Short term oral minocycline treatment of meibomianitis.

AIM: To evaluate the clinical impact, aqueous tear parameters, and meibomian gland morphology in patients with primary meibomianitis before, during, and 3 months after a course of oral minocycline. METHODS: 16 patients were prospectively enrolled, 11 male and five female (mean age 69 years old). Each patient received routine clinical evaluations before, after 3 months therapy, and at 6 month study follow up visit. The clinical appearance, tear volume, flow and turnover, evaporation, Schirmer I test, meibomian gland dropout, lissamine green staining, and bacteriology wer evaluated. RESULTS: Improvement was observed in clinical signs of meibomianitis at the second and third visits. Microbial culture findings improved. Decreased aqueous tear volume and flow, and increased evaporation rate range at 35-45% relative humidity (RH) (p < 0.05) were also detected. Other related tear parameters did not change. Meibomian gland dropout showed no improvement. CONCLUSIONS: 3 months of oral minocycline resulted in clinical improvements in all meibomianitis signs that persisted for at least 3 months after discontinuation despite decreased aqueous tear volume and flow with increased evaporation (35-45% RH). However, there was improvement in the turbidity of secretions. Short term minocycline therapy probably has efficacy in the management of meibomianitis that extends beyond eradication of bacteria.

Fourth-generation fluoroquinolone penetration into the aqueous humor in humans.

PURPOSE: To compare the penetration and levels of the fourth-generation fluoroquinolones moxifloxacin 0.5% ophthalmic solution and gatifloxacin 0.3% solution in the aqueous humor (AH) in humans after topical application with published levels of other available fluoroquinolones under similar dosing conditions. DESIGN: Prospective, randomized, double-masked clinical trial. PARTICIPANTS: Forty-six patients undergoing cataract extraction. METHODS: Patients scheduled for routine phacoemulsification and intraocular lens implantation were provided either moxifloxacin 0.5% ophthalmic solution (n = 22) or gatifloxacin 0.3% ophthalmic solution (n = 24) to use 4 times daily the day before surgery plus 1 drop 1 hour before the surgical entry into the anterior chamber on the day of surgery. This regimen simulated a realistic postoperative dosing schedule. Aqueous humor samples were obtained and analyzed by high-pressure liquid chromatography. Aqueous humor fluoroquinolone concentrations were calculated by peak comparison with a known concentration peak for ciprofloxacin that was used as an internal standard. These values were compared with published concentrations of other available fluoroquinolones under similar dosing conditions. RESULTS: The mean age of the moxifloxacin 0.5% group was 67.8+/-9.7 years, whereas that of the gatifloxacin 0.3% group was 69.9+/-8.7 years. The moxifloxacin AH concentration was 1.86+/-1.06 microg/ml, and that of gatifloxacin was 0.94+/-0.72 microg/ml. This 2-fold difference was statistically significant (P = 0.001). CONCLUSIONS: Aqueous humor antibiotic concentrations achieved at the time of cataract surgery after topical application can serve as an effective surrogate for what can be achieved with typical postoperative topical dosing (e.g., 4 times daily). Both fourth-generation fluoroquinolones achieved a greater AH concentration after 4 times daily dosing relative to prior-generation fluoroquinolones. Moxifloxacin 0.5% ophthalmic solution achieved a 2-fold higher aqueous humor concentration than gatifloxacin 0.3% ophthalmic solution. The superior penetration of moxifloxacin into the AH may be attributed partially to its high degree of lipophilicity, greater solubility at neutral pH, and higher concentration in the commercial formulation. The enhanced penetration of moxifloxacin 0.5% ophthalmic solution may provide better protection against ocular infections.

Minocycline effect on meibomian gland lipids in meibomianitis patients.

The objective of this research was to determine the effect of oral minocycline on the meibomian gland nonpolar and free fatty acid lipids of chronic blepharitis patients. Patients--seborrheic blepharitis (SBBL), acne rosacea (AR) without ocular involvement, and acne rosacea with meibomianitis (AR-MKC). Minocycline treatment--50mg orally for 2 weeks followed by 100mg to the end of 3 months; this was followed by 3 more months with no treatment. Meibomian gland secretions (meibum) were collected before treatment, at the end of the 3 months on treatment, and 3 months after stopping treatment. Lipids were separated and analyzed for wax and sterol esters, triglycerides, diglycerides, free cholesterol and free fatty acids. Data were analyzed statistically by ANOVA. Minocycline treatment resulted in decreased diglycerides and free fatty acids in the group AR-MKC, which continued into the second 3 months (off treatment) and was significant. Cholesterol decreased, but triglycerides initially decreased with treatment and then increased when treatment in the group was discontinued (second 3 months); these results, however, were not significant. Thus, minocycline has its greatest effect on lipid types, which result from degradation (lipase) reactions, suggesting a lipase inhibition effect and/or direct effect on ocular flora. This minocycline effect continues even after treatment is discontinued, suggesting a more lasting effect on ocular microflora. Minocycline may be most effective when the treatment period is longer than 3 months. These results give insight into disease mechanisms associated with chronic blepharitis.

The lipid layer: the outer surface of the ocular surface tear film.

The outer layer of the tear film--the lipid layer--has numerous functions. It is a composite monolayer composed of a polar phase with surfactant properties and a nonpolar phase. In order to achieve an effective lipid layer, the nonpolar phase, which retards water vapor transmission, is dependent on a properly structured polar phase. Additionally, this composite lipid layer must maintain its integrity during a blink. The phases of the lipid layer depend on both lipid type as well as fatty acid and alcohol composition for functionality. Surprisingly, the importance of the composition of the aqueous layer of the tear film in proper structuring of the lipid layer has not been recognized. Finally, lipid layer abnormalities and their relationship to ocular disease are beginning to be clarified.

Changing concepts in the diagnosis and management of blepharitis.

PURPOSE: Chronic blepharitis is one of the most common conditions seen in the ophthalmologist's office; but, it is difficult to treat effectively. Nevertheless, much progress has been made over the last quarter century, not only in diagnosis but also in treatment of blepharitis. METHODS: Perhaps the most important progress has been made as the result of extensive and detailed clinical evaluations of patients, sometimes over extended periods of time with diverse patient populations. RESULTS: The availability of sophisticated instrumentation and laboratory techniques, as well as an array of antibiotics, has enhanced the whole picture for effective blepharitis treatment. CONCLUSION: Although much progress has been made, it is important to build on the present understanding. Most important is the continued development of targeted treatment protocols that address specific signs, as is now possible with microbial abnormalities. Progress in the understanding and treatment of relevant inflammatory processes will benefit from continuing biomedical discoveries.

Association of meibum oleic acid with meibomian seborrhea.

PURPOSE: We sought to determine whether patient meibum fatty acid unsaturation is associated with meibomian gland secretion consistency. METHODS: Meibomian gland secretions were dissolved in chloroform and separated into lipid classes by thin-layer chromatography. Fatty acids in individual lipid classes were characterized by gas chromatography after transmethylation. RESULTS: Meibum from patients with meibomian seborrhea was higher, and meibum from patients with meibomian keratoconjunctivitis (meibomianitis) was lower in the monounsaturated fatty acid, oleic acid, than that of other disease groups and normal subjects. CONCLUSION: Our results strongly suggest that the melting characteristics of meibum, influenced primarily by the amount of oleic acid in wax and sterol esters and free fatty acids, greatly influence the consistency of meibomian gland secretions.

Keratoconjunctivitis sicca associated with meibomian secretion polar lipid abnormality.

OBJECTIVE: To determine whether an association between keratoconjunctivitis sicca (KCS) and meibomian gland lipids exists in patients with chronic blepharitis. METHODS: Meibomian gland lipids were collected from normal patients and those with chronic blepharitis. Some of the chronic blepharitis patients had an ocular surface abnormality with apparent aqueous deficiency similar to KCS. Lipids were separated by thin-layer chromatography and polar lipids were further separated by high-pressure liquid chromatography with detection by UV absorbance. Lipids were identified by retention time with comparison with standards and by gas chromatography and mass spectroscopy. RESULTS: A strong association between specific lipids and KCS signs was observed only with the polar lipids. Low levels of 2 phospholipids, identified as phosphatidylethanolamine and sphingomyelin, were significantly (P < .05) associated with ocular surface abnormalities that were consistent with KCS. CONCLUSIONS: Evaporative KCS syndrome (rather than tear insufficiency) in many individuals may be the result of polar lipid abnormalities. We believe that the 2 associated phospholipids identified in the patients with chronic blepharitis act as important structural components in the polar phase of the tear film lipid layer. We suggest that a deficiency in these lipids results in a poorly structured polar phase that in turn affects the nonpolar phase. Ultimately water transmission through the tear film lipid layer increases, thus resulting in evaporative KCS. These results should aid in development of tear film substitutes directed toward specific abnormalities.

Meibomian gland triglyceride fatty acid differences in chronic blepharitis patients.

In this study, we analyzed the triglyceride fraction of human meibomian gland secretions to determine whether specific fatty acids were significantly associated with specific chronic blepharitis disease groups. Triglycerides, isolated from the lipid component of human meibomian secretions by thin-layer chromatography, were transmethylated with sodium methoxide/methanol. Samples from individuals were then analyzed by gas chromatography-mass spectroscopy (GC-MS). Significant fatty acid differences were determined by nonparametric analyses, utilizing Kruskal-Wallis analysis of between group differences and Student-Newman-Keuls multiple comparisons. The analyses showed that the triglyceride samples contained the expected normal, iso, and anteiso fatty acids; disease group differences (from normals) in some of these fatty acid types were significant only with a Bonferroni adjustment. The triglycerides also contained previously unreported polyunsaturated fatty acids as well as two four-member families of fatty acids that had mass spectra and retention times consistent with dimethylated carbon chains. Additionally, some members of the meibomian keratoconjunctivitis (MKC) group contained an unusual pattern of normal 20-carbon fatty acids, including a higher level of saturated and lower levels of unsaturated fatty acids. An important exception was the presence of a monosaturated fatty acid whose GC retention time and mass spectrum were consistent with the uncommon cis-10-20:1 isomer. This pattern was associated with the presence of patient posterior hordeola. Thus, the association of triglyceride fatty acid composition with chronic blepharitis disease signs could be much more important than previously thought. Furthermore, this is the first example of the association of specific fatty acids with a specific chronic blepharitis disease sign.

Role of wax ester fatty alcohols in chronic blepharitis.

PURPOSE: This study was performed to determine the difference in the composition of wax ester fatty alcohols from meibomian gland secretions from normal people and those with blepharitis, and to determine which lipids are associated significantly with specific chronic blepharitis disease groups. METHODS: Fatty alcohols, isolated by thin-layer chromatography from the wax and sterol ester fraction of human meibum, were analyzed by gas chromatography-mass spectroscopy after oxidative ozonolysis and silylation of the alcohol groups. Relative amounts of individual lipids or lipid groupings in each patient group were analyzed statistically by Dunnett's comparison, with the overall significance level adjusted for multiple testing (Bonferroni adjustment). RESULTS: Significant differences (P < 0.05) between the normal group and five disease groups were found in certain alcohol groups. These alcohols included certain normal (straight chain-methyl group on chain end) and anteiso (methyl group on second carbon from chain end) alcohols, as well as the ratio of iso (methyl group on first carbon from chain end) to anteiso alcohols. The results also suggested that alpha-oxidation activity was significantly different for certain groups. The unsaturated alcohols were primarily normal alcohols. Epoxy-fatty acids also were present in the alcohol fraction. CONCLUSIONS: These data suggest that meibomian gland lipid differences may contribute significantly to some chronic blepharitis disease signs and also suggest that peroxisomal or endoplasmic reticulum abnormalities may contribute in part to some of these lipid differences.

Relation of cholesterol-stimulated Staphylococcus aureus growth to chronic blepharitis.

PURPOSE: Many types of chronic blepharitis have been believed to be primarily microbial in origin; however, it was proposed that differences and changes in lipid composition of meibomian secretion may be the initiating factor in some of these. It was recently reported that there are two subgroups of normals, those whose meibomian secretions contain high levels of cholesterol esters and those whose secretions contain very low levels of these esters. Thus, these subgroups of normals were defined on the basis of detailed lipid analyses of meibomian secretions from individuals showing no clinical signs of chronic blepharitis. All secretions from patients in the various disease groups contain high levels of these esters. Based on previous observations that in some chronic blepharitis disease groups certain Staphylococcus species were capable of hydrolyzing cholesterol esters, the authors tested the hypothesis that the resulting cholesterol might affect growth of Staphylococcus aureus. METHODS: Staphylococcus aureus growth stimulation in Mueller-Hinton broth by cholesterol was determined by colony forming units. Growth stimulation by cholesterol and other additives was also determined by the optical density 650 nm method. Statistical analyses included analysis of variance and the Student's t test. RESULTS: Cholesterol stimulated Staphylococcus aureus growth was significant during the first 24 hr period (20% increase at 25 microM cholesterol, P < 0.02), and for the total 48 hr period (40% increase at 400 microM cholesterol, P < 0.005) when compared to the respective control. Growth stimulation, determined by OD at 650 nm, in the presence of cholesterol was significantly greater (P < 0.02) than that in the presence of either sitosterol or cholestanol when the sterol concentration was 190 microM. CONCLUSION: These results suggest that the presence and hydrolysis of cholesterol esters of meibomian secretions may contribute to the proliferation of Staphylococcus spp, especially Staphylococcus aureus, observed in some chronic blepharitis disease groups.

The role of cholesterol in chronic blepharitis.

Chronic blepharitis has been a difficult disease to define either microbiologically or biochemically. Sterols from meibomian secretions of normal subjects and patients were analyzed, and important differences were observed. Based on analyses of these secretions, two significantly different (P less than 0.001) types of normal subjects were found, those with and those without cholesterol esters [Norm(CP) and Norm(CA), respectively]. All patients' secretions contained cholesterol esters. Evidence was obtained which suggests that oxysterols may control the ester cholesterol accumulation. Furthermore, only when cholesterol esters were present did wax and sterol esters containing unsaturated fatty acids accumulate. Over 90% of these unsaturated fatty acids were normal (unbranched); the rest were iso-fatty acids. Preliminary results also suggest that the ester fatty alcohols are much more complex than previously reported; seven alcohols were common to all samples analyzed. Additionally, highly oxygenated alcohols were detected, especially in the meibomian keratoconjunctivitis (MKC) disease group. The MKC samples also contained an alcohol (mass, M/Z 378) not present in any of the other samples analyzed. Based on analysis of variance and linear-regression models, it was determined that the long-chain (C20-28) fatty acids were more important in determining disease signs. Furthermore, in the MKC group, the ratio of unsaturated C18 fatty acids to cholesterol in the wax and sterol esters was significantly different (P less than 0.05) from the Norm(CP) group. The authors discuss the fact that rabbit meibomian secretions are stable, despite containing a very high percentage of ester sterols, and relate this to their high percentage of branched-chain fatty acids and low percentage of unsaturated fatty acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Uridine diphosphate glucose breakdown is mediated by a unique enzyme activated by fructose 2,6-bisphosphate in Solanum tuberosum.

In the presence of inorganic phosphate, uridine 5'-diphosphate glucose (UDPG) is specifically hydrolyzed to glucose 1-phosphate and UDP by a unique enzyme, UDPG phosphorylase. The activity of the enzyme was maximally stimulated by fructose 2,6-bisphosphate, a regulatory metabolite recently discovered in both plants and animals, and by 2-phosphoglyceric acid. At 1 muM, fructose 2,6-bisphosphate stimulated UDPG phosphorolysis 10-fold, whereas 2-phosphoglyceric acid was required at higher concentrations (100 muM) to produce a similar effect. Fructose 2,6-bisphosphate appears to increase the affinity of the enzyme for inorganic phosphate, with a change in K(m) from 1.6 mM to 0.3 mM. The results suggest that fructose 2,6-bisphosphate participates in the regulation of other pathways of carbohydrate metabolism in addition to playing its recognized role in glycolysis and gluconeogenesis.