Showing papers on "Typing published in 1985"

Identity verification through keyboard characteristics

Abstract: Most personal identity mechanisms in use today are artificial. They require specific actions on the part of the user, many of which are not “friendly”. Ideally, a typist should be able to approach a computer terminal, begin typing, and be identified from keystroke characteristics. Individuals exhibit characteristic cognitive properties when interacting with the computer through a keyboard. By examining the properties of keying patterns, statistics can be compiled that uniquely describe the user. Initially, a reference profile is built to serve as a basis of comparison for future typing samples. The profile consists of the average time interval between keystrokes (mean keystroke latency) as well as a collection of the average times required to strike any two successive keys on the keyboard. Typing samples are scored against the reference profile and a score is calculated assessing the confidence that the same individual typed both the sample and the reference profile. This mechanism has the capability of providing identity surveillance throughout the entire time at the keyboard.

Method for the serological typing of the capsular polysaccharides of Staphylococcus aureus.

Abstract: A method is described for typing Staphylococcus aureus capsular polysaccharides that is based on direct bacterial cell agglutination and immunoprecipitation of cell extracts with monospecific antisera. Encapsulated strains were identified by their inagglutinability with teichoic acid antisera. The typing sera reacted specifically with extracts of eight prototype strains.

Development of a bacteriophage typing system for Campylobacter jejuni and Campylobacter coli.

Abstract: A bacteriophage typing system for Campylobacter jejuni and Campylobacter coli was developed with phages isolated from poultry feces. Data for phage selection were generated from a set of isolates of C. jejuni and C. coli from humans in Illinois. Selection of 14 phages from the 47 phages available was assisted by determination of the Sneath-Jaccard similarity coefficients and subsequent unweighted pair-group arithmetic averaging cluster analysis. The typing set was reproducible and stable in the 255 isolates from Illinois. Of these isolates, 94.5% were typable, with 46% represented by the four most common phage patterns. In a set of 51 isolates from humans outside of Illinois, 88.1% of the C. jejuni isolates were typable. Phage typing for C. jejuni and C. coli has excellent epidemiologic potential and should serve as a useful adjunct or alternative to serotyping systems in current use.

Importance of ovine cytotoxic T cells in protection against bluetongue virus infection.

Abstract: In sheep, bluetongue virus (BTV) was shown to induce anti-BTV cytotoxic T lymphocytes (CTL) and their effect to be maximal around 14 days post inoculation (p.i.) of virus. Using cellular adoptive transfer techniques in monozygotic sheep, such cells were shown to partially protect animals from BTV challenge. A short-lived cross-protective mechanism was identified involving thoracic duct lymphocytes (TDL) and nonneutralising antibody. These observations suggest that T lymphocytes play an important role in protection against BTV and that current vaccine design based on in vitro serological typing of BTV can be improved.

Biochemical and serological investigations on clinical isolates of klebsiella.

Abstract: A series of 925 clinical isolates of klebsiella was examined by serological and biochemical typing. To perform serological typing (capsular swelling) 77 capsular antisera were prepared, tested against the type strains and grouped in 13 pools. With this serotyping method 80% of the cultures were typable and 63 distinct types could be recognized. All strains were typable biochemically by means of the numerical coding system of the API-20E system supplemented by digits derived from 15 additional conventional biochemical tests. With the API-20E system 24 different biotypes could be distinguished whereas the combination of API-20E and the 15 additional tests produced 93 biotypes. Maximum discrimination of strains was achieved by the combination of serological and biochemical typing (256 bioserotypes). The reproducibility, typability and discriminating power of the biotyping system was not inferior to serotyping. For epidemiological purposes biotyping can replace serotyping of Klebsiella species, especially in laboratories less well equipped.

Typing Chinese, Japanese, and Korean

Abstract: W hat can be said of an alphabet containing over 50,000 letters? If nothing else, it certainly makes a language hard to touch-type. The Chinese, Japanese, and Korean scripts are based on ancient Chinese ideographic characters, whose vast number has precluded the development of convenient typing devices until quite recently. The advent of the minicomputer has stimulated a technological and social revolution in Asia by making it practical to type Chinese, Japanese, and Korean.

The HLA Complex

Abstract: The history of HLA typing originates in the early attempts to define the types of leukocytes. Although red cell antigens had been known since the time of Landsteiner, early efforts to apply the techniques of red cell typing to detect the antigens on leukocytes were fraught with technical problems. A comprehensive review of these historical methods and techniques is provided by Walford1 and by Killman.2

Comparison of neutralization and DNA restriction enzyme methods for typing clinical isolates of human adenovirus.

Abstract: Sixty-five adenovirus isolates collected over a 3.5-year period were typed by both standard microneutralization techniques and restriction endonuclease digestion of viral DNA. Of the 65 isolates, 47 (72.3%) representing six adenovirus types could be typed by microneutralization. Eighteen isolates demonstrated partial neutralization with standard antisera to two or more adenovirus serotypes and thus could not be definitively typed. DNA analysis permitted typing of 64 of the 65 isolates (98.5%) (including four isolates which contained mixtures of two adenovirus types), and 12 different types were identified. Neutralization and DNA typing disagreed for five isolates, and in each case, digestion with multiple restriction endonucleases and DNA hybridization studies were consistent with the type assigned by DNA analysis. In addition, the DNA analysis method allowed the identification of genomic variants (genome types) of five adenovirus types. We conclude that typing clinical isolates of adenovirus by restriction endonuclease digestion of viral DNA can be done rapidly, provides additional epidemiological and typing information, and provides fewer ambiguous results than does typing by neutralization. Images

Typing of heat-stable and heat-labile antigens of Campylobacter jejuni and Campylobacter coli by coagglutination.

Abstract: A coagglutination system has been devised for typing heat-stable and heat-labile antigens of Campylobacter jejuni and C. coli. The use of protein A-positive Staphylococcus aureus cells carrying Campylobacter sp. serotype antibody and the treatment of Campylobacter sp. cells with DNase in the antigen suspension permitted rapid and specific coagglutination of rough (autoagglutinable) as well as smooth cultures. Cells of S. aureus were sensitized with Campylobacter sp. serotype antisera. Four to five types of sensitized S. aureus cells were pooled. A strain of Campylobacter sp. was first tested with the pools and then typed with the individual reagents of the reactive pool. After the described procedures, 68 serotype strains tested blindly as unknowns were correctly typed according to their heat-stable or heat-labile antigens. The two most commonly used typing schemes which are based separately on the heat-stable or the heat-labile antigens as assayed by passive hemagglutination and slide agglutination, respectively, can be utilized simultaneously in the coagglutination system for strain characterization. The coagglutination system is simple, yields results rapidly, conserves typing reagents, and offers the flexibility of formulating the pools of reagents according to the experimental design or the prevalence of serotypes in a geographic location. It should be a practical system for the typing of Campylobacter spp. in public health or clinical laboratories.

Comparison of immunofluorescence with commercial monoclonal antibodies to biochemical and biological techniques for typing clinical herpes simplex virus isolates.

Abstract: Immunofluorescence with monoclonal antibody reagents from two commercial sources for differentiating herpes simplex viruses types 1 and 2 demonstrated 100% agreement with cell culture selectivity (chicken embryo and guinea pig embryo cells) and (E)-5-(2-bromovinyl)-2'-deoxyuridine sensitivity for typing a total of 94 clinical herpes simplex virus isolates.

Klebsiella marker systems.

Abstract: Klebsiella marker systems include determination of susceptibility patterns, serotype, bacteriocin susceptibility, bacteriophage susceptibility, biotype, and plasmid content, size and endonuclease fragment size. Susceptibility patterns are useful only if unusual patterns (ie, aminoglycoside resistance) occur. Serotypes are stable, reproducible markers. Over 90% of isolates can be serotyped and epidemiologically unrelated strains are widely distributed among the 72 standard types. Antisera are not available commercially except to types 1 to 6 and serotyping is expensive and time-consuming. Bacteriocin susceptibility typing is easier and cheaper but reproducibility is sometimes poor. Depending on the producer strains used, between 67% and 96% of strains are typable. As a single typing method, bacteriophage typing is not very sensitive. Only 70% of strains are typable and 20% are of a single type. There are two major problems with most biotyping systems: poor reproducibility and poor sensitivity. A high percent of strains is the same type. Plasmid analysis is technically the most complicated but is important if strains are aminoglycoside resistant. No one method is ideal, and characterization of isolates from an outbreak is best done by using several different marker systems.

The basic phage set for typing bovine staphylococci.

Abstract: Two hundred and sixty-nine Staphylococcus aureus cultures isolated from bovine milk were subjected to phage typing using the International basic set of 16 phages at Routine Test Dilution. In the current study 73.6% of cultures were 'typable' compared with 84-89% in 1972 when the set was first recommended. The set remains capable of typing the majority of bovine staphylococci but shows a reduction in lysogenicity of most of its phages.

Comparison of four methods for typing low-passage herpes simplex virus isolates.

Abstract: Clinical isolates of herpes simplex virus (HSV) were identified as HSV type 1 or type 2 by sensitivity to (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU), by differential replication in chick embryo cells versus guinea pig embryo cells, by restriction endonuclease analysis, and by a direct fluorescent antibody technique using monoclonal antibodies. More than 550 isolates were typed by two or three of the systems with complete agreements as to virus type between systems for each isolate. In appropriately equipped laboratories, any of the above typing systems can be used with complete confidence. However, the BVDU sensitivity assay, particularly when used in a continuous cell line as described, can be economically utilized in any virology laboratory.

Fifty-fourshigella sonnei colicin types and their typing by specific indicator strains

Abstract: Fifty-fourS sonnei colicin types and 92 indicator strains used for their determination are listed Most of the indicators were prepared by conjugational transfer of Col factors from shigellae to the recipient strains ofE coli K13 HfrRnalr andE coli K12 ROW or by selection of resistant mutants of these strains or by combination of both methods Ten indicators areS sonnei strains The indicator strains are suitable forE coli colicin typing

The QWERTY keyboard hampers schoolchildren

Abstract: The introduction of microcomputers into schools has created a new generation of unskilled keyboard users whose needs are quite different from those of the skilled typist. In particular, their interaction with the keyboard is likely to be the keying in of a single word or a single letter in response to a prompt from a computer-aided learning program, rather than the continuous typing of running text. A standard keyboard skills program for the BBC micro was adapted to allow comparison of an alphabetic (ABCDE) keyboard with the standard QWERTY keyboard layout on speed of single key processing. Three groups (age 8, 12 and 20 years) of inexperienced keyboard users were tested with each layout in a counterbalanced repeated measures design. As expected, mean response time was significantly faster for the older subjects. The major finding, however, was that, in contrast to previous studies of adult continuous typing, the QWERTY layout resulted in significantly worse performance for all three age groups. The QWERTY responses were not only slower but also showed a much greater variability than the ABCDE responses.

Avirulence andAltered Physiological Properties ofCystic Fibrosis Strains ofPseudomonas aeruginosa

Abstract: Twenty Pseudomonas aeruginosa strains isolated frompatients withcystic fibrosis ingoodandpoorclinical condition weretyped bytheAmerican Scientific (Difco Laboratories, Detroit, Mich.) Typing Scheme.Onlyfive strains wereagglutinated with asingle typing serum.Tenstrains wereagglutinated withmore thanoneserum, andfive were notagglutinated withany serum,suggesting some typeoflipopolysaccharide alteration inthe majority ofthese strains. Ofthestrains frompatients ingoodclinical condition, 72% demonstrated proteolytic activity, while 60%ofthestrains frompatients inpoorclinical condition demonstrated no proteolytic activity. Twenty-three cystic fibrosis strains ofP.aeruginosa examined demonstrated reducedbacteremic virulence whencompared witha virulent burnstrain witha 50%lethal dose(LD50) of1.5x 10'CFU inan invasive burned mouse model. Ninety-two percent ofthestrains tested were avirulent atdosesof103to105CFU.The LD50swere determined for10selected strains whichexhibited specific important morphological and physiological deficiencies. Fiveofthestrains tested gaveLD50s > 106CFU.Reducedvirulence ofthese strains was associated withloss oftwoor more physiological characteristics associated withvirulence. Thecystic fibrosis strains ofP.aeruginosa whichmorphologically andphysiologically resembled thevirulent burnstrain werethemostvirulent (LD50s of102to104). Results suggest that somedegree ofvirulence isassociated onlywith classic strains prevalent inearly infections. Thedatasuggest that a selection transition occursinthelungs of patients withcystic fibrosis thatfavors P.aeruginosa avirulence. Theavirulent state may becausedby alterations inthecell envelope, including associated factors suchas motility andchemotaxis andprotease production.

Hospital infection caused by non-typable Staphylococcus aureus: application of reverse typing

Abstract: Hospital infections caused by strains of Staphylococcus aureus non-typable (NT) by phages have occurred in three Spanish hospitals since 1981. Reverse typing allowed characterization of the strains in all three cases.

Simplified restriction endonuclease method for typing and subtyping adenoviruses.

Abstract: Restriction endonuclease digestion of viral DNA labelled in vivo with phosphorus-32 has been used to type and to subtype both conventional and enteric adenoviruses. The method is a modification of that already described for typing and subtyping herpes simplex virus and, like the latter, needs far less material than methods previously described.

HLA typing and karyotyping of limited numbers of lymphocytes is facilitated by in vitro expansion with TCGF.

Abstract: It is often difficult to obtain sufficient quantities of leukocytes from bone marrow (BM) transplant recipients for post-transplant immunological monitoring and evaluation of engraftment. We have developed a cell culture expansion technique that allows HLA-A,B, and DR typing as well as karyotyping on limited numbers (less than 10(7)) of lymphocytes. Lymphocytes from healthy control donors were allo-activated in vitro and further expanded by culturing in T-cell growth factor (TCGF). After 14 days of culture, these cells were sent for blind HLA-A,B and DR typing and for karyotyping. Surface marker studies showed that 90% of the T-cells expanded in growth factor are OK-la positive. HLA typing with these DR-bearing in vitro expanded T-cells showed excellent correlation with HLA typing on fresh unexpanded lymphocytes. Karyotyping of expanded T-cells showed normal male or female cells as expected. This technique may be especially valuable when testing pediatric or adult patients with very low lymphocyte counts.

Preparation of anti-Gm antibodies and their application to enzyme-linked immunosorbent assay (ELISA) and immunoblotting for Gm typing

Abstract: Gm typing has not yet come into widespread use in forensic science practice because of the short supply of anti-Gm sera and anti-Rh0 sera indispensable for the conventional hemagglutination-inhibition method. To overcome the shortage of human anti-Gm sera, rabbit anti-Gm sera were prepared by immunization with normal IgG subclass proteins and their fragments. These heteroantisera—anti-Glm(2), anti-Glm(3), anti-G3m(5), anti-G3m(16), and anti-G3m(21)—can distinguish the nine Gm phenotypes in the Japanese. Indicator cells alternative to anti-Rh0-coated cells were prepared by coupling IgG subclass proteins to red cells using the chromic chloride method. The Glm(2), Glm(3), and G3m(21) antigens could be identified by this method. As a typing technique which involves no hemagglutination reaction, a solid-phase micro-ELISA (enzyme-linked immunosorbent assay) for Gm typing was developed. The Glm(3), G3m (16), and G3m(21) antigens could be detected with the rabbit anti-Gm sera and the monoclonal anti-G3m(21) antibody produced by the hybridoma technique. Satisfactory results were obtained by an immunoblotting technique with the monoclonal anti-G3m(21) antibody. Gm typing by the ELISA and immunoblotting with anti-Gm antibodies promise to become new typing methods alternative to the conventional method. Monoclonal anti-Gm is best suited for these methods because of its high titer and specificity.

The assessment and application of a bactenocin typing scheme for Clostridium perfringens

Abstract: SUMMARY A collection of 50 bacteriocins was assembled and used to type 802 isolates of ClJostridium perfrinyens from food poisoning outbreaks and a variety of other sources. It was found that strains of the same serotype within an outbreak showed similar patterns of susceptibility to bacteriocins, and the use of a ' one difference ' rule is proposed for interpretation of the typing patterns of epidemiologically related strains. Isolates of diSerent serotype or of the same serotype isolated from difFerent sources produced many variations in bacteriocin susceptibility patterns. Two computer programs were developed to assist in the interpretation of bacteriocin typing patterns. Their use showed that related and unrelated strains formed different clusters and enabled a range of the 20 most discriminatory bacteriocins to be selected. Isolates of C. perfringens from a wide range of sources were screened for their ability to produce bacteriocins A much greater proportion of the strains from food poisoning outbreaks was bacteriocinogenic than were isolates from human and animal infections, various foods and the environment. The relevance of these findings to the occurrence of C. perfrinyens food poisoning is discussed.

Immunologic typing of splenic lymphocytes of intrauterine human fetuses used as donors of pancreatic islet cells

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