Cross-neutralization tests

Baxby D. The surface antigens of Orthopoxviruses detected by cross-neutralization tests on cross-absorbed antisera. J Gen Virol. 1982 58 251-262. 

Specific diagnosis of VEE can be accomplished by virus isolation, serologic testing, or both.110 During the first 1 to 3 days of symptoms of nonspecific febrile illness, VEE virus may be recovered from either the serum or the nasopharynx.111 Despite the theoretical possibility of person-to-person transmission of virus present in the nasopharynx, no evidence of such occurrences has been reported. Identification of the VEE subtype of an isolate involved can be accomplished by cross-neutralization tests. HI, enzyme-linked immunosorbent assay (ELISA), or plaque reduction neutralization (PRN) antibodies appear as viremia diminishes. Complement-fixing (CF) antibodies make their appearance later during convalescence. VEE IgM antibodies are present in acute phase sera,63 and it has been reported that the VEE IgM tests do not react with sera from patients with EEE or WEE.112 Since patients with encephalitis typically come to evaluation later in the course of clinical illness, virus is recovered less often from them,112 and they usually have serum antibody by the time of clinical presentation.113... 

Certain neutral technetium complexes can be used to image cerebral perfusion (Fig. 4). Those in Figure 4a and 4b have been approved for clinical use. Two other complexes (Fig. 4c and 4d) were tested in early clinical trials, but were not developed further. An effective cerebral perfusion agent must first cross the blood brain barrier and then be retained for the period necessary for image acquisition. Tc-bicisate is retained owing to a stereospecific hydrolysis in brain tissue of one of the ester groups to form the anionic complex TcO(ECD) , which does not cross the barrier. This mechanism of retention is termed metaboHc trapping. 

Many issues surrounding neutralizing antibodies remain such as standardization of the neutralizing antibody assay, testing recommendations, and treatment recommendations for positive tests 41 Neutralizing antibodies may disappear even with continued treatment. Neutralizing antibodies exhibit cross-reactivity with the other beta interferons.41... 

Molecular Size of the Compounds The size and molecular length of the PPCP compound can also influence the efficacy of the membrane. Molecular length is, in this instance, defined as the maximum length of the molecule, whereas molecular width refers to its cross-sectional diameter. Kimura et al. (2003) tested 11 neutral pharmaceutically active compounds that greatly vary in molecular weight, octanol-water partition coefficients (Xqw), and dipole moments for regeneration by two distinctly different RO membranes. AU of the assays were conducted at 20°C (pH 7 + 0.1) and filtration was done over a 24-h period. A key assumption from that experiment was that by the end of that duration, the membrane was saturated. The percent regeneration K) of the compound by the membrane was calculated from... 

To explain the shift in current onset.S< cm/sec if o <10 ccm. This is a reasonable number for a neutral surface state,c herefore, this explanation for the observed shift in current onset passes a test of reasonableness. On the other hand, it is hard to be more quantitative without some independent measure of capture cross sections. A method jrf measuring cross sections applicable in some cases has been reported— and will be discussed later in this section. 

The problem of definition of modulus applies to all tests. However there is a second problem which applies to those tests where the state of stress (or strain) is not uniform across the material cross-section during the test (i.e. to all beam tests and all torsion tests - except those for thin walled cylinders). In the derivation of the equations to determine moduli it is assumed that the relation between stress and strain is the same everywhere, this is no longer true for a non-linear material. In the beam test one half of the beam is in tension and one half in compression with maximum strains on the surfaces, so that there will be different relations between stress and strain depending on the distance from the neutral plane. For the torsion experiments the strain is zero at the centre of the specimen and increases toward the outside, thus there will be different torque-shear modulus relations for each thin cylindrical shell. Unless the precise variation of all the elastic constants with strain is known it will not be possible to obtain reliable values from beam tests or torsion tests (except for thin walled cylinders). 

The solubility behaviour of an unknown compound will serve to classify it into one of the three main divisions, namely, acidic, basic or neutral. This information, supplemented by elemental analysis if deemed necessary, and as noted above cross-correlated with spectroscopic inferences, forms the basis for the subsequent systematic search to identify definitively the functional group or groups present. It cannot be too clearly emphasised that inexperience in spectroscopic interpretation can lead to erroneous conclusions of structure. The value of chemical tests is that they reduce the chance of this happening, furthermore they are frequently easily and quickly performed and provide experience in accurate and reliable observation and reporting. 

Koppers "Book Keeping" Process. In view of the limitation of the Wei T o process, chemists at the Koppers Company developed a "Book Keeper" process by dispersing submicron particles of basic metal oxides, hydroxides or salts of calcium, magnesium, or zinc, in a suitable gas such as Freon or liquid medium, so that the active chemicals can be transferred and deposited electrostatically on the surface of paper. It also does not require pre-drying of books as is required for both the DEZ and Wei T o processes. The testing results appear satisfactory as shown in Table I. The major concern with this process is the distribution of the alkaline reserve on the paper. It appears the process deposits alkaline chemicals on the surface of paper and achieves surface deacidification. However, acid formed in the core of the paper is not neutralized. Koppers intends to prove the degrees of chemical penetration and neutralization of acid in the center layers by examination of the cross-section of paper by SEM. 

This vaccine was tested for safety and immunogenicity in 24 human subjects. The injection elicited local moderate pain with no other notable physiologic abnormalities found. The vaccine increased antibody levels up to 12 months after the initial vaccination. Using functional tests such as activation of white cells ex vivo, cytokine generation, and bacterial clearance, the authors found a higher capacity for neutralizing bacteria and activating white cells (Cross et al., 2003). 

Posner test This mechanical testing procedure is designed for measuring spatial-visual attention and orientation (M.L Posner et al., 1988). The test persons are required to sit in front of a computer monitor using a cross in the middle of the screen as a fixation point. A square is visible on either side of the cross. In the neutral position, a question mark is displayed as a cue 200 milliseconds before the stimulus (= asterisk) appears in one of the squares. In the valid position, the cue is an arrow... 

Immunological specificity is best inferred from neutralization or blocking tests. It is fallacious to deduct degrees of cross-reactivity or shared reactivity of a given antiserum in EIH from the results of EIA. Sensitivity and specificity are determined to a high degree by the design of the test as shown in Chapter 2 for the AA and the AM tests, and may, therefore, be very different in EIH and EIA. 

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