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Biomedical subjects

J H Lass

Publications and source records attributed to J H Lass.

At least 37 records · Page 2Linked to original sources
PubMed1994

Infiltration of CD4+ T cells into cornea during development of Onchocerca volvulus-induced experimental sclerosing keratitis in mice.

Sclerosing keratitis is the major cause of blindness due to onchocerciasis caused by the parasite Onchocerca volvulus. Although the importance of T cells in the pathogenesis of onchocerciasis has been suggested, their precise role in onchocercal sclerosing keratitis has not yet been defined. Using immunohistological techniques and a murine model of onchocercal sclerosing keratitis, we have performed a temporal analysis of the inflammatory T cells infiltrating into the cornea at Days 4, 7, and 21 following intrastromal challenge with soluble O. volvulus antigens into presensitized mice. The maximum number of CD3+ T cells were observed in the corneal stroma at Day 21 when sclerosing keratitis was most severe. The majority (> 85%) of the CD3+ T cells were CD4+ at all time points. A few infiltrating cells bore IL-2 receptors indicating possible activation of a small fraction of the T cells. These results suggest that CD4+ T cells play an important role in onchocercal sclerosing keratitis.

Animals↗
PubMed1994

Epidermal growth factor and insulin use in corneal preservation. Results of a multi-center trial. The Corneal Preservation Study Group.

PURPOSE: The ability of DexSol medium, supplemented with two growth factors, human epidermal growth factor (hEGF) and human insulin, to improve long-term endothelial survival after penetrating keratoplasty was evaluated in a multi-center, randomized, prospective, double-masked clinical trial. METHODS: Donor cornea pairs, one stored in DexSol and the other in DexSol with hEGF (10 ng/ml) and human insulin (10 micrograms/ml) (ProCell), were transplanted into 105 pairs of recipients matched by diagnosis and procedure and followed postoperatively for graft and endothelial survival. RESULTS: No primary donor failures occurred in either group. Graft clarity did not differ between the ProCell and DexSol groups at all postoperative periods: 3 months (98% versus 99%), 6 months (94% versus 98%), and 1 year (95% versus 97%), respectively. Postoperative complications (e.g., glaucoma, rejection) occurred with comparable frequencies in both groups. Mean endothelial cell loss did not significantly differ between the ProCell and DexSol groups at 3 months (5.7% versus 5.1%), 6 months (8.1% versus 10.1%), and 1 year (12.3% versus 15.6%), respectively. Similarly, there were no clinically and statistically significant differences in other endothelial morphometric parameters. CONCLUSIONS: The use of corneas stored in DexSol medium with added hEGF and insulin in corneal transplantation resulted in a safety and efficacy profile comparable with that observed in patients receiving DexSol-stored corneas; however, there were no clinically and statistically significant differences in postoperative endothelial morphometric parameters.

Adult↗
PubMed1994

The effect of hEGF and insulin on corneal metabolism during Optisol storage.

We examined the effect of the growth factors, human epidermal growth factor (hEGF) and insulin, on corneal metabolism during storage in Optisol, a chondroitin-sulfate-(CS)-based storage medium. Paired cat corneas, in either Optisol only or Optisol with growth factor(s), were analyzed using ex vivo 31P nuclear magnetic resonance, after storage for 1 week at 4 degrees C. Lysosomal enzyme release into the media at the end of the storage period also was measured fluorometrically. Both epithelial-intact and epithelial-denuded corneal pairs were examined for all conditions. Considering corneas having either intact epithelia or epithelium-denuded corneas, the addition of either growth factor alone to Optisol did not alter the relative corneal concentrations of five of the six phosphatic metabolite spectral bands measured or two metabolic ratios calculated from these bands. Phosphodiesters, however, were significantly lower in corneas stored in Optisol containing both hEGF and insulin (23%) than in corneas stored in Optisol alone (30%). Intracorneal pH was unaffected by the addition of growth factor(s). A significantly higher release of alpha-glucosidase and alpha-mannosidase was noted in those corneas stored in Optisol containing both hEGF and insulin. Optisol maintains high-energy phosphate corneal metabolism similar to other CS-based media, K-Sol and Chondroitin Sulfate Corneal Storage Medium (CSM). The addition of the growth factors hEGF and insulin to Optisol alters corneal metabolic activity during storage in a manner indicative of conserving corneal phospholipids.

Animals↗
PubMed1994

Clinical evaluation of a computerized topography software method for fitting rigid gas permeable contact lenses.

Computerized videokeratoscope software programs now have the ability to assist in the design of rigid gas permeable (RGP) contact lenses and simulate fluorescein patterns. We evaluated the performance of Computed Anatomy's Topographic Modeling System (TMS-1) and its Contact Lens Fitting Program (version 1.41) in fitting RGP lenses in 31 subjects. Computerized topographic analysis, balanced manifest refraction, slit lamp examination, and keratometry were performed. Initial lens parameters were ordered according to manufacturer's programmed recommendations for base curve, power, lens diameter, optic zone diameter, and edge lift. Final lens parameters were based on clinical performance. Lenses were recorded for base curve changes of 0.1 mm or more, power alterations of +/- 0.50 D or more, or for any alteration in diameter/optic zone. Twenty-seven patients were analyzed for all five recommended parameters. Thirteen of 27 patients (48%) required no parameter changes. Nine of 27 patients (33%) required one parameter change, four of 27 patients (15%) required two parameter changes, and one patient (4%) needed three parameters altered. The most prevalent change was a power alteration, required in nine of 27 patients (33%); however, comparisons of all initial to final parameters showed no statistically significant differences. Comparison of initial base curves to that which would have been chosen via standard keratometry also showed no significant difference. This study found the TMS-1 default lens recommendations to be clinically unacceptable. This system, however, could be an alternative method of initial lens selection if used to titrate a fit or if software enhancements are incorporated to account for lens movement and flexure.

Astigmatism↗
PubMed1994

Localization of the complement membrane attack complex inhibitor (CD59) in human conjunctiva and lacrimal gland.

Recent studies have established that complement is present in the eye and participates in ocular defense. The mechanisms by which ocular tissues are protected from bystander injury arising from local activation of the cascade, however, have not been characterized. Decay accelerating factor (DAF or CD55) and the membrane inhibitor of reactive lysis (MIRL or CD59) are cell surface regulatory proteins that protect blood cells from uptake of autologous C3b and polymerization of autologous C9 on their surfaces. In previous studies, we found that DAF is expressed in high levels on corneal, conjunctival, and lacrimal gland acinar surfaces. In this study we assayed ocular and lacrimal gland tissues for CD59. Immunohistochemical analyses demonstrated large amounts of the protein the same locations. The presence of CD59 in these sites is consistent with the proposal that CD59 functions together with DAF in protecting ocular tissues from autologous complement-mediated injury.

Antibodies, Monoclonal↗
PubMed1993

Immune-mediated Onchocerca volvulus sclerosing keratitis in the mouse.

Sclerosing keratitis is the major cause of blindness due to onchocerciasis; its pathogenesis is poorly understood. We have previously reported an immune-mediated model of experimental interstitial keratitis in guinea pigs following intrastromal challenge with soluble antigens from Onchocerca volvulus. This model system is ideal for evaluation of pathogenicity of multiple purified antigen preparations; however, reagents necessary for detailed immunologic analysis of the inflammatory cellular infiltrate are not yet available for guinea pigs. Because of the ready availability of these reagents for mice, a mouse model has been developed. The inflammatory response observed in this model was analogous to that seen in human onchocercal sclerosing keratitis as well as in the guinea pig model of onchocercal sclerosing keratitis. Granulocytes were present in the acute inflammatory response, whereas the chronic response showed lymphocytes, plasma cells, and histiocytes. Neovascularization and scarring of the corneal stroma was also observed. This model will be helpful in examining the mechanisms of immunopathogenesis and the contribution of the host genetic background to the disease.

Animals↗
PubMed1993

Metabolic compatibility of abattoir and human corneas: an ex vivo 31P nuclear magnetic resonance spectroscopic study of intact tissues.

This study establishes the metabolic similarities and differences of intact abattoir corneas and the human cornea ex vivo, using 31P nuclear magnetic resonance spectroscopy. Phosphorylated sugars (SP), inorganic orthophosphate (Pi), phosphodiesters, ATP, ADP, and the nucleoside diphosphosugars and dinucleotides (NS&DN) were quantitated. The intracorneal pH also was determined. In addition, metabolic indices ATP/Pi, ATP/ADP, ATP/(ADP + Pi), SP/Pi, the phosphorylation potential, and the 31P energy modulus were calculated. Significant differences were observed between the abattoir and human corneas in phosphorylated sugars, NS&DN, and intracorneal pH, as well as in the indices ATP/ADP and SP/Pi. The overall energy status as measured by the 31P energy modulus was significantly higher in the bovine cornea when compared to the porcine and human corneas, suggestive of a very high energy reserve in the bovine cornea.

Adenosine Diphosphate↗
PubMed1993

Antimicrobial activity and in vitro corneal epithelial toxicity of antimicrobial agents for gram-positive corneal pathogens.

We assessed in vitro the antimicrobial activity of four agents (vancomycin, teicoplanin, mupirocin, and imipenem) which are effective against Gram-positive cocci causally associated with bacterial keratitis, as well as their corneal epithelial cytotoxicity. Minimal inhibitory concentrations inhibiting 90% of strains (MIC90s) against 10 strains each of methicillin-susceptible and -resistant Staphylococcus aureus and Staphylococcus epidermidis, penicillin-susceptible and -resistant Streptococcus pneumoniae, and viridans group streptococci were as follows: vancomycin (MIC90s 0.25-2 micrograms/ml), teicoplanin (MIC90s 0.25-4 micrograms/ml, mupirocin (MIC90s 0.12-4 micrograms/ml), and imipenem (MIC90s 0.008-0.25 micrograms/ml, except for methicillin-resistant staphylococci with MIC90 of 16 micrograms/ml). Cytotoxicity was assayed by uptake of 3H-thymidine by rabbit corneal epithelial cell cultures at drug concentrations of 12.5-100 mg/ml for vancomycin and teicoplanin, 1-8 mg/ml for mupirocin and 0.125-8 mg/ml for imipenem, with exposure times of 5, 30 and 60 min. Cytotoxicity was as follows: imipenem < mupirocin < vancomycin < or = teicoplanin. Resistance to methicillin-resistant S. aureus and S. epidermidis for imipenem and resistance to S. epidermidis and cytotoxicity for teicoplanin limit their consideration for suspected Gram-positive keratitis. On the other hand, vancomycin and mupirocin, because of their excellent therapeutic indices, should be considered for this indication.

Animals↗
PubMed1993

Enhanced healing of cat corneal endothelial wounds by epidermal growth factor.

PURPOSE: The authors investigated whether healing of cat corneal endothelial wounds could be enhanced in vivo by human epidermal growth factor (EGF). METHODS: EGF was administered in sodium hyaluronate to the anterior chamber of cats after an endothelial touch injury. Control contralateral eyes received sodium hyaluronate alone. At selected times after injury, the corneas were evaluated for thickness, the rate of endothelial wound closure, the endothelial cell density, any variation in cell size, the percentage of hexagonal cells, and endothelial cell mitosis. RESULTS: Two days after injury, endothelial wounds of eyes treated with EGF had healed an average of 65 +/- 4% of the initial 38.5 mm2 wound area; paired control eyes had healed an average of 59 +/- 4% (P < 0.05). Both EGF-treated and control wounds had resurfaced over 90% of the initial wound area on day 4 after injury, and the wounds were completely resurfaced by 7 and 14 days after injury in both treatment groups. On days 4 and 7 after injury, the EGF-treated corneas were 5% and 8% thicker (835 versus 796 microns and 786 versus 728 microns, respectively) than the paired control corneas (P < 0.03). On days 10 and 14 after injury, both EGF-treated and control corneas were 19% and 12% thicker, respectively, than prewound the corneal thickness (621 microns). Seven days after injury, the corneas treated with EGF had an average of 76 +/- 28% more (P < 0.05) endothelial cell nuclei labeled with tritiated thymidine compared with that of the paired control eyes (2472 versus 1543 labeled nuclei). Fourteen days after injury, the central endothelial cell density of EGF-treated corneas was an average of 38 +/- 11% higher than that of the paired control eyes (P < 0.01, 1708 versus 1235 cells/mm2). The percentage of hexagonal cells in the wound area was an average of 14 +/- 4% higher (P < 0.01) than that of the paired control eyes (82% versus 69%), and the coefficient of variation of the cell size for EGF-treated corneas was an average of 31% (P < 0.05) smaller than that of the paired control corneas (0.21 versus 0.29 [standard deviation]/mean cell size). CONCLUSIONS: A single intraocular application of EGF formulated in sodium hyaluronate after an endothelial cell injury significantly enhanced multiple parameters that are closely related to improved endothelial cell regeneration.

Animals↗
PubMed1992

Optisol corneal storage medium.

We compared the safety and efficacy of Optisol (Chiron Ophthalmics, Irvine, California), a new corneal storage medium, with McCarey-Kaufman and Dexsol corneal storage media (Chiron Ophthalmics, Irvine, California) and K-Sol corneal storage medium (Cilco, Huntington, West Virginia). Optisol contains dextran, 2.5% chondroitin sulfate, vitamins, and precursors of adenosine triphosphate (adenosine, inosine, and adenine). In in vitro studies, rabbit and human corneas stored in Optisol were thinner after 12 to 14 days at 4 C than tissue stored in other media. Thymidine uptake showed increased mitotic activity in human corneal endothelial cells cultured in Optisol, compared to Dexsol. Specular microscopic fields showed larger are-as of visibly intact endothelial cells and ultrastructural examination disclosed fewer structural changes in endothelial cells stored in Optisol, compared to tissue stored in Dexsol. In vivo, no clinical signs of epithelial toxicity or histologic evidence of intraocular inflammation were observed in rabbit eyes in which Optisol drops were instilled four times a day for 14 days. Finally, 51 patients undergoing penetrating keratoplasty with tissue stored in Optisol for one to six days (mean, 3.6 days) were enrolled in an uncontrolled, open-label clinical study. The percentage of clear grafts (93%, 41 of 44 patients examined at three months; and 98%, 42 of 43 patients examined at six months) and endothelial cell loss (5.0% and 11.5% at three and six months, respectively) were comparable to data from previous studies that used tissue stored in other short-term and intermediate-term media. The results suggest that Optisol storage preserves corneal endothelial cells for up to two weeks at 4 C, thereby permitting flexibility in the use of donor tissue for corneal transplantation, and that Optisol storage yields thinner tissue, which may allow for more accurate evaluation and more effective surgical manipulation.

Adult↗
PubMed1992

A randomized, prospective, double-masked clinical trial of Optisol vs DexSol corneal storage media.

We compared Optisol and DexSol, two chondroitin-sulfate-based media for corneal storage at 4 degrees C, by transplanting 31 donor cornea pairs (one cornea stored in Optisol and its mate in DexSol for 20 to 134 hours) into 31 pairs of recipients (62 patients). All grafts were clear 1 year after transplantation except for one primary donor failure (Optisol group). Optisol-stored corneas were significantly thinner than DexSol-stored corneas after cardinal suture placement (0.64 mm vs 0.76 mm) and at the end of surgery (0.69 mm vs 0.78 mm); at all points afterward through 1 year the two groups did not differ. The activity of two lysosomal enzymes released into the media during storage, alpha-mannosidase and alpha-glucosidase, was lower in the Optisol group. Epithelial status and all endothelial morphometric parameters, except the figure coefficient at 1 year, did not differ between the two groups before surgery and 3, 6, and 12 months after surgery. Mean endothelial cell loss at 1 year was 15% for the Optisol group and 21% for the DexSol group (P = .22). Thus, Optisol-stored corneas were thinner during surgery than DexSol-stored corneas and there was less lysosomal enzyme activity in the Optisol medium after tissue storage. There were no significant differences in postoperative clinical or endothelial morphometric parameters, however.

Adult↗
PubMed1991

The effects of age on phosphatic metabolites of the human crystalline lens.

Paired human lenses ranging from 2 to 96 yr old (n = 17) were harvested within 2 hr post-mortem and immersed in liquid nitrogen. Phosphorus containing metabolites from perchloric acid extracts were quantitated using phosphorus-31 nuclear magnetic resonance spectroscopy. Low-energy metabolites detected include the phosphomonoesters (PME) hexose-6 phosphate, alpha-glycerol phosphate, fructose 1,6-diphosphate, beta-glycerol phosphate (beta-GP), uncharacterized phosphomonoesters at 4.63 delta, 4.34 delta and 3.05 delta, phosphorylethanolamine (PE), inosine and adenosine monophosphates, and phosphorylcholine (PC). Inorganic orthophosphate (Pi), glucose 1-phosphate and glycerol 3-phosphorylcholine were the other low-energy metabolites detected. High-energy metabolites phosphocreatine (PCr), adenosine tri- and di-phosphates (ATP, ADP), nucleoside diphosphorylsugars (NS) and the dinucleotides were also detected. The following metabolic indices were calculated: PCr/Pi, PME/Pi; ATP/Pi, PCr/ATP, ATP/ADP, PE + PC, PC/PE, energy charge, phosphorylation potential, and the energy modulus. A significant linear increase with age (P less than 0.05) occurred only in the uncharacterized resonance at 3.05 delta (r = 0.4593). Significant linear decreases with age (P less than 0.05) occurred in the uncharacterized resonance at 4.63 delta (r = -0.5950), beta-GP (r = -0.5018), PCr (r = -0.4495), N.S. (r = -0.4882). There was a significant (P less than 0.05) linear decrease in the energy modulus (ratio of high-energy to low-energy metabolites).

Adolescent↗
PubMed1991

Antimicrobial efficacy and corneal endothelial toxicity of DexSol corneal storage medium supplemented with vancomycin.

Despite the presence of gentamicin in corneal storage medium, postoperative endophthalmitis may result from the transmission of bacteria via contaminated corneal tissue. The authors evaluated the antimicrobial activity and endothelial toxicity of vancomycin (10 micrograms/ml) in combination with gentamicin (100 micrograms/ml) in DexSol corneal storage medium. When tested against a panel of common ocular pathogens, vancomycin combined with gentamicin proved more effective than gentamicin alone for inhibiting the growth of Streptococcus pneumoniae at 4 degrees C after 1- and 5-day incubation periods. Ultrastructural and morphometric analyses of paired human corneas stored for 5 days in either DexSol supplemented with vancomycin combined with gentamicin or DexSol with gentamicin alone did not show a significant difference in endothelial toxicity between the two groups. These results suggest that vancomycin combined with gentamicin has superior antimicrobial effect and similar corneal toxicity when compared with media supplemented with gentamicin alone.

Bacteria, Aerobic↗
PubMed1991

Infectious crystalline keratopathy. Role of nutritionally variant streptococci and other bacterial factors.

Infectious crystalline keratopathy (ICK) is a chronic corneal infection characterized by interlamellar plaques of gram-positive coccal bacteria in the absence of inflammatory cells. It generally occurs within a corneal graft. Viridans streptococci are usually isolated, but the clinical response to antibiotics is poor and disparate with the in vitro antimicrobial sensitivities. These features suggest the possibility of unusual bacterial factors in pathogenesis. Four cases caused by nutritionally variant viridans streptococci are described. The organisms were fully characterized. They have a rare nutritional requirement for pyridoxal and require defined culture conditions and specific identification. Nutritional variant streptococci (NVS) are principally described as causing endocarditis, another infection involving an avascular collagenous tissue, and exhibiting similar biologic behavior. Electronmicrographic evidence is also adduced that suggests the possible importance of intracorneal glycocalyx deposition. Such factors might explain the anomalous clinical characteristics of this condition.

Adult↗
PubMed1991

Phosphatic metabolism and corneal edema.

From three groups of patients with corneal edema, the degree of edema was clinically quantified prior to penetrating keratoplasty. Corneas from patients with failed grafts (n = 16) had the greatest edema (mean score 3.8 +/- 0.6 SE), corneas with Fuchs' endothelial dystrophy (n = 12) had the least edema (1.4 +/- 0.4), and corneas with aphakic and pseudophakic bullous keratopathy (n = 40) had intermediate edema (2.7 +/- 0.5). Phosphorus-31 nuclear magnetic resonance spectroscopy was used to quantitate five high-energy phosphates and nine low-energy phosphates and calculate 12 metabolic indices from the specimens of these three edematous groups. Corneas with aphakic and pseudophakic bullous keratopathy had lower alpha-glycerophosphate (alpha-GP) and glycerol 3-phosphorylethanolamine and glycerol 3-phosphorylcholine (GPE & GPC), and higher phosphocreatine (PCr), adenosine diphosphate (ADP), monoesters/diesters, PCr/Pi (phosphocreatine/inorganic orthophosphate), and PCr/ATP (phosphocreatine/adenosine triphosphate) than corneas with Fuchs' endothelial dystrophy (p less than 0.05). Corneas from failed grafts had lower alpha-GP, ethanolamine phosphate (EP), ethanolamine phosphate and choline phosphate (EP&CP), monoesters/Pi, ATP/Pi, and energy modulus, no detectable GPE and GPC, and higher Pi, phosphorylglycans (PG), PCr, ADP, diesters, PCr/Pi, and PCr/ATP than those with Fuchs' endothelial dystrophy (p less than 0.05). Corneas from failed grafts had lower ATP, monoesters/Pi, ATP/Pi, PCr/Pi, and energy modulus and higher Pi, PG, ADP, diesters, and PCr/ATP than corneas with aphakic and pseudophakic bullous keratopathy (p less than 0.05). In summary, there was increasing decline in the high-energy metabolites and energy status with increasing edema.

Adenosine Triphosphate↗