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Biomedical subjects

L Dionne

Publications and source records attributed to L Dionne.

At least 19 recordsLinked to original sources
PubMed1998

Ovarian function in superoxide dismutase 1 and 2 knockout mice.

Copper/zinc superoxide dismutase (SOD1) and manganese superoxide dismutase (SOD2) are the two major intracellular enzymes which inactivate superoxide radicals. SOD1 is present in both cytoplasmic and nuclear compartments whereas SOD2 is localized to mitochondria. Both enzymes are expressed in multiple tissues as well as ovaries of several species including humans and rodents. Dominant mutations in SOD1 are associated with amyotrophic lateral sclerosis. We have previously demonstrated that SOD2-deficient mice die within three weeks of birth due to oxidative mitochondrial injury in central nervous system neurons and cardiac myocytes. In this report, we demonstrate that female homozygous mutant mice lacking SOD1 can survive to the adult stage but are subfertile. Whereas breeding of 5 SOD1 heterozygote females produced an average of 1.0 litter/month with 8.6 offspring/litter (n = 31 litters), only 11 of 16 SOD1 homozygote mice over a 2-6 month period became pregnant averaging 0.23 litters/month with an average litter size of 2.7 (n = 21 litters). Histological analysis of the ovaries from SOD1-deficient mice often reveals many primary and small antral follicles but few corpora lutea. In addition, ovaries from postnatal SOD2-deficient mice, transplanted to the bursa of wild-type hosts, show all stages of folliculogenesis including corpora lutea and can give rise to viable offspring. These studies support an important role of SOD1 in female reproductive function and suggest that SOD2 is not essential for ovarian function.

Animals↗
PubMed1996

Neurodegeneration, myocardial injury, and perinatal death in mitochondrial superoxide dismutase-deficient mice.

Manganese superoxide dismutase (SOD2) converts superoxide to oxygen plus hydrogen peroxide and serves as the primary defense against mitochondrial superoxide. Impaired SOD2 activity in humans has been associated with several chronic diseases, including ovarian cancer and type I diabetes, and SOD2 overexpression appears to suppress malignancy in cultured cells. We have produced a line of SOD2 knockout mice (SOD2m1BCM/SOD2m1BCM) that survive up to 3 weeks of age and exhibit several novel pathologic phenotypes including severe anemia, degeneration of neurons in the basal ganglia and brainstem, and progressive motor disturbances characterized by weakness, rapid fatigue, and circling behavior. In addition, SOD2m1BCM/SOD2m1BCM mice older than 7 days exhibit extensive mitochondrial injury within degenerating neurons and cardiac myocytes. Approximately 10% of SOD2m1BCM/SOD2m1BCM mice exhibit markedly enlarged and dilated hearts. These observations indicate that SOD2 deficiency causes increased susceptibility to oxidative mitochondrial injury in central nervous system neurons, cardiac myocytes, and other metabolically active tissues after postnatal exposure to ambient oxygen concentrations. Our SOD2-deficient mice differ from a recently described model in which homozygotes die within the first 5 days of life with severe cardiomyopathy and do not exhibit motor disturbances, central nervous system injury, or ultrastructural evidence of mitochondrial injury.

Animals↗
PubMed1992

The effects of speech and language therapy for a case of dysarthria associated with Parkinson's disease.

We report the results of a single-subject multiple baseline across behaviours experiment of a 74-year-old woman presenting with Parkinson's disease. Her speech was typical of a hypokinetic dysarthria. The main features of her dysarthric speech were: a restriction in the modulation of fundamental frequency, an inappropriate pitch level and a rate disturbance. Three measures of prosody were operationally defined as follows: (1) linguistic modulation of fundamental frequency, (2) mean fundamental frequency and (3) rate. Treatment focused on ameliorating these aspects employing a multiple baseline design. Measures during and post-therapy documented improvement for each of these three aspects of prosody. Independent judges were also more capable of understanding her speech and her speech prosody after therapy. Upon follow-up measures 10 weeks later, most of the improvement was maintained.

Aged↗
PubMed1987

Extratelencephalic projections of the avian visual Wulst. A quantitative autoradiographic study in the pigeon Columbia livia.

The efferent projections of the pigeon visual Wulst upon the diencephalon and mesencephalon were investigated using the autoradiographic technique following the combined injection of [3H] proline and [3H] leucine into the rostral hyperstriatum accessorium. Repeated measures of silver grain densities were performed bilaterally in different brain structures using a computer-assisted system of image analysis. The density values were compared (Mann-Whitney U-Test) with those recorded in three homolateral control structures (tractus opticus, n. rotundus, n. pretectalis principalis) and in corresponding contralateral areas and nuclei. The data showed ipsilateral projections from the visual Wulst and via the tractus septomesencephalicus upon the dorsal thalamus (n.: dorsolateralis anterior superficialis parvocellularis), ventral thalamus (n.: intercalatus, ventrolateralis, geniculatus lateralis pars ventralis--GLv), pretectum (n.: superficialis synencephali, geniculatus pretectalis, griseus tectalis, pretectalis: diffusus, pars lateralis and pars medialis, area pretectalis) as well as to the nucleus of the basal optic root, n. spiriformis medialis and optic tectum (layer 2-4, 6, 7, 12 and 13). Crossed projections were observed to pass through the supraoptic decussation and the posterior commissure, however only the contralateral n. GLv was found to be significantly labeled. Interspecies variations in the organization of descending visual Wulst projections, related to the terminal distribution and relative size of the crossed components may be linked to differences in the degree of overlap of the binocular fields. Correspondingly, this may reflect the degree of bilateralization upon the Wulst of direct input from the visual thalamus.

Animals↗
PubMed1984

Asynchronous pheochromocytoma in childhood.

A case of asynchronous pheochromocytoma in a 13-year-old boy is reported. Two years elapsed between excision of the right adrenal gland and the appearance of another tumour in the contralateral gland. Selective central venous sampling for plasma catecholamine measurement and adrenal phlebography were of diagnostic value. Excision of the tumour with partial adrenalectomy was the preferred surgical treatment in the remaining contralateral adrenal; no clinical or biochemical abnormalities were observed 2 years after removal of the second pheochromocytoma. This case stresses the importance of a closer follow-up in children for early detection of a second pheochromocytoma.

Adolescent↗
PubMed1983

Internal mammary lymphoscintigraphy in breast carcinoma--a surgeon's perspective.

Internal mammary lymphoscintigraphy (IML) should now be considered a standard staging procedure in the present state of the art of the management of the patient with breast carcinoma. It provides clues for assessing the extent of disease and helps one to select individualized therapy. The interpretation is reliable enough in expert hands, to rule out the necessity of internal mammary node histopathologic diagnosis. In view of the significance of nodal invasion in relation to distant spread of the disease, one would be entitled to use this test as an indication for complementary systemic therapy when positive. On the other hand, if systemic therapy is to be employed without selection according to the multitude of relevant criteria, there may be no need to carry out this staging procedure prior to a management decision. The authors have reviewed their experience with more than 1000 examinations and have shown some of the practical implications of IML as a staging procedure as well as a guide to therapy.

Breast Neoplasms↗
PubMed1981

[Breast neoplasms: a 1980 dilemma].

For many reasons, breast cancer is still the most controversial topic in oncology. Questions raised many years ago in relation to diagnosis and treatment have not yet been answered. Clinical classification, such as the TNM system, is open to many pitfalls and the degree of error in axillary staging is still high, even in expert hands. The situation with regard to management is similar. The types of treatment are numerous and controversial, so that interpretations of results is unreliable. The fundamental questions will be answered only by clinical trials.

Breast Neoplasms↗