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Biomedical subjects

D R Meyer

Publications and source records attributed to D R Meyer.

At least 91 records · Page 5Linked to original sources
PubMed1990

Ultrastructural and immunohistological characterization of the SIRC corneal cell line.

A widely utilized rabbit corneal cell line, SIRC, was characterized ultrastructurally and immunohistologically. Although SIRC cells are often described as being of epithelial origin, important ultrastructural and antigenic characteristics indicate that these cells are fibroblastic and not epithelial. SIRC cells lack desmosomes, cytoplasmic filaments, and cytokeratin-structures that are characteristic of corneal epithelial cells. By contrast, the dendritic morphology, presence of vimentin, and the extensive dense accumulations of ribosomes and rough endoplasmic reticulum are consistent with a fibroblastic phenotype. Collectively, the morphology, ultrastructural features, and antigenic composition favor the hypothesis that SIRC cells are fibroblastic cells (keratocytes) and not corneal epithelial cells.

Animals↗
PubMed1990

Assessment of tear drainage after canalicular obstruction using fluorescein dye disappearance.

Assessment of tear drainage impairment after monocanalicular obstruction can be difficult. The authors used fluorescein dye disappearance to evaluate tear drainage after experimental obstruction of upper, lower, neither, or both canaliculi in 20 subjects. Marked impairment was noted in all subjects when both canaliculi were occluded (P less than 0.004). Monocanalicular obstruction (either upper or lower) generally resulted in minimal or no impairment, though 10% of subjects showed marked impairment. Fluorescein dye disappearance proved a reliable, rapid method for assessing tear drainage and detecting lacrimal obstruction.

Fluorescein↗
PubMed1990

Iontophoresis for eyelid anesthesia.

Local anesthesia is appropriate for eyelid surgery, but patients fear the pain of injections. We evaluated iontophoresis of lidocaine for eyelid skin anesthesia to pinprick pain sensation in normal subjects, and prior to regional infiltration of the anesthetic agent in patients undergoing eyelid surgery. After iontophoresis of lidocaine hydrochloride 4% solution to one randomly chosen eyelid, pinprick skin sensation was tested in a double-masked manner. Subjective pain scores of 10 subjects were significantly less (P less than .008) on the iontophoresis treated eyelids (0.25) than on the untreated eyelids (2.55). Nine patients undergoing bilateral upper eyelid surgery had iontophoresis applied to one randomly chosen eyelid prior to the usual anesthetic injections. In this double-masked evaluation, patients reported significantly less pain (P less than .02) on the treated eyelids (1.4) than on the untreated eyelids (4.7). We conclude that iontophoresis is effective for achieving short-term, superficial anesthesia of eyelid skin.

Anesthesia, Local↗
PubMed1990

In vivo and in vitro collagenolytic activity of Acanthamoeba castellanii.

Axenic cultures of Acanthamoeba castellanii contained a collagenolytic enzyme that digested collagen shields and purified collagen in vitro. Specificity of biologic activity was determined by the addition of selected enzyme inhibitors to the assays and revealed that the parasite-conditioned medium contained both collagenase and lower concentrations of other proteolytic enzymes. However, most of the collagenolytic and pathogenic activity was directly attributable to specific collagenase. Intrastromal injection of sterile, Acanthamoeba-conditioned culture medium into naive Lewis rats produced corneal lesions clinically similar to and closely resembling those found in biopsy specimens of human patients diagnosed with acanthamoebic keratitis. Histopathologic analysis revealed moderate-to-severe neutrophil infiltration, disruption of stromal lamellae, and edema. Identical pathologic sequelae were produced by intrastromal injection of purified collagenase (25 units/ml). The pathogenicity of the soluble parasite-derived product was removed by passage over affinity columns armed with antibody specific for collagenase. These results indicated that soluble parasite-derived factors were capable of producing lesions characteristic of acanthamoebic keratitis and that the pathogenicity of these factors was either directly or indirectly attributable to specific collagenase activity.

Acanthamoeba↗
PubMed1989

Quantitating the superior visual field loss associated with ptosis.

The effect of blepharoptosis on the superior visual field was assessed using a series of specially designed contact lenses to simulate ptosis in normal subjects. We found a progressive decrease in the superior visual field at the 90 degree vertical meridian, which was proportional to the degree of simulated ptosis. Our results were in close agreement with both a theoretical model and previous clinical observations. These results are important in evaluating patients contemplating ptosis surgery, as well as in visual field testing for neuro-ophthalmic disorders.

Adult↗
PubMed1988

Increased intraocular pressure in the immediate postoperative period after extracapsular cataract extraction.

We evaluated the immediate intraocular pressure increase after extracapsular cataract surgery in 58 eyes. Two to three hours postoperatively, 34 eyes (59%) developed an intraocular pressure greater than or equal to 25 mm Hg. We found an intraocular pressure of at least 40 mm Hg in seven eyes. Mean intraocular pressure two to three hours postoperatively was 8.9 +/- 9.8 mm Hg greater than the preoperative intraocular pressure. The use of intraocular sodium hyaluronate had no apparent effect on intraocular pressure.

Aged↗
PubMed1987

City employment change in the Republic of Korea, 1960-1970.

Changes in the employment characteristics of Korean cities during the 1960s, a period of polarized development and rapid industrialization, are examined. The expectation of modernization and world-system/dependency theorists that the national metropolis, Seoul, increased its dominance in many key sectors is supported. Other cities, however, also grew rapidly, specialized in different economic sectors, and changed their economic structures. Polarized development, therefore, need not imply atrophy of noncore cities. Both modernization and world-system/dependency theorists need to apply more complex conceptualizations of systems of cities in developing nations.

Asia↗
PubMed1986

Optimization of parameters for maximization of plateletpheresis and lymphocytapheresis yields on the Haemonetics Model V50.

Automated apheresis techniques afford the opportunity of tailoring collection parameters for each donor's hematologic profile. This study investigated the effect of various settings of the volume offset parameter as utilized in the Haemonetics Model V50 instrumentation during platelet- and lymphocytapheresis to optimize product yield, purity, and collection efficiency. In both types of procedures, increased product yield could be obtained by using an increased volume offset for donors having lower hematocrits. This improvement was related to an increase in collection efficiency. Platelet products also contained fewer contaminating lymphocytes with this approach. Adjustment of the volume offset parameter can be utilized to make the most efficient use of donors and provide higher-quality products.

Automation↗
PubMed1986

Temporal neocortical injuries in rats impair attending but not complex visual processing.

The effects of variations of the distance between the relevant stimuli and the animals' response sites were observed upon the performances of a black-white discrimination habit for normal rats or subjects prepared with either bilateral injuries to the visual or temporal neocortex. In addition, the animals were given a strict test of visual form perception. Subjects with injuries to the visual cortex failed the test of visual form perception but performed like normals in discriminating a spatially discontiguous problem. In contrast, subjects with temporal injuries exhibited enormous performance deficits when trained on a spatially discontiguous problem but performed like normals on the test of form perception. The findings parallel the results of studies using primates and suggest that bitemporal injuries result in impairments of attending and not of complex visual processing.

Animals↗
PubMed1982

Synthesis of terfenadine.

The synthesis of alpha-[4-(1,1-dimethylethyl)phenyl]-4-(hydroxydiphenylmethyl)-1- piperidinebutanol (terfenadine, RMI 9918, Triludan, Teldane, resp.) is described. A limited structure-activity analysis of the central nervous system-mediated side effects of this compound and related analogs is made relative to the antipsychotic agent, haloperidol. Modification of the piperidine 4-position substituents of haloperidol to give a 4-(alpha, alpha-diphenylmethanol) moiety has conveyed histamine H1 -antagonism to the anti-psychotic agent, haloperidol. Structural changes of this fluorobutyrophenone have progressively reduced and finally eliminated centrally-mediated side effects. The result of this exercise is terfenadine, a preferred antihistamine, potent and selective in antagonizing histamine H1-receptor-mediated responses but lacking the usual side effect profile of known histamine H1-receptor antagonists.

Animals↗