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Biomedical subjects

F Robinson

Publications and source records attributed to F Robinson.

At least 19 recordsLinked to original sources
PubMed1992

The acute effect of topical epinephrine on macular blood flow in humans.

The acute effect of topical epinephrine HCl 2% on macular capillary blood flow was studied in 18 healthy human volunteers using the blue-field simulation technique. This technique provides a method for quantifying the velocity of leukocytes flowing in macular capillaries. Subjects adjusted the velocity of simulated leukocytes on a computer screen to match that of their own entoptically perceived leukocytes before instilling the drug and 2 hr thereafter. An artificial tear solution was instilled into the fellow eye for a control. Epinephrine instillation resulted in a 8% increase in macular leukocyte velocity and presumably blood flow (P less than 0.03, paired student t-test).

Administration, Topical↗
PubMed1989

Long-term follow-up of idiopathic central serous chorioretinopathy by fluorescein angiography.

Idiopathic central serous chorioretinopathy (ICSC) is typically described as a self-limited, unilateral disease that affects healthy, young adult males. The authors studied 13 patients (14 eyes) who had documented spontaneous resolution of symptomatic macular detachments. These patients were evaluated in a longitudinal fashion to determine the fate of the retinal pigment epithelium (RPE) as viewed angiographically, both in the initially affected eyes and the fellow eyes. At the time of follow-up examination of the initially affected eyes, nonleaking RPE defects had developed inside the areas of previous serous detachment in all cases. Nonleaking RPE defects had developed outside these areas in six (43%) eyes. Two (14%) eyes had new, asymptomatic macular detachments. Six (42%) fellow eyes had new RPE window defects; two (17%) of them also had active RPE dye leakage resulting in asymptomatic macular detachment at the final examination. Four (29%) originally involved eyes and one (8%) fellow eye lost more than two lines of Snellen visual acuity during the follow-up period. The authors' results suggest that ICSC may be a progressive bilateral disease that develops asymmetrically and causes diffuse RPE changes not localized to the area of serous detachment. Long-term follow-up of these patients may, therefore, be advisable.

Adult↗
PubMed1986

Leucocyte elastase activity in meningococcal septicaemia associated coagulopathy.

The concentration of the elastase-alpha 1 proteinase inhibitor complex (E-alpha 1 PI) in a meningococcal infection in an index case with severe changes in haemostasis was measured. The concentration of the E-alpha 1 PI complex was increased throughout the duration of the illness, although concentrations of the blood clotting factors were severely decreased. The release of polymorphonuclear elastase activity may contribute to the depletion in clotting factors.

Blood Proteins↗
PubMed1986

Retinal blood flow autoregulation in response to an acute increase in blood pressure.

The response of the retinal circulation to an acute elevation in systemic blood pressure was studied in three healthy normotensive volunteers using the noninvasive laser Doppler velocimetry (LDV) technique combined with retinal vessel size measurements. Isometric exercise was employed to induce the acute rise in arterial pressure. There was no detectable change in retinal blood flow until the mean brachial artery blood pressure was elevated to an average of 115 mm Hg, which represented an average rise in mean blood pressure of 41% above baseline values. Above this value, blood flow increased along with further increments in blood pressure. The parallel rise between the ophthalmic artery pressure and the brachial artery pressure indicates that the regulation of retinal blood flow observed in the above mentioned pressure range is achieved through an increase in retinal vascular resistance rather than by a mechanism that would act to maintain a constant ocular perfusion pressure.

Adult↗
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↗
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↗