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Biomedical subjects

C M Thomas

Publications and source records attributed to C M Thomas.

At least 181 records · Page 10Linked to original sources
PubMed1992

Specific and nonspecific immunoassays to detect HAMA after administration of indium-111-labeled OV-TL 3 F(ab')2 monoclonal antibody to patients with ovarian cancer.

The development of human anti-mouse antibodies (HAMA) may cause problems in radioimmunotargeting studies, but may also improve survival of patients. To identify the presence of HAMA in blood samples from patients intravenously injected with 1 mg of 111In-labeled OV-TL3-F(ab')2, we developed three specific OV-TL 3-based HAMA assays and tested these along with two commercially available nonspecific HAMA assays (Sorin and Immunomedics). The specific assays were positive for HAMA with 10 postinjection serum samples from 7 patients. Eight of the 10 samples were also HAMA positive with one or both nonspecific HAMA assays. Conflicting results were observed with half the number of samples. The two nonspecific assays also reacted positively with another 11 serum samples from 5 patients including their preinjection samples. Despite some contradictory results, the nonspecific HAMA assays identify both pre-existent and Mab-induced HAMA, whereas the specific OV-TL3-based HAMA assays identify specific immune-responses occurring after the OV-TL 3 injection.

Animals↗
PubMed1992

The effects of oral contraceptives and multivitamin supplementation on serum ferritin and hematological parameters.

We have studied the effects of oral contraceptive (OC) use and of subsequent multivitamin supplementation on several hematological parameters. Hemoglobin (Hb), hematocrit (Ht), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular hemoglobin (MCH), and serum iron status (serum iron, total iron binding capacity and ferritin) were tested in groups of women with and without OC in view of preconceptional status. The group taking sub-50 OC comprised 28 women while 31 women were included in the group of non-OC users. Blood samples were taken on days 3 and 23 of the first cycle to obtain baseline values of each analyte. Multivitamin supplementation started on day 1 of the second cycle and this was continued daily throughout three consecutive cycles until the end of the study. Comparison of the baseline values of each parameter as determined on days 3 and 23 of the first cycle of the two groups revealed no significant different hematological parameters due to OC-use unlike the parameters of serum iron status which were all significantly increased for the group of OC-users as compared to the group of non-OC users. The effects of multivitamin supplementation on the hematological and iron status parameters were studied within each group. The consistency of each effect of multivitamin supplementation between the two groups was also tested. A multivitamin supplementation significantly decreased MCHC within either group, and caused increases of MCV, whereas Ht and MCH remained unaltered. With respect to the iron balance, serum iron and total iron binding capacity significantly increased, whereas serum ferritin decreased during multivitamin supplementation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

The effect of chronic oral methadone treatment on monkey chorionic gonadotropin, estradiol, dehydroepiandrosterone sulfate, progesterone, prolactin and cortisol levels during pregnancy in the cynomolgus monkey (Macaca fascicularis).

The effect of chronic methadone treatment upon the serum levels of Estradiol (E2), Progesterone (P), Prolactin (Prl), monkey chorionic gonadotropin (mCG), dehydroepiandrosterone sulfate (DHEAS) and Cortisol (C) in pregnant Cynomolgus monkeys (Macaca fascicularis) is described in comparison with the hormone levels in a control group. Only DHEAS was significantly decreased in late pregnancy in the methadone group. From these data it can not be concluded that methadone treatment compromises (feto)placental function. The observed intra-uterine growth retardation in the methadone treated group might be a result of a direct influence of methadone upon growth.

Animals↗
PubMed1991

Carcinoma-associated mucin serum markers CA M26 and CA M29: efficacy in detecting and monitoring patients with cancer of the breast, colon, ovary, endometrium and cervix.

Two recently developed monoclonal antibody (MAb)-based anti-mucin assays, CA M26 and CA M29, were studied in 250 cancer patients and compared to 3 well-established marker tests, viz., CA 125, CA 15.3 and SCC, in order to assess their clinical usefulness as serum tumor markers. Pre-treatment sera were obtained from patients with predominantly low-stage epithelial malignancies comprising 200 adenocarcinomas (of the ovary, endometrium, breast and large intestine) and 50 squamous-cell carcinomas (of the uterine cervix). Pretreatment sera of 50 patients with benign ovarian tumors were included to evaluate levels in benign disease, CA M26 and CA M29 cut-off levels were established in 89 healthy controls. In patients with adenocarcinomas, overall positivity for CA M29 was 24%, ranging from 10% in breast cancer to 60% in ovarian cancer. Overall positivity was highest for CA 125 (30%) and lowest for CA M26 (18%) with CA M29 (24%) being similar to CA 15.3 (25%). In adenocarcinomas the combined CA M26-CA M29 assays equalled results obtained with the CA 125-CA 15.3 combination (33% vs. 36%). Elevation of 2 or more markers was highly indicative of advanced disease (p less than 0.025). A majority of positive patients showed either CA M26 or CA M29 elevations, indicating that both antibodies detect distinct epitopes. After adjustment for tumor site and stage, the profile of CA M26 as a single marker differed significantly from the profiles of CA 125 and of CA M29. CA M26 was frequently (32%) elevated in patients with squamous-cell carcinoma of the cervix and CA M26 levels were often independently elevated. CA M26 seems to be valuable as an additional marker in breast cancer and perhaps as a new marker in cervical cancer. CA M29 may be useful in ovarian cancer in addition to CA 125.

Adenocarcinoma↗
PubMed1991

Multivitamin supplementation in oral contraceptive users.

The effects of oral contraceptives (OC) containing 30 micrograms of ethinyl oestradiol and of subsequent multivitamin and folic acid supplementation on vitamin A, total B2 [including its three individual constituents, i.e. riboflavine, RB; flavine-mono-nucleotide, FMN; and flavine-adenine-dinucleotide, FAD], B12, C and folate concentration in serum and red blood cells have been studied in a group of 59 non-pregnant female volunteers. The group taking OC comprised 28 women while 31 women were included in the group of non-OC users serving as the controls. The women were studied for four cycles. Blood samples were taken on days 3 and 23 of the first cycle to obtain baseline values of each analyte. Multivitamin and folic acid supplementation started on day 1 of the second cycle and this was continued daily throughout three consecutive cycles until the end of the study. Vitamin A levels were significantly higher and vitamin B12 levels were significantly lower in the group using OC. Comparison of the baseline values of vitamin total B2, FAD, C, serum and red blood cell folate as determined on days 3 and 23 of the first cycle of the two groups compared revealed no significant differences. Multivitamin and folic acid supplementation did not affect the concentrations of vitamin A and vitamin B12 with either group, whereas all other vitamins increased significantly in both groups. The consistency of each effect of multivitamin supplementation between the two groups was also tested. The degree of these effects was not statistically different between both groups. The results suggest that the vitamin status is indeed affected by OC treatment, but the effects of multivitamin supplementation are not different in OC and non-OC users. Supplementation during OC use or just after discontinuing treatment cannot be justified for healthy young women. However, in the case of women with a critical vitamin balance or higher folate needs, multivitamin supplementation may be considered.

Adult↗
PubMed1991

Retrograde seeding of endometrial epithelial cells by uterine-tubal flushing.

OBJECTIVE: To estimate the amount of endometrial epithelial cells in peritoneal fluid (PF) after uterine-tubal flushing (40 mL) throughout the menstrual cycle. DESIGN: We cultured the cell pellet of flush medium present in the peritoneal cavity. SETTING: University Hospital Nijmegen, The Netherlands. PATIENTS: Ninety-two women with various infertility-related factors. INCLUSION CRITERIA: (1) ovulatory cycle, (2) patent tubes, and (3) no adhesions. INTERVENTIONS: None MAIN OUTCOME MEASURE(S): The number of developing epithelial cell colonies were counted after 7 days. We started to record the amount of flush medium recovered during the study. RESULTS: The amount of flush medium recovered was positively correlated with the presence of endometriosis (P = 0.017). Endometrial epithelial cells were identified in 85 flush media (92%). The number of epithelial cell colonies varied from 0 to 100 or more and was higher when flushing was performed during the early follicular phase (P less than 0.01). High estradiol-17 beta and progesterone levels in culture medium did not change the number of developing cell colonies. Methylene blue significantly reduced the number of cell colonies (P = 0.002). CONCLUSIONS: Uterine-tubal flushing results in varying numbers of endometrial epithelial cells in PF. Methylene blue adversely affects the growth potential of these cells.

Cell Division↗
PubMed1991

The korF region of broad-host-range plasmid RK2 encodes two polypeptides with transcriptional repressor activity.

Broad-host-range IncP plasmid RK2 possesses a series of operons involved in plasmid maintenance, whose expression is coordinated by a number of regulators, most of which are encoded in the central regulatory korA-korB operon. The nucleotide sequence of two new cistrons in this operon, comprising what we have previously designated the korF locus located between coordinates 57.0 and 56.0 kb on the genome of the IncP alpha plasmid RK2, is presented. The cistrons encode polypeptides of 173 and 175 amino acids. Each can repress transcription from the promoters for the kfrA (a monocistronic operon which follows the korA-korB operon) and trfA (a polycistronic operon encoding a putative single-stranded-DNA-binding protein as well as the essential plasmid replication protein TrfA) operons. In addition, the korF loci allow korB to repress kfrA transcription. Both polypeptides contain hydrophobic segments, suggesting that they may be membrane associated. KorFI is highly basic protein whose predicted properties are similar to those of histone like proteins.

Amino Acid Sequence↗
PubMed1991

Transcriptional analysis, translational analysis, and sequence of the kilA-tellurite resistance region of plasmid RK2Ter.

The tellurite resistance (Ter) determinant of the IncP alpha plasmid RK2Ter, a variant of RK2 (also called RP4), is located between the kilA and korA genes involved in plasmid replication control. Transcriptional and translational fusions were constructed between the gene for beta-galactosidase and the kilA and Ter genes by using the transpositional phage mini-Mu. These fusions indicated that the Ter genes are transcribed in the same direction as kilA and that transcription and translation of the cloned kilA gene are occurring and may not be lethal to the bacterial cell even in the absence of korA. The nucleotide sequence of this region was determined, and three open reading frames (ORFs) were identified. The first ORF codes for KilA, a 28-kDa hydrophilic protein. The second ORF, telA, codes for a hydrophilic protein of 42 kDa. The third ORF, telB, codes for a hydrophobic protein of 32 kDa. This protein appears to be located in the inner membrane of the bacterial cell, since fusions of TelB to alkaline phosphatase were obtained by using TnphoA. All three proteins were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after overproduction using the T7 RNA polymerase/promoter system. The same three proteins were produced when Tes and Ter derivatives of RP4 were expressed in an in vitro transcription-translation system. A single Ser-to-Cys missense mutation in telB was found to be responsible for mutation of RK2 to Ter.

Alkaline Phosphatase↗
PubMed1991

Pulsatile secretion of luteinizing hormone and prolactin in lactating and nonlactating women and the response to naltrexone.

To investigate the mechanisms responsible for the postpartum suppression of reproductive function, LH and PRL levels were determined at 10-min intervals for 8 h in 10 lactating women, in 10 nonlactating women treated with bromocriptine, and in 5 nonpuerperal women. The lactating women were studied on postpartum day 7 (n = 5) or between days 28 and 35 (n = 5). All nonlactating women were studied on day 7. Five of them were treated with the opioid antagonist naltrexone to evaluate the role of endogenous opioids. By using a specific LH assay which does not cross-react with hCG, we were able to measure pulsatile LH secretion in the early puerperium for the first time. On day 7, LH levels were below the detection limit in both lactating and nonlactating women, hence no pulses could be detected. Chronic opioid blockade in bromocriptine-treated non-lactating women did not result in increased LH levels. Pulsatile LH secretion was present between days 28 and 35 of lactation, although pulse amplitude (P less than 0.05) and mean LH level (P less than 0.05) were lower than in nonpuerperal women. Mean LH in lactating women was negatively correlated with mean PRL (-0.87, P less than 0.05). Deconvolution analysis of the PRL responses to suckling revealed that PRL was secreted in distinct bursts, separated by intervals of secretory quiescence. Mean duration of PRL bursts was 40 +/- 4 min and the maximum secretory rate was reached around the end of suckling. We conclude that pulsatile LH secretion is completely suppressed during early lactation and partially suppressed during late lactation. Because the duration of suckling was similar, the relatively strong suppression during the early puerperium must be due to additional inhibitory factors. It has been suggested that endogenous opioids are involved in this process, but our results in puerperal women do not support this hypothesis.

Adult↗
PubMed1990

Cell lines of human oral squamous-cell carcinomas retaining their differentiated phenotype.

Two cell lines from head-and-neck squamous-cell carcinomas (SCC) have been established and characterized. Cell line R105 was derived from a xenografted SCC of the floor of the mouth and cell line T87/rc from a SCC of the epiglottis. Identification of individual cytokeratins 4, 5, 7, 8, 10, 13, 14, 18 and 19 led to the conclusion that both cell types had squamous characteristics and that keratinization occurred in xenografts. Ultrastructurally, junctional complexes were observed in both cell lines. Characteristic marker chromosomes were found and although both cell lines were derived from male patients, the Y chromosome was missing from all examined cells. The basic biological parameters of both cell lines were modal chromosome numbers of 59 (R105) and 60 (T87/rc), a doubling time of 60 (R105) and 45 hr (T87/rc) and a DNA index of 1.54 (R105) and 1.31 (T87/rc). The tumorigenicity of the 2 cell lines was proved by the ability to form colonies on a plastic substratum, as well as in a soft agar assay. Furthermore, the cells could produce multi-cellular tumour spheroids, and formed tumour nodules after subcutaneous inoculation into nude mice. The R105 tumour cells appeared to be better differentiated than the T87/rc as observed by histology and immuno(histo)chemistry. Both cell lines appear to retain SCC differentiation after being xenografted into nude mice, cultured for more than 40 passages in vitro and thereafter again xenografted into nude mice.

Animals↗
PubMed1990

Identification of a seventh operon on plasmid RK2 regulated by the korA gene product.

Broad-host-range IncP plasmids possess a series of operons involved in plasmid maintenance, whose expression is coordinated by a series of regulators, most of which are encoded in a central regulatory operon. The nucleotide sequence of a new monocistronic operon located between coordinates 55.0 and 56.0 kb on the genome of the IncP alpha plasmids RK2 and RP4 is presented. The operon encodes a 34 kDa protein which has a net negative charge. Transcription of the operon, designated by us kfrA (korF-regulated), is repressed not only by the product of the previously described korA gene but also by the product of a gene which we have designated korF and which has not been described previously. The korF gene is encoded downstream from korB within the key korA/korB regulatory operon. We propose that K or F binds to a novel inverted repeat overlapping the promoter for the kfrA operon.

Amino Acid Sequence↗
PubMed1990

Sugarbeet mitochondria contain an open reading frame showing extensive sequence homology to the subunit 2 gene of the NADH: ubiquinone reductase complex.

Sequence analysis of a transcribed region of mitochondrial DNA (mtDNA) from male fertile sugarbeet (Beta vulgaris L.) revealed an open reading frame showing extensive sequence homology to the subunit 2 gene of the NADH: ubiquinone reductase complex (nad2). Sugarbeet nad2 in common with its proposed counterpart in animal mitochondria has no intron and thereby differs from the corresponding chloroplast gene. Northern RNA analysis of sugarbeet nad2 suggested that transcription of this locus gives rise to at least three transcripts. No differences in transcript profile were detected between male fertile and cytoplasmic male sterile sugarbeet. This constitutes the first report of a mitochondrial nad2 gene in higher plants.

Amino Acid Sequence↗
PubMed1990

Elevated folate levels in amniotic fluid after oral supplementation.

During oral supplementation of 5 mg folic acid and 1 microgram vitamin B12, the daily folate levels in plasma, red cells and midtrimester amniotic fluid were significantly higher in ten pregnant women during the 15th-18th week of menstrual age as compared to ten non-supplemented women serving as controls. In the control group as well as in the supplemented group, the folate concentrations in amniotic fluid were found to be lower than in the corresponding maternal plasma and red cells. Of all women investigated there was a significant positive correlation between maternal plasma folate concentrations and amniotic fluid levels (r = 0.72, p less than 0.001) and no correlation between red cell folate concentrations and amniotic fluid levels (r = 0.30, p = 0.22). Oral supplementation of vitamin B12 did not elevate maternal blood concentrations and amniotic fluid levels. Vitamin B12 levels in amniotic fluid in this group and controls were always higher than in plasma. These data suggest that the orally administrated dosages of folic acid unlike those of vitamin B12 augment both plasma, red cells and amniotic fluid levels.

Administration, Oral↗
PubMed1990

Monoclonal antibodies that discriminate between human ovarian carcinomas and benign ovarian tumours.

Three hybridoma cell lines producing monoclonal antibodies (MAbs) against ovarian carcinomas were obtained after immunizing mice with an undifferentiated human ovarian cystadenocarcinoma extract. The hybridoma cell supernatants were initially screened for a positive immunohistochemical reaction with ovarian carcinomas concomitant with a negative reactivity with a benign ovarian cystadenoma. The antibodies OV-TL 15 (IgM), OV-TL 30 (IgG1) and OV-TL 31 (IgM) reacted positively with 84, 84 and 74% of the ovarian carcinoma samples (n = 76) respectively. Reactivity with ovarian cysts and cystadenomas (n = 21), with non-ovarian carcinomas (n = 77) and with normal human tissue samples (n = 63) was absent or limited to weak reactivity on incidental samples. All three antibodies were shown by immunoelectron microscopy to react with surface antigens (OA 15, OA 30 and OA 31) of ovarian carcinoma cells. Cross reactivity between OV-TL 15, OV-TL 30, OV-TL 31 and OC 125 monoclonal antibodies was excluded by competitive binding assays on NIH:OVCAR-3 cells. Antigen levels (OA 15 and OA 31) in tumour extracts and cyst fluids were quantified by immunoradiometric assays and compared to the CA 125 antigen levels. High levels of CA 125, OA 15 and OA 31 were found in cyst fluids from ovarian cancers. In benign ovarian cyst fluids, however, the CA 125 content was also high while OA 15 antigen was hardly detectable. The OA 31 antigen was present at relatively low levels. The IRMA data confirmed the immunohistochemical data showing that, in contrast to OC 125, the newly developed MAbs OV-TL 15, OV-TL 30 and OV-TL 31 discriminate between benign ovarian cystadenomas and malignant ovarian cancers.

Antibodies, Monoclonal↗
PubMed1990

Use of a novel cassette to label phenotypically a cryptic plasmid of Bacillus subtilis and map loci involved in its stable maintenance.

In order to facilitate studies on the maintenance of cryptic plasmids from Gram-positive bacteria we have constructed a novel cassette cAPG1000 (5.0 kb) which carries both a selectable marker (chloramphenicol resistance from Staphylococcus aureus plasmid pC194) and a screenable marker (the xylE gene from the TOL plasmid of Pseudomonas putida expressed from a cloned promoter of Bacillus phage SPO2) and which is flanked by terminators to prevent transcription from the cassette activating or inhibiting loci adjacent to the site of insertion. To demonstrate the usefulness of this cassette we have mapped loci required for stable maintenance of an 8.6 kb cryptic plasmid endogenous to Bacillus subtilis (pPOD2000) from the properties of cAPG1000 insertion and insertion/deletion derivatives. We have identified the replication region as well as separate regions required for segregational and structural stability. The segregational mechanism is very efficient since it allows no detectable loss despite the fact that bacteria carrying the plasmid have a greatly increased mean generation time.

Bacillus subtilis↗