Risks associated with introduction of poeciliids for control of mosquito larvae: first record of the non-native Gambusia holbrooki in Argentina.

This study confirms the presence of two species of the non-native mosquitofish Gambusia in Argentina. The risks that they represent to native biota, their potential dispersal in the region, and their effectiveness in mosquito larvae control are discussed.

Molecular mechanisms of the anomalous thermal aggregation of green fluorescent protein.

The peculiarities of thermal denaturation and interaction with water of the cycle-3 mutant of green fluorescent protein (GFP) were analyzed by NMR techniques and compared with those of bovine carbonic anhydrase II (BCA-II). Irreversible thermal denaturation was accompanied by massive GFP aggregation with no detectable accumulation of soluble denatured protein. Analysis of the spin diffusion data suggested that the internal part of the GFP ß-can is involved in intensive interactions with water molecules. As a result, at high temperatures, the GFP structure does not unfold but rather breaks, consequently leading to enhanced protein aggregation. This is very different from typical BCA-II behavior.

Legacy of Multiple Stressors: Responses of Gastropod Larvae and Juveniles to Ocean Acidification and Nutrition.

Ocean acidification poses a significant threat to calcifying invertebrates by negatively influencing shell deposition and growth. An organism's performance under ocean acidification is not determined by the susceptibility of one single life-history stage, nor is it solely controlled by the direct physical consequences of ocean acidification. Shell development by one life-history stage is sometimes a function of the pH or pCO2 levels experienced during earlier developmental stages. Furthermore, environmental factors such as access to nutrition can buffer organismal responses of calcifying invertebrates to ocean acidification, or they can function as a co-occurring stressor when access is low. We reared larvae and juveniles of the planktotrophic marine gastropod Crepidula fornicata through combined treatments of nutritional stress and low pH, and we monitored how multiple stressors endured during the larval stage affected juvenile performance. Shell growth responded non-linearly to decreasing pH, significantly declining between pH 7.6 and pH 7.5 in larvae and juveniles. Larval rearing at pH 7.5 reduced juvenile growth as a carryover effect. Larval rearing at pH 7.6 reduced subsequent juvenile growth despite the absence of a negative impact on larval growth, demonstrating a latent effect. Low larval pH magnified the impact of larval nutritional stress on competence for metamorphosis and increased carryover effects of larval nutrition on juvenile growth. Trans-life-cycle effects of larval nutrition were thus modulated by larval exposure to ocean acidification.

Astigmatism associated with adnexal masses in infancy.

High degrees of astigmatism are common in infants with hemangiomas but have not been well documented with other adnexal masses. We reviewed records of 65 patients (69 eyes) with chalazions, epibulbar or orbital dermoids, hemangiomas, and dacryoceles. Astigmatism greater than +1.25 diopters (as high as +5.50 diopters) was most commonly associated with dacryoceles (eight of 12 eyes) and with hemangiomas (14 of 17 eyes). Plus cylinder axes were consistently oriented toward the lesion, and astigmatism tended to resolve with resolution of the lesions. Only one of the 17 eyes with dermoids and two of the 23 eyes with chalazions had astigmatism. Anisometropic amblyopia has been a prominent concern in the treatment of infants with hemangiomas. Patients with dacryoceles may be at similar risk. Repeated cycloplegic refractions are important in determining appropriate treatment of adnexal masses.

Classification of normal corneal topography based on computer-assisted videokeratography.

We evaluated the topography of 399 normal corneas in 212 subjects with computer-assisted videokeratography. The mean subject age was 37 years (range, 8 to 79 years). Mean spherical equivalent refraction was -1.00 diopters (range, +5.50 to -8.37 diopters). A qualitative classification system for corneal topography was derived based on patterns seen on color-coded topographic maps. Corneas were classified into groups by three independent masked ophthalmologists based on this system. Patterns included round (22.6%), oval (20.8%), symmetric bow tie (17.5%), asymmetric bow tie (32.1%), and irregular (7.1%). All corneas were steeper centrally and flatter peripherally. There was a statistically significant difference among patterns for keratometric astigmatism, but not for spherical equivalent refraction, mean keratometric power, or age of subject. Classification of normal corneal topography is an important step in the process of characterizing the shape of normal and pathologic corneas.

Computer-assisted videokeratography of corneal topography after radial keratotomy.

We used computer-assisted videokeratography to compare the topographies of 32 corneas from 23 subjects after radial keratotomy with those of 47 normal corneas from 47 subjects controlled for age and preoperative keratometric and refractive power. Three ophthalmologists independently classified color-coded videokeratographs based on the color-coded pattern of dioptric power distribution and the cross-sectional shape. Corneas that had radial keratotomy exhibited a polygonal pattern not seen in normal eyes; this occurred in 59% of corneas. All normal corneas demonstrated a cross-sectional shape configuration that was steeper centrally than peripherally; 79% of corneas after radial keratotomy had a shape that was flatter centrally than peripherally. After radial keratotomy, the dioptric power increased from the center to the periphery (radius of approximately 4.6 mm) by 2.8 +/- 2.2 diopters (mean +/- SD), with a sharp inflection zone ("paracentral knee") 2.7 mm from the center; normal corneas showed a smooth decrease in power from the center to the periphery of 1.9 +/- 0.5 diopters.

Determination of corneal image-forming properties from corneal topography.

Keratometry provides useful information about the cornea's image-forming properties, such as corneal astigmatism, but is inaccurate on irregular corneas. Quantitative corneal topographic information is now obtainable on irregular corneas, but is difficult for the clinician to interpret. We developed a method to determine the spherical power, astigmatism, and topographic irregularity of a cornea by finding the best-fit spherocylinder that was closest to its measured topography. Keratometric measurements and two videokeratographs were gathered prospectively on 262 normal and abnormal corneas. The best-fit measurements of spherical power, astigmatism, and topographic irregularity were reproducible with one standard deviation of 0.75 diopter or better; agreement with keratometric measurements in normal eyes was good (0.60 diopter or better). Topographic irregularity averaged 0.1 diopter on precision spheres, 0.4 diopter on 146 normal eyes, 0.8 diopter on 29 eyes after radial keratotomy, 2.0 diopters on 58 eyes after penetrating keratoplasty, and 3.0 diopters on 29 eyes with advanced keratoconus. We conclude the following: basic corneal image-forming properties can be measured from videokeratographs; the properties can be determined, by our methods, on irregular corneas in which keratometry is unreliable; and topographic irregularity provides a measure of irregular astigmatism.

Patterns of corneal topography after penetrating keratoplasty.

BACKGROUND: The topography of corneas after penetrating keratoplasty is highly variable. We classify the topography into five groups. METHODS: We performed videokeratography on 45 clear compact penetrating keratoplasties, with all sutures removed. Three ophthalmologists classified the keratographs independently into five previously defined topographic groups, based on the pattern of the normalized color-coded videokeratograph. RESULTS: The five topographic patterns included: prolate bow tie, 14 (30%); oblate bow tie, 14 (30%); mixed prolate and oblate bow tie, 8 (17%); asymmetric, 3 (9%); and steep/flat, 6 (14%). The three ophthalmologists agreed in their initial classification in 87% of the cases and after discussion, in 96%. CONCLUSION: The topography of the cornea after penetrating keratoplasty can be classified into five qualitative groups by trained observers, with good clinical reliability.

Unexplained unilateral vision loss during centrifugation.

Vision loss during a centrifuge run is an expected occurrence given the G-profile, physical fitness of the subject, expected visual endpoint [central light loss (CLL) or peripheral light loss (PLL)] of the experimental protocol, and the cyclic nature of the anti-G straining maneuver (AGSM). During a relatively low level G exposure, a subject experienced a unilateral loss of vision that did not resolve spontaneously upon removal of the G load. An extensive medical workup did not reveal any medical explanation for the vision loss.