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Biomedical subjects

C Leonard

Publications and source records attributed to C Leonard.

At least 19 recordsLinked to original sources
PubMed1990

Biclonal chromosome evolution of chronic myelomonocytic leukemia in a child.

A monosomy 7 was first detected in a 6-month-old boy with a chronic myelomonocytic leukemia. After etoposide treatment, relapse occurred after 29 months, with transformation of the disease into an acute myeloblastic leukemia. After bone marrow transplantations, two abnormal clones were found in marrow cells: 45,XY,-7,del(12)(p11p12)(66%), and 45,XY,-7,t(3;12)(q26;p12)(33%). Several karyotypic studies performed until the terminal phase exhibited the persistence of these two clones in the same proportion, although both independently acquired additional and often similar anomalies. The clone with t(3;12) acquired der(7),der(11),der(17),der(8),der(10),-5,-20, and the clone with del(12p), del(5q),der(4),der(8),der(10),der(17),-5,-20. The anomalies in 12p12 appear to represent an important although secondary event of the neoplastic process. The other anomalies may correspond to either those of a secondary acute nonlymphocytic leukemia, since they occurred after treatment by etoposide and alkylating agents, or to the natural evolution of myelomonocytic leukemia.

Bone Marrow↗
PubMed1990

Brain and plasma quinolinic acid in profound insulin-induced hypoglycemia.

Profound insulin-induced hypoglycemia is associated with early-onset neuronal damage that resembles excitotoxic lesions and is attenuated in severity by antagonists of N-methyl-D-aspartate receptors. Hypoglycemia increases L-tryptophan concentrations in brain and could increase the concentration of the L-tryptophan metabolite quinolinic acid (QUIN), an agonist of N-methyl-D-aspartate receptors and an excitotoxin in brain. Therefore, we investigated the effects of 40 min of profound hypoglycemia (isoelectric EEG) and 1-2 h of normoglycemic recovery on the concentrations of QUIN in brain tissue, brain extracellular fluid, and plasma in male Wistar rats. Plasma QUIN increased 6.5-fold by the time of isoelectricity (2 h after insulin administration). Regional brain QUIN concentrations increased two- to threefold during hypoglycemia and increased a further two- to threefold during recovery. However, no change in extracellular fluid QUIN concentrations in hippocampus occurred during hypoglycemia or recovery as measured using in vivo microdialysis. Therefore, the increases in brain tissue QUIN concentrations may reflect elevations of QUIN in the intracellular space or be secondary to the increases in QUIN in the vascular compartment in brain per se. L-Tryptophan concentrations increased more than twofold during recovery only. Serotonin decreased greater than 50% throughout the brain during hypoglycemia, while 5-hydroxyindoleacetic acid concentrations increased more than twofold during hypoglycemia and recovery. In striatum, dopamine was decreased 75% during hypoglycemia but returned to control values during recovery, while striatal 3,4-dihydroxyphenylacetic acid and homovanillic acid were increased more than twofold during both hypoglycemia and recovery.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Slot blot method for the quantification of DNA sequences and mapping of chromosome rearrangements: application to chromosome 21.

As an alternative to the methods of gene dosage based on either RFLP studies or Southern blots using specific and reference probes, we designed a "slot blot" method for the evaluation of the copy number of unique chromosome 21 sequences. Varying amounts of denatured DNA from a normal control, a trisomy 21 patient, and the subject to be analyzed were loaded on the same membrane. Successive hybridizations with reference probes and chromosome 21 probes were then carried out. Intensities of the signals on autoradiograms were quantified by densitometric scanning. Graphic and statistical analysis of the linear regressions between reference and chromosome 21 probe signals were performed, and the conclusion that the DNA from the studied subject had two or three copies for a given chromosome 21 sequence was assessed by statistical comparison of the slopes. As a test for the validation of this method, 10 coded blood DNAs from five normal controls and from five trisomy 21 patients were analyzed, by using two reference (COL1A1 and COL1A2) and two chromosome 21 (D21S11 and D21S17) probes. Among the 10 DNAs analyzed, it was possible to diagnose, with 100% accuracy, normal controls and trisomic 21 individuals. Application of this methodology to the mapping of partial chromosome 21 rearrangements is presented.

Base Sequence↗
PubMed1989

Genetic aspects of artificial insemination with donor semen: the French CECOS Federation guidelines.

The genetic problems raised by assisted reproduction using donor gametes (AID) are numerous and often complex. They concern the legitimacy and the appropriate forms of genetic screening for both gamete donors and recipients; the identification of genetic indications justifying the use of this method of reproduction; and ascertainment of the state of health of the conceptus at birth. The experience and guidelines of the French CECOS Federation, which comprises 20 AID treatment centers, are described. The discussion emphasizes the need for an international exchange of view on this subject.

Eugenics↗
PubMed1988

Retrograde changes in transglutaminase activity after peripheral nerve injuries.

It has been previously demonstrated that transglutaminase activity in rat superior cervical ganglion is rapidly and transiently increased minutes after nerve injury. The present series of experiments sought to determine: (1) whether or not similar changes are expressed by other peripheral neuronal systems, and (2) if injury-induced changes in the enzyme activity can be detected along the injured nerve, and if so do they occur in axons or in non-neuronal cells. In the nodose ganglion transglutaminase activity increased (approximately 40%) 48 h after the vagus nerve was crushed 25 mm from the ganglion. In the vagus nerve the activity was transiently increased (approximately 100%) within 1 h, followed by a second increase (approximately 140%) after 3 h. This occurred only in the proximal nerve stump close to the injury site and not in the section of nerve closer to the ganglion. Comparable enzyme activity was found in unoperated vagus nerve and in distal stumps of previously ligated vagus nerves. In dorsal root ganglia no changes were found for up to 24 h after the sciatic nerve was crushed 40 mm from the ganglion. In the facial nucleus a transient increase was observed after the facial nerve was crushed about 14 mm distally with a peak (approximately 300) at 3 days and a decline within 14 days. A second lesion of the facial nerve made 12 days following a conditioning lesion led to a rebound of enzyme activity in the facial nucleus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Eleven new cases of del(9p) and features from 80 cases.

We report 11 cases of del(9p) and review 69 previously published ones. Of the 80 cases, 39 have a del(9p) as the sole anomaly. The symptoms are typical and diagnosis should be suspected at birth. The sex ratio does not appear to be unbalanced. A cardiac murmur is often present but surgery is rarely necessary. Mean IQ is 48. The number of reported cases with an associated trisomy has previously been underestimated. Death in infancy, owing mainly to gross visceral malformations, occurs more often in cases of del(9p) with another unbalanced chromosome segment (16/41) than in cases of del(9p) as the sole anomaly (1/39).

Abnormalities, Multiple↗
PubMed1987

Proposal for a scoring of the quality of the banding of chromosomes.

We propose an objective scoring of the quality of the banding of mitoses based on the number of bands (B), the length (L), and the width (W) of chromosome 7 in metaphase as used in the formula [LnB square root L/W]2. When no figure shows the quality of mitoses from which a breakpoint is described, this scoring could give information about it. It could be applied in cytogenetic cancer studies as well as for preparations with high resolution banding.

Bone Marrow Cells↗
PubMed1987

Characterization of the blast cell population in two neonates with Down's syndrome and transient myeloproliferative disorder.

The phenotype and in vitro growth properties of blood and marrow blast cells detected in two neonates with Down's syndrome and a transient leukaemic picture are presented. In both patients, blast cells at diagnosis were heterogeneous and expressed predominantly megakaryocyte and erythroid markers identified by membrane fluorescence using monoclonal antibodies or ultrastructural detection of platelet peroxidase and ferritin. An additional trisomy involving chromosome 22 was detected in blast cells from one patient. Blood and marrow cells colony-assays performed at diagnosis revealed precursors with an abnormal differentiation capacity similar to those found in acute myelogenous leukaemia colony assays. However, an unusual feature was the persistence of high numbers of precursor cells (namely erythroid) following a normal differentiation pathway. Phenotypically and cytogenetically abnormal cells spontaneously disappeared by week 4-6, but overt relapse occurred in one patient 20 months later. These results bring strong arguments in favour of the neoplastic nature of the transient leukaemic picture observed in some neonates with Down's syndrome. Furthermore, we suggest that this disorder can be individualized as a separate entity with specific phenotypic and biological properties.

Bone Marrow↗
PubMed1986

Multiple intestinal atresia and amyoplasia congenita in four unrelated infants: a new association.

Four unrelated infants with multiple segments of nonduodenal intestinal atresia and amyoplasia congenita are described. The extreme rarity of each of these conditions as a single entity indicates that their concurrent incidence in four separate unrelated patients is of significance with respect to pathogenesis. The nature of the relationship between the two conditions is unknown.

Arthrogryposis↗
PubMed1986

Genetic screening for artificial insemination by donor (AID). Results of a study on 676 semen donors.

We report the results of our ten-year experience in the Centre for Study and Conservation of Human Semen (CECOS) in Paris-Bicêtre. A total of 676 potential semen donors were interviewed by a geneticist and karyotyped; 6.0% were excluded, i.e. 2.6% for a cytogenetic reason and 3.4% for a genic reason. Our experience stresses the subjectivity and difficulty of the exclusion decision. It also shows how useful it is to take into account the recipient's familial pathology when choosing the donor. Finally, it reveals the importance of the geneticist's participation in the functioning of a centre.

Chromosome Aberrations↗
PubMed1985

Persistent vegetative state. Extension of the syndrome to include chronic disorders.

Twenty-nine institutionalized patients had the vegetative state as a sequela of chronic progressive neurologic disorders. During three years, the state was persistent; none improved, ten died. Eight similar patients were reviewed retrospectively post mortem. Eight patients with severe dementia, while acutely ill or sedated, temporarily met the criteria for persistent vegetative state (PVS) but improved when the underlying condition was treated. Abnormalities on electroencephalography or computed tomographic scan are not specific for the PVS. Electroencephalograms were normal in three patients with PVS. The computed tomographic scans showed extensive destruction of the brain parenchyma but were not different from those of severely demented patients without the PVS. The PVS is a feature of the terminal phase of several progressive neurologic disorders. Patients should be treated without excessive intervention.

Coma↗
PubMed1979

The self-assessment of confidence, by one vocational trainee.

A list of important topics in general practice was constructed and a trainee was asked to indicate his confidence about each topic on a one to five scale. Repeated use showed different confidence ratings by the same trainee, and an attempt was made to correlate factual knowledge by using a multiple choice questionnaire.Despite important limitations, which are described, this method may be useful in identifying suitable topics for teaching during the trainee year.

Education, Medical, Graduate↗
PubMed1976

[Suicidal behavior and meterological conditions].

Six hundred and seventy five cases of attempted suicide observed in a resuscitation department were confronted with a certain number of biometeorological factors recorded daily: atmospheric pressure, air temperature, degree of insolation, precipitation, relative humidity, water vapour pressure, wind (speed and direction), hydrometeores, index of solar eruption, density of F2 layer. The confrontation is made for the two days before the intoxication and for the day when suicide is attempted. Parameters are then studied by statistical calculation (calculation of X2 and of the number of degrees of freedom). There does not seem to be any significant relationship, in spite of disconcerting series, between most meteorological factors and the number of attempted suicides observed. However, it is noted that no suicides were recorded during periods of solar eruption, and that there seems to be a marked correlation between suicide and winds, particularly according to their direction. Thus, winds charged with ionised particles seem to coincide with a high rate of self-destruction.

Atmospheric Pressure↗