摘要:

“In vitro”epinephrine (10−6to 10−4M) stimulates the rat inferior rectus, one of the extraocular muscles (EOMs). When applied to resting muscles, it induces a slow rising tension in about one half of the preparations. The amplitude of this tension is equivalent to about 9% of the maximal tetanic response. This effect is blocked by propranolol (10−7to 10−6M). When epinephrine is applied prior to a depolarization of the muscle fibers with 30 mM K, the drug consistently induces a significant potentiation of the long lasting tonic tension normally evoked by that elevated K concentration. One possible explanation for these results is that epinephrine induces a slow rising tension by increasing a resting Ca conductance of the sarcolemma of the tonic or Felderstruktur fibers of EOM.

ISSN:0271-3683    

DOI:10.3109/02713688709034840

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

We studied the effect of optic nerve section on the pattern electroretinogram (PERG) of 10 pigeons. Base line PERG and flash ERG were measured prior to surgery and then one optic nerve was cut. We measured PERG at various time intervals up to 24 weeks after the section. There was a sharp drop in PERG amplitude immediately following the section. It gradually returned to normal levels in the following 24 weeks. Significant decreases in time to peak were noted at 1 and 16 weeks for 0.5 cycle per degree checks and at 1, 2 and 9 weeks for 0.25 cycle per degree checks. The ERG generated by a TV stimulus did not change in amplitude but had a shorter time to peak at 24 weeks for a high intensity stimulus and at 16, 18, 24 weeks for a low intensity stimulus. Light and electron microscopic sections (at 24 weeks) revealed an almost complete loss of nerve fibers in the optic nerve. Retinal sections revealed only a few surviving ganglion cells and a few nerve fibers. This suggests that in pigeons, PERG is not generated by ganglion cells.

ISSN:0271-3683    

DOI:10.3109/02713688709034841

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Twenty-five uveal melanomas were stained with seven monoclonal antibodies (MoAbs) recognizing different antigens on cutaneous melanomas. A two step immuno-peroxidase procedure was used. Phenotypic heterogeneity was observed for four MoAbs (M.2.2.4, AMF-7, 225.28S, PAL-M1) while two MoAbs (NKI-beteb, CL203.4) reacted strongly with most (85%) uveal melanomas, and one MoAb (R-24) showed very low reactivity. Despite heterogeneity, co-expression of some antigens was observed. Expression of the antigen recognized by MoAb M.2.2.4. was significantly lowered by pre-enucleation irradiation while the other antigens remained unchanged. Expression of antigens on uveal melanomas differed markedly from primary cutaneous melanomas. The clinical relevance of these findings awaits further study.

ISSN:0271-3683    

DOI:10.3109/02713688709034842

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Clonidine and other selective alpha-2 adrenergic agonists have been found to lower intraocular pressure in the eyes of rabbits and primates, including humans. It has been suggested that the ocular hypotensive response to alpha-2 agonists may be mediated, in part, by prejunctional inhibition of norepinephrine secretion at intraocular synapses. In this study, we have investigated the effects of adrenergic agonists and antagonists on field-stimulated, Ca++-dependent release of3H-norepinephrine (3H-NE) from isolated, perfused rabbit iris-ciliary bodies and have utilized radioligand binding methods to identify prejunctional adrenoceptors in this tissue. Clonidine (10−910−5M) produced a dosage-dependent inhibition of stimulation-evoked H-NE secretion (EC50≜3×10−8M), but did not alter basal secretion. Other adrenergic agonists capable of activating alpha-2 adrenoceptors (e.g., epinephrine, norepinephrine and xylazine) also significantly depressed3H-NE secretion, whereas selective alpha-1 adrenergic or beta adrenergic agonists were without effect. Clonidine-mediated inhibition of3H-NE release was reversed by the selective alpha-2 antagonist yohimbine (10−7M), but was unaffected by prazosin or timolol. Yohimbine alone markedly enhanced3H-NE secretion, indicating tonic activation of prejunctional alpha-2 adrenoceptors by endogenous released norepinephrine. Forskolin or 8-bromo-cAMP, which alone enhanced norepinephrine secretion, failed to attenuate the inhibitory responses to alpha-2 agonists.3H-rauwolsclne binding measurements showed a small decrease in alpha-2 receptor sites in iris-ciliary body membranes following surgical sympathetic denervation. It is concluded that the rabbit irisciliary body contains functional, prejunctional alpha-2 adrenoceptors which may play an autoregulatory rolein vivoand contribute to the ocular effects of adrenergic drugs.

ISSN:0271-3683    

DOI:10.3109/02713688709034843

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Sodium hyaluronate is a potential vehicle for drugs given topically to the eye. In the present study, the effect of sodium hyaluronate on the miosis induced by pilocarpine in rabbits was investigated. Addition of 0.2 and 0.75% sodium hyaluronate to 1% pilocarpine hydrochloride in buffer resulted in an increased effect measured as area under the miosis-time curve (AUC) and duration of miosis. A comparison between a commercially available 1% pilocarpine preparation and the preparations containing sodium hyaluronate showed that sodium hyaluronate improves the effect parameters. No adverse effects with sodium hyaluronate were observed. Possible mechanisms inducing these improvements are discussed.

ISSN:0271-3683    

DOI:10.3109/02713688709034844

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Endothelial vesicles on the luminal front of retinal and iridial vessels were studied by perfusion fixation after intravenous injection of peroxidase, and by perfusion fixation of glutaraldehyde with tannic acid or ruthenium red. Many luminal vesicles contained peroxidase reaction product after intravenous injection of peroxidase, but were virtually empty after perfusion fixation. Both tannic acid and ruthenium red delineated the majority of luminal vesicles, singular or in clusters, surface-associated or“free”in the cytoplasm. Only a few free vesicles were unlabeled by the dye. No transendothelial channels were seen. The results suggest that most of the vesicles on the luminal front of endothelial cells are continuous with the cell surface at the time of fixation. The function of these vesicles is not fully understood; some appear to be involved in endocytosis of macromolecules from the vascular lumen.

ISSN:0271-3683    

DOI:10.3109/02713688709034845

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Monocyte/macrophages play a prominent role in several forms of retinal pathology including proliferative vitreoretinopathy, senile macular degeneration, and retinal wound healing. In each of these entities, the retinal pigment epithelium (RPE) is characteristically involved as well. Since RPE cells are known to secrete chemoattractants for astrocytes, we considered the possibility that they might secrete chemotactic factors for monocytes in addition. We have found in in vitro assays that a 5% concentration of medium from 6 different well-established RPE culture lines each consistently induced monocyte migration greater than that elicited by either buffer or unconditioned medium.“Checkerboard”analysis indicated that RPE culture supernatants induced optimal migration with a stimulus gradient (chemotaxis as opposed to chemokinesis alone). Chemotactic activity could be detected in eluates from ion exchange high performance liquid chromatography or gel filtration columns. Several peaks of activity suggested that more than one factor may be responsible for the ability to induce cell migration. The chemotactic activity was largely heat stable. The chemotactic factor induced only minimal migration of polymorphonuclear leukocytes. The secretion of chemotactic factors for monocytes could contribute significantly to the pathogenesis of several retinal diseases.

ISSN:0271-3683    

DOI:10.3109/02713688709034846

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

The capacity of cynomolgus and rhesus monkey conjunctiva, anterior uvea and eyelids to synthesize cyclo-oxygenase and lipoxygenase products from arachidonic acid was assessed. Both conjunctiva and eyelid tissues of cynomolgus and rhesus monkeys synthesized detectable amounts of cyclo-oxygenase and lipoxygenase products, indicating the presence of cyclo-oxygenase and 5-and 12-lipoxygenase activities in these tissues. In comparison, cynomolgus anterior uvea synthesized a considerably lesser amount of cyclo-oxygenase products. The cyclo-oxygenase activity was considerably greater than the lipoxygenase activity in cynomolgus and rhesus conjunctiva and eyelids.

ISSN:0271-3683    

DOI:10.3109/02713688709034847

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Corneal thickness was monitored on seven cynomolgus monkeys (Macaca fascicularis) over a 76 hour period. During this time, corneal thickness measurements were also made on six monkeys after overnight wear of a hydrogel contact lens in one eye. Mean corneal thickness was 417±12um. An overall diurnal variation of 16±5um (3.8±1.2%) was found. During the first half hour after waking, corneal thickness changes ranged from -9um to +14um. After overnight contact lens wear, the cornea had swelled an average of 42±24um (9.1±4.8%). Following lens removal, the cornea returned to normal thickness within approximately 90 minutes. These results are similar to those found in humans and indicate that with respect to contact lens induced corneal thickness changes, the cynomolgus monkey is a suitable model for the physiological response to contact lens wear.

ISSN:0271-3683    

DOI:10.3109/02713688709034848

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

The experiments described were undertaken to determine which cells of guinea pigs immunized by different ocular routes produce the IgGl and IgG2 antibodies detected in the serum.Guinea pigs were immunized intravitreally, topically, or by intravitreal immunization followed by topical conjunctival challenge. An indirect plaque assay was used to detect antibody producing cells in the cervical lymph nodes and ocular tissues. Passive hemagglutination, passive cutaneous anaphylaxis and ELISA assays were used to detect serum antibody.Both the topical and intravitreal methods initiated a primary antibody response. The guinea pigs developed IgGl and IgG2 serum antibodies, but IgE and IgA antibodies were not detected. IgGl and IgG2 plaque forming cells (PFC) were found in the lymph node and uveal tissues of the intravitreally immunized guinea pigs, and in the lymph node and conjunctival tissues of the topically immunized animals. IgA plaque forming cells were not detected in topically immunized animals.Ho antibody producing cells were found in intravitreally immunized guinea pigs sacrificed after the first conjunctival challenge (two months after sensitization). The highest numbers of lymph node and conjunctival PFC were found in the animals sacrificed three days after the second or third topical challenge. The numbers of IgGl antibody producing cells in this group of guinea pigs were usually higher than the numbers of IgG2 PFC. Serum antibody levels, undetectable before challenge, increased after the second challenge.We conclude that both lymph node and ocular cells produce antibody in guinea pigs immunized by ocular routes.

ISSN:0271-3683    

DOI:10.3109/02713688709034849

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor