The effect of cleaning and disinfection of soft contact lenses on corneal infectivity in an animal model

PURPOSE

Bacterial contamination of previously worn soft contact lenses, especially at sites of lens deposits, might play a role in the pathogenesis of lens-associated bacterial keratitis. We studied the effects of three commercial contact lens cleaners and disinfectants in a rabbit model to determine whether cleaning and disinfection reduced infectivity.

METHODS

Duragel 75 soft contact lenses, designed to fit the eyes of rabbits, were worn by rabbits under tarsorrhaphies, then were removed and cleaned in one of three cleaner and disinfectant solutions according to the manufacturers' instructions. The lenses were contaminated by overnight incubation in a suspension of 10(8) Pseudomonas aeruginosa/ml and were placed under tarsorrhaphies on the eyes of fresh rabbits. The rabbits were observed for two weeks for signs of infection. Control rabbits wore new, uncleaned but contaminated lenses or worn, uncleaned but contaminated lenses.

RESULTS

The rates of infection with the three commercial cleaner and disinfectant solutions ranged from 18% (two of 11) to 31% (four of 13); these incidences were not significantly different from one another or from the 19% (three of 16) incidence with new, contaminated but uncleaned lenses. By contrast, when worn, uncleaned but contaminated lenses were placed in rabbits' eyes, seven of eight were infected, a rate that is significantly higher than that of the other four groups (P = .0003).

CONCLUSIONS

These data indicate that the three commercial lens cleaner and disinfectant solutions were of similar efficacy in reducing the infectivity of contaminated contact lenses to a level similar to that of new, unworn lenses.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of intraocular pressure by palpation

PURPOSE/METHODS

Corneal specialists may assess the intraocular pressure by palpation although this technique has never been validated. We explored the reliability of a tactile assessment of the intraocular pressure in comparison to Goldmann tonometry.

RESULTS/CONCLUSION

There was little correlation between tactile assessment of the intraocular pressure and tonometry. However, palpation was moderately successful in identifying most eyes (five of seven eyes) with an intraocular pressure greater than 30 mm Hg. Although palpation was generally inaccurate, it may serve as a warning for marked increases in intraocular pressure exceeding 30 mm Hg.

On the location of the cone and the etiology of keratoconus

I suggest that the location of the cone in keratoconus is most often located in the paracentral inferonasal quadrant of the cornea due to the presence of the most senile epithelial cells in this location. These cells may be more vulnerable than younger epithelial cells to the chronic subtle trauma of eyelid rubbing and may be more prone to release enzymes that thin the cornea.

[John Snow (1813-1858): experimental studies on rebreathing of anesthetic gases in exhaled air]

As early as in 1850 (only 4 years after the first clinical performance of ether anaesthesia by W. T. G. Morton on 16 October 1846) John Snow recognised that ether and chloroform were exhaled unchanged with the expired air. To reuse these unchanged vapours in the following inspiration and thereby prolonging the narcotic effect of a given amount of anaesthetic vapour, he converted his ether inhaler into a To-and-Fro Rebreathing System: The apparatus was equipped with a facemask without an expiratory valve and a large reservoir bag containing pure oxygen; an aqueous solution of caustic potash was used as CO2 absorbent. In several experiments, performed on himself, Snow succeeded to demonstrate that rebreathing of the exhaled vapours was possible following carbon dioxide absorption, and that it resulted in a pronounced prolongation of the narcotic effects of the volatile anaesthetics. Furthermore, Snow performed experiments on animals using a closed system for evaluating the carbon dioxide production during anaesthesia. It is all the more worthwhile to introduce Snow's publications on these topics, as, despite their extraordinary theoretical and practical significance, they remained nearly unnoticed. Even in the fundamental articles by D. Jackson and R. Waters, both being the respected protagonists of the rebreathing technique in anaesthesia, the Snow papers remained uncited.

Management and motivational factors in the control of noise induced hearing loss (NIHL)

This paper describes a study investigating attitudes to noise as an occupational hazard. The objectives of the study were to understand the individual and organizational factors which affect attitudes towards noise induced hearing loss (NIHL) and to relate these to the standards of hearing conservation achieved in industry as demonstrated by compliance with the Noise at Work Regulations. The study comprised a survey of 48 organizations across Britain, and a more detailed examination of 10 of these as case studies. Methods used included desk research, audits of hearing conservation programmes, questionnaires and interviews. Whilst there is widespread acceptance that industrial noise is a hazard, it is one that is frequently taken for granted, and measures to deal with it are often inadequate. Most organizations place the onus on the workforce to protect their own hearing through the use of personal hearing protectors. Workers reactions to noise tended however to be passive and much of the time neither managers nor the workforce are concious of the noise hazard. This is the case even where some managers are committed to good industrial housekeeping and accident prevention. As effective hearing conservation programme requires three management attributes: leadership from senior management, the ability of middle management (particularly in production and engineering) to put hearing conservation measures into practice, and specialist technical knowledge of noise and of the legislation. The study points to the need for more education and motivation of senior managers as the priority in improving standards of hearing conservation and noise control.

[A simple bite protector for the laryngeal mask]

A new simple gag is presented securing the width of the tube of the laryngeal mask. The device is a 45 degrees-angled, u-shaped, synthetic-coated aluminium rod. This gag, while being additionally an aid to ensure the proper position of the laryngeal mask, is easy to handle and can be re-used after disinfection. Due to its rounded shape and the soft synthetic coating, accidental damage of the teeth seems to be nearly impossible.

Three-dimensional structure of echistatin and dynamics of the active site

The snake venom protein echistatin contains the cell recognition sequence Arg-Gly-Asp and is a potent inhibitor of platelet aggregation. The three-dimensional structure of echistatin and the dynamics of the active RGD site are presented. A set of structures was determined using the Distance Geometry method and subsequently refined by Molecular Dynamics and energy minimization. Disulfide pairings are suggested, based on violations of experimental constraints. The structures satisfy 230 interresidue distance constraints, derived from nuclear Overhauser effect measurements, five hydrogen-bonding constraints, and 21 torsional constraints from vicinal spin-spin coupling constants. The segment from Gly5 to Cys20 and from Asp30 to Asn42 has a well-defined conformation and the Arg-Gly-Asp sequence, which adopts a turn-like structure, is located at the apex of a nine-residue loop connecting the two strands of a distorted beta-sheet. The mobility of the Arg-Gly-Asp site has been quantitatively characterized by 15N relaxation measurements. The overall correlation time of echistatin was determined from fluorescence measurements, and was used in a model-free analysis to determine internal motional parameters. The active site has order parameters of 0.3-0.5, i.e., among the smallest values ever observed at the active site of a protein. Correlation of the flexible region of the protein as characterized by relaxation experiments and the NMR solution structures was made by calculating generalized order parameters from the ensemble of three-dimensional structures. The motion of the RGD site detected experimentally is more extensive than a simple RGD loop 'wagging' motional model, suggested by an examination of superposed solution structures.

Crystal structure and NMR conformation of a cyclic pseudotetrapeptide containing urethane backbone linkages

Urethane bonds, derived from the hydroxyl group of the tyrosine side chain, have been investigated as a new type of amide bond mimetic in the design of pseudopeptides. The structure of a representative cyclic pseudotetrapeptide that consists of an -Ala-Tyr(urethane)Ala-Tyr(urethane) sequence fused into a rigid ring has been studied in the solid state by x-ray crystallography and in solution by two-dimensional nmr techniques. The cyclic pseudotetrapeptide has an oblong shape. The backbone urethane bonds assume a trans-trans conformation. The carbonyl groups in the ring have an alternating pattern of down, up, down, up with respect to the average ring plane. Solution nmr studies give observed nuclear Overhauser effects and coupling constants largely in agreement with the crystal structure. However, in solution the observed structure is likely to be conformationally averaged, and in the averaged structure, the urethane bond is perpendicular to the plane of the aromatic ring of the tyrosine, while in the crystal it is close to this plane. These differences may be explained by intermolecular hydrogen-bonding interactions. Four aspects of the conformation of the cyclic pseudotetrapeptide were investigated in detail: the tyrosine residue with the attached side-chain urethane bond (the tyrosine-urethane unit), the conformation of the two urethane backbone linkages, the conformation of the two conventional peptide bonds within this unusual ring structure, and the tight turns within the cyclic pseudotetrapeptide. The conformation of the tight turns present in the cyclic pseudotetrapeptide is very similar to that of a beta-bend of type II. Intermolecular hydrogen bonding, joining adjacent layers of the cyclic pseudotetrapeptide in the solid state, resemble a parallel beta-pleated sheet. The presence of these structural motifs in the cyclic pseudotetrapeptide indicates that the tyrosine urethane unit may find applications in peptide and protein engineering.

[Low flow anesthesia]

It is a strange contradiction that increasingly sophisticated anaesthesia machines are developed meeting all requirements for rebreathing techniques and the highest safety standards, but the usual anaesthetic management is still based on the use of fresh gas flows that preclude substantial rebreathing. The advantages of rebreathing can only be realised if low-flow anesthesia techniques are adopted. Increasing acceptance of these methods is due to the availability of comprehensive anaesthetic gas monitoring. Different techniques of low-flow anaesthesia, the characteristic features, technical requirements, and considerations concerning their performance and contraindications are discussed. This paper presents a topic that is left unmentioned by most anaesthesia textbooks. The use of new inhalational anaesthetics such as desflurane that require comparatively high concentrations, or even xenon, will motivate to sparing use. Increasingly stringent health and safety regulations as well as sharpened ecological awareness will prompt anaesthetists to minimise all anaesthetic gas emission according to the possibilities of available equipment. Last but not least, the demand for economical working methods will be an argument for applying low-flow anaesthesia techniques.

Backbone dynamics of (Pro-Hyp-Gly)10 and a designed collagen-like triple-helical peptide by 15N NMR relaxation and hydrogen-exchange measurements

The backbone dynamics of specific residues in two collagen-like triple-helical peptides with (X-Y-Gly)n sequences have been investigated using two-dimensional inverse-detected 15N NMR relaxation measurements and hydrogen-exchange experiments. One peptide, (POG)10, has the highest possible imino acid content and is considered to be a very stable prototype of a triple helix. The second peptide, (POG)3ITGARGLAGPOG(POG)3 (denoted T3-785), models an imino acid poor region of type III collagen and contains 12 residues from near the unique collagenase cleavage site. 15N relaxation parameters and hydrogen-exchange data were obtained for a glycine residue in the center of (POG)10 and for the tripeptide unit Gly-Leu-Ala in the middle of T3-785. Analysis of the relaxation data of the rodlike triple-helical peptides required the assumption of anisotropic overall motion, and the model-free approach of Lipari and Szabo (1982) was used to derive overall motional parameters and the order parameter, S2, that describes the amplitudes of the internal motion. First the mobilities of the Gly, Leu, and Ala residues in peptide T3-785 were compared. Both hydrogen-exchange methods and relaxation measurements indicated that the residue in the Y position (Ala) is more mobile than residues in the Gly and X positions (Leu). The slower exchange rates of Gly and Leu compared to that of Ala are consistent with the two-hydrogen-bonded model for the triple helix. Then the backbone mobilities of the central Gly residue were compared for the two peptides (POG)10 and T3-785. In this case, 15N relaxation measurements give different results from hydrogen exchange. The glycine residues in the trimer form of both T3-785 and (POG)10 have high values for the order parameter (near 0.85), suggesting similar small-amplitude internal motions and rigid backbones in both peptides. In contrast to the similar values of the order parameters, hydrogen-exchange data indicate that the central Gly exchanges at a faster rate in the trimer form of T3-785 than in (POG)10. These results suggest that a Gly in the imino acid rich environment of (POG)10 is dynamically different from a Gly in the imino acid poor environment of T3-785 and that the difference lies in the slower motion related to stability, rather than the faster motion on the picosecond time scale. This sequence-dependent difference in dynamical properties may have important consequences for recognition processes in collagen.

Juvenile arthritis

Juvenile arthritis encompasses a group of chronic arthritides in childhood with unclear etiologies. Careful clinical observation has led to categorization and nomenclature identifying three main subtypes of the disease, each with varying natural histories and prognoses. Management centers around antiinflammatory drugs, long-term disease-modifying agents, physical and occupational therapy, joint replacement, and ongoing psychosocial assessment and care. The majority of patients achieve reasonable control of their symptoms and are able to attain independent and satisfying adult lives.

Characterization of collagen-like peptides containing interruptions in the repeating Gly-X-Y sequence

Glycine is found as every third residue along the entire length of triple helices in fibrillar collagens, but the triple-helix regions of nonfibrillar collagens and other proteins usually contain one or more interruptions in this repeating pattern. A set of four peptides was designed to model the effect of interruptions in the (Gly-X-Y)n repeating pattern on triple-helix formation, stability, and folding. Into the middle of the stable triple-helical peptide (Pro-Hyp-Gly)10, an interruption was introduced representing one of the four possible categories: a glycine deletion, a deletion of a hydroxyproline (Y position), an alanine insertion, or a glycine to alanine substitution. As shown by sedimentation equilibrium, NMR, and CD studies, the introduction of an interruption still allowed formation of trimers in solution, but with marked decrease in stability. The degree of destabilization and the thermodynamic basis for the loss of stability depended on the type of interruption. The glycine substitution and alanine insertion were the least disruptive, followed by the hydroxyproline deletion, with the glycine deletion being the most destabilizing. Our results suggest that the breaks in these peptides affect both the triple-helical conformation and the monomer conformation. These studies provide a basis for considering the structural and functional consequences of different kinds of interruptions in collagen.

Benefits and disadvantages of joint hypermobility among musicians

BACKGROUND

Joint hypermobility is considered to be both an advantage and a disadvantage. However, the degree of hypermobility in members of particular occupations requiring intense physical activity and the nature of the association between symptoms referable to specific joints and their hypermobility are unknown.

METHODS

We interviewed 660 musicians (300 women and 360 men) about work-related symptoms such as joint pain and swelling and examined them for joint hypermobility according to a standard protocol. We then determined the relation between the mobility of their fingers, thumbs, elbows, knees, and spine and any symptoms referable to these regions.

RESULTS

Five of the 96 musicians (5 percent) with hypermobility of the wrists, mostly instrumentalists who played the flute, violin, or piano, had pain and stiffness in this region, whereas 100 of the 564 musicians (18 percent) without such hypermobility had symptoms (P = 0.001). Hypermobility of the elbow was associated with symptoms in only 1 of 208 musicians (< 1 percent), whereas 7 of 452 (2 percent) without this hypermobility had symptoms (P = 0.45). Among the 132 musicians who had hypermobile knees, 6 (5 percent) had symptoms, whereas only 1 of 528 (< 1 percent) with normal knees had symptoms (P < 0.001). Of the 462 musicians who had normal mobility of the spine, 50 (11 percent) had symptoms involving the back, as compared with 46 of the 198 musicians (23 percent) who had hypermobility of the spine (P < 0.001).

CONCLUSIONS

Among musicians who play instruments requiring repetitive motion, hypermobility of joints such as the wrists and elbows may be an asset, whereas hypermobility of less frequently moved joints such as the knees and spine may be a liability.

Two-dimensional NMR assignments and conformation of (Pro-Hyp-Gly)10 and a designed collagen triple-helical peptide

Homonuclear and heteronuclear 2D NMR methods are used to study two triple-helical peptides. One peptide, (POG)10, is considered to be the most stable prototype of a triple helix. The second peptide, (POG)3ITGARGLAGPOG(POG)3 (denoted T3-785), was designed to model an imino acid poor region of collagen and contains 12 residues from near the unique collagenase cleavage site in type III collagen. Both peptides associated as trimers, with melting temperatures of 60 degrees C for (POG)10 and 25 degrees C for the T3-785 peptide. Sequence-specific assignments were made for a tripeptide unit POG in (POG)10, and 80% of the POG triplets are found to be in an equivalent environment. In T3-785, with nonrepeating X-Y-Gly units incorporated in the sequence, the three chains of the homotrimer can be distinguished from one another by NMR. The solution conformation of (POG)10 is very similar to the model derived from X-ray fiber diffraction data, although the peptide contains less ordered regions at the peptide ends. In the trimer from of T3-785, the central residues of the three chains are closely packed, and the data are consistent with a triple-helical model with a one-residue stagger of three parallel chains. For T3-785, in contrast to (POG)10, there are also resonances from a less ordered form, which are probably due to the presence of a small amount of monomer. The similarity of the backbone conformations of T3-785 and (POG)10 suggests that an alternative conformation is not present in the imino acid poor region.

Structure and stability of the molten globule state of guinea-pig alpha-lactalbumin: a hydrogen exchange study

A partially folded state of guinea pig alpha-lactalbumin (the A-state or molten globule state), formed by denaturation at low pH, has been studied using hydrogen exchange methods. The overall distribution of exchange kinetics, measured by 1-D NMR, suggests that fewer than 20 amides in the structure are involved in highly persistent residual structure, although CD results suggest that many other parts of the chain are folded, for a significant proportion of the time, into less stable structural elements. The pH-jump experiments show that some amides that are strongly protected from exchange in the native state become freely accessible in the A-state but that conversely a majority, at least, of those that are slow to exchange in the A-state retain that protection in the native state. This suggests that the persistent structure in the A-state is native-like although the possibility that nonnative like structural elements persist cannot be eliminated. Resonance assignments for key residues in the NMR spectrum of the native state have enabled us to use the pH-jump method also to identify the majority of the most protected amides in the A-state: they are located in two hydrophobic segments, corresponding to the B- and C-helices of the native structure. This strongly suggests that the most persistent structure of the A-state includes these regions. A variety of lines of evidence, including fluorescence quenching data and, most remarkably, very effective protection from exchange of an indole NH in a tryptophan side chain, suggest that some form of hydrophobic core in the helical domain of the native structure persists in the A-state, although without the stereochemical rigidity of the native tertiary structure. The other domain of the native structure, including the beta-sheet, appears not to contain structural elements which persist to the same extent in the A-state, emphasizing that the molten globule is highly heterogeneous, in terms of the stability and specificity of both backbone and side chain interactions.

Structure and dynamics of the acid-denatured molten globule state of alpha-lactalbumin: a two-dimensional NMR study

Two-dimensional 1H-NMR spectroscopy has been used to study the acid-denatured molten globule (A-state) of alpha-lactalbumin. The NMR spectra show that chemical shift dispersion is limited but significantly greater than that expected for a random coil conformation. The small chemical shift dispersion of side-chain resonances in the A-state together with line broadening associated with conformational averaging indicates that most of the long-range tertiary structure in the A-state is likely to be nonspecific. Side-chain resonances in the A-state are generally shifted somewhat upfield of random coil values; this and the observation of a large number of interresidue NOEs, however, indicate that some side-chain interactions, at least at the level of hydrophobic clustering, exist in the A-state. Analysis of NOESY spectra shows no evidence for an ordered structure for either of the two major clusters of aromatic residues which in the native structure make up part of the hydrophobic core of the helical domain of the native protein. A new aromatic cluster in the A-state which results from rearrangement of the side chains of Tyr103, Trp104, and His107 from their native state positions was, however, detected by a number of well-defined interresidue NOE effects. Similar NOE patterns are observed in a peptide corresponding to residues 101-110 of alpha-lactalbumin in trifluoroethanol, suggesting that the non-native structure in the 101-110 region of the A-state is not dependent on specific interactions with the rest of the chain. Trapping experiments indicate that amide protons from regions of the sequence which in the native state are helical are among those strongly protected from solvent exchange in the A-state; those from one of the helices (the C helix) were specifically identified. Taken together, these results reinforce a model of the A-state which has stable regions of localized secondary structure but a largely disordered tertiary structure.

Structural characterization of monellin in the alcohol-denatured state by NMR: evidence for beta-sheet to alpha-helix conversion

Two-dimensional 1H NMR spectroscopy and hydrogen exchange methods have been used to characterize the alcohol-denatured state of monellin. Monellin is a sweet tasting protein composed of two chains. In the native state, the A-chain consists entirely of beta-structure, and the B-chain contains both alpha- and beta-structure. Upon addition of either 50% ethanol or 50% trifluoroethanol (TFE), the native structure of monellin is disrupted resulting in an alcohol-denatured state with properties different from those of the random coil state. In the alcohol-denatured state, the far-UV circular dichroism (CD) spectrum displays a higher helical content relative to the native state and the intensity of the near-UV CD signal is completely lost. One-dimensional NMR studies show that there are approximately 14 amide protons protected from exchange with solvent in the alcohol-denatured state and that large portions of the protein exchange at a rate that is comparable to the exchange rate of the protein in urea. Utilizing hydrogen exchange trapping techniques, the slowly exchanging residues are identified at pH 2.0 in 50% ethanol and 50% TFE (A10-A15, A18, A19, A21, A24, and A39) and are found to be clustered on one region of the A-chain. Preliminary 2D NMR assignments show that in the alcohol-denatured state the A-chain of monellin undergoes structural reorganization, with one strand of the native state beta-sheet on the A-chain (residues A17-A30) becoming an alpha-helix in the alcohol-denatured state. The secondary structure of the A-chain in the alcohol-denatured state is different from the native state structure, although the slowly exchanging residues are similar.

Hypermobility: prevalence and features in a Swedish population

In this investigation, parallel to an earlier study [1] of 660 musicians from the USA, 606 individuals from a factory in Ostersund, Sweden, were studied to determine the prevalence and nature of their hypermobility. They were examined using the same protocol and by the same examiner as in the earlier study for the presence of five well recognized features of hypermobility. In this mostly middle-aged population of workers, as in the earlier population of mostly young musicians, joint laxity was found to be far more common among females. In both sexes hypermobility is seen to decline with age, the rate of fall being about the same for men and women.

1H-NMR assignments and local environments of aromatic residues in bovine, human and guinea pig variants of alpha-lactalbumin

1H-NMR assignments have been defined for the aromatic-ring protons of the bovine, guinea pig and human variants of alpha-lactalbumin. Spin-system networks were identified by means of double-quantum-filtered two-dimensional J-correlated spectroscopy and two-dimensional relayed coherence spectroscopy data. Analysis of two-dimensional nuclear-Overhauser-enhancement spectroscopy data of the proteins indicated that in each case two clusters of aromatic residues exist. The two clusters are also evident in the crystal structure of the human protein, and this evidence, in conjunction with sequence differences between the three proteins, permitted sequence-specific assignments to be made for the majority of aromatic residues. Remaining ambiguities in the assignments could be resolved by analysis of photochemically induced dynamic nuclear polarization (PCIDNP) effects. Comparison of the PCIDNP spectra of the three proteins indicated the presence of only minor differences in the surface exposure of conserved aromatic residues. Taken together, these results indicate that the environments of the conserved aromatic residues in bovine, guinea pig and human alpha-lactalbumin in solution are very similar to each other, and that the solution and the crystal forms of at least the human protein are similar.

An improved apparatus for transscleral iontophoresis of gentamicin

The authors previously found that positively charged substances are less well-transported into the vitreous humor by transscleral iontophoresis than are negatively charged substances. There was more bubble formation in the eye cup with positively charged than with negatively charged substances. The authors hypothesized that these bubbles might account for the poorer conductance of the positively charged species by causing interruptions of the current. Therefore, the authors developed a modified eye cup in which the diameter of the fluid column was larger than that in the old device (1.0 rather than 0.5 mm). This modification allowed larger voltage to be applied than with the older device, because bubbles could be more easily cleared from the conjunctiva than with the narrower-bore eye cup. Although the efficiency of the apparatus was the same with the two eye cups (micrograms per milliliter in vitreous humor divided by milliampere minutes of current applied), vitreal concentrations of gentamicin with the modified eye cup were fourfold higher than with the older eye cup (83 versus 19 micrograms/ml; P < 0.001). These studies suggest that modifying the eye cup to permit easier removal of bubbles resulted in improved delivery of gentamicin into the ocular humors.

Acanthamoebae bind to glycolipids of rabbit corneal epithelium

By use of a thin-layer chromatogram (TLC) overlay procedure, 35S-labeled acanthamoebae were shown to bind to seven glycolipids of rabbit corneal epithelium. Corneal epithelial cells were grown in culture and were subjected to Folch extraction to isolate a chloroform-rich lower phase containing neutral glycosphingolipids (NGSL) and an aqueous upper phase containing gangliosides, i.e., sialic acid-containing glycolipids. Thin-layer chromatography of the upper phase revealed the presence of 10 ganglioside components. Acanthamoebae were shown to bind to four of these components, referred to as 2, 3, 6, and 7. On TLC plates, ganglioside components 2 and 3 migrated slightly ahead of the glycolipid standard GD1a, component 7 comigrated with standard GM3, and component 6 migrated a little more slowly than GM3. Likewise, of the 10 NGSL known to be present in the lower phase, acanthamoebae bound to components 1, 5, and 6. NGSL components 1, 5, and 6 migrated on TLC plates with relative mobilities similar to those of standards asialo GM1, asialo GM2, and ceramidetrihexoside, respectively. We propose that one or more of the Acanthamoeba-reactive glycolipids of corneal epithelium identified in this study may play a role in the pathogenesis of Acanthamoeba keratitis by mediating the adherence of the parasites to the cornea.