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Biomedical subjects

R D Young

Publications and source records attributed to R D Young.

67 records · Page 4Linked to original sources
PubMed1980

Morphological and ultrastructural aspects of the dermal papilla during the growth cycle of the vibrissal follicle in the rat.

The dermal papilla is highly implicated as the source of regulatory stimuli upon which the progression of the hair growth cycle depends. Using light and electron microscopes, the large dermal papilla of the vibrissal follicle has been studied during anagen, catagen and telogen phases of the growth cycle. The transition of the papilla from its mature anagen condition to a greatly reduced and morphologically distinct form at telogen is associated with various intra- and extracellular changes. With the reduction in ground substance during catagen papillary cells aggregate as organelles of synthetic function are replaced by lysosomes and autophagic vacuoles. Maximal diminution of the papilla at telogen coincides with the cessation of vibrissa production in the matrix and a prominent thickening of the basal lamina with dense projections into the regressed papilla. These observations are collated with previous studies on pelage follicle morphogenesis and are discussed with reference to the control of the hair growth cycle.

Animals↗
PubMed1979

Hyperactive boys in their classroom: assessment of teacher and peer perceptions, interactions, and classroom behaviors.

Teacher ratings, peer perceptions, peer interactions, and classroom behaviors of 17 hyperactive and 17 active elementary school-age boys, nominated by their teachers, were compared using multivariate analyses and planned comparisons in order to better describe and assess hyperactivity in its most probable setting--the classroom. Hyperactive boys were found to be significantly different from actives on measures from all data sources in that they were perceived and interacted more negatively. Cluster analyses of teacher ratings of 90 hyperactives from a clinical sample and 17 hyperactives from the current sample were used to discriminate among different types of hyperactives. Four types were named anxious, conduct problems, inattentive, and low problem hyperactives. The fact that six conduct problem hyperactives were found to be more disruptive and have higher activity level ratings than six inattentive hyperactives, when observed in their classrooms, points to the need to study and treat hyperactives as heterogeneous groups.

Attention↗
PubMed1976

Morphological changes associated with the growth cycle of vibrissal follicles in the rat.

Morphological changes which occur in the growth cycle of the rat vibrissal follicle during the transitional period between consecutive anagen phases are described. In contrast with pelage hair follicles, there is no shortening of the follicle, no formation of a papilla 'rest' and no close synchrony between club differentiation and follicle regression. Telogen is therefore considered to occur after loss of the matrix of the hair bulb and maximal diminution of the dermal papilla to a small aggregation of cells. These difference are discussed in relation to current nomenclature of the hair cycle and the function of the vibrissal follicle.

Animals↗
PubMed1975

Results of combination chemotherapy of non-Hodgkin's lymphoma.

The analysis of the results of CVP and MOPP chemotherapy in 80 patients with advanced stages of non-Hodgkin's lymphoma shows that 36 achieved a complete remission. Twenty-five percent of all patients remain free of disease for periods ranging from 4 months to over 7 years, with a projected median duration of complete remissions of 3 1/2 years. Well differentiated and nodular histology were positive determinants for survival, confirming the overall clinical validity of the Rappaport classification system for the non-Hodgkin's lymphomata. However, it has been demonstrated that it is possible to achieve a complete remission using combination chemotherapy even in the most clinically aggressive histological subgroups, and that these responses can be correlated with an extended survival. An analysis of patterns of relapse from complete remission in patients with non-Hodgkin's lymphoma treated with combination chemotherapy has demonstrated differences between histological subgroups. Patients with diffuse histiocytic lymphoma who achieved a complete remission after 6 months of treatment without maintenance have remained disease-free, whereas those with nodular poorly differentiated lymphocytic and diffuse well differentiated lymphocytic lymphomata demonstrate a pattern of continuous late recurrence. The initial sites of relapse from complete remission in lymphocytic lymphoma were lymph nodes and bone marrow which were involved before treatment.

Antineoplastic Agents↗
PubMedDate not supplied

Ultrastructural studies of corneal collagen during the development of experimental scleritis in rabbits.

An active Arthus reaction induced in the rabbit cornea leads to scleral disease resembling that in humans. Collagen damage was located in the corneal stroma at the site of the immune reaction. In the electron microscope, some regions of corneal stroma, without loss of lamellar integrity, demonstrated the apparent swelling of individual, scattered collagen fibrils such that a helical arrangement of component microfibrils was evident. In areas showing more extensive damage, fibril fragmentation and solubilization was associated with the aggregation of fibrous banded material. These observations are discussed with reference to possible mechanisms underlying the development of scleritis in the rabbit and which might also contribute to an understanding of the pathology of the disease in humans.

Animals↗