Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0021051 (immunodeficiency)
71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Measurement of CD4 T-lymphocyte levels is clinically useful in monitoring immune status in a number of conditions, including human immunodeficiency virus (HIV) infection, in which the absolute CD4 count is used to guide therapy. The absolute CD4 count is obtained by multiplying the results of the leukocyte count and the differential with a hematology cell counter and the percentage of CD4+ T lymphocytes determined by flow cytometry. These techniques require expensive, complex instrumentation, and interlaboratory results are difficult to standardize and reproduce. The rapid growth of HIV infection worldwide has increased the need for more-reproducible and cost-effective methods for CD4 T-cell monitoring. The TRAx CD4 test kit is based on a novel adaptation of conventional enzyme-linked immunosorbent assay (ELISA) and permits the simple quantitation of total CD4 protein from whole-blood lysates. In this study, the relationship between total CD4 protein measured in units per milliliter (TRAx) and in cells per microliter (flow cytometry and hematology) was defined in a multisite clinical study using linear regression analysis. Data from 230 HIV-seronegative and 321 HIV-seropositive specimens were used to calibrate the TRAx assay recombinant CD4 standards and controls in equivalent CD4 T lymphocytes per microliter (cells per microliter). The calibration of the TRAx CD4 assay in cells per microliter was validated with a second group of specimens from 17 healthy volunteers and 20 HIV-seropositive patients which were collected and tested under strictly controlled conditions intended to minimize the effects of specimen aging on the results of the reference method. These data were also used to estimate the variability of absolute CD4 count by cytometric methods as well as the precision of the TRAx CD4 result after it was calibrated in cells per microliter. Overall, correlations between the two methods ranged from 0.87 to 0.95. Additional studies demonstrated that the contribution of CD4 protein from monocytes and any soluble CD4 in sera are negligible in the TRAx assay and do not significantly affect results. This new method represents a promising alternative to absolute CD4 T-cell enumeration by flow cytometry and hematology.
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PMID:Comparison of CD4 cell count by a simple enzyme-linked immunosorbent assay using the TRAx CD4 test kit and by flow cytometry and hematology. 771 1

Eight Belgian AIDS Reference Laboratories established a multicentre quality control to evaluate the performance of their diagnostic human immunodeficiency virus type 1 (HIV-1) DNA polymerase chain reaction (PCR). A set of Belgian and African HIV-1 seropositive and seronegative patient samples, collected in Belgium, and the British Medical Research Council (MRC) HIV-1 PCR reference reagent kit, containing plasmid HIV-1 DNA at several dilutions in human carrier DNA with appropriate negative controls, were tested by the laboratories. No false positive results were reported. All laboratories were able to detect one to two copies of HIV-1 DNA. Among the 17 Belgian and African HIV-1 seropositives, some laboratories reported up to four indeterminate results, mainly due to failure of the SK38-39, SK68-69 (Ou et al. (1988) Science 239, 295-297) and/or gag881-882 (Simmonds et al. (1990) J. Virol. 64, 864-872) primers and a poorly performing algorithm. Only the H1POL4235-4538 nested pol primer set, developed by one of the laboratories, correctly identified all the tested HIV-1 positive and negative samples. Consequently, the laboratories decided to evaluate these pol primers as a reference primer set and to standardise the testing algorithm. All laboratories achieved a sensitivity and specificity of 100% on testing 10 additional Belgian and African patient samples, when adapting a standardised algorithm based on three HIV-1 primer sets, one of which is the H1POL4235-4538 primer set.
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PMID:Standardisation of primers and an algorithm for HIV-1 diagnostic PCR evaluated in patients harbouring strains of diverse geographical origin. The Belgian AIDS Reference Laboratories. 773 51

We used a colorimetric polymerase chain reaction (PCR)-based assay in kit form to detect directly human immunodeficiency virus type 1 (HIV-1) proviral gag sequences in peripheral blood cells from 68 healthy blood donors, 51 subjects at risk for HIV infection, 122 patients with HIV-1 infection, 11 patients with indeterminate Western blot (immunoblot) results, 4 blood donors HIV-1 positive by enzyme immunoassay, and 13 children born to HIV-1-seropositive mothers. The results obtained in the blood donors and HIV-1-infected patients demonstrated the high degree of diagnostic specificity and sensitivity of the PCR method. HIV-1 infection was excluded in 10 of the 11 patients with indeterminate Western blot results and in all four enzyme immunoassay-positive blood donors. A diagnosis of HIV infection was ruled out by negative PCR results in 5 of 13 children from seropositive mothers, which excluded vertical transmission of the infection in these cases; these children were younger than 3 months and had positive serological results. Two at-risk patients with negative serological results had positive PCR results. All results were confirmed by conventional PCR. In conclusion, colorimetric PCR, which is commercially available in kit form, is an easy and reliable technique that can be used to detect proviral HIV-1 genomes in blood cells, and despite the limitations owing to HIV genome variability, it is useful in the clinical setting for the diagnosis of HIV infection in selected categories of patients.
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PMID:Direct detection of proviral gag segment of human immunodeficiency virus in peripheral blood lymphocytes by colorimetric PCR assay as a clinical laboratory tool applied to different at-risk populations. 775 70

The experimental evidence available for animal and plant RNA viruses, as well as other RNA genetic elements (viroids, satellites, retroelements, etc.), reinforces the view that many different types of genetic alterations may occur during RNA genome replication. This is fundamentally because of infidelity of genome replication and large population sizes. Homologous and heterologous recombination, as well as gene reassortments occur frequently during replication of retroviruses and most riboviruses, especially those that use enzymes with limited processivity. Following the generation of variant genomes, selection, which is dependent on environmental parameters in ways that are poorly understood, sorts out those genome fits enough to generate viable quasispecies. Chance events can also be destabilizing, as illustrated by recent results on fitness loss and other phenotypic changes accompanying bottleneck transmission. Variation, selection, and random sampling of genomes occur continuously and unavoidably during virus evolution. Evolution of RNA viruses is largely unpredictable because of the stochastic nature of mutation and recombination events, as well as the subtle effects of chance transmission events and host/environmental factors. Among environmental factors, alterations resulting from human intervention (deforestation, agricultural activities, global climatic changes, etc.) may alter dispersal patterns and provide new adaptive possibilities to viral quasispecies. Current understanding of RNA virus evolution suggests several strategies to control and diagnose viral diseases. The new generation of chemically defined vaccines and diagnostic reagents (monoclonal antibodies, peptide antigens, oligonucleotides for polymerase chain reaction amplification, etc.) may be adequate to prevent disease and detect some or even most of the circulating quasispecies of any given RNA pathogen. However, the dynamics of viral quasispecies mandate careful consideration of those reagents to be incorporated into diagnostic kits. Broadening diagnosis without jeopardizing specificity of detection will be challenging. There is a finite probability (impossible to quantify at present) that a defined vaccine may promote selection of escape mutants or a particular diagnostic kit may fail to detect a viral pathogen. Of particular concern are the potential long-term effects of weak selective pressures that may initially go unnoticed. Variant viruses resulting from evolutionary pressure imposed by vaccines or drugs may insidiously and gradually replace previous quasispecies. The great potential for variation and phenotypic diversity of some important RNA virus pathogens (human immunodeficiency virus, the hepatitis viruses, the newly recognized human hantaviruses, etc.) has become clear. Prevention and therapy should rely on multicomponent vaccines and antiviral agents to address the complexity of RNA quasispecies mutant spectra.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:RNA virus quasispecies: significance for viral disease and epidemiology. 782 89

The testing of dried blood spots (DBSs) for the presence of human immunodeficiency type 1 (HIV-1) proviral DNA by PCR was first described in 1991. The technology has proven to be particularly valuable for resolving the infection status in HIV-1-indeterminate infants born to HIV-1-seropositive mothers. To broaden the applicability of DBS PCR, we adapted it to a standardized, commercially available microwell plate amplification and detection kit, Amplicor HIV-1, produced by Roche Diagnostic Systems. The microwell assay is rapid and easy to perform and uses equipment that is readily available in routine diagnostic laboratories. The high level of performance of the assay was demonstrated in 1,168 duplicate tests performed on 584 DBSs from 178 uninfected and 100 HIV-1-infected individuals, including 56 children with perinatally acquired HIV-1. Of 12 infants who were followed prospectively from birth, 3 (25%) were infected in utero (PCR positive at birth) and 9 (75%) were infected intrapartum (PCR negative, culture negative at birth). Overall, HIV-1 DNA was identified in 3 of 11 (27.3%) DBSs collected from infected infants during the first 4 days of life, 8 of 9 (88.9%) DBSs collected between 10 and 15 days postpartum, and 166 of 167 (99.4%) DBSs collected after 15 days of age. All 320 DBSs from uninfected children were PCR DNA negative. These findings indicate that use of the Roche microwell DBS PCR assay provides a powerful new approach for large-scale perinatal screening programs and population-based studies of vertical transmission.
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PMID:Rapid screening for early detection of mother-to-child transmission of human immunodeficiency virus type 1. 785 49

With the increase in the prevalence of human immunodeficiency virus (HIV) infection in India, there is an urgent need to explore cost-containing methods of HIV antibody detection. We compared the indirect immunofluorescence assay (IFA) with the widely used but expensive confirmatory test, the Western blot (WBT). A panel of sera comprising 42 WB positive, 46 antibody negative (27 ELISA negative and 19 ELISA reactive but WB negative) and 58 sera with indeterminate WB profiles were tested by a commercial IFA kit. The sensitivity of IFA was found to be 97.6 per cent and specificity 97.8 per cent. Of the indeterminate sera, 18 (31%) were positive in IFA while 26 (45%) were negative and 14 (24%) were equivocal. In general, the IFA positivity was associated with the presence of the gag and env antibodies of HIV while negativity associated with the presence of lone antibodies. The cost of testing by IFA is less than 20 per cent of that of WB testing. Thus IFA appears to be a cost-containing alternative to WB in centres in India where immunofluorescent microscopy is routinely done.
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PMID:Comparison of the indirect immunofluorescence assay with western blot for the detection of HIV antibody. 792 64

To investigate mother-to-infant transmission of hepatitis C virus, serial follow-up of anti-HCV and hepatitis C virus RNA was undertaken in 11 infants born to hepatitis C virus-infected mothers who had been screened from 11,688 pregnant women. None of the hepatitis C virus-infected mothers was infected by human immunodeficiency virus. Anti-HCV was checked by the second-generation enzyme immunoassay kit, and hepatitis C virus RNA was examined by reverse transcriptase-nested polymerase chain reaction. Hepatitis C virus RNA was found in more than two serum samples in two of these 11 infants; those two infants were regarded as hepatitis C virus-infected. One of the two had hepatitis C virus RNA at the age of 1, 3, and 6 months, but not later. The course of hepatitis C virus RNA and anti-HCV in this baby may reflect fluctuating viral replication in chronic infectious disease or viral clearance in acute infection. The other infant had hepatitis C virus RNA detectable at the age of 3 months and at 15, 18 and 24 months. In the other nine non-hepatitis C virus-infected infants, maternally acquired anti-HCV gradually disappeared by the age of 6 months. The liver function profile fell to the normal range in all the infants, including the two hepatitis C virus-infected infants. This may indicate the subclinical nature of hepatitis C virus infection in infancy. Seven fathers and four siblings of these 11 infants were checked for anti-HCV and liver function tests; none had evidence of hepatitis C virus infection.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Temporal profile of hepatitis C virus antibody and genome in infants born to mothers infected with hepatitis C virus but without human immunodeficiency virus coinfection. 807 41

There are several methods to detect human immunodeficiency virus (HIV) infection; the detection of antibodies against HIV, the detection of HIV particles, and the detection of HIV infected cells. The detection of anti-HIV antibodies is practical, but the antibodies are undetectable both on a seronegative person at the superacute phase, and the new-born baby from a seropositive mother. No other method is ideal for all purposes. Thus the detection of the HIV-specific nucleotide sequence especially using the PCR method has been expected. We developed a quantitational PCR method to assay HIV-infected PBMC cell number, and the result correlated with that of the quantitational culture method, and also correlated with the CD4 count, that is inversely related to the clinical stage of HIV infection. Our quantitational PCR method must be improved before application to a practical routine test. A new PCR kit to detect HIV infected cells qualitatively has been developed and purchased in Europe. This kit is especially workable to test specimens where the antibody detection method cannot be used. PCR can be used on other specimens and can be applied to HIV infection. HIV RNA (both genomic RNA and viral mRNA) can be detected by a combination with the reverse transcriptase reaction. This method (RT-PCR) will be ideal to detect HIV particles. With PCR, the sequence-differentiation between each clinical virus strain may be detected, thus the characterization of a virus strain such as drug resistance, latency, or the prognosis may be recognized. PCR is indeed a valuable method to detect HIV-infection, provided its limits are properly understood.
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PMID:[The diagnosis of HIV infection by detecting specific nucleotide sequence]. 828 1

An important goal in the de novo design of enzymes is the control of molecular geometry. To this end, an analog of the protease from human immunodeficiency virus 1 (HIV-1 protease) was prepared by total chemical synthesis, containing a constrained, nonpeptidic type II' beta-turn mimic of predetermined three-dimensional structure. The mimic beta-turn replaced residues Gly16,17 in each subunit of the homodimeric molecule. These residues constitute the central amino acids of two symmetry-related type I' beta-turns in the native, unliganded enzyme. The beta-turn mimic-containing enzyme analog was fully active, possessed the same substrate specificity as the Gly16,17-containing enzyme, and showed enhanced resistance to thermal inactivation. These results indicate that the precise geometry of the beta-turn at residues 15-18 in each subunit is not critical for activity, and that replacement of the native sequence with a rigid beta-turn mimic can lead to enhanced protein stability. Finally, the successful incorporation of a fixed element of secondary structure illustrates the potential of a "molecular kit set" approach to protein design and synthesis.
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PMID:Structural engineering of the HIV-1 protease molecule with a beta-turn mimic of fixed geometry. 835 91

Sera have been submitted to the authors' laboratory for syphilis testing at a dramatically increased rate since the start of the human immunodeficiency virus type 1 epidemic. Thus they were interested in evaluating a new enzyme immunoassay, the DCL Syphilis-G test kit (DCL-G, Diagnostic Chemicals Ltd., Oxford, CT) for detection of immunoglobulin G antibodies to Treponema pallidum. The enzyme immunoassay format, with its potential for automation, is ideally suited for large volume batch testing. Five hundred eighty-five sera collected primarily from pediatric patients were subjected to rapid plasma reagin and DCL-G testing. The patients ranged in age from 1 day to 45 years (mean, 14.4 years). Sera yielding positive or equivocal results in duplicate by either method were tested further for T. pallidum immunoglobulin G and M antibodies by the fluorescent treponemal antibody absorbed test and the DCL Syphilis-M test kit. The sensitivity and specificity of DCL-G, considering the combined rapid plasma reagin and fluorescent treponemal antibody absorbed results as the reference, were 100% and 99.8%, respectively. It was concluded that the DCL-G assay was a simple, efficient, and accurate method for obtaining confirmed serologic evidence of past or present syphilis.
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PMID:Evaluation of the DCL Syphilis-G enzyme immunoassay test kit for the serologic diagnosis of syphilis. 844 90


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