-
[show abstract]
[hide abstract]
ABSTRACT: To investigate the corneal virulence of toxin-deficient mutants of Staphylococcus aureus in young and aged mice in a topical inoculation model of keratitis.
Corneas of young and aged A/J mice were scarified and topically inoculated with a log phase S. aureus parent strain (8325-4), an alpha-toxin-deficient mutant (DU1090), or an Agr-defective mutant (ISP546) deficient in production of multiple toxins or with purified alpha-toxin. Slit lamp examination (SLE) and histopathology were performed, and bacterial colony-forming units (CFU) and myeloperoxidase (MPO) activity were determined.
The infection of young mice with the mutant strains demonstrated significantly lower SLE scores (P < or = 0.0001) and reduced histopathologic changes compared with infections with the parent bacterial strain. Either mutant strain of S. aureus produced SLE scores in aged mice through 9 days after infection (PI) that were significantly lower than those of aged mice similarly infected with the toxin-producing parent strain (P < or = 0.0001). Despite use of identical inocula, the CFU per eye were greater for the parent than the mutant strains from 1 to 5 days PI in the young mice (P < or = 0.0372) and from 1 to 3 days PI in the aged mice (P < or = 0.0018). MPO activities were at the maximum at day 1 PI and were similar overall for all infections. Administration of purified alpha-toxin caused greater gross and histopathologic changes in eyes of aged mice than in those of young mice.
Bacterial toxins, and especially alpha-toxin, can mediate corneal disease in mice. Differences in severity of S. aureus keratitis in aged versus young mice correlates with their susceptibility to alpha-toxin.
Investigative Ophthalmology & Visual Science 07/2005; 46(6):2064-70. · 3.60 Impact Factor
-
Elizabeth E Mannick,
Rae L Cote,
Jill R Schurr,
Halina S Krowicka, Gregory D Sloop,
Adriana Zapata-Velandia,
Hernan Correa,
Bernardo Ruiz,
Ronald Horswell,
Jennifer J Lentz,
Patrick Byrne,
M Mariella Gastanaduy,
Conrad A Hornick,
Zhiyun Liu
[show abstract]
[hide abstract]
ABSTRACT: Interferon regulatory factor-1 (IRF-1) is a transcription factor with antiviral, proinflammatory and tumor suppressor properties. We examined the role of IRF-1 in dextran sulfate sodium colitis, a murine model of inflammatory bowel disease, to determine if absence of the gene would protect against colitis.
C57BL/6J mice with a targeted disruption of IRF-1 and wild-type C57BL/6J controls received five 7-day cycles of 2% dextran sulfate sodium alternating with five 7-day cycles of water. Colonic tissue was formalin fixed for histological analysis and total RNA extracted for gene chip and SYBR green real-time polymerase chain reaction (PCR) analysis.
Histological analysis revealed increased distortion of crypt architecture in the dextran sulfate sodium-treated, IRF-1 -/- animals as compared to dextran sulfate sodium-treated wild-type animals. Five of 15 dextran sulfate sodium-treated IRF-1 -/- mice, but only one of 14 dextran sulfate sodium-treated wild-type mice, developed colonic dysplasia. Microarray analysis comparing colonic gene expression in IRF-1 -/- and wild-type animals revealed decreased expression of caspases, genes involved in antigen presentation, and tumor suppressor genes in the IRF-1 -/- animals. Increased expression of genes involved in carcinogenesis and immunoglobulin and complement genes was also noted in the knock-out animals.
Absence of IRF-1 is not protective in dextran sulfate sodium colitis.
Journal of Gastroenterology and Hepatology 04/2005; 20(3):371-80. · 2.87 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To assess the frequency of shedding of herpes simplex virus type 1 (HSV-1) DNA in tears and saliva of asymptomatic individuals.
Fifty subjects without signs of ocular herpetic disease participated. Serum samples from all subjects were tested for HSV IgG antibodies by enzyme-linked immunosorbent assay (ELISA) and for HSV-1 by neutralization assay. HSV-1 DNA copy number and frequency of shedding were determined by real-time polymerase chain reaction (PCR) analysis of tear and saliva samples collected twice daily for 30 consecutive days.
Thirty-seven (74%) of the 50 subjects were positive for HSV IgG by ELISA. The percentages of positive eye and mouth swabs were approximately equivalent: 33.5% (941/2806) and 37.5% (1020/2723), respectively. However, the percentage of samples with high HSV-1 genome copy numbers was greater in saliva than in tears, which may have been a result of the sample volume collected. Shedding frequency in tears was nearly the same in men (347/1003; 34.6%) and women (594/1705; 34.8%); in saliva, men had a higher frequency of shedding (457/1009; 45.3% vs. 563/1703; 33.1%, men versus women). Overall, 49 (98%) of 50 subjects shed HSV-1 DNA at least once during the course of the 30-day study.
The percentage of asymptomatic subjects who intermittently shed HSV-1 DNA in tears or saliva was higher than the percentage of subjects with positive ELISA or neutralization antibodies to HSV. Because most HSV transmission occurs during asymptomatic shedding, further knowledge of the prevalence of HSV-1 DNA in tears and saliva is warranted to control its spread. Shedding is simple to study, and its suppression may be an efficient way to evaluate new antivirals in humans.
Investigative Ophthalmology & Visual Science 02/2005; 46(1):241-7. · 3.60 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Peripheral facial nerve palsy is a common sequela of traumatic craniofacial injury, often resulting in dramatic and sometimes permanent functional deficits. Exogenous agents and methods of repair that accelerate axonal regeneration would be of great benefit to the multitude of patients with facial nerve injuries. The objective of this study was to evaluate the effect of FK506 at the time of facial nerve repair using entubulation neurorrhaphy, and to compare entubulation neurorrhaphy versus interposition autograft in critical facial nerve gap defects. The study design was a prospective, randomized, blinded animal study with a control group. Twenty-five New Zealand White rabbits were assigned to 4 experimental groups and a control group. The buccal branch of the facial nerve was used in all procedures. Group 1 was the control group. Rabbits in group 2 underwent sham surgery. Group 3 was an interposition autograft group in which a 6-mm segment of nerve was transacted, flipped, and followed by epineural repair. Groups 4 and 5 underwent transection followed by entubulation neurorrhaphy with topical administration of either a carrier molecule (group 4) or an FK506 carrier molecule (group 5). Outcome measures included daily subjective assessment of upper lip movement; electromyographic studies at weeks 3, 5, and 8 postoperatively; and blinded quantitative histomorphometric evaluation after 8 weeks. All rabbits in all groups were noted to have spontaneous movement after 8 weeks, with 1 rabbit in group 5 obtaining the highest functional score among all study groups. Electrophysiologic studies showed polyphasic potentials, indicating reinnervation in 1 rabbit in group 5. Histomorphometric examination of group 5 rabbits revealed a similar cross-sectional area distal to transection and remyelination. Other groups showed decreased cross-sectional area and/or incomplete remyelination distal to the transection. FK506 applied topically at the time of facial nerve repair using entubulation neurorrhaphy demonstrated superior results in nerve regeneration versus entubulation neurorrhaphy carrier protein alone, and interposition autograft.
Annals of Plastic Surgery 05/2004; 52(4):407-13. · 1.32 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To examine whether the atherosclerotic risk from cholesterol is modified by serum glucose level.
Data from the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study of 1530 individuals with complete autopsy data for total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and hemoglobin A1c (HbA1c) were examined with any atherosclerotic raised lesions (RL) >0% of surface area on any of three arterial specimens as the outcome. A TC/HDL-C ratio was categorized into quintiles and HbA1c was dichotomized as the upper quartile versus lower three quartiles. Odds ratios (ORs) were estimated from logistic regression models adjusting for sex, race, age, body mass index, smoking and hypertension. Results: An interaction product term of TC/HDL x HbA1c was statistically significant (P=0.006) despite adjustment for the main effects and other covariates. In models stratified by HbA1c, ORs (3.0, 3.9, 1.9, 3.5) for four upper quintiles of TC/HDL-C in the upper HbA1c stratum were substantially higher than those in the lower HbA1c stratum (0.9, 1.3, 1.4 and 1.1). Strata differences were even more striking in the subset of those > or =25 years old.
These results suggest a synergistic interaction between glucose and cholesterol that magnifies the atherosclerotic risk associated with TC/HDL-C for those with higher HbA1c levels.
Atherosclerosis 02/2004; 172(1):115-20. · 3.79 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To define factors that protect the eye from Staphylococcus aureus keratitis and limit tissue damage once keratitis occurs.
Rabbit tears were analyzed for bactericidal and phospholipase A(2) (PLA(2)) activities on S. aureus. Inhibition by spermidine of PLA(2) anti-staphylococcal activity in tears was tested in vitro and in vivo. Rabbits immunized with heat-inactivated alpha-toxin were challenged with intrastromal injection of S. aureus.
Arachidonic acid was cleaved from S. aureus by purified PLA( 2) or rabbit tears. Spermidine inhibited these reactions in vitro and facilitated keratitis in vivo. PLA(2) activity decreased with advanced age and shortly following sleep, but increased with keratitis. Antibody to alpha-toxin significantly reduced corneal damage and epithelial cell sloughing during keratitis.
PLA(2) is a major host-defense component of rabbit tears. Alpha-toxin is a major mediator of corneal damage, and antibody to alpha-toxin reduces pathologic changes during keratitis.
Ocular Immunology and Inflammation 10/2003; 11(3):171-81. · 1.25 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To establish, in the scarified mouse eye, a new model of Staphylococcus aureus keratitis suitable for studies of pathogenesis and host defense mechanisms.
Corneas of three strains of mice (BALB/c, A/J, and C57BL/6) were scarified and inoculated with S. aureus strain 8325-4. Mice underwent slit lamp examination (SLE) at 1, 3, 5, 7, and 9 days after infection and were killed. Histopathologic analyses, determination of bacterial colony-forming units (CFU), and myeloperoxidase (MPO) activity assays were performed at each time point.
S. aureus keratitis developed in both BALB/c and A/J strains of mice, but not in C57BL/6. The BALB/c and A/J strains demonstrated greater susceptibility to infection, as evidenced by significantly higher SLE scores and more viable bacteria per infected eye than in C57BL/6 mice at 5, 7, and 9 days after infection (P <or= 0.0001). Histopathologic analysis and MPO assays of infected A/J mice both revealed an influx of polymorphonuclear leukocytes (PMNs). Histology demonstrated presence of leukocytes in the aqueous humor, migration of PMNs into infected tissue, corneal erosion, and edema in the eyes of infected A/J mice. Whereas infected BALB/c mice demonstrated both PMN migration and corneal edema, eyes of infected C57BL/6 mice failed to show even mild histopathologic changes.
These studies demonstrate the establishment of Staphylococcus keratitis in the mouse eye. This model should provide for a large range of future studies that are currently unavailable in the rabbit keratitis model, particularly those requiring a genetically altered host or specific immunologic reagents.
Investigative Ophthalmology & Visual Science 04/2003; 44(4):1591-7. · 3.60 Impact Factor
-
Journal of Thoracic Imaging 02/2003; 18(1):1-13. · 0.98 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To determine the pathogenic role of gamma- and alpha-toxin in a rabbit model of Staphylococcus aureus keratitis.
S. aureus strains Newman (expressing gamma-toxin), Newman Delta(hlg) (deficient in gamma-toxin), Newman Delta(hlg)/pCU1 hlg(+) (chromosomal gamma-toxin-deficient mutant rescued by a plasmid encoding gamma-toxin), and Newman Delta(hla) (alpha-toxin-deficient) were intrastromally injected into rabbit corneas. Eyes were scored by slit lamp examination (SLE), and bacterial colony-forming units (CFU) per cornea were determined at 15, 20, and 25 hours after infection. Histologic examination of corneas was performed. Rabbits were immunized against alpha-toxin and subsequently challenged with S. aureus strain Newman. Western blot analyses of culture supernatants were performed to detect alpha-toxin production.
All strains grew equivalently, producing approximately 7 log CFU per cornea at 25 hours after infection. SLE scores at 20 and 25 hours after infection revealed that strains Newman Delta(hlg) and Newman Delta(hla), although virulent, caused significantly less ocular damage and inflammation than their parent or the gamma-toxin genetically rescued strain (P <or= 0.0006). Histologic and SLEs revealed that all strains except Newman Delta(hla) produced corneal erosions. Rabbits immunized actively or passively to alpha-toxin had reduced SLE scores (P <or= 0.0003 and P <or= 0.0033, respectively) and no epithelial erosions when infected with strain Newman. Western blot analysis demonstrated that strains Newman and Newman Delta(hlg), but not Newman Delta(hla), produced alpha-toxin.
These results illustrate that the virulence of strain Newman involves both alpha- and gamma-toxin, with alpha-toxin mediating corneal epithelial erosions. An additional uncharacterized toxin could also be active in damaging the cornea.
Investigative Ophthalmology & Visual Science 05/2002; 43(4):1109-15. · 3.60 Impact Factor
-
Gregory D Sloop
Methods in Enzymology 02/2002; 352:340-7. · 2.04 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Atherosclerotic plaque-like lesions are prevalent in synthetic arteriovenous shunts created to provide vascular access for hemodialysis. Similarities to atherosclerotic plaques in native arteries include eccentric location, immunoreactivity for smooth muscle actin, dystrophic calcifications, superimposed thrombi, and foam cells. Fatty streaks were not grossly identified on Sudan IV staining. Because of the similarities to atherosclerosis in native vessels, these findings may have several implications for atherogenesis. The development of raised, fibrous lesions does not require decades. The presence of smooth muscle in atherosclerotic plaque-like lesions does not require a source from tunica media. A precursor fatty streak may not be required for the development of raised, fibrous lesions. Finally, development of atherosclerotic plaque-like lesions does not require putative inflammatory effects from cholesterol or LDL accumulation, or even a native vessel that can respond to injury. The atherosclerotic plaque-like lesions in this study probably developed from organization of mural thrombi.
Atherosclerosis 02/2002; 160(1):133-9. · 3.79 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A case of furuncular myiasis is reported. The life cycle of the parasite, differential diagnosis, host response, and therapy are briefly discussed.
The Journal of the Louisiana State Medical Society: official organ of the Louisiana State Medical Society 158(1):14-5; quiz 16, 45.
-
[show abstract]
[hide abstract]
ABSTRACT: To determine the effect of age on the extent of pathogenesis of Staphylococcus keratitis in the mouse.
Corneas of young and aged mice (BALB/c, A/J, and C57BL/6) were scarified and topically inoculated with S. aureus. Slit lamp examination (SLE) and histopathology were performed, and bacterial colony forming units and myeloperoxidase activity were determined.
SLE scores of infected eyes of aged mice were significantly higher at days 1 and 3 postinfection (PI) as compared to infected young mice. Histopathological changes observed in all aged mice were more severe than those in young mice. Young BALB/c and A/J mice demonstrated minimal signs of keratitis by day 3 PI, whereas aged mice of both strains demonstrated severe keratitis by day 3. Young C57BL/6 mice showed no clinical signs of keratitis, whereas aged C57BL/6 mice demonstrated moderate keratitis.
Aged mice with S. aureus keratitis demonstrated increased pathology as compared to young mice.
Current Eye Research 29(4-5):269-75. · 1.28 Impact Factor
