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Biomedical subjects

R Drouin

Publications and source records attributed to R Drouin.

68 records · Page 4Linked to original sources
PubMed1988

Human chromosome banding specific for electron microscopy.

Electron microscopy (EM) provides much higher resolution than that obtained with light microscopy (LM). Until now, however, no chromosome banding procedure specifically adapted for EM was available. To produce an easy and reproducible banding method that would allow accurate chromosome identification, we investigated the applicability of an immunochemical method. BrdU-substituted chromosomal regions can be accurately visualized by applying a monoclonal antibody against BrdU, followed by a gold-tagged secondary antibody. Since BrdU is incorporated during the last part of the S-phase, regions of darkly stained G- and C-bands are substituted. A characteristic C-banding pattern is revealed, and the G-banding obtained is sharp and allows discrimination between subbands. Its similarity with the classical G-banding observed by LM makes it easy to interpret and facilitates karyotyping.

Chromosome Banding↗
PubMed1988

High-resolution R-banding at the 1250-band level. 1. Technical considerations on cell synchronization and R-banding (RHG and RBG).

A comparative analysis of variables for cell synchronization was made and led to the description of optimal conditions capable of yielding, in over 95% of cases, a large number of excellent quality cells in prometaphase and late prophase. Thymidine presents advantages over amethopterin as the synchronizing agent. The block was released with either thymidine or 5-bromo-2'-deoxyuridine (BrdU) for which various concentrations were tested. The presence of colcemid was also evaluated. Without colcemid, the optimal length of the release period was precisely determined so that the wave of synchronized cells could be harvested while going through the early stages of mitoses. Subsequently, GTG, RHG and RBG banding were produced on these elongated chromosomes. A comprehensive approach to RHG banding ensured an easier and well reproducible banding technique. Nine interrelated factors which influence banding quality were studied. The analysis of their effects on this banding pattern revealed new data for the understanding of its mechanism. A high-resolution R-banding technique after BrdU incorporation and Giemsa staining is presented; it is simple, reliable and reproducible. Different conditions for the FPG (Fluorochrome-Photolysis-Giemsa) technique were studied in order to obtain sharper borders and higher contrast between positive and negative bands. Optimal conditions for the incorporation of BrdU and the FPG method produced excellent band separation and band contrast even in very elongated prophase chromosomes. They did not decrease the mitotic index, did not increase chromosomal damage significantly, and did not greatly vary from subject to subject nor with the age of the slide (between 1 day and 36 months). Homologue discordance correlated to band range was compared for GTG, RHG and RBG banding.

Adult↗
PubMed1987

Idiograms of horse chromosomes at prometaphase, early metaphase, and midmetaphase after R-banding by BrdU incorporation followed by the fluorochrome-photolysis-Giemsa technique.

We present three idiograms of equine chromosomes, R-banded after BrdU incorporation and stained by the fluorochrome-photolysis-Giemsa technique. The haploid set of prometaphasic chromosomes shows 591 bands (range 7-38 per chromosome), the early metaphasic set 404 (range 5-26), and the midmetaphasic set 272 (range 3-18). Following cell synchronization with thymidine, more than twice as many R-bands were revealed on the resulting prometaphasic chromosomes, making possible the establishment of a very accurate and characteristic representation of this banding pattern in the domestic horse.

Animals↗
PubMed1987

Protein supplements, mitogens and antibiotics in lymphoblast transformation and cytogenetic analysis.

The in vitro effects of four protein supplements, foetal calf serum (FCS), gammaglobulin-depleted FCS (FCS-A), human serum albumin (HSA) and autologous serum (AS), and of four antibiotics on lymphocyte blast transformation and on lymphocyte proliferation for cytogenetic studies, were evaluated. 3H-thymidine incorporation was measured in the lymphocytes obtained from sixteen healthy adults and stimulated with phytohaemagglutinin (PHA), concanavalin A (Con A), pokeweed mitogen (PWM), PWM + PHA and PWM + Con A. The most efficient protein supplement was AS, although great variability was observed between subjects. HSA came second, while FCS and FCS-A were the least effective. The presence of immunoglobulins did not modify mitogen-induced lymphocyte responses. In unsupplemented media, peak responses to PHA and Con A occurred at lower mitogen concentrations. Furthermore, the addition of the antibiotics tested did not impede blast transformation whether or not a protein supplement was present. This work also showed that for chromosome analysis, protein supplements are necessary for optimum whole-blood lymphocyte cultures and that HSA can replace FCS.

Adult↗
PubMed1987

Human serum albumin as a substitute for foetal calf serum in blast transformation assays and cytogenetic analyses.

Diverse factors in serum produce complex effects on lymphocytes. Indeed, when used as a protein supplement for lymphocyte culture, serum has many disadvantages. A need exists for media in which serum is replaced by purified active serum components. The in vitro effects of human serum albumin (HSA) were evaluated and compared with the widely used foetal calf serum (FCS). Unstimulated and mitogen-activated lymphocyte proliferation was measured by 3H-thymidine incorporation. Phytohaemagglutinin (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM) were used to transform the lymphocytes obtained from 36 healthy adults. Six concentrations of HSA, 0.5, 1, 2.5, 5, 10 and 20%, were studied. The last two concentrations produced an inhibition of lymphocyte proliferation. HSA, which was not itself mitogenic permitted a 4- to 5-fold higher transformation than 10% FCS. Maximum transformation occurred at HSA concentrations between 2.5 and 5% for PHA and PWM, and between 1 and 2.5% for Con A. In whole-blood lymphocyte cultures, the addition of 1% HSA gave a number of mitoses comparable to that obtained with the 10% FCS supplement. HSA is an interesting substitute for FCS: it is chemically well understood and standardized, species specific, readily available, relatively inexpensive, and has a long shelf life. HSA appears to be an excellent protein supplement for support of human lymphocyte proliferation in vitro, and can be recommended for routine use in lymphocyte cultures.

Adult↗
PubMed1985

Analysis of high-resolution R-bands, obtained by heat-denaturation and Giemsa staining, on human prophase chromosomes.

RHG-bands (heat-denatured Giemsa R-bands) of human prophase chromosomes were analyzed at high resolution, and the banding patterns at prophase and metaphase are presented. The bands were compared with those of the International Standard Cytogenetic Nomenclature idiograms and of the G-band idiograms proposed by J. J. Yunis. The number, size, and position of the RHG-bands correspond rather well with their equivalent G-negative bands, but some differences were noted in the zones of preferential stretching, the juxtacentromeric regions, and the telomeres. Variations in the centromere index and the banding pattern in heterochromatin were also discussed.

Adult↗
PubMed1983

R-banding of human chromosomes by heat denaturation and Giemsa staining after amethopterin-synchronization.

Human late prophase to late metaphase chromosomes were prepared after amethopterin cell synchronization. R-banding was produced by heat denaturation followed by Giemsa staining (RHG). Haploid sets of prophase chromosomes contain approximately 850 bands. Sequences of chromosomes of different degrees of condensation are presented; their analysis provides helpful information to identify the elongated chromosomes and to follow band subdivision. The heat denaturation technique is free from most of the disadvantages encountered with R-banding by 5-bromodeoxyuridine incorporation. Giemsa stained R-bands produced by heat denaturation on prophase and prometaphase chromosomes are useful to analyse the numerous chromosome anomalies involving R-bands. In conjunction with G-banding, it is also important to compare adequately the positive and negative regions of each chromosome to define the anomalies with precision.

Azure Stains↗
PubMed1983

High-resolution idiogram of Giemsa R-banded human prophase chromosomes.

The schematic representation of RHG-banded chromosomes (R-banding was produced by heat denaturation followed by Giemsa staining (RHG) in the 850-band range per haploid set, was prepared showing the relative position, the specific size, and the characteristic staining intensity for each band. To this idiogram was adapted the new International Standard Cytogenetic Nomenclature. Our aim was to produce a realistic idiogram which could help in the preparation of R-banded prophase karyotypes and in the localization of chromosomal rearrangements. A comparative analysis of bands at prophase and metaphase revealed certain aspects of the dynamics involved in chromosome condensation and in R-band organization. The effect of chromosome elongation on the appearance of R-bands within heterochromatic regions has also been discussed.

Adult↗
PubMed1965

[Thyroid suppression test].

A test in which thyroid function is suppressed was evaluated in regard to its ability to confirm the diagnosis of hyperthyroidism in borderline cases. An effort was made to establish a standard technique by determining the required duration of administration of tri-iodothyronine. Twenty-seven normal controls received tri-iodothyronine (T(3)) for a 10-day period, and 24-hour I(131) uptake was determined after three, six and 10 days. Twenty-two normal controls were similarly studied after four days of T(3) treatment. Twenty-one patients with an elevated I(131) uptake without goitre or toxicity, 10 with non-toxic goitre and 11 with toxic goitre were also studied. The T(3) suppression test was found to be particularly useful in distinguishing toxic goitre from euthyroid patients with an elevated I(131) uptake. Four days of suppression were found to be sufficient for purposes of evaluation in a large majority of cases.

Adult↗