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PubMed1994

The Clostridium perfringens Tet P determinant comprises two overlapping genes: tetA(P), which mediates active tetracycline efflux, and tetB(P), which is related to the ribosomal protection family of tetracycline-resistance determinants.

The complete nucleotide sequence and mechanism of action of the tetracycline-resistance determinant, Tet P, from Clostridium perfringens has been determined. Analysis of the 4.4 kb of sequence data revealed the presence of two open reading frames, designated as tetA(P) and tetB(P). The tetA(P) gene appears to encode a 420 amino acid protein (molecular weight 46,079) with twelve transmembrane domains. This gene was shown to be responsible for the active efflux of tetracycline from resistant cells. Although there was some amino acid sequence similarity between the putative TetA(P) protein and other tetracycline efflux proteins, analysis suggested that TetA(P) represented a different type of efflux protein. The tetB(P) gene would encode a putative 652 amino acid protein (molecular weight 72,639) with significant sequence similarity to Tet(M)-like cytoplasmic proteins that specify a ribosomal-protection tetracycline-resistance mechanism. In both C. perfringens and Escherichia coli, tetB(P) encoded low-level resistance to tetracycline and minocycline whereas tetA(P) only conferred tetracycline resistance. The tetA(P) and tetB(P) genes appeared to be linked in an operon, which represented a novel genetic arrangement for tetracycline-resistance determinants. It is proposed that tetB(P) evolved from the conjugative transfer into C. perfringens of a tet(M)-like gene from another bacterium.

Amino Acid Sequence↗

PubMed1975

Antigenic determinants of the W28 molecule different from but spatially close to W28 determinant.

The existence of two allelic determinants, subtypic to W28 (named TO54 and TO55), and of an antibody cross-reacting W28 times HL-A10, is demonstrated. These new determinants have been studied by means of population and family studies and with the following serological techniques: absorption, elution, lysostrip and blocking by F(ab)-2 fragment. The results suggest that determinants TO54 and TO55 are very similar each other and are spatially close to the supertypic factor.

Adsorption↗

PubMed1979

Phylogeny of the rabbit gamma-chain determinants: a d12-like antigenic determinant in Pronolagus rupestris.

A survey for constant region gamma-chain allotypes (de locus) was undertaken in different lagomorph genera. As yet only Pronolagus rupestris, a paleolaginae, showed the presence of a determinant similar to rabbit d12 although it lacked the widespread e15 determinant. All seven individuals possessed the d12 like determinant which was studied by immunodiffusion, haemagglutination inhibition, radiobinding and binding inhibition assays. In addition, a new enzymic method for typing for d12, based on the presence of the asymmetric rabbit hinge carbohydrate linked to the d12 characteristic threonine, is presented. This method suggests, however, that, unlike the d12 rabbit, Pronolagus does not seem to have a majority of IgG molecules with a glycosylated hinge.

Animals↗

PubMed2002

Homocysteine determinants and the evidence to what extent homocysteine determines the risk of coronary heart disease.

Cardiovascular diseases (CVD), especially coronary heart disease (CHD), are the most important causes of death in industrialized countries. Increased concentrations of total plasma homocysteine (tHcy) have been associated with an increased risk of CHD. Assuming that this relation is causal, a lower tHcy concentration will reduce the occurrence and recurrence of CHD. Therefore, it is important to know which factors determine the tHcy concentration. In the general population, the most important modifiable determinants of tHcy are folate intake and coffee consumption. Smoking and alcohol consumption are also associated with the tHcy concentration, but more research is necessary to elucidate whether these relations are not originating from residual confounding due to other lifestyle factors. The most important nonmodifiable determinant is the 677 C>T polymorphism in the gene that encodes methylenetetrahydrofolate reductase (MTHFR), a regulating enzyme in homocysteine metabolism. Especially subjects with the homozygous form of this polymorphism (i.e., 677TT genotype) and a low folate status have elevated tHcy concentrations. Specific clinical conditions like the use of antiepileptic drugs or methotrexate, renal failure, cancer, rheumatoid arthritis, and hypothyroidism may lead to elevated tHcy concentrations. The available epidemiological evidence indicates that an increased tHcy concentration is not an important risk factor for CHD in healthy subjects. However, prospective studies, which included subjects at high risk of CHD, and secondary prevention trials with intermediary endpoints consistently show that elevations in the tHcy concentration may be an important risk factor in these subjects for a (recurrent) CHD event. The induction of vascular endothelial dysfunction by homocysteine may underlie this increased risk. Ongoing intervention trials will indicate whether homocysteine-lowering through vitamin supplementation, prevents CHD in the treatment groups.

Adult↗

PubMed1987

Comparison of the genetic determinant coding for the S-fimbrial adhesin (sfa) of Escherichia coli to other chromosomally encoded fimbrial determinants.

DNA probes specific for different regions of the S-fimbrial adhesin (sfa) determinant were constructed and hybridized with DNA sequences coding for P (F8 and F13), mannose-sensitive hemagglutinating type 1 (F1A), and F1C fimbriae. While the sfa and F1C DNA determinants exhibited homology along their entire lengths, the P-fimbrial and type 1-fimbrial determinants exhibited homology to regions of the sfa cluster responsible for the control of transcription and, to a minor extent, to regions coding for proteins involved in biogenesis and/or adhesion of the fimbriae and for the N-terminal part of the fimbrillin subunit.

Adhesins, Escherichia coli↗

PubMed2006

A study to determine if human umbilical cord hematopoietic stem cells can survive in baboon extra-embryonic celomic fluid: a prerequisite for determining the feasibility of in-utero stem cell xeno-transplantation via celocentesis.

OBJECTIVES: To determine if: (1) human umbilical cord stem cells could survive for 20 h in extra-embryonic celomic fluid obtained at 40 days of development from baboon pregnancies by ultrasound-guided celocentesis and, (2) human hematopoietic stem cell survival could be enhanced by adding increasing concentrations of hematopoietic stem cell culture medium to the celomic fluid. METHODS: CD34+ cells were isolated from umbilical cord blood using a magnetic activated cell sorter and flow cytometry. Cells were then cultured in five platforms containing different combinations of baboon extra-embryonic celomic fluid and hematopoietic stem cell culture medium to determine cell survival kinetics over a 20-hour period in each of the conditions. RESULTS: Human umbilical cord stem cells can survive for at least 20 h in baboon's celomic fluid. Chi-square for linear trends demonstrated that the number of viable cells was significantly enhanced by adding the increasing concentrations of culture medium to the celomic fluid (29% cell survival in pure celomic fluid, 48% at 1:8, 50% at 1:2, 54.5% at 1:1, 61% in pure culture medium; p < 0.001). CONCLUSIONS: Human umbilical cord stem cells survive in baboon celomic fluid and cell survival improves when the celomic fluid is mixed with greater concentrations of hematopoietic stem cell culture medium. Based on these findings, future in-vivo experiments in the pregnant baboon animal model can be directed at determining whether in-utero injection of human hematopoietic stem cells prior to 10 weeks of pregnancy can lead to permanent chimeras.

Animals↗

PubMed1994

A novel liposome immune lysis assay (LILA) for determination of CRP antigen using two monoclonal antibodies recognizing different antigenic determinants.

We have already developed the liposome immune lysis assay (LILA) for the determination of C-reactive protein (CRP) by employing an inhibition method and a sandwich method. We herein report a new LILA system involving the use of monoclonal antibodies-bearing liposomes. We established five monoclonal antibodies to CRP antigen, AC-1, -2, -3, -4, -5 which had the capacity to activate complement and form antigen-antibody complex. Each of these antibodies was covalently coupled to carboxyfluorescein-entrapped multilamellar liposomes. When the liposomes were incubated with CRP antigen in the presence of guinea pig complement, CRP antigen-dependent liposome lysis was observed but the sensitivity was not great enough for practical use. On the other hand, when liposomes coupling two monoclonal antibodies (AC-1, AC-2) which recognized distinct CRP antigenic determinants were employed in the assay, the sensitivity increased compared with that using only one monoclonal antibody, and the detectable concentration range was 5-300 ng/ml. These results indicated that the combination of two or more monoclonal antibodies which recognize distinct CRP antigenic determinants is effective for increasing the sensitivity of the assay.

Animals↗

PubMed2001

The determinants of systolic pulmonary venous flow reversal by transthoracic pulsed Doppler in mitral regurgitation: its value in determining the severity of regurgitation.

OBJECTIVE: Systolic pulmonary venous flow reversal (SPVFR) has been evaluated in mitral regurgitation (MR) primarily by transoesophageal echocardiography (TEE). There is limited study on the value of SPVFR obtained from transthoracic echocardiography (TTE) for the quantification of MR. In this study, determinants of SPVFR and the accuracy of SPVFR obtained with TTE in determining the severity of MR were investigated. METHODS AND RESULTS: Fifty patients with MR in whom reference quantitative Doppler evaluation was carried out formed the study group. Thirty-nine of them underwent cardiac catheterization. In all patients, SPVFR was evaluated by pulsed Doppler echo placed both at the right and left pulmonary vein in the apical four-chamber view. The SPVFR was present in 26 (52%) patients. Atrial fibrillation, and grade III-IV MR by catheterization were more frequent in patients who had SPVFR. Patients with SPVFR had increased values for regurgitant orifice area, regurgitant volume, regurgitant fraction, and left atrium/left ventricle diameters and volumes compared to patients without SPVFR. After multivariate analysis regurgitant fraction (RF) was the single and most powerful determinant of SPVFR (p<0.001). The SPVFR had high sensitivity, specificity and accuracy for the diagnosis of severe MR (89, 95 and 92%, respectively). CONCLUSION: It was concluded that SPVFR is a useful method for the evaluation of the severity of mitral regurgitation.

Adult↗

PubMed1986

Determination of L-ascorbic acid in tomato by isotachoelectrophoresis. Application of computer simulation system for setting of determination conditions to avoid the mixed-zone problem.

When the isotachoelectrophoretical method is used with HCl-beta-alanine as the leading electrolyte solution (pH 3.6), ascorbic acid forms a mixed zone with glutamic acid, and it is difficult to separate the two. Therefore, the application of a computer simulation system to separate the two acids was investigated. This system can be used with compounds for which the absolute electrophoretical mobility and dissociation constant have already been determined. Values for glutamic acid alone were entered in the data bank "SIPS-1", and then those for ascorbic acid were estimated from the values of similar compounds. Values for aspartic acid were used, and the electrophoretical behavior of ascorbic and glutamic acids was simulated at pH range from 3 to 9.9. Based on this simulation, separation appeared possible at pH 9.0 to 10.0, and indeed, experimental determination of ascorbic acid was successfully performed with a leading electrolyte solution composed of HCl-ethanolamine (pH 9.4) without any glutamic acid interference. Even though ascorbic acid is highly susceptible to oxidation in an alkaline medium, because the ascorbic acid solution is injected at the interface of the leading and terminal electrolyte solutions in the electrophoretical procedure, it does not come in contact with air during electrophoresis. This explains why ascorbic acid can be determined in an alkaline medium.

Ascorbic Acid↗

PubMed1975

Quantitative determination of drugs by means of densitometry of thin-layer chromatograms. Part 4: Determination of vitamins A and E in pharmaceutical preparations.

A quantitative method for the determination of vitamins A and E is proposed based on the direct densitometry of thinlayer chromatographic spots. An appropriate solvent system for the chromatographic separation of the vitamins and the conditions under which a linear relationship between the absorbed light and the logarithm of concentration exists (1--10 mug range) are found. The precision of the method is evaluated by a statistical treatment of the results. Satisfactory reproducibility is established-- the variation coefficient for the determination of the two vitamins is about 4--5%. The method is applied for the analysis of oil and aqueous injection solutions, mixtures containing the three vitamins A, E and D2 and some pharmaceutical preparations (Pharmavit¿ and Devitforte¿). The presence of the decomposition products and other substances (other pharmaceuticals, stabilizers, solubilizers etc.) does not affect the determination. The analysis is performed without preliminary treatment of the sample.

Chromatography, Thin Layer↗

PubMed1975

[Quantitative determination of the main metabolites of acetylsalicylic acid. 1. A method for the quantitative determination of salicylic acid and its metabolites. Studies in healthy individuals].

For special purposes a combination of methods is described which allows to determine salicylic acid (including acetylsalicylic acid) and its main metabolites in blood plasma and urine separately and quantitatively. Salicylic acid (SA) and salicyluric acid (SU) are extracted from the acidified fluid with ether and afterwards reextracted in an aqueous phase. By fluorometry at different wavelengths, it is possible to differentiate between SA and SU. The conjugates of SA and SU are hydrolyzed with sulfuric acid and then extracted in the form of SA and SU. The four analyses (SA, SU and their conjugates) are of satisfying accuracy and sensitivity. To test the validity of the method in vivo, the concentrations of SA and its conjugates were determined in the plasma and urines of healthy volunteers. By a simplified, but nevertheless accurate, modification of the described method total salicylate in the urine can be determined.

Adult↗

PubMedDate not supplied

[Determination of melittin antigenic determinants in a model membrane].

Monospecific polyclonal antibodies labelled with colloid gold were obtained against melittin in different conformations (monomer, tetramer and complex with BSA). They were used for electron analysis of the position of antigenic determinants of melittin in DMPC model membrane. The antibodies reacted in cross-immunoassay in different titres with all antigenes and this evidences for the presence of common antigenic determinants in their structures. It was found that melittin antigenic determinants in the model membrane are exposed and accessible to reaction with antibodies and, therefore, they serve the agent for stimulation of immune response and production of antibodies.

Antibody Formation↗

PubMed1977

[An ion exchange method to determine free metal concentrations, adapted for use in biological fluids: methods and determination of (Mg2+)].

An ion exchange method for measuring concentrations of free (ionized) metal ions and its application to the determination of [Mg2+] is described. A surface sulfonated polystyrene material is used as the "twodimensional" cation exchanger. The sample-volume is 1 ml. About 50 determinations can be performed within 1 hr having a standard error of +/- (2-4)% in the optimal range of measurement. Advantages and disadvantages of the method compared with other ones are demonstrated and discussed. Free Mg2+ ion concentrations were measured in solutions containing pyrophosphate as well as haemoglobin and compared with those which were determined by equilibrium calculation or ultrafiltration.

Cation Exchange Resins↗

PubMed1991

[Determination of working length in endodontics. 2. Endometric determination of canal length].

Electronic determination of endodontic working length has become very popular in the past few years. Nevertheles it has shown that the use of electronic apex locators cannot replace radiographic length determination, but can be a useful additional device in endodontics. Indication, benefits and limits of electronic length determination are described in this paper.

Dental Pulp Cavity↗

PubMedDate not supplied

Atomic absorption spectrophotometric determination of calcium and magnesium and colorimetric determination of phosphorus in cheese: collaborative study.

The determination of calcium, phosphorus, and magnesium in cheese was collaboratively studied. The sample is dried and ashed and the residue is dissolved in an acidified aqueous solution. Calcium and magnesium are determined by atomic absorption spectrophotometry and phosphorus is determined by colorimetry. The study was repeated 3 times because of high within- and between-laboratory relative standard deviations (RSDr and RSDR, respectively). Poor precision in the first 2 studies was caused by a number of factors, including use of contaminated glassware, improperly maintained instruments, and impure reagents as standards. In each study, 5 varieties of cheese were distributed as 10 blind duplicate samples along with a practice sample. Thirteen laboratories participated in the third study, which was generally problem-free. The range of results and the average RSDr and RSDR found in the cheeses were: calcium, 608-1107 mg/100 g. 1.5%, 2.6%; magnesium, 23.9-50.6 mg/100 g, 2.8%, 3.8%; phosphorus, 444-695 mg/100 g, 1.2%, 1.6%. The method has been adopted official first action by AOAC.

Calcium↗

PubMed1988

The nature of hemopoietic histocompatibility determinants. Differential sensitivity of Hh-1b and H-2b determinants to tunicamycin.

NK cell-dependent resistance of F1 hybrid mice to parental H-2b hemopoietic allografts is directed to cell surface structures controlled by the Hh-1 locus in or near the H-2D region. Crucial to an understanding of this enigmatic phenomenon is the information on the biochemical nature of the Hh-1 locus-controlled structures. Therefore, we examined the effect of tunicamycin (TM), an inhibitor of asparagine-linked glycosylation and ganglioside biosynthesis, on the expression of Hh-1 determinants in H-2b/Hh-1b lymphomas. The Hh-1b determinants on EL-4 and RBL-5 cells were no longer detectable after TM treatment, as demonstrated by the failure of the treated cells to inhibit hybrid resistance to parental H-2b bone marrow cells in vivo. This interpretation was supported by the unaltered ability of the TM-treated cells to localize in the spleens of irradiated F1 hybrid recipients. In contrast, TM caused only moderate reduction in H-2Kb and H-2Db expression as measured by binding of specific antibodies. This was accompanied by reduced susceptibility to alloimmune anti-H-2Db CTL, but not to anti-H-2Kb CTL. No decrease was found in the susceptibility to NK cell cytotoxicity in vitro. These data indicate that N-linked glycosylation or ganglioside synthesis is crucial for the expression of the Hh-1 locus-controlled target structures, but not for the H-2 class I molecules. The data also show that the Hh-1b determinants are substantially different from those which confer the susceptibility to NK cell-mediated in vitro cytotoxicity.

Animals↗

PubMed1979

[The determination of the left ventrical volume curve without background correction and its validation by direct intercomparison with the ejection fractions as determined by biplane laevocardiography (author's transl)].

Background corrections applied on the left ventricular volume curve determined by the "gated blood pool"--method are based on an estimated rather than on a directly measured background. This imposes an uncertainty on the values determined from the volume curve, especially on the ejection fraction. A method which does not require background correction may be applied if all available measurement and evaluation facilities are utilized fully. High temporal and spatial resolution is of fundamental importance, permitting the exact determination of the time-dependent scintigraphic contour variations of the left ventricle during the mechanical action of the heart. A good criterion of the validity of the volume curves with respect to interfering background radiation is the ejection fraction calculated from these curves. The direct intercomparison of 10 ejection fractions obtained by an expanded "gated blood pool"-method, employing cardiac catheterization, immediately before a biplane laevocardiography demonstrated very good agreement. A small systematic underestimation of the ejection fraction by the nuclear method was observed. This understimulation shows that the influence of the true background is small if other interfering count rate contributions or methodical uncertainties are excluded systematically.

Angiography↗

PubMed1977

[Total body analysis of rats with special regard to fat determination. Possibility of determining fat and proteins by calculation].

The authors present a method for the whole body analysis of rats which combines the animal body preparation according to Mickelsen with the lipid analysis according to Folch; the liquid analysis has been somewhat modified. In this way and by the non-gutting of the animals, the determination of the body fat becomes less laborious. The body fat content can also be calculated from the water content. The body water content was determined gravimetrically. The body protein content was determined according to Kjeldahl; the protein content may also be calculated from the fat and water contents if an error range of +1% is acceptable.

Animals↗