This study examines the differential contributions of motor cortex (MCx) and red nucleus (RN) neurons to the initiation of a targeted limb response and to the control of trajectory. These questions were assessed in two ways. First, by comparing the characteristics of task-related neuronal activity in MCx and RN. Second, by determining the changes in reaction time and trajectories produced by the reversible inactivation of corticospinal fibers in the crus cerebri (CSTc), the rubrospinal tract (RST) and the RN, using microinjections of lidocaine, gamma-aminobutyric acid, or muscimol. Neurons in forelimb areas of both MCx and RN were modulated in advance of forelimb force production. RN neurons more frequently had a phasic discharge pattern, while neurons in MCx more frequently had a tonic pattern. Whereas the modulation of most forelimb area neurons in MCx correlated with responses in a specific direction, the majority of RN neurons were non-directional. Reversible inactivation of CSTc, RN and RST prolonged reaction time. The normal stereotyped form of isometric force trajectories was unaffected by injections at any site. While CSTc inactivation resulted in hypometric responses, response amplitude was unchanged during RN and RST inactivation. We conclude that both MCx and RN contribute to response initiation, but that only MCx is involved in the proper scaling of targeted responses.

Animals↗

PubMedDate not supplied

Developing outcome assessment methods.

Describing the development of an outcome assessment method for accreditation, the authors discuss development of criterion definitions and the evaluation of results from a pilot study using student portfolios. The subsequent design of an outcome assessment tool to provide concrete, objective data, the evolution of the evaluation process using this tool, and how the outcome data are currently used for curriculum evaluation are discussed.

Accreditation↗

PubMedDate not supplied

Endothelial nitric oxide synthase: correlation with histologic grade, lymph node status and estrogen receptor expression in human breast cancer.

Nitric oxide is produced by several isoenzymes which are present in many different tissues. We have recently reported the presence of inducible nitric oxide synthase in a breast cancer cell line. The purpose of this study was to examine the distribution of endothelial nitric oxide synthase (eNOS) in a series of human breast tumours. Immunohistochemical investigations demonstrated immunolabelling of tumour cells with the primary antibody, bovine endothelial anti-nitric oxide synthase. Although there was no correlation between eNOS staining and tumour size, there was a significant (p < 0.005) negative correlation (rho = -0.65) between the percentage of tumour cells staining positive for eNOS and the histologic grade of the tumour; there was also a significant (p < 0.05) negative correlation (rho = -0.40) between the percentage of tumour cells staining positive for eNOS and the number of positive lymph nodes. A significant (p < 0.005) positive correlation (rho = 0.63) between the percentage of tumour cells staining positive for eNOS and estrogen receptor (ER) expression by the tumour was also observed. In conclusion, our results demonstrate that eNOS is expressed by human breast tumours and that its presence negatively correlates with histologic grade and lymph node status and positively correlates with ER expression.

Animals↗

PubMedDate not supplied

Crystals in a gastric schwannoma.

A gastric schwannoma containing large numbers of intracytoplasmic crystals is described. The latter are compared with intracytoplasmic crystals found in the cells of other tumors and their nonneoplastic cell counterparts. The extreme morphologic and histochemical heterogeneity of the different types of crystals is emphasized.

Crystallization↗

PubMedDate not supplied

Simple technique to facilitate tissue sampling for electron microscopy.

The need to examine certain components of a specimen with the electron microscope is frequently recognized only after study of the paraffin sections, by which time the total specimen has usually been fixed in Formalin. Such specimens are frequently large, with the result that representative samples for electron microscopy may be difficult to isolate. A simple, quick, and inexpensive method for overcoming this sampling problem is described. This technique is best employed in laboratories that routinely use a single tissue fixative suitable for both light and electron microscopy. The specimen is taken direct from the Formalin, and very thin slices are prepared by hand with a blade, stained with methylene blue, and examined in the wet state under the microscope. On identification, representative tissue is removed by micro-dissection and processed further for electron microscopy.

Histological Techniques↗

PubMedDate not supplied

Differential effects of retinoids on nitric oxide production by promonocytic U937 cells and ZR-75-1 human breast cancer cells.

We demonstrated the presence of inducible and endothelial nitric oxide synthases in histiocytic lymphoma U937 cells by staining with anti-iNOS and anti-eNOS antibodies. We also investigated the effects of retinol and retinoic acid on nitric oxide production by both U937 cells and ZR-75-1 human breast cancer cells. U937 cells which had been treated with either retinol or retinoic acid (10-10-10-6 M) exhibited no significant difference in nitric oxide secretion into conditioned medium. Conversely, for ZR-75-1 cells, both retinol and retinoic acid (10-10-10-6 M) caused a significant (p<0.001) increase in the amount of nitrite secreted. Our results indicate that retinoid induced growth inhibition of breast cancer cells is associated with an increase in NO production, however, an increase in NO synthesis does not mediate retinoid induced differentiation of U937 cells.

Antineoplastic Agents↗

PubMedDate not supplied