Viral infections, cytokine dysregulation and the origins of childhood asthma and allergic diseases

BACKGROUND

The origins of asthma and allergic disease begin in early life for many individuals. It is vital to understand the factors and/or events leading to their development.

METHODS

The Childhood Origins of Asthma project evaluated children at high risk for asthma to study the relationships among viral infections, environmental factors, immune dysregulation, genetic factors, and the development of atopic diseases. Consequently wheezing illnesses, viral respiratory pathogen identification, and in vitro cytokine response profiles were comprehensively evaluated from birth to 3 years of age, and associations of the observed phenotypes with genetic polymorphisms were investigated.

RESULTS

For the entire cohort, cytokine responses did not develop according to a strict T helper cell 1 or T helper cell 2 polarization pattern during infancy. Increased cord blood mononuclear cell phytohemagglutin-induced interferon-gamma responses of mononuclear cells were associated with decreased numbers of moderate to severe viral infections during infancy, especially among subjects with the greatest exposure to other children. In support of the hygiene hypothesis, an increased frequency of viral infections in infancy resulted in increased mitogen-induced interferon-gamma responses at 1 year of age. First year wheezing illnesses caused by respiratory viral infection were the strongest predictor of subsequent third year wheezing. Also, genotypic variation interacting with environmental factors, including day care, was associated with clinical and immunologic phenotypes that may precede the development of asthma.

CONCLUSIONS

Associations between clinical wheezing, viral identification, specific cytokine responses and genetic variation provide insight into the immunopathogenesis of childhood asthma and allergic diseases.

Ocular complications after organ and bone marrow transplantation in children

BACKGROUND

Organ and bone marrow transplantation commonly are performed in children. Ocular complications usually are described as secondary to post-transplantation medications. The complication rate is unknown.

METHODS

A retrospective chart review was performed of 93 children who were younger than 18 years of age and had transplantation surgery from 1989 to 2004. The rate and type of ocular complications, including those requiring ocular surgery, were analyzed. Medications and visual loss associated with adverse effects also were studied.

RESULTS

Of the 93 patients, 74 patients met the entry criteria. Sixty-one patients had at least 1 year of follow-up, and the longest follow-up duration was 14 years. The 1-year post-transplantation complication rate was 16.0% (95% confidence interval 6.8-24.4%). Adverse effects included cytomegalovirus (CMV) retinitis, cataract, graft-versus-host disease, lymphoproliferative disorder, persistent strabismus, and transient visual loss. Four patients underwent eye surgery, including lensectomy for cataract, tarsorrhaphy for corneal ulcer, and iris biopsy. They had surgery 0.9 to 4.7 years after transplantation. Most patients were taking prednisone and cyclosporine when their complication was diagnosed. One patient's visual acuity deteriorated to no light perception in one eye and 20/250 in the other eye secondary to CMV retinitis. Most patients had a final visual acuity > or =20/40.

CONCLUSION

Transplantation surgery in children produces a significant risk of ocular impairment. The 1-year complication rate was 16.0%. Eye surgery may be required within the first few years after transplantation. Although most patients maintained a final visual acuity of 20/40 or better, one patient became bilaterally legally blind.

The Effects of Lingual Exercise on Swallowing in Older Adults

OBJECTIVES

To determine the effects of an 8-week progressive lingual resistance exercise program on swallowing in older individuals, the most "at risk" group for dysphagia.

DESIGN

Prospective cohort intervention study.

SETTING

Subjects were recruited from the community at large.

PARTICIPANTS

Ten healthy men and women aged 70 to 89.

INTERVENTION

Each subject performed an 8-week lingual resistance exercise program consisting of compressing an air-filled bulb between the tongue and hard palate.

MEASUREMENTS

At baseline and Week 8, each subject completed a videofluoroscopic swallowing evaluation for kinematic and bolus flow assessment of swallowing. Swallowing pressures and isometric pressures were collected at baseline and Weeks 2, 4, and 6. Four of the subjects also underwent oral magnetic resonance imaging (MRI) to measure lingual volume.

RESULTS

All subjects significantly increased their isometric and swallowing pressures. All subjects who had the MRI demonstrated increased lingual volume of an average of 5.1%.

CONCLUSION

The findings indicate that lingual resistance exercise is promising not only for preventing dysphagia due to sarcopenia, but also as a treatment strategy for patients with lingual weakness and swallowing disability due to frailty or other age-related conditions. The potential effect of lingual exercise on reducing dysphagia-related comorbidities (pneumonia, malnutrition, and dehydration) and healthcare costs while improving quality of life is encouraging.

Predictors and Outcomes of Candiduria in Renal Transplant Recipients

BACKGROUND

The epidemiology of candiduria in renal transplantation is unknown.

METHODS

We performed a nested case-control study to evaluate the epidemiology of candiduria in renal transplant recipients at the University of Wisconsin (Madison) over an 8-year period.

RESULTS

Renal transplantations were performed on 1738 patients during this period, 192 of whom had 276 episodes of candiduria. Candida glabrata, which was recovered from 98 (51%) of 192 case patients, was the most common pathogen identified. Most case patients were asymptomatic. Independent predictors of candiduria were female sex (odds ratio [OR], 12.5; 95% confidence interval [CI], 6.7-23.0), intensive care unit admission (OR, 8.8; 95% CI, 2.3-35.0), antibiotic use during the month before candiduria (OR, 3.8; 95% CI, 1.7-8.3), presence of an indwelling bladder catheter (OR, 4.4; 95% CI, 2.1-9.4), diabetes (OR, 2.2; 95% CI, 1.3-3.9), neurogenic bladder (OR, 7.6; 95% CI, 2.1-27), and malnutrition (OR, 2.4; 95% CI, 1.3-4.4). Log-rank testing of Kaplan-Meier curves revealed that 60-day, 90-day, and cumulative survival rates were significantly different between case and control patients; there was no difference in the survival rate during the first 30 days after transplantation. A variety of regimens were used for treatment; 119 case patients (62%) underwent removal of the indwelling bladder catheter within 1 week after diagnosis of candiduria. Candiduria cleared in 148 case patients (77%). Treatment of candiduria was not associated with an improved survival rate.

CONCLUSIONS

Candiduria occurs commonly in renal transplant recipients. Risk factors for candiduria in such persons are similar to those in hospitalized patients who have not received a transplant. Candiduria is associated with reduced survival rates among persons who have undergone renal transplantation; this is likely a marker for severity of illness. Treatment of asymptomatic candiduria in renal transplant recipients does not appear to result in improved outcome.

Gene-environment interaction effects on the development of immune responses in the 1st year of life

Asthma is a common disease that results from both genetic and environmental risk factors. Children attending day care in the 1st year of life have lower risks for developing asthma, although the mechanism for this "day care" effect is largely unknown. We investigated the interactions between day care exposure in the 1st 6 mo of life and genotypes for 72 polymorphisms at 45 candidate loci and their effects on cytokine response profiles and on the development of atopic phenotypes in the 1st year of life in the Childhood Onset of Asthma (COAST) cohort of children. Six interactions (at four polymorphisms in three loci) with "day care" that had an effect on early-life immune phenotypes were significant at P<.001. The estimated false-discovery rate was 33%, indicating that an estimated four P values correspond to true associations. Moreover, the "day care" effect at some loci was accounted for by the increased number of viral infections among COAST children attending day care, whereas interactions at other loci were independent of the number of viral infections, indicating the presence of additional risk factors associated with day care environment. This study identified significant gene-environment interactions influencing the early patterning of the immune system and the subsequent development of asthma and highlights the importance of considering environmental risk factors in genetic analyses.

Recalculation of the NHANES database SD improves T-score agreement and reduces osteoporosis prevalence

In attempt to improve diagnostic agreement between manufacturers, a recent software update incorporated NHANES III data in GE Lunar densitometers. As a result, the femur neck and trochanter T-scores were lowered, and osteoporosis prevalence was increased. Use of a recalculated young-normal SD for the GE Lunar-adjusted NHANES III database improved diagnostic agreement and is recommended.

INTRODUCTION

Use of manufacturer-specific normative databases for T-score derivation leads to discordance in T-score values and differences in diagnostic classification. To address this issue, the International Committee for Standards in Bone Measurement (ICSBM) recommended the NHANES III database for femur T-score derivation. Acquired on Hologic (Hol) instruments, this database requires conversion equations for application to other DXA systems. NHANES III total femur (TF) conversions for GE Lunar (GE) have previously been available, and femoral neck (FN) and trochanter (TR) equations were reported recently. Per the ICSBM recommendation, GE Lunar incorporated these values into their female database. This should produce T-score and diagnostic agreement between Hol and GE instruments; however, this has not been evaluated.

MATERIALS AND METHODS

We compared GE femur scans in 115 postmenopausal women using software before and after the NHANES III software update. Subsequently, T-scores derived from femur scans obtained on GE and Hol densitometers were compared in a different group of 89 postmenopausal women.

RESULTS

The NHANES III software update had no effect on measured BMD (g/cm2) at any femur region. However, because of changes in values used for T-score calculation (increase in the mean young-normal BMD at the FN and TR and a reduction in SD at the TR), the T-scores were lower (mean, 0.48 and 0.68, respectively) at the FN and TR using post-NHANES III software. Consequently, this update increased femur osteoporosis prevalence in these 115 women from 7.8% to 18.3%. Comparison of GE with Hol total proximal femur T-scores revealed a minimal difference (<0.1) and equal diagnoses of osteoporosis. FN and TR differences were larger, with mean GE T-scores lower than Hol (p < 0.001) by 0.17 and 0.50, respectively, thereby introducing osteoporosis diagnostic disagreement (13 [GE] versus 9 [Hol]). Our evaluation suggested that this disparity resulted from direct application of published NHANES III SDs at the FN and TR. As such, we applied the conversion formulae to the NHANES III published Hologic data and found the FN and TR SDs were greater than assumed by GE. Using our recalculated SD to derive T-scores reduced the mean GE/Hol T-score difference to 0.03 at the FN and 0.32 at the TR and resolved osteoporosis diagnostic disagreement.

CONCLUSION

The GE NHANES III software update leads to lower FN and TR T-scores than obtained with Hol or prior GE software. Recalculation of the young-normal SD reduces this difference and is recommended. Clinicians are advised to avoid using the TR for diagnosis or, at a minimum, use caution when making treatment decisions based solely on T-score at this site.

A Study of Iridectomy Histopathologic Features of Latanoprost- andNon–Latanoprost-Treated Patients

OBJECTIVES

To examine the histopathologic features of iridectomy specimens from patients undergoing glaucoma surgery and to compare histologic abnormalities in a group of patients with a history of latanoprost therapy with those in a group of patients who had no history of prostaglandin therapy (controls).

METHODS

Iridectomy specimens and patient history forms were submitted to the central Latanoprost Pathology Center. These were independently examined by 3 ophthalmic pathologists in a masked fashion. Specimens were evaluated for malignant, premalignant, and other changes including differences in levels of pigmentation, degrees of cellularity, inflammation, vascular abnormalities, and changes in the iris pigment epithelium.

RESULTS

Specimens were received from 449 patients with a history of latanoprost treatment and 142 patients who had no history of treatment with latanoprost or other prostaglandin analogues. No evidence of malignant or premalignant changes was found. In latanoprost-treated irides, the prevalence of iris freckles was higher (P = .001) than in control irides, as was the combined number of stromal fibroblasts and melanocytes (P<.001). In a subgroup of specimens received through June 2002, there was no significant difference in mean melanocyte counts (P=.35) obtained by immunohistochemical staining techniques between the latanoprost-treated and control groups.

CONCLUSIONS

These findings support previous studies indicating that latanoprost-induced eye color changes are due to an increased amount of melanin within the iris stromal melanocytes. The increased numbers of freckles may be a focal manifestation of this effect.

Intravitreal Triamcinolone for the Treatment of Macular Edema AssociatedWith Central Retinal Vein Occlusion

OBJECTIVE

To investigate the safety and efficacy of intravitreal triamcinolone acetonide as treatment for macular edema associated with central retinal vein occlusion (CRVO).

METHODS

We reviewed the medical records of 13 consecutive patients (13 eyes) with macular edema associated with CRVO who were treated with an injection of intravitreal triamcinolone acetonide (4 mg) at the University of Wisconsin and the Bascom Palmer Eye Institute. Each intravitreal injection was delivered through the pars plana using a 27- or 30-gauge needle.

MAIN OUTCOME MEASURES

Change in Snellen visual acuity, clinical appearance of macular edema, measurement of foveal thickening with optical coherence tomography (OCT), and frequency of complications.

RESULTS

The median age of the 13 patients was 67 years (interquartile range, 57-77 years), and the median duration of symptoms before injection was 8 months (interquartile range, 4-9 months). Mean baseline visual acuity was 20/500 in the affected eye. Mean visual acuity at the 6-month follow-up examination was 20/180 in the affected eye. All 13 patients completed the 6-month examination. Eyes with nonischemic CRVO (n = 5) demonstrated a significant improvement in visual acuity, whereas eyes with ischemic CRVO (n = 8) demonstrated a nonsignificant visual acuity improvement. No patient had a decrease in visual acuity. Mean baseline foveal thickness as measured by OCT was 590 micro m (retinal thickening = 416 micro m). Mean foveal thickness as measured by OCT at the 1-month follow-up examination in 12 patients was 212 micro m (retinal thickening = 38 micro m). At the 3-month follow-up examination, mean foveal thickness as measured by OCT for 13 patients was 193 micro m (retinal thickening = 19 micro m). Between the 3- and 6-month follow-up examinations, 4 patients developed a recurrence of macular edema. Three of the 4 patients were retreated with a second injection of triamcinolone. Two of these 3 patients experienced an improvement in visual acuity following retreatment. At the 6-month follow-up examination, mean foveal thickness as measured by OCT for 13 patients was 281 micro m (retinal thickening = 107 micro m). No adverse effects such as retinal detachment or endophthalmitis occurred. One patient experienced an increase in intraocular pressure that was controlled with 2 aqueous suppressants.

CONCLUSIONS

Intravitreal injection of triamcinolone appears to be a possibly effective treatment in some patients with macular edema associated with CRVO. Patients with nonischemic CRVO may respond more favorably than patients with ischemic CRVO, and retreatment may be necessary in some patients. In this case series, severe complications were not noted.

The efficacy of switching from etanercept to infliximab in patients with rheumatoid arthritis

OBJECTIVE

To describe the degree of clinical benefit in patients with rheumatoid arthritis (RA) who receive infliximab therapy after lack of efficacy with etanercept.

METHODS

In a retrospective study among 6 centers primarily designed to assess the safety of infliximab in combination with leflunomide, a standardized chart review form was used to collect data on 93 patients with RA. During that study, it was noted that some of these patients had switched from etanercept to infliximab. In this study, we compared the response of subjects switching from etanercept to infliximab (n = 20) to that of subjects receiving infliximab with no prior tumor necrosis factor (TNF) therapy (n = 73).

RESULTS

The swollen and tender joint count, patient and physician global assessments, morning stiffness, and C-reactive protein all improved substantially in both groups, with no statistical difference in the degree of benefit between the groups. At the time of chart review, switchers had received a statistically higher dose of infliximab than controls (4.4 vs 3.19 mg/kg; p = 0.006) with a total of 5.7 and 5 infusions, respectively.

CONCLUSION

In this retrospective study, previous lack of efficacy with etanercept did not predict lack of efficacy with infliximab. Indeed, the degree of clinical improvement was similar in both groups, although switchers were receiving a higher dose of infliximab at the time of chart review. Our findings suggest that clinical response may differ between anti-TNF agents, and lack of response to one agent may not predict a lack of response to another.

Cytokine response patterns, exposure to viruses, and respiratory infections in the first year of life

Daycare attendance and siblings are associated with viral-induced wheezing in children. Preexisting immunologic factors may influence the expression of viral infections in infancy, and in turn, recurrent infections may influence the development of immune responses. A total of 285 children were enrolled in the Childhood Origins of Asthma Project at birth and followed for at least 1 year. Cord blood and 1-year mononuclear cells were stimulated with phytohemagglutinin, and cytokine-response profiles were measured by enzyme-linked immunosorbent assay. Nasal lavage was performed for moderate to severe respiratory illnesses. Daycare attendance and/or siblings significantly increased the likelihood of contracting respiratory syncytial virus (1.5-1.6-fold increase) and rhinovirus (1.8-2.1-fold increase), and increased the risk of rhinovirus-induced wheezing (14-18% vs. 2%, p = 0.011). Cord blood IFN-gamma responses were inversely related to the frequency of viral respiratory infections (r(s) = -0.11, p = 0.05), and more significant for subjects with high exposure to other children (r(s) = -0.27, p = 0.028). The interval change in infantile IFN-gamma responses correlated positively with the frequency of viral infections in infancy (r(s) = 0.12, p = 0.047). These data suggest that neonatal IFN-gamma responses may influence antiviral activity, or may represent a marker of antiviral immunity maturation. Conversely, the frequency of viral infections in infancy can influence IFN-gamma responses.

Are Wisconsin physicians knowledgeable about male osteoporosis?

It is unknown if recent research defining the relatively frequent occurrence and pathophysiology of male osteoporosis has been conveyed to clinicians. To assess if physicians have incorporated such information, 5646 licensed Wisconsin physicians received a 1-page survey consisting of 14 statements regarding general knowledge, diagnosis, and treatment of osteoporosis in men. Twenty-six percent (1488) responded; 69% (1033) were family physicians or internists, 7% (106) orthopedic surgeons, and 5% (63) endocrinologists or rheumatologists. Of these physicians, 61% to 78% recognized that osteoporosis is not rare in men. Most (68%-97%) agreed that low-trauma fracture or corticosteroid therapy initiation are indications for bone mass measurement. Treating osteoporosis at a T-score of -2.5 was accepted by 79% to 89% of responders. Overall these physicians: (1) recognize osteoporosis as an important disease in men; (2) accept corticosteroid therapy and prior low-trauma fracture as indications for bone mass measurement; and (3) utilize T-scores in treatment decisions. These data suggest that knowledge regarding male osteoporosis has been conveyed to practicing physicians. Evaluation of methods by which physicians will translate this knowledge into action, thereby optimizing patient care, are needed.

Iris melanocyte numbers in Asian, African American, and Caucasian irides

PURPOSE

The anatomical basis for iris color has long been a controversial issue in ophthalmology. Recent studies demonstrated that in Caucasians, blue-eyed, gray-eyed, and hazel-eyed individuals have comparable numbers of iris melanocytes. The present investigation was carried out to compare melanocyte numbers in the irides of Asian, African American, and Caucasian brown-eyed individuals.

METHODS

Paraffin-embedded sections from 71 brown-colored irides were incubated with rabbit anti-cow antibody against S100a, linked with an FITC conjugate antibody, and counterstained with Evans blue. Cells were counted under a fluorescence microscope and scored as melanocytes or other cells. Cell number, density, and iris area were calculated for each specimen.

RESULTS

Caucasian and African American irides had comparable mean total melanocyte numbers. Asian irides had fewer total melanocytes than African American (P = .042) and Caucasian (P = .001) irides and smaller total number of cells (ie, melanocytes plus other cells) than African American (P = .054) or Caucasian (P = .009) irides.

CONCLUSIONS

There is a statistically significant smaller mean total melanocyte number and mean total cellularity in Asian irides as compared to Caucasian and African American irides. This difference appears to be due to the combination of smaller iris area and lower melanocyte density in the Asian irides. The possibility exists that this may be a factor in ethnic variations in certain ocular diseases.

A hierarchical model for spatially clustered disease rates

Maps of regional disease rates are potentially useful tools in examining spatial patterns of disease and for identifying clusters. Bayes and empirical Bayes approaches to this problem have proven useful in smoothing crude maps of disease rates. In recent years, models including both spatially correlated random effects and spatially unstructured random effects have been very popular. The spatially correlated random effects have been proposed in an attempt to capture a general clustering in the data. As an alternative, we propose replacing the spatially structured random effect with fixed clustering effects associated with particular areas. A reversible jump Markov chain Monte Carlo (RJMCMC) algorithm for posterior inference is described. We illustrate the model using the well-known New York leukaemia data.

Risk of hemolytic uremic syndrome after antibiotic treatment of Escherichia coli O157:H7 enteritis: a meta-analysis

CONTEXT

The use of antibiotics for treatment of Escherichia coli O157:H7 infection has become controversial since a recent small study found that it may increase the risk of hemolytic uremic syndrome (HUS). However, other larger studies have reported a protective effect or no association.

OBJECTIVE

To determine whether antibiotic therapy for E coli O157:H7 enteritis increases the risk of HUS.

DATA SOURCES

PubMed and MEDLINE computer searches were performed for studies published from January 1983 to February 2001 using the key words hemolytic uremic syndrome, risk factor, antibiotics, and Escherichia coli O157:H7. Reference lists of relevant publications were reviewed, and 12 experts in the field were contacted to identify additional reports. No language restrictions were applied to the search.

STUDY SELECTION

Studies were included if they reported a series of patients with documented E coli O157:H7 enteritis, some of whom developed HUS; had clear definitions of HUS; and had adequate data delineating the relationship between antibiotic therapy and the occurrence of HUS. Nine of the 26 identified studies fulfilled these criteria.

DATA EXTRACTION

Two authors (N.S. and A.S.) independently reviewed each report identified by the searches and recorded predetermined information relevant to the inclusion criteria. A pooled odds ratio was calculated using a fixed-effects model, with assessment of heterogeneity among the studies.

DATA SYNTHESIS

The pooled odds ratio was 1.15 (95% confidence interval, 0.79-1.68), indicating that there does not appear to be an increased risk of HUS with antibiotic treatment of E coli O157:H7 enteritis. Incomplete reporting of data in individual studies precluded adjustment for severity of illness.

CONCLUSION

Our meta-analysis did not show a higher risk of HUS associated with antibiotic administration. A randomized trial of adequate power, with multiple distinct strains of E coli O157:H7 represented, is needed to conclusively determine whether antibiotic treatment of E coli O157:H7 enteritis increases the risk of HUS.

A weighted average likelihood ratio test for spatial clustering of disease

We consider methods proposed for detecting localized spatial clustering. We propose a new test statistic, the weighted average likelihood ratio test, as an alternative to the spatial scan (maximum likelihood ratio) test statistic. Two different types of weights are considered. We propose an unbiased cluster selection criterion and evaluate the bias of the tests through simulation. We also examine the power of the tests through simulations and apply the methods to the well-known New York leukaemia data.

Bayesian detection and modeling of spatial disease clustering

Many current statistical methods for disease clustering studies are based on a hypothesis testing paradigm. These methods typically do not produce useful estimates of disease rates or cluster risks. In this paper, we develop a Bayesian procedure for drawing inferences about specific models for spatial clustering. The proposed methodology incorporates ideas from image analysis, from Bayesian model averaging, and from model selection. With our approach, we obtain estimates for disease rates and allow for greater flexibility in both the type of clusters and the number of clusters that may be considered. We illustrate the proposed procedure through simulation studies and an analysis of the well-known New York leukemia data.

Enthacrynic and acid effects on inner wall pores in living monkeys

PURPOSE

The influence of the inner wall of Schlemm's canal on aqueous outflow facility remains poorly understood. We examined the relationship between inner wall pore characteristics and outflow facility in living primate eyes in which facility had been pharmacologically increased by ethacrynic acid (ECA) infusion and in contralateral control eyes.

METHODS

Outflow facility (two-level constant pressure perfusion) was measured in eight pairs of living monkey eyes before and after administration of a bolus dose of either 0.125 mM ECA or vehicle. After exsanguination, eyes were fixed in situ under constant-pressure conditions (mean fixation pressure approximately 19 mm Hg). The density and diameter of inner wall pores and the number and area of platelet aggregates on the inner wall of Schlemm's canal were measured by scanning electron microscopy.

RESULTS

In ECA-treated eyes, outflow facility increased 63% (P < 0.0001), intracellular pore density decreased 46% (P = 0.0094), intracellular pore size increased 27% (P = 0.049), platelet aggregate density increased 158% (P < 0.0001), and area covered by platelets increased 210% (P = 0.012) relative to contralateral controls. Although the average density and size of intercellular pores were essentially unaffected by ECA, an increased density of large (> or = 1.90 microm) intercellular pores was seen in ECA-treated eyes. The density of intracellular pores increased with the duration of fixative perfusion. Other than a weak negative correlation between outflow facility and intracellular pore density in ECA-treated eyes (P = 0.052), facility was not correlated with inner wall pore features.

CONCLUSIONS

Our data are most consistent with a scenario in which ECA promotes formation of large intercellular pores in the inner wall of Schlemm's canal, which are then masked by platelet aggregates. Masking of intercellular pores, combined with fixation-induced alteration of inner wall pore density, greatly complicates attempts to relate facility to inner wall structure and suggests that in vivo pore density is smaller than in fixed tissue. Additionally, facility-influencing effects of ECA on the juxtacanalicular tissue cannot be excluded.

Latrunculin-A increases outflow facility in the monkey

PURPOSE

To determine the effect of Latrunculin (LAT)-A, a macrolide that binds to G-actin, which leads to the disassembly of actin filaments, on shape, junctions, and the cytoskeleton of cultured bovine aortic endothelial cells (BAECs) and on outflow facility in living monkeys.

METHODS

Latrunculin-A dose-time-response relationships in BAECs were determined by immunofluorescence and phase contrast light microscopy, facility by two-level constant pressure anterior chamber perfusion.

RESULTS

In BAECs, LAT-A caused dose- and incubation time- dependent destruction of actin bundles, cell separation, and cell loss. Cell-cell adhesions were more sensitive than focal contacts. Recovery was also dose- and time-dependent. In monkeys, exchange intracameral infusion and topical application of LAT-A induced dose- and time-dependent several-fold facility increases. The facility increase was completely reversed within several hours after drug removal. However, for at least 24 hours after a single topical LAT-A dose, perfusion with drug-free solution caused an accelerated increase in facility beyond that attributed to normal resistance washout.

CONCLUSIONS

Pharmacological disorganization of the actin cytoskeleton in the trabecular meshwork by specific actin inhibitors like LAT-A may be a useful antiglaucoma strategy.

Risk factors for high-risk proliferative diabetic retinopathy and severe visual loss: Early Treatment Diabetic Retinopathy Study Report #18

PURPOSE

To identify risk factors for the development of high-risk proliferative diabetic retinopathy (PDR) and for the development of severe visual loss or vitrectomy (SVLV) in eyes assigned to deferral of photocoagulation in the Early Treatment Diabetic Retinopathy Study (ETDRS).

METHODS

Multivariable Cox models were constructed to evaluate the strength and statistical significance of baseline risk factors for development of high-risk PDR and of SVLV.

RESULTS

The baseline characteristics identified as risk factors for high-risk PDR were increased severity of retinopathy, decreased visual acuity (or increased extent of macular edema), higher glycosylated hemoglobin, history of diabetic neuropathy, lower hematocrit, elevated triglycerides, lower serum albumin, and persons with mild to moderate nonproliferative retinopathy, younger age (or type 1 diabetes). The predominant risk factor for development of SVLV was the prior development of high-risk PDR. The only other clearly significant factor was decreased visual acuity at baseline. In the eyes that developed SVLV before high-risk proliferative retinopathy was observed, baseline risk factors were decreased visual acuity (or increased extent of macular edema), older age (or type 2 diabetes), and female gender.

CONCLUSIONS

These analyses supported the view that the retinopathy-inhibiting effect of better glycemic control extends across all ages, both diabetes types, and all stages of retinopathy up to and including the severe nonproliferative and early proliferative stages and the possibility that reducing elevated blood lipids and treating anemia slow the progression of retinopathy.