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Biomedical subjects

F Robinson

Publications and source records attributed to F Robinson.

At least 55 records · Page 3Linked to original sources
PubMed1985

Does topical phenylephrine, tropicamide, or proparacaine affect macular blood flow?

The acute effect of topical phenylephrine HCl 10%, tropicamide 1% and proparacaine HCl 0.5% on macular capillary blood flow was studied in six healthy human volunteers using the blue field simulation technique. This technique provides a method for quantifying the velocity of leukocytes flowing in one's own retinal macular capillaries. Patients adjusted the velocity of computer simulated leukocytes moving on a CRT screen to match that of their own entoptically perceived leukocytes before instillation of each of the tested preparations and for 35 minutes immediately thereafter A 5% NaCl solution was used as a control. We found no significant difference in leukocyte velocity between the control drop and any of the tested drugs. With the six subjects tested, the calculated average minimum percentage change in leukocyte velocity detectable with this technique (P less than 0.05, paired t-test) was 9%. None of the tested drugs affected macular leukocyte velocity, and presumably blood flow, by more than this amount.

Administration, Topical↗
PubMed1985

The acute effect of cigarette smoking on macular capillary blood flow in humans.

The acute effect of cigarette smoking on retinal macular blood flow was studied in 14 healthy habitual smokers using the blue field simulation technique. This technique provides a method for quantifying the velocity of leukocytes flowing in one's own macular capillaries. Subjects adjusted the mean velocity of computer simulated leukocytes moving on a CRT screen to match that of their own entoptically perceived leukocytes before, during, and immediately after smoking a cigarette. Smoking resulted in a 12 +/- 5% (SEM) increase in macular leukocyte velocity and presumably blood flow. Possible mechanisms for this increase are discussed.

Adult↗
PubMed1981

Corticopontine projections of the lateral suprasylvian cortex: de-emphasis of the central visual field.

Layer V pyramidal cells of the cat lateral suprasylvian visual areas project to the pontine nuclei. Although all 6 of the suprasylvian visual areas project to the pons, the densest projections are from 3 areas: anterior medial lateral suprasylvian (AMLS), posterior medial lateral suprasylvian (PMSL) and ventral lateral suprasylvian (VLS). The organization of the corticopontine pathway from one of these areas (PMLS) suggests a disproportionate representation of the peripheral visual fields. This pattern of projection would serve to de-emphasize the central visual field.

Animals↗
PubMed1980

Corticopontine visual projections in macaque monkeys.

These experiments were designed to study the projections to the pons from visual and visual association cortex of monkeys by degeneration staining and horseradish peroxidase (HRP) methods. When lesions were made in these cortical visual areas, degenerated fibers were found in the rostral dorsolateral area of the pontine nuclei. When HRP was injected among visually responsive cells in this region of the pons, layer V cortical pyramidal cells were labeled. These labeled cells were concentrated most heavily on both banks of the superior temporal and intraparietal fissures, and on the rostral bank of the parieto-occipital fissure. The efferent targets and receptive field properties of these cortical regions are consistent with their possible role in visual guidance of movement.

Animals↗
PubMed1980

Visual pontocerebellar projections in the cat.

1. Projections of pontine visual cells onto the cat cerebellar cortex were studied by antidromic activation and by the retrograde transport of horseradish peroxidase (HRP). 2. Cells in the medial pontine visual area, which receive visual cortex projections, were activated antidromically principally from the contralateral cerebellar hemisphere. Cells in the dorsolateral pontine visual area, which receive an input from the superior colliculus, were activated principally from the vermis and ipsilateral hemisphere. There is some overlap in the projections of these two different populations of pontine cells, which probably occurs by way of bifurcated axons. 3. The HRP technique confirmed that there is a major difference in the pattern of projections from these two pontine visual regions. Many cells in the rostral-medial portion of the pontine nuclei, which receive their input from visual cortex, were labeled following HRP injections in the contralateral cerebellar hemisphere. Far fewer of these cells were labeled following vermal injection. Cells in the dorsolateral pontine nucleus, which receive visual input from the superior colliculus, were labeled following an HRP injection in the vermis or the ipsilateral hemisphere. Cells in the region of pontine nuclei that receive input from the ventral lateral geniculate nucleus were also labeled after a vermian injection. 4. If the vermis is related to the control of whole-body movements and the hemisphere to control of ipsilateral limbs, these results suggest that the corticopontocerebellar and the tectopontocerebellar pathways may be involved in different classes of visually guided movement.

Animals↗
PubMed1978

Small hemorrhages vs. small calcifications in brain tumors: difficulty in differentiation by computed tomography.

The difficulty in differentiating multiple small hemorrhages from multiple small calcifications in brain tumors by computed tomography (CT) is discussed. Illustrative CT scans are presented and the theoretical basis for this problem is elaborated. The difficulty is attributed to the relatively large size of the voxel and the ensuing partial volume effect, particularly with small intraparenchymal lesions of different sizes and attenuations.

Adult↗
PubMed1976

Studies on normal human bone marrow cultures in controlled environment thin-film culture systems.

Two thin film culture systems, the controlled environment steady state system (SS) and the rocker tube configuration of that system (RT), were used to identify some of the conditions that appear to maintain morphologic and functional characteristics of cells of human bone marrow explants in vitro. The systems configuration assured continual gassing, control and easy monitoring of the cultures. Cytocentrifuge preparations of media of specimens cultured in RT disclosed, though in decreasing numbers, various hematopoietic cells for periods exceeding one month. Hematopoietic cells shed from specimens cultured in the SS system were retained in the culture tubes; cells of the myelocytic series predominated for the first two weeks while an increasing number of monocytes and macrophages appeared in the media of of older cultures. Histologic examination of cultured explants disclosed preservation of the marrow architecture and the persistence of hematopoietic cells. Specimens cultured in RT tubes tended to be less cellular than similar cultures placed in dialysis bags or as cultured in the SS system. Immunoglobulins (Ig) were released into the culture media at a constant rate throughout the period of culture. Specimens that were cultured at a controlled pH of 7.4 released 2 to more than 4 times as much Ig as similar specimens maintained at a pH level of 7.1. There were no definitive differences in Ig levels in the cultures maintained at comparable pH levels and overlaid with various CO2 concentrations, i.e. 2%, 5%, 10% similarly, no differences in Ig levels were found in specimens cultured in media containing fetal bovine sera as opposed to horse sera.

Bone Marrow↗
PubMed1976

Embryogenesis of the human occipital bone.

From an original study of fetal specimens, the embryogenesis of the human occipital bone is described. The occipital bone in man is derived from cartilage, except for the interparietal segment which has a membranous origin. Normally there is no midline cerebellar fissure or synchondrosis.

Bone Development↗
PubMed1976

Anomalies of the craniovertebral border.

Pertinent embryology is reviewed as a background for understanding anomalies of the craniovertebral border. These anomalies constitute a variable spectrum due either to incomplete assimilation or abnormal fusion.

Animals↗
PubMed1976

The os incae.

The The os incae is an integral feature of reptilian and various mammalian skulls which demonstrate intramembranous ossification centers behind the parietal bones. In man, the interparietal portion of the occipital squamosa arises in membrane from a single ossific focus. Normally it fuses with the supraoccipital segment of the occipital squamosa. Occasionally there are multiple ossification centers in the interparietal bone which fail to fuse, resulting in one of several varieties of os incae.

Animals↗