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Query: UMLS:C0021311 (Infection)
 38,178 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Combinations of porcine respiratory coronavirus (PRCV) and either of two swine influenza viruses (H1N1 or H3N2) were administered intranasally and by aerosol to six- to eight-week-old specific pathogen-free pigs. The clinical responses, gross respiratory lesions and growth performances of these pigs were studied and compared with those of single (PRCV, H1N1 or H3N2) and mock-infected animals. PRCV infection caused fever, growth retardation and lung lesions, but no respiratory symptoms. Infection with swine influenza viruses caused rather similar, mild symptoms of disease, with H1N1 infection being the least severe. Combined infections with influenza viruses and PRCV did not appear to enhance the pathogenicity of these viruses. Furthermore, viruses were isolated more frequently from tissues and nasal swabs taken from 'single' than 'dual' infected animals, suggesting a possible in vivo interference between replication of PRCV and swine influenza virus.
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PMID:Pathogenicity of concurrent infection of pigs with porcine respiratory coronavirus and swine influenza virus. 133 65

Sindbis virus (SIN) is a small positive-strand enveloped RNA virus that infects a broad range of vertebrate and insect cells. A SIN vector (called dsSIN), designed for transient expression of heterologous RNAs and proteins, was engineered by inserting a second subgenomic mRNA promoter sequence into a nonessential region of the SIN genome. By using this vector, dsSIN recombinants have been constructed that express either bacterial chloramphenicol acetyltransferase, a truncated form of the influenza hemagglutinin (HA), or mini-genes encoding two distinct immunodominant cytotoxic T lymphocyte (CTL) HA epitopes. Infection of murine cell lines with these recombinants resulted in the expression of approximately 10(6)-10(7) chloramphenicol acetyltransferase polypeptides per cell and efficient sensitization of target cells for lysis by appropriate major histocompatibility complex-restricted HA-specific CTL clones in vitro. In addition, priming of an influenza-specific T-cell response was observed after immunizing mice with dsSIN recombinants expressing either a truncated form of HA or the immunodominant influenza CTL epitopes. This SIN expression system allows the generation of high-titered recombinant virus stocks in a matter of days and should facilitate mapping and mutational analysis of class I major histocompatibility complex-restricted T-cell epitopes expressed via the endogenous pathway of antigen processing and presentation.
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PMID:Infectious Sindbis virus transient expression vectors for studying antigen processing and presentation. 137 87

Standardized bacterial and viral mouse infection models have been developed. Infections with extracellular bacteria (K. pneumoniae, S. pneumoniae, S. pyogenes A) were produced by either of two routes: via the intravenous route (i.v.) resulting in septicaemia and the intranasal route (i.n.) giving infections confined to the respiratory apparatus. Infections with intracellular bacteria (L. monocytogenes, S. typhimurium) were produced only by the i.v. route. Two types of viral infection, mild and severe, were produced. Infection with influenza virus was by aerosol and herpes virus HSV-1 by the intraperitoneal route. All infection models produced under strictly controlled conditions were shown to be characterized by a remarkable reproducibility regarding both the pattern of development and death rate. The infection models lend themselves to estimation of the efficacy of a drug as well as the designing of new therapeutic strategies.
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PMID:Standardized mouse infection models as a way of evaluating the potency of anti-infectious agents. 142 54

Infection by influenza virus results in the stimulation of cytotoxic T lymphocytes specific for killing virally infected cells. Specificity is provided by clonally distributed, hypervariable T-cell receptors on cytotoxic T lymphocytes which react with peptide fragments that are derived from viral proteins expressed in the cytoplasm and 'presented' on the surface of infected cells, bound to class I histocompatibility glycoproteins. Here we describe the structure of the complex between the human class I histocompatibility glycoprotein HLA-Aw68 and the influenza virus nucleoprotein peptide Np 91-99 as determined by X-ray cryocrystallography. Residues at both ends of the peptide are substantially buried in the peptide binding-site, whereas those in the middle of the peptide, P4 to P8, are predominantly exposed and could be recognized directly by T-cell receptors. The extended conformation of the bound viral peptide is remarkably similar to that of a collection of endogenous peptides with a different sequence motif bound to another human allele, HLA-B27. The structure defines in atomic detail the antigenic surface constructed of major histocompatibility complex and viral peptide atoms that is recognized by T-cell receptors.
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PMID:Atomic structure of a human MHC molecule presenting an influenza virus peptide. 144 44

During the 1970s and the early 1980s, immunization practices in the United States were unchanged. Immunization against pertussis, tetanus, diphtheria, measles, mumps, rubella, and polio were routinely administered to children. Infections with these organisms declined dramatically. Nonetheless, research was vigorous, culminating in the 1980s in new vaccines and changes in immunization strategies and practices. This presentation will focus on these changes: universal hepatitis B immunization; two-dose schedule for the measles, mumps, rubella (MMR) vaccine, Hemophilus influenza type B vaccine for infants, acellular pertussis vaccine as booster immunizations, the inactivated polio vaccine, and the yet-to-be-licensed live varicella vaccine.
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PMID:Immunization update. 149 Jun 20

Infection control, nursing and occupational health at St Mary's Hospital and Marian Villa Home for the Aged collaborated to develop, present and evaluate a successful influenza immunization program for patients, residents and staff. The methods used may be applied to any health care facility for a major immunization program. The success of the program can be attributed to the enthusiastic efforts of all three departments and a dedicated task force.
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PMID:Influenza immunization program in long term care facilities. 152 80

We investigated the possible involvement of oxidative mechanisms in the pathogenesis of influenza A/PR8/34 virus infection in mice. As a biochemical marker of oxidative stress, we determined the endogenous concentrations of the antioxidants glutathione and vitamins C and E in their reduced and oxidized forms in the lungs, liver and blood plasma of control and infected animals. Following intranasal infection with 8 to 10 LD50, influenza virus was detected in the lungs, but not in the plasma, liver or other organs. Infection resulted in a decrease in the total concentration of glutathione and vitamins C and E, whereas no relevant change in the ratio of oxidized to total concentration of antioxidants was observed. Changes in the concentration of hepatic antioxidants were significant in the early stages of the infection. The results suggest that hepatic alterations may be caused indirectly by mechanisms related to the host response to virus infection. The observed general decrease in the antioxidant buffering capacity may reduce the ability of tissues to protect against potential oxidative stress. Such stress can occur during bacterial superinfections, which are common in influenza, thereby rendering the host more susceptible to the pathogenic effects of such agents. In addition, reactive oxygen species produced in the lung may inactivate protease inhibitors, resulting in increased protease activity. Using an in vitro system consisting of alpha 1-antiprotease, trypsin and HOCl as the oxidant, we have shown that the infectivity of influenza viruses can be increased up to 10,000-fold by proteolytic cleavage of haemagglutinin, leading to activation of the fusogenic properties of this protein.
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PMID:Alterations in antioxidant defences in lung and liver of mice infected with influenza A virus. 153 Sep 63

Dendritic cells (DC) have a potent antigen-presenting capacity for recruiting resting T cells into immune responses. They also promote expansion of already activated memory T cells. By contrast, macrophages (M phi) are only effective in stimulating memory responses. Infection and depletion of DC occur in human immunodeficiency virus (HIV)-infected individuals and recruitment of T cells into primary responses is blocked. Here comparisons between DC and M phi in stimulating secondary T-cell responses in HIV infection were made. Adherent M phi, and DC isolated by a new method, were separated from peripheral blood of patients in different stages of HIV infection and from uninfected controls and added to allogeneic lymphocytes in mixed leucocyte reactions (MLR). Some were pulsed with influenza virus or tetanus toxoid and used to stimulate autologous T cells. Responses were measured from uptake of [3H]thymidine in 20 microliters hanging drop cultures. DC, but not M phi, from normal individuals stimulated MLR but both populations stimulated secondary responses to recall antigens. DC from all HIV seropositive individuals caused little or no stimulation of any lymphocyte responses. However, M phi from HIV seropositive asymptomatic individuals and those with persistent generalized lymphadenopathy stimulated responses to recall antigens. There was no stimulation using cells from acquired immune deficiency syndrome (AIDS) patients. Blocked DC but not M phi function may underlie progressive immunological non-responsiveness in HIV infection. Without recruitment of resting T cells, loss of memory T cells may be cumulative; failure of secondary activation (e.g. by M phi) would lead to lost T-cell activity. Identification and circumvention of the defect in DC could offer new therapeutic approaches.
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PMID:Antigen-presentation by macrophages but not by dendritic cells in human immunodeficiency virus (HIV) infection. 153 9

Infections of the respiratory airways are frequently responsible for exacerbations of chronic obstructive pulmonary disease (COPD) and attacks of asthma. However, the causal infectious agents in practice are rarely precisely identified. We have undertaken a prospective study with the aim of researching into the bacteria and viruses associated with these exacerbations. Forty-seven patients who were in hospital between 1987 and 1989 for attacks of asthma (13 episodes) or exacerbations of COPD (35 episodes) were included in this study. The microbiological analysis consisted of: 1) the bacteriology of expectorated material or the products aspirated by fibroscopy with direct examination, quantitative cytology and culture; 2) samples taken from the nasal airways to identify and isolate pneumotropic viruses and mycoplasma; 3) serial serology looking for antibodies against pneumotropic bacteria and viruses. One of more infectious agents were shown in 47% of the episode studies of which 57% were exacerbations of COPD and treated 23% attacks of asthma. In the cases COPD bacteria were identified in 13 cases including Haemophilus influenzae [3], Streptococcus pneumoniae [3], Pseudomonas aeruginosa [3]. Amongst the 14 viruses recovered, the influenza virus [8] and the respiratory syncytial virus (VRS) [4] predominated. In 14 cases of acute asthma only 4 infectious agents were shown; Mycoplasma pneumoniae, influenza A, VRS and parainfluenza virus. The influenza virus was the agent most frequently discovered (26%) during the course of exacerbation of COPD and of asthma.
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PMID:[Infectious agents associated with exacerbations of chronic obstructive bronchopneumopathies and asthma attacks]. 156 31

Of all the salivary glands, the parotid gland is most commonly affected by an inflammatory process. Infections of the parotid gland range from acute to severe. Assessment of the disease process should differentiate local primary parotid infection from systemic infection when this gland is also involved as part of a generalized inflammatory condition. Viral parotitis can be caused by paramyxovirus (mumps), Epstein-Barr virus, coxsackievirus, and influenza A and parainfluenza viruses. Acute suppurative parotitis is generally caused by Staphylococcus aureus, Streptococcus species, and rarely, gram-negative bacteria. Anaerobic bacteria, mostly Peptostreptococcus species and Bacteroides species, and pigmented Porphyromonas species and Prevotella species have been recently recognized as an important cause of this infection. beta-Lactamase-producing organisms can be isolated in almost three fourths of the patients. Predisposing factors to suppurative infections are dehydration, malnutrition, oral neoplasms, immunosuppuration, sialolithiasis, and medications that diminish salivation. Pus, aspirated from a suppurative parotic abscess, should be plated on media that are supportive for the growth of aerobic and anaerobic bacteria, mycobacteria, and fungi. Early and proper antimicrobial therapy may prevent suppuration. Initial empiric therapy that is directed against both aerobic and anaerobic bacteria may be required until a specific causal diagnosis is available. Surgical drainage may be indicated when pus has formed. This may prevent complications and facilitate recovery.
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PMID:Diagnosis and management of parotitis. 157 Nov 13


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