Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “quantitative complementation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 937 records · Page 52Linked to original sources
PubMed2001

Phosphite additives and their transformation products in polyethylene packaging for gamma-irradiation.

Infrared (IR) spectroscopy has been used to identify and quantify the phosphite antioxidant, tris(2,4-di-tert.butylphenyl) phosphite, and its corresponding phosphate in high density polyethylene (HDPE) food trays, both in the original, commercial trays and also as a function of gamma-irradiation and post-irradiation, storage conditions. This direct method of inhibitor analysis complements time-consuming (some times non-quantitative) extraction methods, which for organo-phosphites are complicated by their facile conversion to phosphates by peroxidic impurities in the solvent. Because of the complete destruction of phosphite to give mainly phosphate at quite low gamma-irradiation doses (approximately 5 kGy) and phosphate formation during melt processing and radiation sterilization of these HDPE trays must take into account products from the irradiation of phosphate. Any residual phosphite is lost progressively in post-irradiation reactions, which are complex, producing a less than-quantitative yield of phosphate.

Chromatography, High Pressure Liquid↗
PubMed1984

Requirement for the coexpression of T3 and the T cell antigen receptor on a malignant human T cell line.

The association between T3 and the T cell antigen receptor was examined using the T3 bearing T cell leukemic line Jurkat. A monoclonal antibody, C305, was produced, which reacted with idiotypic-like determinants expressed on Jurkat. The molecule with which this antibody reacted was a disulfide-linked heterodimer of 90 kD, composed of polypeptides of 42 and 54 kD. Thus, C305 reacted with a molecule with characteristics of the putative T cell antigen receptor described by others. A series of mutants of Jurkat, induced with ethyl methane sulfonate or radiation, was selected for T3 or antigen receptor negativity. In every instance, there was a concomitant loss of both T3 and the antigen receptor as assessed by quantitative absorption, indirect immunofluorescence, and antibody plus complement-mediated cytotoxicity. The absence of antigen receptor molecules was confirmed on diagonal gels, excluding the possibility that conformational changes of the antigen receptor on such T3-negative mutants were responsible for the failure of such mutants to react with C305. Moreover, in a mutant that expressed a marked decrease in the level of T3 expression, there was a comparable decrease in the expression of antigen receptor determinants. These results suggest that there is an obligate requirement for the coexpression of T3 and the T cell antigen receptor. Furthermore, attempts to activate such mutants with the lectin phytohemagglutinin suggested that the expression of T3 and/or the antigen receptor was required for activation of these cells.

Animals↗
PubMed2001

The leucine-rich repeat domain can determine effective interaction between RPS2 and other host factors in arabidopsis RPS2-mediated disease resistance.

Like many other plant disease resistance genes, Arabidopsis thaliana RPS2 encodes a product with nucleotide-binding site (NBS) and leucine-rich repeat (LRR) domains. This study explored the hypothesized interaction of RPS2 with other host factors that may be required for perception of Pseudomonas syringae pathogens that express avrRpt2 and/or for the subsequent induction of plant defense responses. Crosses between Arabidopsis ecotypes Col-0 (resistant) and Po-1 (susceptible) revealed segregation of more than one gene that controls resistance to P. syringae that express avrRpt2. Many F(2) and F(3) progeny exhibited intermediate resistance phenotypes. In addition to RPS2, at least one additional genetic interval associated with this defense response was identified and mapped using quantitative genetic methods. Further genetic and molecular genetic complementation experiments with cloned RPS2 alleles revealed that the Po-1 allele of RPS2 can function in a Col-0 genetic background, but not in a Po-1 background. The other resistance-determining genes of Po-1 can function, however, as they successfully conferred resistance in combination with the Col-0 allele of RPS2. Domain-swap experiments revealed that in RPS2, a polymorphism at six amino acids in the LRR region is responsible for this allele-specific ability to function with other host factors.

Alleles↗
PubMed2000

The status of evidence and outcomes in Stages of Change research.

The Stages of Change model has become a prominent feature within health promotion and most of the literature associated with the model portrays it as being 'effective'. Based on an extensive review of the literature, this paper suggests that contrary to this view, there exist a relative paucity of sufficiently strong supportive evidence. The paper describes the features of the existing evidence base, and highlights problems in relation to various aspects of design and execution. Two wider issues relating to the core nature of the model and the evidence associated with it are identified as important and discussed. Two main conclusions are drawn. First, better quality quantitative outcome studies are needed. These should be complemented with significant qualitative case studies with a focus on practitioner and organizational utilization of the model. Second, the disproportionate popularity of the model may be skewing the practical and conceptual nature of health promotion. Stages of Change activities are seen to equate to 'health promotion' at the expense of other activities and approaches.

Health Behavior↗
PubMed1988

Improved peptide function from random mutagenesis over short 'windows'.

We have applied random mutagenesis over short contiguous residue tracts ('windows') within an active peptide (the alpha-peptide of beta-galactosidase) such that all window residues are replaced simultaneously. A novel technique using mixed synthetic oligonucleotides and selection against an EcoK restriction site has allowed the construction of libraries of mutants for two separate windows, sites A and B. Mutant phenotypes can be easily assessed in vivo by a complementation test, and panels of mutants have been quantitatively tested in vitro. This allowed the rapid probing of structural requirements for each site. The two windows yielded markedly disparate results. Site B was much less stringent in its sequence requirements for significant function than Site A, and mutants with improved function were isolated at Site B alone. In addition, one Site B mutant with wild-type levels of activity showed enhanced stability to heat or a protein denaturant. We propose that short tracts with the characteristics of Site B constitute 'secondary' interaction sites which are more tolerant of sequence diversity. Random manipulation of such secondary sites is thus more likely to yield upmutations for standard or altered environments. Window mutagenesis can in principle be applied to any protein--protein or protein--ligand interaction.

Amino Acid Sequence↗
PubMed2003

Serial analysis of gene expression and cancer.

Serial analysis of gene expression has been widely used to characterize gene expression patterns associated with tumor formation. These studies resulted in the identification of tumor-specific markers, transcriptional pathways, or therapeutic targets. In this review, recent applications and developments of serial analysis of gene expression and their impact on the diagnosis and treatment of cancer are discussed. A combination of serial analysis of gene expression and small-scale microarray analysis represents a strategy that should facilitate the identification and exploitation of tumor-specific gene expression for diagnostic or therapeutic purposes. In addition, cancer diagnosis and treatment may benefit from a complementation between serial analysis of gene expression and quantitative proteomics in the future.

Biomarkers, Tumor↗
PubMed1993

An interleukin-6-induced acute-phase response does not confer protection against lipopolysaccharide lethality.

Lipopolysaccharide (LPS), a component of gram-negative bacterial outer cell walls, can stimulate lymphoreticular cells to produce cytokines such as tumor necrosis factor alpha (TNF-alpha), interleukin-1 (IL-1), and IL-6. One of these proinflammatory cytokines, IL-6, induces hepatic synthesis of a class of proteins termed acute-phase proteins. D-Galactosamine inhibits acute-phase protein synthesis and concurrently sensitizes mice to a lethal dose of LPS approximately 10,000-fold. From these observations, we hypothesized that the acute-phase response may serve as a defense mechanism for protection of the host against the deleterious effects of LPS. To test this hypothesis, murine recombinant IL-6 (mrIL-6) was used to induce an acute-phase response prior to a lethal LPS challenge in both D-galactosamine-treated and normal mice. Induction of the acute-phase response by mrIL-6 was quantitated by measuring the concentrations of fibrinogen and complement component C3, two well-characterized acute-phase proteins, in the circulation. The effect of acute-phase and normal serum on TNF-alpha release by peritoneal macrophages stimulated with LPS in vitro was also examined. The results of these studies confirmed the induction of the acute-phase response by mrIL-6, as reflected in an approximate doubling in circulating levels of fibrinogen and C3. However, when either D-galactosamine-sensitized or normal mice were challenged with a lethal dose of LPS at various times after mrIL-6 administration, the acute-phase response induced by mrIL-6 did not alter either cumulative lethality or the kinetics of lethality. Additionally, compared with normal serum, acute-phase serum did not affect TNF-alpha release by peritoneal macrophages following LPS-mediated stimulation in vitro. Collectively, these studies would not support a dominant role for an IL-6-mediated acute-phase response as contributing to the resistance of normal mice compared with D-galactosamine-sensitized mice in LPS-induced lethal toxicity.

Acute-Phase Reaction↗
PubMed1983

The use of conventional electromyography to assess external sphincter neuropathy in man.

Conventional electromyography was used to measure motor unit potential duration in the external anal sphincter in normal subjects and patients with idiopathic faecal incontinence. The results revealed a direct correlation between age and mean motor unit potential duration in control subjects, but no differences between age-matched male and female subjects. Patients with faecal incontinence exhibited prolongation of mean motor unit potential duration compared with matched controls. This technique provided useful quantitative data on reinnervation within the anal sphincter, complementing the results of single fibre electromyography.

Action Potentials↗
PubMed2004

Can the use of HIV-1 derived gene transfer vectors for clinical application be justified?

Vectors derived from human immunodeficiency virus type 1 (HIV-1) are an attractive option for many gene therapy applications as they can transduce non-cycling cell populations, and can integrate their genome into the host cell chromosome. The rationale underlying the design of most retroviral vector systems is to segregate the viral cis sequences, which are required for transfer of the viral genome, from the trans sequences that encode viral proteins. This allows the efficient production of replication incompetent virus and has been successfully applied to the generation of HIV-1 vectors. Nonetheless, the possibility that recombination events in the vector production system can generate replication-competent virus, combined with the pathogenic nature of HIV-1, raises major bio-safety issues. Numerous HIV-1 vectors have now been reported, with each generation significantly improved in ways designed to reduce the risk of replication-competent virus being produced. However, progress in vector design needs to be complemented by the development of methods for the quantitation of the probability of replication competent virus being produced. Assaying individual events in the multi-step pathway that can lead to the production of replication-competent virus, rather than relying on the detection of replication-competent virus per se, will be important for quality control purposes. This review will specifically examine the approaches to HIV-1 vector design that have been postulated as increasing bio-safety, possible methods for evaluating bio-safety and whether these approaches are likely to be sufficient to overcome resistance to the use of HIV-1 for clinical application. In addition, we discuss the possible justifications for developing vectors from lentiviruses other than HIV-1.

Genetic Therapy↗
PubMedDate not supplied

Image cytometry DNA analysis of invasive squamous cell carcinoma of the esophagus.

The Feulgen-DNA content of squamous carcinoma cell nuclei from the human esophagus was assessed in punch biopsies from 47 untreated patients. Forty-four of the 47 biopsies (93.6%) demonstrated aneuploid cell populations, and the remaining 3 (6.4%) were non-diploid. Previous studies have demonstrated that in esophageal dysplasias adjacent to invasive squamous cell carcinoma, DNA in single cells is substantially altered. Thus the process of esophageal carcinogenesis can be monitored not only by histological changes, but also by DNA aberrations in single cells. Quantitative DNA measurement appears, therefore, to be a complement to the histological evaluation of esophageal lesions with suspected, but not unequivocal, evidence of neoplastic growth.

Adult↗
PubMed1985

Predictive value of quantitative renography for successful treatment of atherosclerotic renovascular hypertension.

Twenty patients with severe atherosclerotic renal artery stenosis were studied by quantitative gamma camera renography before angioplasty or surgery. Sixteen patients were treated by angioplasty and two each by bypass surgery and nephrectomy. Total and relative renal function, renal perfusion, and tracer transit times through the affected and contralateral kidney were calculated. All but one of the angioplasty patients and one of the two bypass surgery patients also had quantitative renography performed one to two weeks after treatment to assess changes in renal function. In the remaining four patients, changes in renal function were assessed by serial serum creatinine estimations. Patients were classified as cured, improved, or not improved according to their blood pressure response. Five had evidence of unilateral functionally significant stenoses and normal contralateral kidneys (four cured, one improved). Ten had functionally significant stenoses but with abnormal contralateral kidneys (all improved). Five had no evidence of functionally significant stenoses (all not improved). Quantitative renography provides functional and prognostic information to complement anatomical assessment by angiography. It is a simple, safe, and non-invasive means of predicting the outcome for patients with hypertension and renal artery stenosis.

Adult↗
PubMed1986

Human C81 (alpha-gamma) polymorphism: detection in the alpha-gamma subunit on SDS-PAGE, formal genetics and linkage relationship.

The molecular basis of human C81 (alpha-gamma) polymorphism could be elucidated by immunoprecipitation of human C81 allotypes and separation of the alpha-gamma and beta subunits on sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) under nonreducing conditions. If the C8 molecules were completely reduced, C81 polymorphism was no longer detectable on SDS-PAGE. It is concluded that C81 variation depends on charge rather than molecular weight differences. Four C81 allotypes, the common A and B and two rare allotypes provisionally named A2 and B1, could be distinguished. The rare allotype A1 as detected by isoelectric focusing with subsequent C8 (alpha-gamma)-dependent functional overlay could no longer be visualized on SDS-PAGE. This allotype may therefore be elicited only in the intact C8 molecule. The beta-chain polymorphism named C82, probably also reflecting charge variation of the C8 molecule, could not be detected yet on SDS-PAGE. The distributions of C81 phenotypes and their respective allele frequencies were in good agreement with previously reported data. In the study of 30 families with 100 offspring, no deviation from the rule of at least four codominant alleles at one genetic locus was found. Linkage between C81 gene(s) and PGM1a encoded on chromosome 1 could be confirmed. The following estimates were obtained: (formula; see text) with S theta being the standard error of the maximum likelihood estimate theta. The new technique for allotyping human C81 at the subunit may provide a new tool for the differentiation of qualitative and quantitative variation of the eighth component of human complement.

Alleles↗
PubMed1997

Immunosuppression in dogs with pyoderma and/or demodicosis.

The occurrence of decreased activity of the immune system was studied in a group of 66 dogs with various combinations of pyoderma and demodicosis. Our complex examination of the dogs included the following: leukocyte count, differential count, phagocytosis, blastogenic lymphocyte transformation and quantitation of total serum immunoglobulins, lysozyme and haemolytic complement. Immunosuppression was found in 19 (28.8%) cases. Immunosuppression was rare in dogs with demodicosis and did not appear without a concurrent pyoderma. An increase in the neutrophil counts and total serum immunoglobulin levels significant was found in dogs with demodicosis combined with pyoderma. On the contrary, marked immunosuppression was detected in dogs with deep pyoderma. A considerable immunosuppression was present in 7 of 10 German shepherds dog pyoderma (GSP). Significant depressions were found in phagocyte activity and lymphocyte activity. Immunosuppression was observed in 4 of 9 dogs in other breeds with uncomplicated deep pyoderma. All groups of dogs with pyoderma showed a significant increase in total serum immunoglobulins. Conclusion from these findings is that deep pyoderma more than Demodicosis was concerned with immunosuppression. German shepherds with deep pyoderma had more expressed immunosuppression than other breeds.

Animals↗
PubMed1997

[Effects of bisphosphonates on the mechanical efficiency of normal and osteopenic bones].

Bone mechanical competence (stiffness, strength) at organ level is determined by mechanical quality (intrinsic stiffness) and spatial distribution (macro-architecture) of bone material in cortical tissue (in every bone) and trabecular network (in vertebral bodies). These properties are inter-related and controlled according to mechanical usage by a feed-back mechanism known as mechanostat. Therefore, the effects on bone fragility of any treatment should be evaluated concerning the way they may have affected bone material or geometric properties as well as the mechanostatical interactions between them. Standard densitometry does not provide the necessary data, but some alternative methodologies (as peripheral quantitative computed tomography, pQCT) are being developed to complement or even substitute SPA, DPA or DXA determinations. Bisphosphonate (BP) effects on bone biomechanics have been studied only in animal models. Many sources of variation of results (type of compound, dose, mode of administration, species, race, sex, age, age since menopause, type of bone, remodeling ability of the skeleton, endocrine-metabolic status, interactions with other treatments, etc.) have been reported. In general terms, BPs are beneficial concerning cortical bone strength in purely modeling species (rodents) and trabecular strength in remodeling mammals (dogs, baboons). This positive action at organ level depends on independent improvements in bone macro-architecture (mainly affected by bone modeling) and material stiffness (chiefly affected by bone composition and remodeling). On one hand, bone macro-architecture has been positively affected by BPs in normal (not in ovariectomy (OX), steroid- or disuse-induced osteopenic) animals. On the other, bone material quality has been improved in the latter but not in the former. Mechanostatic interrelationships have been differently affected according to the compound employed. Results reported by ours and other laboratories concerning the three derivatives available nowadays in Argentina were reviewed and summarized. Pamidronate improved small rodents' cortical bone strength and geometric properties at low doses but impaired mineralization, material properties and strength at toxic doses. In normal, remodeling animals it improved mechanical properties in vertebral bodies but not in long bones. It also prevented the negative impact of OX-, steroid- or disuse-induced osteopenia in rats by improving bone material properties without affecting normal mechanostatic interrelationships. Olpadronate exerted positive effects on long-bone strength at any dose in normal rats and mice by improving cross-sectional properties and preserving both mineralization and material properties. These effects were highly dependent upon bone deformability, body weight, and mechanical usage of the limb as an evidence of an anabolic interaction induced on bone modeling and mechanostatic interrelationships. This compound also prevented the OX- or disuse-induced impairment in rat cortical long-bone strength and recovered rat cortical bone when given since 3 months after OX by improving only bone material quality. No interaction with bone mechanostat was detected in these studies. Alendronate effects on bone biomechanics in normal rats and dogs were positive only in long treatments. They were highly dependent on body weight of the animals, hence a positive interaction with bone mechanostat should be hypothesized. It also prevented the negative impact of OX in rat femurs by improving cortical material quality with no effect on cross-sectional properties, i.e., exerting an anti-catabolic interaction with bone mechanostat. The effects of all the three compounds were found positive for bone health, yet their mechanisms of action varied with type of bone and subject condition. A striking dissociation between (positive) effects on bone strength and (variable) effects on bone stiffness was repeatedly observed in these studies. Also an enla

Animals↗
PubMed1997

Quantitative analysis of C4Ab and C4Bb binding to the C3b/C4b receptor (CR1, CD35).

Complement-dependent clearance of immune complexes in humans is dependent on the activation and binding of the early components of the classical complement cascade. This prevents immune complex precipitation and promotes binding of the complexes by the C4b/C3b complement receptor CR1 (CD35) found on erythrocytes. The fourth component of human complement is encoded by two closely linked genes within the MHC. These genes give rise to the isotypic forms C4A and C4B, and recent studies suggest that CR1 binds activated C4A (C4Ab) to a greater extent than activated C4B (C4Bb). To study this difference in a more quantitative way the binding reactions between CR1 and C4Ab- and C4Bb-coated immune complexes and between CR1 and soluble dimers of C4Ab (C4Ab2) and C4Bb (C4Bb2) were analysed using the native receptor on human erythrocytes. The binding reaction between immune complexes with equivalent amounts of covalently bound C4Ab or C4Bb and erythrocyte CR1 showed a two-fold higher binding of complexes coated with C4A. Furthermore, erythrocyte CR1 bound C4Ab2 with an apparent four-fold higher affinity (Kd approximately 1.4 x 10(-7) M) than C4Bb2 (Kd approximately 4.8 x 10(-7) M), indicating a preferential binding of CR1 for C4A.

Antigen-Antibody Complex↗