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C M Thomas

Publications and source records attributed to C M Thomas.

At least 235 records · Page 13Linked to original sources
PubMed1987

Time-resolved immunofluorometric assay for the ovarian carcinoma-associated antigenic determinant CA 125 in serum.

A time-resolved immunofluorometric assay (IFMA) is described for quantifying the ovarian carcinoma-associated antigenic determinant CA 125 in human serum. Monoclonal antibody to CA 125 is immobilized onto a microtiter well, and the same antibody labeled with a europium chelate is used as a tracer. After the immunoreaction the bound portion of the labeled antibody is quantified by dissociating the Eu3+ in a fluorescence-enhancement solution and measuring its fluorescence with a time-resolved fluorometer. The detection limit of the IFMA is 1.5 arb. units/mL, being about the same as that of a commercially available immunoradiometric assay (IRMA) for CA 125 (1.4 arb. units/mL). The analytical range of the IFMA extends to 2000 arb. units/mL, whereas the range of the IRMA is 500 arb. units/mL. For 29 serum samples from ovarian-cancer patients measured simultaneously in the IFMA and IRMA, orthogonal regression analysis gave the equation CA 125 (IFMA) = 0.9937 CA 125 (IRMA) - 1.211 arb. units/mL (Syx = 6.8681, r = 0.9932). Apparently, the IFMA for CA 125 is a convenient alternative to the IRMA for CA 125 because of short counting times, the use of nonradioactive, stable reagents, and the much-extended measuring range. Additionally, the microtiter format should lend itself to more fully automated procedures in laboratories doing many such analyses.

Antigens, Neoplasm↗
PubMed1987

[Campylobacter pyloridis and gastroduodenal pathology].

After the first report by Marshall and Warren of the presence of gastritis associated Campylobacter pyloridis in antral mucosa, many groups have found the same association in many countries of Europe, USA, Japan. In France, too C.P. is found in antral mucosa. We have studied 119 dyspeptic patients; during endoscopy 3 biopsy specimens were taken, one for microaerophilic culture and 2 for pathologic examination. We found the germ in 27 p. 100 of 22 normal subjects but no culture was positive. In chronic interstitial gastritis it is found in 90 p. 100 of cases and in 98 p. 100 if a duodenal ulcer is associated. Ten patients with healed duodenal ulcer have been treated by V Penicillin: 3 millions unit/day during 2 weeks. In five cases C.P. disappeared but 2 of them relapse 2 months later.

Adult↗
PubMed1986

The nucleotide sequence and transcription of minicircular mitochondrial DNA's associated with male-fertile and cytoplasmic male-sterile lines of sugarbeet.

Male-fertile (MF) and cytoplasmic male-sterile (CMS) lines of sugarbeet possess characteristic low molecular weight minicircular mitochondrial DNA's, and Southern hybridizations revealed sequence homologies between them. The complete nucleotide sequences of minicircle a present in MF and CMS lines, and minicircle d present in some MF lines have been determined and compared to minicircle c present in all MF lines. Computer analysis revealed sequences common to all three DNA's: these may be essential to their maintenance in sugarbeet mitochondria. Analysis of the extent and arrangement of homologous sequences in minicircle a and minicircle d suggests the latter may have arisen from an intramolecular recombination event in minicircle a. The G+C contents of the minicircles differ and their possible origins are discussed. All three DNA's are transcribed. Minicircle c and minicircle d transcripts are exclusive to MF mitochondria, but are unlikely to encode protein products. Two transcripts of sufficient size and the predicted polarity to encompass a short open reading frame on minicircle a are common to both MF and CMS mitochondria.

Base Composition↗
PubMed1986

The trfB region of broad host range plasmid RK2: the nucleotide sequence reveals incC and key regulatory gene trfB/korA/korD as overlapping genes.

We report the nucleotide sequence of the trfB region of broad host range plasmid RK2. This region encodes the following loci: trfB, identical to korA and korD, which encodes a key transcriptional repressor of certain RK2 operons; incC, which appears to be involved in plasmid maintenance, possibley through post-transcriptional regulation of trfA product levels; the start of korB, which encodes a second transcriptional repressor of operons involved in stable inheritance of RK2. These loci are expressed as part of the trfB operon. In combination with deletion analysis, transcriptional and translation fusions and 'maxicell' analysis of polypeptides, the DNA sequence allows a number of conclusions to be drawn. First, the korB ORF start codon overlaps the incC ORF stop codon, suggesting the possibility of translational coupling between these two genes. Second, the trfB ORF lies entirely within the first third of the incC ORF using a different phase. Third, the incC ORF appears to contain a second transcriptional start whose function appears to be coupled to translation of the trfB ORF. Analysis of codon usage in the region of overlap between incC and trfB suggests that the incC gene may have evolved before the trfB gene. Determination of the DNA sequence of a mutant in which the product of trfB is rendered defective for transcriptional repression reveals an amino acid alteration within a region of this polypeptide which exhibits homology to the alpha helix-turn-alpha helix motif characteristic of many DNA binding proteins, and which is probably responsible for recognition of the trfB operator by this protein.

Amino Acid Sequence↗
PubMed1986

An analysis of semantic relations between mild dysphasic and nondysphasic speakers.

The availability of different semantic relations between mild anomic dysphasic and nondysphasic subjects was investigated using a picture description task. Results of the analyses revealed statistically nonsignificant differences between the two groups for the variables of total utterances and mean length of utterances. Of the different cases examined, a significant difference between the two groups of subjects was revealed in their use of the "other" case relation category. Also, within the dysphasic group maximum verbal paraphasias occurred for the object case. Discussion of the obtained results relate the selective availability of specific cases to the possible differences in linguistic coding between the two groups. Also, the interrelationship between quantity of verbal output and incidence of verbal paraphasia is discussed.

Adult↗
PubMed1986

Analysis of the vegetative replication origin of broad-host-range plasmid RK2 by transposon mutagenesis.

A range of Tn1723 transposon mutants of the oriV region of broad-host-range plasmid RK2 have been isolated, and the internal EcoRI fragment of the transposon has been deleted from each to reduce the insertion size from 9.6 kb (Tn1723) to 35 bp (delta Tn1723). Sequencing from the delta Tn1723-derived EcoRI site has allowed the precise mapping of these insertions to various points dispersed through the origin region. Using these mutants we have determined which regions of oriV RK2 are of functional importance to plasmid establishment following transformation of the host species Escherichia coli, Pseudomonas putida, and P. aeruginosa. Insertions into an A/T-rich region, and a region containing five direct repeat sequences prevented successful transformation of each host species tested, but the continuity of sequences adjacent to the five repeats were essential only in E. coli and P. putida. The establishment and maintenance in E. coli of a mini-RK2 replicon was found to be inhibited by transcription from an inducible promoter positioned to read into oriV RK2 against the direction of replication. Assays of transcription emerging from Tn1723 demonstrated significant levels from one end of the transposon only. Four mutants with insertions downstream of oriV RK2 were unable to become established in E. coli, and contained Tn1723 in the orientation which would supply transcription toward the oriV RK2 region. These results demonstrate both that the sequence requirements for oriV RK2 function differ between host bacterial species, and that origin function may be further influenced by the genetic environment in which it lies.

Base Sequence↗
PubMed1986

Evidence for the involvement of the incC locus of broad host range plasmid RK2 in plasmid maintenance.

Plasmid pRK2501 is a deletion derivative of broad host range plasmid RK2 and encodes two trfB-regulated operons: the trfA operon which codes for both kilD, which interferes with plasmid maintenance if unregulated, and trfA whose protein product(s) is essential for replication from oriVRK2; and part of the trfB operon, containing both trfB/korA/korD, whose product negatively regulates transcription of both trfA and trfB operons, and incC, the product of which interferes in trans with inheritance of RK2 and certain of its derivatives. Plasmid pRK2501ts3 is a derivative with a point mutation in trfB, rendering plasmid maintenance temperature sensitive. Transcriptional fusions of the trfB operon and the galK gene demonstrate that this mutation derepresses trfB operon transcription at both 30 and 42 degrees C. The trfA operon is also derepressed by this mutation. Since the trfB gene product appears to be defective at both permissive and non-permissive temperatures the temperature sensitivity of pRK2501ts3 must be due to a secondary effect. In fact, it appears to arise from the inhibitory behavior of derepressed incC at the non-permissive temperature since a major class of "revertant" of pRK2501ts3 contains deletions inactivating incC and a reconstruction experiment demonstrates that such a deletion is sufficient for "reversion." Maxicell experiments show that at the non-permissive temperature the trfA operon polypeptide products are produced at much lower levels, an effect partly reversed by a deletion affecting incC. It is proposed that incC normally plays a role in maintenance of IncP plasmids by modulation of trfA operon expression.

Bacterial Proteins↗
PubMed1986

Use of a modified Escherichia coli trpR gene to obtain tight regulation of high-copy-number expression vectors.

It has been found that with high-copy-number vectors utilising the Escherichia coli trp promoter the amount of repressor protein produced from the single chromosomally located trpR gene is inadequate for tight repression to be obtained. An attempt has been made to overcome this problem by inserting the trpR gene in cis into the expression vector. This proved unsuccessful because transcription from the trp promoter of such a plasmid could not be induced with 3,beta-indole acrylic acid, probably because the trpR gene is autogenously regulated. However, it was found that when the natural trpR promoter was replaced with a relatively weak constitutive promoter a useful self-repressible vector could be formed. A modified trpR gene of this type has been used to obtain tightly controlled expression of human interferon-beta (IFN-beta) from a vector having a copy number of 400. Tight regulation is particularly important in this case as IFN-beta is highly toxic to the E. coli cell.

DNA Restriction Enzymes↗
PubMed1986

Construction of a novel gene bank of Bacillus subtilis using a low copy number vector in Escherichia coli.

Low copy number vector plasmid pCT571 was constructed to clone Bacillus subtilis genomic fragments in Escherichia coli. pCT571 confers KmR, TcR and CmR in E. coli and CmR in B. subtilis. It has unique restriction sites within the KmR and TcR markers to allow screening for recombinant plasmids by insertional inactivation of these genes. It contains the pSC101 replicon and replicates normally at six to eight copies per chromosome equivalent in E. coli. It also contains oriVRK2, which when supplied with the product of the trfA gene of RK2 in trans, allows pCT571 to replicate at 35-40 copies per chromosome equivalent. A B. subtilis gene bank was created by cloning partially Sau3A-digested and size-fractionated fragments of B. subtilis chromosomal DNA into the BamHI site of pCT571. DNA from 1097 KmR TcS transformants was extracted and analysed electrophoretically as supercoiled DNA and after digesting with EcoRI or EcoRI and SalI. Approximately 1000 hybrid plasmids were found with reasonably sized B. subtilis fragments. The mean size of the inserts in pCT571 is 8 kb, ranging from 4 to 20 kb in different plasmids. The gene bank covers most of the B. subtilis chromosome, as demonstrated by the results of screening the gene bank for selectable nutritional markers in E. coli and B. subtilis. Hybrid plasmids which complement E. coli mutants for arg, his, lys, met, pdx, pyr and thr markers were identified from the gene bank. In B. subtilis the presence of argC, cysA, dal, hisA, ilvA, leuA, lys, metB, metC, phe, purA, purB, thr and trpC was established by transformation experiments. The effects of copy number on cloning and long-term maintenance in the bacterial strains were also investigated. At high copy number some hybrid plasmids cannot be maintained at all, while others show an increased rate of structural deletions and rearrangements.

Bacillus subtilis↗
PubMed1986

The effects of sulindac and indomethacin on the anti-hypertensive and diuretic action of hydrochlorothiazide in patients with mild to moderate essential hypertension.

In this double-blind two period crossover study, we investigated the effect of indomethacin and sulindac on blood pressure in 25 hypertensive patients being treated with hydrochlorothiazide. The study consisted of seven 4 week periods. In the first and the last period the patients took placebos, in period two, four and six they were treated with hydrochlorothiazide 50 mg once daily alone, and in the third and fifth period hydrochlorothiazide 50 mg once daily was given in combination with either indomethacin 50 mg twice daily or sulindac 200 mg twice daily in double-blind random order. Blood pressure, measured by sphygmomanometer and arteriosonde, and body weight were determined every 2 weeks. Compared with placebo hydrochlorothiazide decreased the mean arterial pressure by 8%. Addition of both indomethacin and sulindac resulted in only slight and generally similar changes of this blood pressure lowering effect. This was found both for the whole group and when both treatment sequence groups were analysed separately. In contrast to sulindac, indomethacin attenuated the hydrochlorothiazide-induced decreases of body weight, plasma potassium and the increase of plasma renin activity. Both non-steroidal anti-inflammatory drugs (NSAID) reduced the 24 h urinary excretion of prostaglandins (PGs), i.e. PGF2 alpha, 6 ketoPGF1 alpha and thromboxane B2 except PGE2. From this study it can be concluded that, in contrast to sulindac, indomethacin attenuated the diuretic action of hydrochlorothiazide, however apparently without consequences for its long-term blood pressure lowering effect. This study does not support the hypothesis that the difference between the two NSAIDs can be explained by different effects on renal PG synthesis.

Adult↗
PubMed1986

Prostaglandins in urology.

This article gives a review of the current place of the different prostaglandins in the urogenital tract and urological pathology. Clinical as well as experimental data are analyzed. The conclusion is that prostaglandins play an important role in the physiology and pathophysiology of each organ of the urogenital tract although no direct clinical applications of prostaglandins or prostaglandin-inhibitors result from our current knowledge and experiences with these substances.

Epididymis↗
PubMed1986

Comparison of the analytical characteristics of ten urinary hCG tests for early pregnancy diagnosis.

A comparison of assay design, sensitivity and specificity is given for 10 urinary human chorionic gonadotrophin (hCG) test kits for early pregnancy diagnosis. One slide test applies a polyclonal anti-hCG serum, while nine, more recently developed, tube and slide tests use one or more monoclonal antibodies toward intact hCG or its free subunits. Colour development for five immunoenzymetric (IEMA) 'sandwich' assays, or (haem/latex) agglutination (HA, LA)-inhibition (HAI, LAI) for the other systems provide assay sensitivities from 1000-50 IU/L within 3-120 min. The 'best' slide-(i.e., LA, LAI), haem-(i.e., HA, HAI) and IEMA-tests detect respectively 500, 75 and 50 IU/L within 2.5, 120 and 3 min. Assay specificities (i.e., as false-positive and false-negative test results) are studied using intact hCG, hLH and their free alpha- and beta-subunits. The presented assays are improved, perform more sensitively at shorter reaction times with increased specificity, and may, therefore, establish pregnancy at an earlier stage with greater reliability.

Agglutination Tests↗
PubMed1986

Effects of danazol on spermatogenesis in adult rats.

Adult male Wistar rats were treated with Danazol (4 mg/day s.c.) for 52 days. The drug produced a marked, rapid drop in serum testosterone concentrations to very low levels and caused a slower decrease in serum FSH, LH and testis weight. Flow cytometric analysis of testicular cell suspensions showed a decline in the absolute numbers of haploid cells (spermatids), tetraploid cells (mainly pachytene spermatocytes) and of cells in the S-phase of the division cycle, suggesting that Danazol inhibited proliferation of spermatogonia and/or primary spermatocytes. Histological counting of the different types of spermatogonia, however, revealed no significant change in their numbers during Danazol treatment. It is concluded that Danazol inhibited spermatogenesis primarily after the preleptotene stage of primary spermatocytes.

Animals↗