Treatment of HeLa cells with bacterial water extracts inhibits Shigella flexneri invasion

Pathogenesis mediated by Shigella flexneri requires invasion of the gastrointestinal epithelium. It has been previously shown that HeLa cells challenged with S. flexneri show alterations in their phosphotyrosine-containing protein profile. In this report, we demonstrated that bacterial water extracts (WE) abrogated the invasion of HeLa cells by S. flexneri in a dose-dependent manner. A proteinaceous component of S. flexneri was shown to be responsible for this inhibitory activity. Proteins encoded on the 140-MDa plasmid were not responsible for the observed inhibition. WE from other Gram-negative bacteria also inhibited Shigella invasion of HeLa cells pretreated with WE showed changes in the profile and the intensity of phosphotyrosine-containing protein bands. These data were consistent with a surface protein component in WE which initiated aberrant host cell signaling at the membrane which may account for the inhibition of bacterial entry.

Biological effects of the interferons and other cytokines

There were seven workshops that primarily concerned the biological effects of the interferons and the other cytokines. These were: Workshop 6, The refractory state in the response to interferons (IFNs) and antibodies in treated patients; Workshop 7, IFNs, multiple sclerosis, and the nervous system; Workshop 9, Viral inhibition of the response to IFNs and other cytokines; Workshop 10, Cell growth inhibition by IFNs and other cytokines; Workshop 12, Cytokines and cell death; Workshop 13, Interactions between cytokines; and, Workshop 14, Cytokine gene therapy. Summaries of each of these sessions follow.

Growth factors and intrauterine growth retardation. I. Serum growth hormone, insulin-like growth factor (IGF)-I, IGF-II, and IGF binding protein 3 levels in normally grown and growth-retarded human fetuses during the second half of gestation

The aim of this study was to relate human fetal growth retardation to specific hormone alterations. Serum levels of GH, IGF-I, IGF-II, and IGF binding protein (BP) 3 were measured during the second half of gestation after cordocentesis in 230 fetuses who were classified into normally grown (n = 166) and growth-retarded (n = 64) groups according to ante- and neonatal measurements. The normally grown group showed a progressive decline in serum GH levels toward term (r = -0.42, p = 0.0001), whereas serum IGF-I was increased (r = 0.55, p = 0.0001), as were serum IGF-II (r = 0.21, p = 0.008) and IGFBP3 levels (r = 0.19, p = 0.02), although less markedly. For all hormone levels, wide individual differences were found at any given age of gestation. The incidental presence of fetal malformations in either the normally grown group (n = 107 cases) or the growth-retarded group (n = 50 cases) had no apparent effect on these hormone levels as compared with members of the groups showing no fetal malformations (n = 73 cases). Comparison of the normally grown group with the growth-retarded group showed that serum IGF-I levels were significantly lower in the growth-retarded group (p = 0.001). No differences were found between the groups in serum GH, IGF-II, and IGFBP3 levels, although if data for the third trimester were taken alone, serum IGF-II levels were found to be lower in the growth-retarded group (p = 0.05). In conclusion, during the second half of gestation, fetal serum IGF-I levels may be influenced by nutritional factors controlling fetal growth. However, the wide individual differences in measurements make it a very poor biologic marker of intrauterine growth retardation.

Evaluation of symptom surveys for occupational musculoskeletal disorders

Symptom surveys have been used extensively as part of workplace ergonomic screening programs and epidemiologic assessments of musculoskeletal disorders in groups of workers. This paper examines the reliability and validity of two musculoskeletal symptom surveys, the Nordic Musculoskeletal Questionnaire (NMQ) and a survey used in conjunction with epidemiologic assessments by the National Institute for Occupational Safety and Health (NIOSH). Journal articles assessing the validity and reliability of the NMQ were reviewed. A retrospective assessment combining two NIOSH cohorts with a total of 852 workers assessed the reliability and validity of that survey. Reliability was assessed through test-retest methods and interitem correlations between similar questions. Validity was assessed by comparison with results from physical examination assessments of workers and self-reports of workers seeking medical care. Both reliability and validity were found to be acceptable for the purposes of workplace ergonomics programs. Implications for use of these surveys for prevention and treatment outcomes research are discussed.

Value of influenza vaccine during an outbreak of influenza A in a nursing home, Pyrenees Atlantiques, France, November-December 1995

A public health officer of the Direction Departementale de l'Action Sanitaire et Sociale des Pyrenees Atlantiques in France was notified of an outbreak of acute respiratory illness among residents of a nursing home on 4 December, 1995. Over 50 of the 69 r

Cluster of cases of haemolytic uraemic syndrome due to unpasteurised cheese

A cluster of four patients (1 girl, 3 boys) from a French village (2,000 inhabitants) had acute haemolytic uraemic syndrome (HUS) between March 1992 and May 1993. All had prodromes with fever and diarrhoea, then acute renal failure, anaemia, schistocytosis and thrombocytopenia. Peritoneal dialysis was carried out in three children (duration 3-12 days). The verotoxin VT2 gene was identified by polymerase chain reaction in the stools of two children. Some days prior to the diarrhoea, all children had eaten a cheese made with unpasteurised mixed cows' and goats' milk from the same farm. A case control study showed that the occurrence of HUS was linked to the consumption of this milk product (P = 0.006). The VT 2 gene was isolated from the cheese and from the stools of goats and cows from the farm, but not from the stools of farm employees.

Health care worker exposure to aerosolized ribavirin: biological and air monitoring

Aerosolized ribavirin is administered frequently to treat severe respiratory syncytial virus infections. The drug's potential reproductive effects in occupationally exposed workers remains a concern among health care workers. In this evaluation, we measured urinary ribavirin concentrations in occupationally exposed health care workers. Ribavirin was detected in 16 of 26 (62%) post-work-shift urine samples that had been provided by nurses, and in five of 22 (23%) post-work-shift urine samples that had been provided by respiratory therapists (range, < 0.01 to 0.22 mumol/L). We also measured airborne ribavirin concentrations in the personal breathing zones of nurses. Ventilators and other administration units that were enclosed by an aerosol containment tent produced significantly lower airborne ribavirin exposures than administration units without a containment tent did (range, < 2.5 to 78 micrograms/m3). On the basis of this and other evaluations of airborne ribavirin concentrations, we recommend using aerosol containment systems with all types of ribavirin administration units except mechanical ventilators.

Decrease of intracellular fluorescein fluorescence polarization (IFFP) in human peripheral blood lymphocytes undergoing stimulation with phytohaemagglutinin (PHA), concanavalin A (ConA), pokeweed mitogen (PWM) and anti-CD3 antibody

In the present study we describe the induction of changes in intracellular fluorescein fluorescence polarization (IFFP) in lymphocytes undergoing activation with a variety of stimulants. These stimulants included the lectins phytohaemagglutinin (PHA), concanavalin (ConA), pokeweed mitogen (PWM) and anti-CD3 antibody. Changes in IFFP were detected in individual cells using the Cellscan apparatus. Our results show that by employing mitogenic concentrations of PHA, as revealed in a [3H]-thymidine incorporation assay, a decrease in the IFFP in human peripheral blood lymphocytes (PBL) occurred within 40 min. ConA and anti-CD3 affected similarly IFFP, whereas PWM, a B lymphocyte lectin, had no effect on IFFP at the concentrations employed. Kinetic analysis revealed that changes in IFFP occurred within 20-40 min after exposure to the stimulants and lasted for 24 h. Our results show that stimulants which activate CD3+ lymphocytes caused immediate changes in IFFP, in an enriched population of human PBL. The possible mechanisms involved in IFFP modulation following exposure to selected stimulants are discussed.

Interleukin-1 alpha mediates the enhanced expression of intercellular adhesion molecule-1 in pulmonary epithelial cells infected with respiratory syncytial virus

The mechanisms of virus-induced enhancement of intercellular adhesion molecule-1 (ICAM-1) expression in epithelial cells are unknown. In the present study, the effect of respiratory syncytial virus (RSV) infection on the expression of ICAM-1 in human pulmonary type II-like epithelial (A549) cells was evaluated. Conditioned RSV media (cRSV) produced from growth of RSV in A549 cells induced a significant increase in the expression of ICAM-1. Treatment of the cells with noninfectious cRSV prepared by ultraviolet (UV) irradiation (UV-cRSV) or ribavirin treatment resulted in the expression of ICAM-1 to a similar extent as infectious cRSV. These results suggested that RSV induces the synthesis of a soluble mediator(s) that regulates the expression of ICAM-1. Cytokine analysis by immunoassay and polymerase chain reaction showed that RSV induces the synthesis of interleukin (IL)-1 alpha and -beta, and tumor necrosis factor alpha (TNF-alpha). Preincubation of UV-cRSV with soluble IL-1 receptor (sIL-1r) almost completely blocked the enhancement of ICAM-1 expression. Furthermore, simultaneous incubation of infectious purified RSV with sIL-1r resulted in a significant reduction in enhancement of ICAM-1 expression. Preincubation with neutralizing antibodies to IL-1 alpha and -beta, and TNF-alpha showed that the predominant ICAM-1 enhancing soluble mediator in UV-cRSV was IL-1 alpha. These experiments provide direct evidence for an autocrine mechanism of enhanced ICAM-1 expression in RSV-infected epithelial cells that is mediated primarily by IL-1 alpha. Pulmonary epithelial cells may play an important immunoregulatory role in the microenvironment of the lower respiratory tract infected with RSV.

Production of interferon gamma messenger RNA by cells of non-immune origin

There is general agreement that IFN-gamma is produced only by cells of immune origin (T-cells, NK cells, and recently macrophages). However, indirect evidence has suggested that undetectable, low levels of IFN-gamma produced by cells of non-immune lineage, such as the murine line L-929, enhanced the antiviral activity of IFNs-alpha and/or beta following induction by agents such as the double stranded RNA poly ICLC. Since L-929 cells were one of the prototypic cell lines for studying murine IFN induction and action, we felt that it would be important to validate this observation by detection of the mRNA for IFN-gamma. If confirmed, it might indicate a role for IFN-gamma in non-immune cells. The present investigations revealed that mouse L-929 fibroblasts produce IFN-gamma message following exposure to conventional IFN-alpha/beta inducers such as poly ICLC or Newcastle disease virus. In addition, we found that IFN-gamma itself will induce its own message. We further show that this is not a phenomenon isolated to transformed cells since we found that normal mouse embryo fibroblasts also produced the message, however in a constitutive fashion.

[Invasive group A streptococcal infections in France]

OBJECTIVES

Following the recent report of necrosing fasciitis cases in Great Britain, we conducted a study of group A streptococci infections in France to evaluate the frequency and severity of the different clinical presentations, particularly necrosing fasciitis.

METHODS

Thirteen hospital laboratories were selected because of the large number of group A streptococci blood cultures they observed in 1993. The microbiologists in these hospitals, in relation with clinicians, identified 83 patients with a group A streptococci bacteraemia between January 1, 1993 and June 30, 1994.

RESULTS

Sixty-three percent of the patients had an underlying condition: 39% had a chronic general or local disease and 24% had severe immunodepression. The skin portal of entry was found for 70% of the cases. Patients were divided into 4 groups according to the clinical picture: there were 16 cases of streptococci shock syndrome, 13 with deep infections, 25 infections of soft tissue (including 3 cases of fasciitis) and 29 cases of isolated bacteraemia.

CONCLUSION

Overall, one-fourth of the patients died due to the streptococci infection, one-half of whom had a toxic shock syndrome. Mortality was correlated with age and health status, but also with the clinical presentation of the disease. Compared with former years, there was no increase in the number of group A streptococci infections, nor in the number of necrotizing fasciitis in France in 1993. However, streptococci shock syndrome is of particular importance because of its frequency and poor outcome.

Vertebrate brains contain a broadly active antiviral substance

Brain tissue extracts from vertebrates were examined for non-specific, broad-spectrum virus inhibitors, previously identified and characterized from other body tissues and fluids. An antiviral activity found in human, bovine, ovine, porcine, lapine, murine and piscine brain tissues shares some properties with a contact blocking-virus inhibitor, which was previously found only in cell culture supernatants. The inhibitor was active against (in order of sensitivity to inhibitor) Banzi, Sindbis, Bunyamwera, Newcastle disease, herpes simplex I, Semliki forest, polio I, mengo, vaccinia and vesicular stomatitis viruses. It is approximately 4000 kDa and possesses a complex structure containing protein, carbohydrate and lipid moieties. The inhibitor does not directly neutralize virus or induce an antiviral state in cells, but appears to act early in the replication cycle, most likely by preventing virus attachment to target cells. Its occurrence in concentrations sufficient to reduce virus yield in cell cultures at least 30-fold may indicate a role in limiting viral infections of the central nervous system.

IFN-alpha treatment suppresses the development of experimental autoimmune myasthenia gravis

Myasthenia gravis (MG) is an Ab-mediated autoimmune neuromuscular disease and is linked to MHC class II beta-chain polymorphism. Corticosteroids and azathioprine are the primary immunosuppressive drugs used in the treatment of MG. These drugs have significant side effects and have limited efficacy. Therefore, drugs with fewer side effects and greater efficacy are being sought. IFN-alpha is a potent immunomodulator and has been shown to down-regulate MHC class II expression on lymphoid cells. MHC class II expression is critical for the development of experimental autoimmune myasthenia gravis (EAMG). Because of the immunomodulating effects of IFN-alpha and its effect on the MHC class II expression, we tested the therapeutic efficacy of IFN-alpha on EAMG induced by immunization with acetylcholine receptor (AChR) in CFA. IFN-alpha (10(5) IU three times weekly for 5 wk) treatment started 1 wk after the second immunization with AChR in CFA, when autoimmunity to AChR is well established, reduced the incidence of clinical EAMG by more than 50% in two separate experiments (p = 0.04 and 0.008). Therefore, IFN-alpha could be a potential agent for the control of MG, and other Ab-mediated autoimmune diseases.

IFN-alpha treatment suppresses the development of experimental autoimmune myasthenia gravis

Myasthenia gravis (MG) is an Ab-mediated autoimmune neuromuscular disease and is linked to MHC class II beta-chain polymorphism. Corticosteroids and azathioprine are the primary immunosuppressive drugs used in the treatment of MG. These drugs have significant side effects and have limited efficacy. Therefore, drugs with fewer side effects and greater efficacy are being sought. IFN-alpha is a potent immunomodulator and has been shown to down-regulate MHC class II expression on lymphoid cells. MHC class II expression is critical for the development of experimental autoimmune myasthenia gravis (EAMG). Because of the immunomodulating effects of IFN-alpha and its effect on the MHC class II expression, we tested the therapeutic efficacy of IFN-alpha on EAMG induced by immunization with acetylcholine receptor (AChR) in CFA. IFN-alpha (10(5) IU three times weekly for 5 wk) treatment started 1 wk after the second immunization with AChR in CFA, when autoimmunity to AChR is well established, reduced the incidence of clinical EAMG by more than 50% in two separate experiments (p = 0.04 and 0.008). Therefore, IFN-alpha could be a potential agent for the control of MG, and other Ab-mediated autoimmune diseases.

Treatment of intracranial alphavirus infections in mice by a combination of specific antibodies and an interferon inducer

Finding an effective treatment for viral infections that cause encephalitis remains an important problem. A model of human alphavirus infections, Semliki Forest virus, causes lethal encephalitis in weanling mice. Mice are viremic within 24 hr of an intraperitoneal challenge with the equivalent of three 75% lethal doses of Semliki Forest virus. Virus reaches the brain by 48 hr, and mortality results in all mice in 5-7 days. Introduction of virus intracranially accelerates the course of the infection. Neither anti-Semliki Forest virus hyperimmune serum nor the potent interferon inducer poly I:CLC given intraperitoneally are protective when used therapeutically after an intracranial virus infection, but a combination of 1,000 U hyperimmune serum and 80 micrograms/mouse of poly I:CLC results in a 50% survival rate. This combination treatment of intracranial Semliki Forest virus infection eliminates detectable viremia and reduces virus load in the brain over the course of the infection. These data show that when combined, specific antibody and an interferon inducer can interact synergistically to protect mice from alphavirus infections of the central nervous system even when given after the virus is replicating in the target organ.

Relationship between muscle fiber types and sizes and muscle architectural properties in the mouse hindlimb

Skeletal muscle fiber and architectural properties both contribute to the functional behavior of a muscle. This study uses discriminant analysis and mathematical modeling to identify the structurally and functionally significant properties. The architectural properties of fiber length, muscle length, and pennation angle are found to be the most structurally significant parameters, whereas fiber length, muscle length, and fiber type distribution are found to be most functionally determining. Architectural speed and fiber type do not appear to be complimentary (i.e., the architectural determinant of speed, fiber length, is not associated with fibers of high intrinsic velocity). However, there does seem to be a synergistic relation between the two property classes and force production. Muscles with large physiological cross sectional areas (PCSAs) tend to contain a greater proportion of larger, faster fibers. Structurally or morphologically significant parameters are not always found to have a large functional effect. Pennation angle, though one of the most structurally significant variables, was found to have very little functional effect.

Sex-related effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridine treatment may be related to differences in monoamine oxidase B

Effects of the parkinsonism inducing neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on striatal dopamine metabolism and the influence of sex on the recovery were investigated in adult (2-month-old) male and female C57/BL mice. We present here evidence that MPTP treatment (2 doses of 30 mg/kg i.p., each at 24 h interval) produced a similar reduction (-65% to -70%) of striatal dopamine in both sexes 24 h after the last injection of MPTP, and a greater loss of the metabolites in the female group. In contrast to the partial recovery observed in the male group, an increased dopamine loss occurred in the female group within 10 days following the last injection of MPTP. This impairment in recovery appears to be different to the one already observed in aged (24-month-old) male mice treated in similar conditions. As the neurotoxic effects of MPTP depend on its conversion to the 1-methyl-4-phenylpyridinium ion (MPP+) by monoamine oxidase B (MAO B), the presence of a different peripheral or central MAO B type in female mice could be in part responsible for these sex related effects. To investigate this possibility, MAO A and B activities were characterized in liver and brain of adult female control mice during the different steps of the oestrous cycle and compared to those of adult control male mice. Significant differences in MAO A and MAO B activities could be detected during the oestrous cycle and between the adult male and female groups. It is concluded that MAO B may be involved in the sex related effects of MPTP.

The interferons: a biological system with therapeutic potential in viral infections

Successful medical use of interferon for chronic viral infections is increasingly dependent on understanding the biologic and molecular mechanisms of the interferon system. Interferon (IFN) is one of the body's natural defenses. Production of IFN is a defensive response to foreign components of microbes, tumors and antigens. This IFN response begins with the production of the IFN proteins (alpha, beta and gamma) which then induce antiviral, antimicrobial, antitumor, and immunomodulatory actions. Thus, the initial production or administration of IFN(s) does not protect directly but instead reacts with specific receptors on cell surfaces to activate cytoplasmic transduction signals that then enter the nucleus to stimulate cellular genes encoding a number of effector proteins which lead to the defensive actions. The known molecular, humoral and cellular mechanisms by which these effector proteins exert their antiviral activities are presented. In addition, the pathogenesis of chronic infections is overviewed in the context of the interferon defenses.

Lymph node micro-metastasis: an investigation, including three-dimensional reconstruction

The mechanism by which malignant cells metastasis to, and colonise, regional lymph nodes is not known. In an attempt to characterise micro-deposits an affected lymph node associated with a primary intra-oral squamous cell carcinoma was studied. Three-dimensional reconstructions of the node and micro-tumour were made and the relationships and distribution of apparently isolated malignant cells present within the node studied. Semi-serial ethanol-fixed paraffin was sections of the node were stained with monoclonal antibody AE3 (cytokeratin). Outlines of the node and occupying micro-tumour were traced onto polystyrene tiles and onto acetate sheets, permitting the construction of both a solid and a transparent three-dimensional model. Additionally, the positions of apparently 'isolated' AE3-positive malignant cells were noted. The solid reconstruction showed that the micro-tumour deposit grew most quickly into the node via the septa and more slowly around the subcapsular region. The transparent reconstruction was less useful. Most isolated, individual malignant cells were found in the peripheral margin of the node.