摘要:

Physiologically healthy elderly individuals often exhibit visual deficits which result from age-related changes in both the transmission characteristics of the ocular media and the functional properties of the neural elements in the visual pathway. Many of the age-related changes in the optical quality of the ocular media have been identified, but the age-dependent variations in visual neurophysiology have not been clearly delineated. This investigation examined age-related alterations in pattern-specific biopotentials generated in the human retina and visual cortex. Counterphasing (2.0 and 7.5 rps) patterns (7.51, 15′, 30′and 60′checks) were used to simultaneously monitor pattern-reversal visual evoked potentials (PRVEPs). Young visual normals (20–30 years of age) and healthy elderly observers (70–80 years of age) with visual acuity of 20/30 or better were studied. All data were corrected for the effects of senile miosis on retinal illumination. Significant variations in the waveform characteristics of both biopotentials were noted for the elderly individuals. PRRP amplitude was uniformly reduced for all stimulus conditions. PRVEP amplitude reductions were also noted but were more stimulus specific than the PRRP amplitude reductions. No significant PRVEP or PRRP latency changes were observed. These results suggest that alterations in the physiological properties of neural elements in both the retina and visual cortex are associated with normal aging.

ISSN:0271-3683    

DOI:10.3109/02713688609000011

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

In the aged lens Dostsynthetically altered molecules comprise the majority of lens proteins. Many proteolytic activities have been observed in lens suoernatants. Since damaged or altered proteins are usually selectively and rapidly degraded in other cells and tissues, the accumulation of these soecies in the lens seemed enigmatic. Initiation of Droteolysis has been studied most extensively in reticulocytes and ts 35 cells. In these systems proteolysis is absolutely ATP dependent, occurs effectively on high molecular weight substrates and, at least for a majority of proteolytic reactions, requires conjugation of ubiquitin to putative substrates. It seemed plausible that the accumulation of high molecular weight protein aggregates in older lenses might be due to the attenuated function of these ubiquitin- and ATP-dependent components in the initial committing processes of proteolysis. This research shows that: 1) ubiquitin is Dresent in_the lens; 2) lens Droteins are conjugated to I-ubiquitin using reticulocyte conjugating systems; 3) the reaction is ATP detiendent; 4) proteins from lens epithelium/outer cortex and core form different ubiquitin conjugates; 5) lens proteins compete with lysozyme and reticulocyte nroteins for the ubiquitin conjugating apparatus; 6) most of the conjugates are of very high molecular weight; 7) there is a temporal nature to the Dattern of conjugates observed; and 8) the ubiquitin conjugation system shows extreme selectivity.

ISSN:0271-3683    

DOI:10.3109/02713688609000012

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

A method is described for the isolation of Herpesvirus simplex (HSV) from corneal discs of patients suffering from chronic stromal keratitis. The discs were removed during penetrating keratoplasty. Virus was successfully isolated from 2 out of 8 discs maintained in vitro.

ISSN:0271-3683    

DOI:10.3109/02713688609000013

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

Epsilon is a recently described eye lens protein from Rana temporaria, an anuran amphibian. It is oligomeric with a subunit M.W. of 35K. The cDNA coding for 35Kϵ- in frog lens does not show any homology with cDNA's coding forα,β,γandδ-crystallins. Immunologically, it also does not react with antibodies directed againstα,β-, andγ-crystallins (1).The ontogeny of this 35K E-protein has been investigated in R. temporaria lens development by the indirect immunofluorescence staining method with an antibody specific for the 35K e-protein.The purity of the isolated 35K protein and the specificity of the antibody were controlled by Tris-SDS gel electrophoresis (2) and immuno-blotting, respectively (3).The first positive immunofluorescence reaction was observed in the inner cell wall of a stage V lens. In the external layer/epithelium the reaction was first detected in a single cell of a stage VI1 lens. Additional positive cells in the external layer/epithelium were detected at an early stage Vlll and the reaction appeared to be patchy. This type of patchy reaction was also observed in the epithelium of froglet (sub-adult) eye lens.

ISSN:0271-3683    

DOI:10.3109/02713688609000014

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

The adherence of microorganisms to contact lenses may be an important initial step in the pathogenesis of contact lens-associated infectious keratitis. Using a strain of Candida albicans whose interaction with various polymers has been well characterized we systematically investigated the adherence of this pathogen to hard hydrophobic and soft hydrophilic extended-wear contact lenses. Yeasts adhere to the hydrophobic lenses in direct proportion to the wetting angle of the lens whereas yeasts adhere to the hydrophilic lenses in direct proportion to the water content of the lens. Tear proteins such as albumin, lactoferrin, and lysozyme in addition to fibronectin enhance yeast adherence to both types of lenses (P<0.01). Concanavalin A reduces adherence of yeasts to both lens types (P<0.01). Among tear components however, only mucin (0.5%) consistently reduced yeast adherence to both lens types. Hydrophilic extended wear lenses worn for at least 28 days by normal patients consistently had greater adherence of yeasts than unworn lenses of the same type, often as much as ten-fold or greater yeasts/mm2of lens surface area (P<0.05). These investigations indicate that tear components both in solution and adsorbed to the lens surface enhance microorganism adherence to contact lenses.

ISSN:0271-3683    

DOI:10.3109/02713688609000015

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

Isolated rabbit corneas bathed in Krebs-bicarbonate Ringer solution were observed for thickness changes after a 90 minute equilibration period. Control corneas swelled an average of 0.5 /im/hr, and placement of a polymethylmethacrylate (PMMA) contact lens on the epithelial surface caused the corneas to swell 24.5, um/hr, an effect similar to 0.5 mM epithelial cyanide exposure. The pronounced swelling induced by PMMA lens placement was much less however, in the epithelial presence of 3.2 mM sodium oxalate (3.22 jtm/hr) or 3.2 mM sodium oxamate (5.38 jum/hr). An equiosmotic excess of 4.8 mM NaCl was least active (15.89/jm/hr). On normal isolated corneas (without contact lenses), the Ringer containing an excess of 4.8 mM NaCl significantly deswelled the corneas (-13.44 im/hr), which contrasted with oxalate and oxamate containing Ringer solutions (1.17 and 1.33 m/hr respectively). The present study supports the notion thatcontactlens-induced edema results from stromal lactate accumulation, and suggests a potential alternative to osmotic therapy for its amelioration. These LDH inhibitors, in the concentrations used, have no acute osmotic or toxic effect on normal corneasvnvitro.

ISSN:0271-3683    

DOI:10.3109/02713688609000016

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

It has been shown using ELISA and affinity chromatography, that extracts from heat-shocked Drosophila melanogaster larvae and cultured cells react with monoclonal antibodies raised against bovine a-crystallin. It is suggested that this cross-reactivity is associated with the region of the sequence corresponding to residues 98–108 of the bovine otA-crystall in chain. This region may be important for the functions of both a-crystallin and the heat-shock proteins.

ISSN:0271-3683    

DOI:10.3109/02713688609000017

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

Retinal S-antigen is thought to play an important role in the immunopathogenesis of uveitis. To investigate whether S-antigen is a sequestered antigen confined to the retina, a sensitive ELISA was developed to determine the levels of this protein in various human ocular tissues, aqueous humour and serum.The ELISA was performed by incubating S-antigen-containing samples with solid-phase bound immunospecific rabbit anti human C-ar.tigen F(ab')?fragments and then incubating the bound S-antigen with mouse anti bovine S-antigen serum and the bound mouse antibodies with peroxidase-labelled rabbit anti mouse IgG; the peroxidase activity is developed with ABTS. This method was demonstrated to be highly sensitive and specific: S-antigen could be measured at concentrations of 5–10 nanograms per ml, irrespective of whether it was present in buffer, undiluted whole serum or tissue extracts.Human retinas were shown to contain approximately 1.2 mg immunoreactive S-antigen per retina. Of the other human ocular tissues, only the vitreous and choroid (including pigment epithelium) contained small amounts of S-antigen. Low levels of S-antigen could also be detected in the aqueous humour of two out of seven patients with posterior uveitis. No immu-noreactive S-antigen could be detected in the serum of either healthy individuals or patients with uveitis. Sera collected from diabetic patients 15 minutes after extensive laser photocoagulation also did aot contain immunoreactive S-antigen. Preliminary experiments with rats to study the clearance of intravenously injected S-antigen from the circulation indicated that the relatively short half-life (±30 min) of circulating S-antigen might account for the absence of detectable S-antigen in the patient sera.

ISSN:0271-3683    

DOI:10.3109/02713688609000018

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

Previous attempts by others to measure the wettability of the corneal epithelium concluded that the surface was strongly hydrophobic, but used methods which seem likely to damage the epithelial cell surface. These experimental techniques were repeated and the effects on the surface analysed by scanning electron microscopy. It is concluded that such methods cannot establish either the hydrophobicity or hydrophilicity of the cornea.

ISSN:0271-3683    

DOI:10.3109/02713688609000019

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

Cyclosporin A (CsA) was administered to chicks of the Smyth delayed-amelanotic (SDA) line from day of hatch to 4, 8 or 12 weeks of age. Animals were evaluated at 8, 12, 16 or 20 weeks with regard to major features of the SDA-line disorder, including extent of feather and choroidal ame-lanosis, choroidal inflammation, and his-topathology of the retinal pigment epithelium and outer retina. A suppression and delay in the onset of both amelanosis and ocular histopathology occurred during CsA administration. However, a rebound enhancement of symptoms occurred 4–8 weeks after withdrawal of CsA that was closely associated with the duration of CsA treatment. These results indicate that CSA may yield therapeutic effects during the period of treatment, but its withdrawal may lead to more severe symptoms that would have occurred without treatment.

ISSN:0271-3683    

DOI:10.3109/02713688609000020

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor