Hz, 120 shocks). The effect of TNF-alpha was studied on the S2/S1 ratio. It was found that stimulation-evoked release of NA from noradrenergic axon terminals in the isolated rat ME was inhibited by TNF-alpha and this effect was concentration-dependent. In contrast, TNF-alpha had no effect on the release of [3H]NA from the spleen. Since NA released in the ME might be involved in the modulation of corticotropin-releasing factor (CRF) production, it is suggested that TNF-alpha, through presynaptic modulation of NA release from noradrenergic nerve terminals in the ME, might regulate CRF and other neurohormone release in this hypothalamic structure.

Purification and characterization of CeqI restriction endonuclease

CeqI, a type II restriction endonuclease, an isoschizomer of EcoRV was purified to apparent homogeneity by a combination of salt precipitation, ion exchange, dye affinity and hydrophobic interaction chromatographies. The crude enzyme was present in the form of large aggregates that could be pelleted by high speed centrifugation. The enzyme was not associated with cellular membranes, though non-ionic detergents lowered the apparent size of the aggregates. The purified enzyme also showed a tendency to form large molecular mass (66-600 kDa) complexes under physiological conditions, in the absence of cleavable DNA. The enzyme formed smaller complexes in the presence of DNA and non-ionic detergents and dissociated into subunits (and undergoes reversible loss of activity) in the presence of high concentrations of salts. According to SDS gel electrophoresis and sedimentation analysis the molecular mass of the monomer 32 +/- 2 kDa. The enzyme had a rather broad PH optimum, extending into the alkaline range and lost specificity and activity in buffers below pH 6.

Effect of RU 38486 on TNF production and toxicity

Glucocorticoid steroids provide considerable protection against the systemic toxicity of tumor necrosis factor-alpha (TNF-alpha, cachexin). In animal experiments RU 38486 (mifepristone), a steroid antagonist, increased the synthesis of TNF and sensitized the animals to the cytotoxic action of TNF. As compared to the control and methylprednisolone-treated groups, mifepristone significantly increased the level of TNF in the serum, liver and spleen of lipopolysaccharide (LPS)-treated animals. In tissue cultures RU 38486 induced the TNF synthesis of myeloid cells and increased the TNF production of genetically modified HeLa cells, which synthesize TNF constitutively. Normal and tumor cell cultures exhibited increased sensitivity toward TNF in the presence of mifepristone.

Positive co-operative interaction between the subunits of CeqI restriction endonuclease

CeqI restriction endonuclease, an isoschizomer of EcoRV, forms complexes of 12-20 subunits under physiological conditions, in the absence of DNA. These molecules partially dissociate in the presence of DNA sequences recognized by CeqI or in the presence of non-ionic detergents. In solutions containing high concentrations of salts (e.g. 1 M-NaCl), the enzyme dissociates into subunits, concomitantly losing its activity. According to our experiments, it is the tetrameric form of the enzyme that binds the DNA and represents the catalytically active molecule. Analysis of the enzyme kinetics revealed a positive co-operative interaction between the subunits of the enzyme. Computer-assisted analysis of these data yielded a Hill coefficient of approx. 1.35, suggesting two binding sites per tetrameric enzyme molecule, two subunits per palindromic recognition site.

Detection of the neor gene expression in animal cells after genetic transformation

A reliable assay is reported for the detection of the marker gene aminoglycoside phosphotransferase activity in cells that express this enzyme transiently or as a result of stable genetic transformation. This method combines the simplicity of the dot assays with the reliability of the more elaborate and time consuming electrophoretic or chromatographic methods. Inhibition of phosphatases and protein kinases during the reaction reduces labeled ATP consumption by these enzymes. As a result, this assay allows the detection of approx 10 times lower levels of the enzyme than currently used methods. To detect the expression of reporter genes in transformed cells aminoglycoside phosphotransferase can be used as well as the widely used chloramphenicol acetyltransferase enzyme.

Complex interaction of yeast nuclear proteins with the enhancer/promoter region of SV40

Though highly complex enhancers found in animal cells have not been reported to occur in yeasts they are able to activate the transcription of adjacent genes in yeast cells. Saccharomyces cerevisiae expresses a large number of nuclear proteins that are able to recognize, and specifically bind to, the enhancer sequences of the SV40 animal tumor virus. The complexity of proteins that interact with different elements of the animal enhancers is similar in yeast and animal cell nuclear extracts. Most enhancer motifs, recognized by known trans-acting factors, are protected in footprinting experiments by yeast nuclear proteins.

Reconstituted Newcastle disease virus envelopes as a split vaccine

Isolated envelope proteins of Newcastle disease virus (NDV) were inserted into the lipid bilayer of artificial vesicles to create a viral envelope-like structure. The structure-containing viral antigens at high density elicited a strong immune response, in contrast to purified viral proteins. The artificial envelopes or immunosomes possessed several advantageous properties when used as vaccines. They elicited a faster response and the immunity lasted longer in animals treated with these vesicles than in controls vaccinated with envelope proteins in combination with traditional adjuvants. A further useful feature of the artificial envelopes is that no inflammatory lesions develop at the site of their injection.

Modified MacNeille cube polarizer for a wide angular field

Well known relationships exist between thicknesses and indices of a stack of optical layers which permit the definition of very good polarizers of light. One of the most famous types of polarizer is the MacNeille cube. In this case the hypotenuse face of an isosceles right angled prism is coated with a polarizing deposit and then cemented to the hypotenuse face of an identical prism. This polarizer can be used over a large spectral range located in the s vibration stop band. Unfortunately, the insertion losses for thep vibration are large when the angular field is larger than +/-2 degrees . Using very simple optical considerations, we design suitable coating structures that allow the use of cube polarizers over a wide angular range, typically +/-10 degrees in air, when T(p)>0.97 and T(s) </= 10(-3). However, the spectral range is reduced. Diagrams are given to calculate the thickness of the layers according to the substrate and the indices of the evaporated materials. The prism angle is also determined to have a symmetric angular field in air. Such polarizers are suitable for semiconductor lasers because they can be used without a collimating lens in spite of their large divergence. Good optical characteristics up to T(p) approximately 0.95 and T(s) approximately 10(-4) over the range of +/-5 degrees have been measured for these polarizers manufactured in the Laboratoires de Marcoussis.

Positive and negative control of nod gene expression in Rhizobium meliloti is required for optimal nodulation

We show that expression of common nodulation genes in Rhizobium meliloti is under positive as well as negative control. A repressor protein was found to be involved in the negative control of nod gene expression. Whereas the activator NodD protein binds to the conserved cis-regulatory element (nod-box) required for coordinated regulation of nod genes, the repressor binds to the overlapping nodD1 and nodA promoters, at the RNA polymerase binding site. A model depicting the possible interaction of the plant-derived nod gene inducer (luteolin), the NodD and the repressor with the nod promoter elements is presented. Mutants lacking the repressor exhibited delayed nodulation phenotype, indicating that fine tuning of nod gene expression is required for optimal nodulation of the plant host.

Entrapment of high-molecular-mass DNA molecules in liposomes for the genetic transformation of animal cells

We modified the Ca/EDTA procedure for the production of liposomes [Papahadjopoulos, Vail, Jacobson & Poste (1975) Biochim. Biophys. Acta 394, 483-491] to entrap intact DNA molecules of very high molecular mass into large unilamellar phospholipid vesicles. The use of DNA-protein complexes and phage particles instead of naked linear DNA increases the efficiency of entrapment and protects the integrity of DNA molecules. We investigated the interaction of mammalian cells with liposome-encapsulated recombinant lambda bacteriophages carrying marker genes. The liposomes bind surprisingly fast to the cellular surface and are taken up by the cells. A significant proportion of the encapsulated DNA is transported to and soon located in or around the nuclei. Experiments prove that these liposomes can be used for the genetic transformation of mammalian cells.

The role of a documented allergic profile as a risk factor for radiographic contrast media reaction

To determine the relevance of a documented allergic profile as a predisposing factor in radiographic contrast media (RCM) reaction, we investigated its incidence among 100 subjects who underwent RCM studies. Fifty of these subjects reacted to RCM (reactors) and 50 were non-reactors (controls). All 100 subjects completed an allergy questionnaire, allergy skin testing, and in vitro assay to common allergens. Sixty-eight percent of reactors and 30% of controls had a positive history of allergy/hypersensitivity (P less than .001). Fifty-six percent of reactors and 24% of controls had positive skin test (P less than .005). These data suggest that allergic individuals are at twice the risk for developing adverse RCM reaction as compared with non-atopic subjects.

'Star' activity and complete loss of specificity of CeqI endonuclease

Restriction endonuclease CeqI, an isoschizomer of EcoRV, exhibits 'star' activity, a relaxation of specificity in the presence of Mn2+, dimethyl sulphoxide or glycerol. The enzyme cleaves a set of sequences that differ from the canonical GATATC by only one nucleotide in positions 2, 3, 4 or 5. Two of these sequences are not cleaved if modified by dam methylase. A further loss of specificity can be observed in circumstances less favourable for the enzyme, namely low-ionic-strength buffers of pH values below 6.0 or above 9.4. This activity seems to cleave DNA at any sequence, producing a smear instead of well-defined bands. Partial renaturation of the denatured enzyme gives rise to a similar non-specific nuclease activity.

Difference in the production of human interferon-alpha and -beta in mouse cells

Human interferon-alpha 1 and interferon-beta genes with their flanking regions were introduced into mouse LMTK- cells. Although transfected cells contained the interferon genes with a similar copy number and produced a similar amount of interferon-specific mRNA, cells containing the human interferon-beta gene secreted about 10 times more human interferon than cells transfected with the human interferon-alpha 1 gene. When the coding region of the interferon-beta gene was replaced by that of the interferon-alpha 1 gene (hybrid interferon beta/alpha gene), the human interferon production of transfected cells fell by approx. one order of magnitude. These results show that in the case of exogenous interferon genes a translational or post-translational mechanism might significantly affect the final level of human interferons, resulting in higher titres of interferon-beta than of interferon-alpha.

Factors affecting cognitive functioning of hemiplegic children

The results of psychological testing, EEGs and CT scans were examined for 41 children with congenital or early acquired hemiplegia. On average, IQ was depressed and the magnitude of this depression was highly correlated with lesion size, degree of hemiparesis and EEG abnormality, but not with location of lesion. There were no significant effects of lesion laterality on Verbal vs. Performance IQ on Wechsler tests. However, receptive vocabulary, as measured by the Peabody Picture Vocabulary Test, was differentially depressed by left-hemisphere damage. Further, on a variety of verbal tasks, patients with congenital lesions performed better than those with acquired lesions. In contrast, no significant differences were found between the two groups on spatial tasks.

Mycosis fungoides involving the central nervous system

The clinical records of nine patients, followed at the University of Chicago, with mycosis fungoides (MF) and neurologic deficits due to direct CNS involvement were reviewed. Lymph node and visceral involvement was present in all patients. Clinical findings included cranial nerve deficits in four patients, altered mental status in eight, gait disturbances in three, and leg weakness in one. Helpful diagnostic studies included lumbar puncture with CSF cytology, computerized tomography (CT) brain scans, brain biopsy, and myelogram. Two patients, who were treated with radiation therapy (RT), survived 14 and 40 weeks, respectively. Survival of less than 4 weeks limited treatment in the other patients. Autopsies were performed on six patients and revealed meningeal infiltration and perivascular infiltration of the brain. In addition, the cerebral parenchyma was infiltrated in one patient and a lymphomatous tumor was found in the brainstem of another. We conclude that the varied clinical and pathologic features of CNS involvement with mycosis fungoides resemble those seen in leukemias and other lymphoproliferative disorders. Better awareness of the clinical features may permit earlier diagnosis and initiation of therapy.

Identification of structural proteins of Rhizobium meliloti temperate phage 16-3

The structural proteins of Rhizobium meliloti temperate phage 16-3 have been analysed by means of polyacrylamide gel electrophoresis, isoelectric focusing and agarose gel electrophoresis. Five major and five minor proteins were identified and characterized with respect to their size, isoelectric point and their distribution between the head ad tail of the phage particle. The synthesis of structural proteins was studied by one- and two-dimensional gel electrophoresis.

Sindbis virus receptor protein of BHK cells

Exposure of cultured BHK 21 cells to very low concentrations of non-ionic detergent Nonidet P40 resulted in the elution of cellular proteins located on the outer surface of the plasma membrane. One of these proteins, partially purified by affinity ultrafiltration and cosedimentation with Sindbis virions, seems to be the "receptor molecule" of Sindbis virus.

Effect of cycloheximide on viral precursor protein B in Sindbis virus-infected BHK cells

The possible role of B protein, a postulated precursor of viral envelope proteins was studied in Sindbis virus-infected BHK cells. Although tryptic digestion of the B protein produces tryptic peptides of the viral envelope proteins it seems unlikely that B molecules accumulated in the cytoplasm of infected cells are subsequently cleaved into structural proteins. We suggest that if B is really the precursor of E1 and PE2 viral envelope proteins, the cleavage takes place on the ribosomes during the synthesis of the second part of the B protein. Low concentrations of cycloheximide completely blocked the synthesis of B protein but did not inhibit the synthesis of viral structural proteins.

The effect of canavanine on the capsid protein of Sindbis virus

In the presence of the arginine analogue canavanine, Sindbis virus-infected BHK 21 cells synthesize a capsid protein of somewhat larger molecular weight than that of controls. This protein can also be seen in short pulse-labelled cells, and probably represents a precursor of the normal capsid protein. In our experiments canavanine had no effect on the viral envelope proteins, and the canavanine containing capsid protein formed nucleocapsids and virus particles as well as normal capsid protein does.

Alterations in Sindbis viral enbelope proteins by treating BHK cells with glucosamine

Addition of d-glucosamine to BHK cells infected with Sindbis virus inhibited the formation of the E-2 viral envelope from its precursor PE-2. Release of virus was blocked, and two new viral protein bands replaced the normal envelope protein bands detected in SDS-gel electropherograms of infected cell extracts.