Repression of catabolites in gram-positive and gram-negative bacteria

Analyzes the mechanism of catabolite repression of grampositive and gramnegative bacteria. The role of cyclic adenosine monophosphate and CRP protein, forming a complex, is shown. Contribution of ATP kinase to manifestation of the catabolic repression phenomenon in grampositive bacteria is discussed.     

Complement activation in septic shock due to gram-negative and gram-positive bacteria

Whole serum complement (CH50) and C3, C4, and C3PA plasma values were studied in 48 patients: 9 with nonseptic shock; 20 with sepsis; 14 with septic shock caused by gram-negative bacteria; 5 with septic shock caused by gram-positive bacteria. All were compared with a control group of 25 healthy individuals. Determinations were made upon admission and again 48 and 96 h later. No significant differences in complement values were found between the patients with nonseptic shock and the control group. In the patients with sepsis, decreased CH50 (p less than 0.001) and increased C3PA (p less than 0.02) values were observed, while C3 and C4 remained unaltered. In the patients with septic shock, markedly decreased levels of CH50, C3, and C4 were seen (p less than 0.001, and p less than 0.001, and p less than 0.001, respectively) without changes in C3PA levels. There were no differences between septic shock due to gram-negative and gram-positive bacteria, or between patients who died and those who survived. After 96 h, the altered values returned to the normal range. This underlines the transitory activation of the complement system through the classic pathway and suggests its possible role in the pathogenesis of septic shock in man.     

Generation of tumor necrosis factor alpha by human nasal epithelial cells and inhibition by fluticasone propionate

Accumulation of mast cells and eosinophils in the nasal epithelial layer occurs in nasal allergic reaction, However, the mechanism of accumulation of these cells has not yet been well clarified. We hypothesized that cytokines generated from the nasal epithelial cells contributed to the accumulation of these cells in the nasal epithelial layer. Recently tumor necrosis factor (TNF) was shown to promote polymorphonuclear neutrophils and eosinophils migration. And also TNF increased eosinophil binding to vascular endothelial cells. In this in vitro study we examined whether or not nasal epithelial cells can produce TNF-alpha and also whether or not glucocorticosteroid fluticasone propionate (FP) can modulate TNF-alpha production from nasal epithelial cells. Nasal epithelial cells constitutively produce TNF-alpha in accordance with the nasal epithelial cells' number and this was substantially increased in the state of nasal epithelial cell's proliferating. FP significantly reduced the level of TNF-alpha in the supernatant of cultured nasal epithelial cells for a period of 6 days. In addition, preincubation of nasal epithelial cells with FP for 6 days caused significant reduction of TNF-alpha level in the supernatant of cultured nasal epithelial cells during a further period of 6 days without FP. These data support the concept that structural cells play an active role in the control of allergic and related inflammatory processes.     

Lipoprotein(a) inhibits lipopolysaccharide-induced tumor necrosis factor alpha production by human mononuclear cells

Lipoproteins can bind lipopolysaccharide (LPS) and decrease LPS-stimulated cytokine production. Lipoprotein(a) [Lp(a)] was as potent as low-density lipoproteins (LDL) in inhibiting LPS-stimulated tumor necrosis factor synthesis by human mononuclear cells. The kinetics of LPS inhibition by Lp(a) was similar to that of LDL. This suggests that circulating Lp(a) may be an important factor determining the amplitude of the response to LPS in humans.     

The growth response to tumour necrosis factor alpha of human gynaecological cancer cell lines

Academic computing initiatives rank high on the list of priorities of many dental schools. However, outcomes of academic computing initiatives have not been presented. The objectives of this program evaluation were to: 1) document a strategic initiative for academic computing over a five-year period; 2) assess outcomes; and 3) demonstrate how outcomes assessment changed strategic goals for the future. In 1992, Temple University School of Dentistry developed an academic computing plan. The plan proposed to develop the computer literacy of faculty, teach students the computer skills they need to be successful in their careers, and introduce computer-aided instruction as a new teaching tool. Before a new five-year plan was developed in 1997, the original plan's outcomes were summarily assessed. Assessment instruments included faculty and student surveys, budgets, inventory records, and utilization statistics. The school has reached two of three goals of the 1992 plan. Eighty percent of all full-time faculty have computers, are computer literate, and use computers for a variety of purposes. The school has implemented a comprehensive predoctoral dental informatics curriculum. However, the implementation of computer-aided instruction has not met expectations. Goals of the 1998-2003 plan include establishing an online learning infrastructure, improving student access, implementing computer-based oral health records, and further improving the computer literacy of faculty and students. Planning and supporting academic computing initiatives is a substantial challenge. Factors such as institutional culture, capital investment, ongoing support, and technological change influence plans and their success. While process and structure can be assessed relatively easily, measures for changed educational outcomes are still lacking.     

Induction of tumor necrosis factor alpha in human neuronal cells by extracellular human T-cell lymphotropic virus type 1 Tax

To examine the role of human T-lymphotropic virus type 1 (HTLV-1) Tax1 in the development of neurological disease, we studied the effects of extracellular Tax1 on gene expression in NT2-N cells, postmitotic cells that share morphologic, phenotypic, and functional features with mature human primary neurons. Treatment with soluble HTLV-1 Tax1 resulted in the induction of tumor necrosis factor alpha (TNF-alpha) gene expression, as detected by reverse-transcribed PCR and by enzyme-linked immunosorbent assay. TNF-alpha induction was completely blocked by clearance with anti-Tax1 monoclonal antibodies. Furthermore, cells treated with either a mock bacterial extract or with lipopolysaccharide produced no detectable TNF-alpha. Synthesis of TNF-alpha in response to soluble Tax1 occurred in a dose-dependent fashion between 0.25 and 75 nM and peaked within 6 h of treatment. Interestingly, culturing NT2-N cells in the presence of soluble Tax1 for as little as 5 min was sufficient to result in TNF-alpha production, indicating that the induction of TNF-alpha in NT2-N does not require Tax1 to be continually present in the culture medium. Treatment of the undifferentiated parental embryonal carcinoma cell line NT2 with soluble Tax1 did not result in TNF-alpha synthesis, suggesting that differentiation-dependent, neuron-specific factors may be required. These results provide the first experimental evidence that neuronal cells are sensitive to HTLV-1 Tax1 as an extracellular cytokine, with a potential role in the pathology of HTLV-1-associated/tropical spastic paraparesis.     

Morphological change in tumor endothelial cells induced by natural-type human tumor necrosis factor

The effects of natural-type human tumor necrosis factor (nh-TNF) on tumor endothelial cells of experimental brain tumors were investigated electron microscopically. Tumor vessels with hypertrophic endothelial cells were observed 12 and 24 hr after an intralesional administration of 5,000 U of nh-TNF. Increased biosynthetic organelles such as the Golgi complex and rough endoplasmic reticulum were evident in the plump cytoplasms. These endothelial cells resembled those in high endothelial venules (HEV) functionally characterized by the high permeability of leukocytes. In addition, close interactions between these endothelial cells and leukocytes were observed. Our findings indicated that nh-TNF could promote the morphological change in tumor endothelial cells into HEV-like cells.     

A human suppressor of c-Jun N-terminal kinase 1 activation by tumor necrosis factor alpha

Tumor necrosis factor alpha (TNFalpha) has pleiotropic effects on cellular metabolism. One of the signaling paths from the TNFalpha receptor induces a stress-activated protein kinase cascade. Components within this TNFalpha kinase cascade include mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinase 1 (MEKK1) and stress-activated protein kinase/extracellular signal-regulated kinase kinase (SEK), which regulate the activity of c-Jun N-terminal kinase 1 (JNK1). Currently, molecules upstream of MEKK1 that link TNFalpha receptor to downstream kinases are not well understood. Besides TNFalpha, many other stimuli including several oncoproteins can activate JNK1. In most cases, the signaling cascade(s) leading from oncoproteins to JNK1 is poorly elucidated. We report here that the human T-cell lymphotrophic virus, type I (HTLV-I) oncoprotein, Tax, can activate JNK1. We isolated a novel human cell factor, G-protein pathway suppressor 2 (GPS2), by its ability to bind the HTLV-I oncoprotein, and we show that this factor can potently suppress Tax activation of JNK1. In trying to understand the mechanism of GPS2 activity, we found that it also suppressed TNFalpha activation of JNK1 but not TNFalpha activation of p38 kinase nor phorbol activation of extracellular signal-regulated kinase 2. Because GPS2 has minimal effect on MEKK1- or SEK-regulated JNK1 activity, it could act at a point between the TNFalpha receptor and MEKK1 in the initial step(s) of this kinase cascade. Alternatively, it is not excluded that GPS2 could work in a parallel pathway that leads from TNFalpha to JNK1. GPS2 represents a new molecule that could contribute important insights toward how cytokine- and oncoprotein-mediated signal transduction might converge.     

Lack of intrathyroidal tumor necrosis factor alpha in Graves'' disease

Human colonic intraepithelial lymphocytes from control subjects down-regulate the proliferative responses of primed allogeneic peripheral blood mononuclear cells on rechallenge with antigens or phytohaemagglutinin (PHA). In contrast, human colonic intraepithelial lymphocytes from patients with inflammatory bowel disease fail to down-regulate the proliferative responses of primed allogeneic peripheral blood mononuclear cells on rechallenge with antigens. These findings may be important in the development and maintenance of the mucosal immunological activation of inflammatory bowel disease.     

Differential induction of tumor necrosis factor alpha in murine and human leukocytes by Mycoplasma arthritidis-derived superantigen

Mycoplasma arthritidis-derived superantigen (MAS) is exclusively produced by M. arthritidis, which is the only known mycoplasma to produce a superantigen. As a superantigen, MAS shows properties similar to those of the staphylococcal enterotoxins and related substances, such as binding to major histocompatibility complex (MHC) class II and V beta-specific stimulation of T cells. In this series of experiments, we demonstrate some differences between MAS and other superantigens. MAS induced the production of tumor necrosis factor alpha (TNF-alpha) mRNA in human as well as in murine leukocytes. However, only in murine leukocytes was the mRNA adequately translated into the protein. In human peripheral blood mononuclear cells, we found only small amounts of TNF, whereas in murine spleen cells we detected levels more than three times higher. The proliferative response to MAS has been shown to be restricted to I-E alpha in the murine MHC. Furthermore, TNF was induced in I-E alpha+ bone marrow-derived macrophages by MAS. In these cells, MAS rapidly induced very high levels of TNF and the amounts of mRNA detected correlated to the amount of protein produced. In comparison with other superantigens, including the staphylococcal enterotoxins, toxic shock syndrome toxin 1, and exfoliative toxin A, the failure of MAS to induce TNF-alpha in human peripheral blood mononuclear cells is specific for MAS and not common to all superantigens. The direct activation of bone marrow-derived macrophages also seems to be specific for MAS. These data suggest that the induction of TNF-alpha by MAS is dependent on the strength of binding to the MHC class II molecule.     

Early activation of c-Jun N-terminal kinase and p38 kinase regulate cell survival in response to tumor necrosis factor alpha

Fas ligand and tumor necrosis factor alpha (TNF) bind to members of the TNF receptor superfamily. Stimulation by Fas ligand results in apoptosis, whereas TNF induces multiple effects including proliferation, differentiation, and apoptosis. Activation of the c-Jun N-terminal kinase (JNK) and p38 kinase pathways is common to Fas and TNF signaling; however, their role in apoptosis is controversial. Fas receptor cross-linking induces apoptosis in the absence of actinomycin D and activates JNK in a caspase-dependent manner. In contrast, TNF requires actinomycin D for apoptosis and activates JNK and p38 kinase with biphasic kinetics. The first phase is transient, precedes apoptosis, and is caspase-independent, whereas the second phase is coincident with apoptosis and is caspase-dependent. Inhibition of early TNF-induced JNK and p38 kinases using MKK4/MKK6 mutants or the p38 inhibitor SB203580 increases TNF-induced apoptosis, whereas expression of wild type MKK4/MKK6 enhances survival. In contrast, the Mek inhibitor PD098059 has no effect on survival. These results demonstrate that early activation of p38 kinase (but not Mek) are necessary to protect cells from TNF-mediated cytotoxicity. Thus, early stress kinase activation initiated by TNF plays a key role in regulating apoptosis.     

A highly polymorphic CA repeat marker at the human tumor necrosis factor alpha (TNFA alpha) locus

A case of partial bone necrosis of the articular tubercle of the temporomandibular joint is presented. It was probably caused by repeated injections of sodium hyaluronate in the joint. A sequestrectomy was performed under general anesthesia, and the postoperative course was uneventful.     

Tumor necrosis factor alpha induces migration of human eosinophils

In order to evaluate the role of tumor necrosis factor alpha (TNF alpha) in the recruitment of eosinophils and neutrophils into the tissues, we studied the effect of TNF alpha on the migration of those cells in vitro, employing a modified Boyden's chamber technique. TNF alpha induced a significant migration of human eosinophils in a dose-dependent manner, and the preincubation of eosinophils with TNF alpha enhanced platelet activating factor (PAF)-induced eosinophil migration. Checkerboard analysis revealed that the eosinophil migration induced by TNF alpha was mainly due to chemokinesis. On the other hand, TNF alpha induced neither neutrophil migration nor enhancement of PAF-induced neutrophil migration. These results indicate that TNF alpha possesses a chemokinetic effect on human eosinophils and that TNF alpha augments the migration of eosinophils by PAF.     

Comparison of the in vitro activity of several cephalosporin antibiotics against gram-negative and gram-positive bacteria resistant to cephaloridine

The in vitro activity of each of two oral [cefatrizine (BL-S640), cephalexin] and three parenteral (cefamandole, cefazolin, cephapirin) cephalosporin antibiotics was compared with that of cephalothin against 168 clinical isolates of gram-negative and gram-positive bacteria selected as resistant to 20 mug of cephaloridine per ml on the basis of agar dilution susceptibility test data. Each of the five other cephalosporins inhibited a greater percentage of gram-negative bacillary isolates than did cephalothin or cephaloridine, with minimal inhibitory concentration values ranging 2- to 50-fold lower. Significant differences between minimal inhibitory concentrations of the compounds tested were also observed in tests against strains of Streptococcus faecalis and of methicillin-resistant Staphylococcus aureus. Potential advantages of including more than a single cephalosporin antibiotic in the panel of antibiotics used for routine susceptibility testing, suggested by these observations, are discussed.     

Possible roles of nonparenchymal cells in hepatocyte proliferation induced by lead nitrate and by tumor necrosis factor alpha

Several proteins from culture supernatants of Streptococcus sobrinus were able to bind avidly to Sephadex G-75. The proteins could be partially eluted from the Sephadex by low-molecular-weight alpha-1,6 glucan or fully eluted by 4 M guanidine hydrochloride. Elution profiles were complex, yielding proteins of 16, 45, 58 to 60, 90, 135, and 145 kDa, showing that the wild-type strain possessed multiple glucan-binding proteins. Two mutants of Streptococcus sobrinus incapable of aggregation by high-molecular-weight alpha-1,6 glucan were isolated. One mutant was spontaneous, from a cell suspension to which glucan had been added, whereas the other was induced by ethyl methanesulfonate. Both mutants were devoid of a 60-kDa protein, as shown by gel electrophoresis of culture supernatants and whole cells. Amino acid analysis showed that the 58- to 60-kDa protein and the 90-kDa protein were distinct, although both were N-terminally blocked. Both mutants retained their ability to adhere to glass in the presence of sucrose and to ferment mannitol and sorbitol. Both mutants retained their glucosytransferase activities, as shown by activity gels. Western blots (immunoblots), employing antibody against a glucan-binding protein of Streptococcus mutans, failed to reveal cross-reactivity with S. sobrinus proteins. The results show that even though S. sobrinus produces several proteins capable of binding alpha-1,6 glucans, the 60-kDa protein is probably the lectin needed for glucan-dependent cellular aggregation.     

Identification and distribution of tumor necrosis factor alpha receptors in pig corpora lutea

This study examined whether the pig CL contains specific tumor necrosis factor alpha (TNF alpha) receptors and compared the binding affinities and capacities of small and large cell membranes. Aliquots of membranes, isolated from intact or dispersed luteal tissue, were homogenized, and membrane protein content was quantified. Luteal membranes were assayed for specific TNF alpha binding by displacement analysis, with use of [125I]TNF alpha and varying concentrations of unlabeled TNF alpha. Preliminary experiments demonstrated that TNF alpha binding was maximal after incubation at 22 degrees C for 180 min. In addition, [125I]TNF alpha binding was displaced by TNF alpha, but not by other cytokines. Small cell membranes contained a TNF alpha binding site with an affinity (Kd = 11.6-19 nM) different (p < 0.05) from that of the binding site on large cell membranes (Kd = 56.2-99.6 nM). TNF alpha binding capacities were similar in small and large cell membranes. These data demonstrate that pig CL contain specific, saturable TNF alpha binding sites. The higher-affinity binding sites were localized in the small cell population, which contains predominantly endothelial cells and small luteal cells, suggesting that TNF alpha acts primarily on one or both of these cell types within the CL.     

Inhibition of tumor necrosis factor alpha alters resistance to Mycobacterium avium complex infection in mice

Increased production of tumor necrosis factor alpha (TNF-alpha) appears to play an important role in the progression of human immunodeficiency virus disease. One treatment strategy being explored is the use of TNF-alpha inhibitors. TNF-alpha also appears to be important in conferring resistance to infections, and the inhibition of this cytokine may exacerbate the emergence of opportunistic pathogens, such as Mycobacterium avium complex (MAC). The present study examines the possibility that inhibition of TNF-alpha will increase the progression of disease in mice infected with MAC. C57BL/6 beige (bg/bg) mice have been shown to be highly susceptible to infection with MAC and are routinely used for testing of antimycobacterial drugs. However, bg/bg mice are known to exhibit impaired phagocyte and natural killer cell function. Since these cell types are important sources of TNF-alpha, the susceptibility of the bg/bg strain to infection with MAC was compared with those of the heterozygous (bg/+) and wild-type (+/+) strains of C57BL/6 mice. The susceptibilities of the bg/bg and bg/+ strains of mice infected with MAC were found to be comparable. The +/+ strain was the least susceptible. Mycobacterial burden and serum TNF-alpha levels increased over time in all the strains of mice tested. The bg/+ strain of C57BL/6 mice was then chosen to measure the activity of TNF-alpha antagonists. Treatment with dexamethasone decreased serum TNF-alpha levels and increased mycobacterial burden. Treatment with anti-TNF-alpha antibody or pentoxifylline did not significantly alter serum TNF-alpha levels but increased mycobacterial burden. Treatment with thalidomide neither consistently altered mycobacterial burden in the spleens or livers of infected mice nor affected serum TNF-alpha levels.     

Cryptosporidium parvum infection of human intestinal xenografts in SCID mice induces production of human tumor necrosis factor alpha and interleukin-8

The protozoan parasite Cryptosporidium parvum invades intestinal epithelial cells and can cause life-threatening diarrhea in immunocompromised individuals. Despite the clinical importance of this organism, much remains to be learned about the pathogenesis of C. parvum-induced diarrhea. To explore the role of the intestinal inflammatory response in C. parvum disease, using C. parvum oocysts we infected human intestinal xenografts in severe combined immunodeficient (SCID) mice. Seven days after infection, we found levels of human tumor necrosis factor alpha and interleukin-8 in C. parvum-infected human intestinal xenografts that were significantly higher than those seen in uninfected control xenografts. These results demonstrate that human intestinal cells produce proinflammatory cytokines in response to C. parvum infection and establish SCID-HU-INT mice as a model system to study the interactions of C. parvum with the human intestine.