摘要:

The uptake of45Ca by the rabbit lens reached equilibrium within 20 hr; the steady state lens/medium ratio was 0.08. This ratio is similar to that found for the lens/medium distribution of extracellular markers. Efflux of45Ca from the lens was rapid and insensitive to iodoacetate. Mathematical analysis of45Ca efflux curves revealed that calcium efflux from the lens could be described solely upon the basis of passive movement from the extracellular space. It is concluded that the exchangeable calcium in the normal rabbit lens is predominantly located in the extracellular space.

ISSN:0271-3683    

DOI:10.3109/02713688209020004

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

The high levels of both enzymes of glutathione synthesis found in the infant human lens rapidly reached lower levels by age 10, and thereafter the rate of decrease diminished. Glutathione synthetase activity in the 6 month old lens was six-fold (units/g lens), four-fold (units/mg soluble protein) and two-fold (units/lens) higher than that in the 83 year old, clear human lens,γ-Glutamylcysteine synthetase activity in the 6 month old lens was sixteen-fold (units/g lens), ten-fold (units/mg soluble protein) and six-fold (units/lens) higher than that in the 83 year old, clear human lens. When lenses from the young adult beagle, rabbit, bovine, and humans are compared, glutathione synthetase activity (units/g lens) varies by about two-fold.γ-Glutamylcysteine synthetase activity (units/g lens) is quite similar in the first three species, whereas the enzyme activity is more than a magnitude less in young adult human lenses, and becomes much less with increasing age and in a high proportion of life-support system organ donors. The enzyme activity was undetectable in a few of the latter lenses. Loss of activity was not due to increased susceptibility to heat denaturation. The low levels of the enzyme, and total loss in some situations, suggest thatγ-glutamylcysteine synthetase may be an Achilles' Heel of human lens metabolism.

ISSN:0271-3683    

DOI:10.3109/02713688209020005

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

In the normal chick embryo the neural retina adheres firmly and irreversibly to the underlying retinal pigment epithelium (RPE) starting on day 17–18 of development, coincident with maturation of photoreceptor outer segments. Retinas from earlier embryos (days 13–16) became prematurely attached to the RPE within 30 minutes after death, if held at 37°C, even though developed outer segments were not yet present. Lower temperatures, or failure to enucleate the eye, retarded but did not prevent this postmortem, precocious adhesion. The biochemical factors involved in this process were explored by altering the incubation medium; the factors appear different from those that help maintain retinal adhesion in the adult mammalian eye.

ISSN:0271-3683    

DOI:10.3109/02713688209020006

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

We created double perforating injuries in both eyes of 22 rabbits. One eye of each animal was given a dose of 600 Rad x-irradiation 24 hours after the injury. The irradiated eyes developed significantly less intraocular proliferation than the non-irradiated eyes.

ISSN:0271-3683    

DOI:10.3109/02713688209020007

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

The retinal function of the delayed amelanotic (DAM) chicken that has progressive retinal degeneration, was investigated electroretinographically (ERG). Subjects showing a gradation of abnormalities of retinal morphology and impairment of visual behaviors were tested. Dark-adapted a-, b-, and c-wave responses to full-field stimuli were studied. In general, the more severe the anatomical abnormalities, the greater the compromise of sensitivity and amplitude of ERG responses. The DAM disease appears to affect c-waves more than a-waves, and a-waves more than b-waves. Dark-adapted responses are affected more than light-adapted responses. In DAM's with moderately to severely impaired visual behaviors, ERG studies should permit analysis of the distal retinal pathophysiology caused by this disease.

ISSN:0271-3683    

DOI:10.3109/02713688209020008

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

Two per cent and 4% solutions of sodium cromoglycate eye drops were compared in patients with bilateral vernal keratoconjunctivitis. The trial was a double—blind within-patient group comparison and patients instilled 2% drops into one eye and 4% drops into the other eye four times daily for six weeks. Patients recorded their symptom severity each day on a diary card and clinical examinations were made at 0, 2, 4 and 6 weeks. Both 2% and 4% solutions of sodium cromoglycate were effective in treating the signs and symptoms of vernal keratoconjunctivitis. No difference in efficacy between the two solutions could be detected on the analysis of diary card scores or clinical assessments. The opinions of efficacy and treatment preferences recorded by patients and clinician at the end of the trial were very similar for each solution. Side effects were generally minor, usually relating to stinging following application of the eye drops.

ISSN:0271-3683    

DOI:10.3109/02713688209020009

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

Six mouse hybrid cell lines were isolated which secrete antibodies to rabbit corneal proteoglycan. All six antibodies interacted with the same fraction of the proteoglycan, precipitating approximately 50% of proteoglycan labelled in the protein moiety. A radioimmunoassay using these antibodies measured concentrations as low as 1 g/m1 unlabelled rabbit corneal proteoglycan. Human corneal proteoglycanj corneal keratan sulfate, and an oligosaccharide fraction from corneal digests all interacted with the antibodies at concentrations similar to whole rabbit proteoglycan. Proteoglycans from cultured rabbit stromal fibroblasts and from sclera were 20 to 50-fold less effective in competition for antibody. Endo-β-galactosidase treatment of proteoglycan reduced antibody binding, but protease or chondroitinase treatments did not. Labelled proteoglycan separated by antibody affinity chromatography contained only keratan sulfate, whereas proteoglycan not bound to affinity columns contained only chondroitin sulfate. The antibodies appear to recognise a carbohydrate structure found only on corneal keratan sulfate proteoglycan. This structure can serve as a basis for separation of corneal proteoglycan types using antibody affinity chromatography.

ISSN:0271-3683    

DOI:10.3109/02713688209020010

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

The purpose of this research was to test the role of certain minerals in the formation of cataract caused by an overdose of selenium. Several pieces of information indicated that lenticular calcium may play an important role in selenite cataractogenesis: 1) Lens calcium concentrations in selenite treated rats were increased more than 5-fold, and the increase in lens calcium was localized in the nucleus. 2) Lens calcium concentrations were elevated at least one full day before actual formation of nuclear cataract, but serum calcium levels were not changed. 3) In older rats not susceptible to selenite cataract, lens calcium was not significantly increased. 4) No evidence was found for a generalized disruption in lens permeability, since no major changes in lens water, sodium, and potassium levels were observed, and 5) when levels of calcium observed in selenite cataract were added to solutions of soluble proteins from rat lenses, light scattering was increased. Selenium-overdose cataracts may provide an important model for studies on the role of calcium in cataractogenesis.

ISSN:0271-3683    

DOI:10.3109/02713688209020011

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

Highly purified preparations of two recombinant-DNA derived human leukocyte interferon subtypes (LeIF-A and LeIF-D) and a similarly derived fibroblast interferon were compared for efficacy against herpes simplex virus, type 1, infection of the rabbit cornea. LeIF-D appeared to be more effective than LeIF-A especially when compared on the basis of interferon units. The fibroblast interferon showed no significant effects. The greater activity of LeIF-D compared with LeIF-A could be due to greater direct antiviral effects, as observed in rabbit cell cultures.

ISSN:0271-3683    

DOI:10.3109/02713688209020012

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

Either isolated normal or preswollen rabbit corneas were perfused across their endothelial surface with various drugs in the specular microscope. The deswelling rate of preswollen corneas was uninfluenced by calmodulin (1 and 10μg/ml), phenylephrine (0.1 and 1 mM), DbcAMP (10–4M), theophylline (10–3and 10–4M), isoproterenol (2×10–7and 2×10–6M), or cyclic GMP (10–4and 10–6M). The swelling rate of normal thickness corneas was increased by furosemide (10–5and 10–4M) and thiocyanate (5×10–2and 5×10–3M) but not by SITS (10–3M), dipyridamole (5×10–5M) or NAP-taurine (10–3M). The results suggest that alteration of endothelial cyclic AMP or cyclic GMP levels has no influence on transendothelial fluid flow. Modulation of the metabolic processes underlying anion fluxes by furosemide and thiocyanate caused corneal swelling but none of the agents which affect passive anion exchange in other systems influenced transendothelial fluid movement. The furosemide and thiocyanate effects confirm that bicarbonate, or chloride, exchange may be important in part in the regulation of corneal dehydration by the endothelium.

ISSN:0271-3683    

DOI:10.3109/02713688209020013

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor