Follow-up after surgical closure of congenital ventricular septal defect.

OBJECTIVES: The purpose of this retrospective study was to assess long-term outcome of children after surgical closure of a ventricular septal defect (VSD). MATERIAL AND METHODS: Between January 1992 and December 2001 a consecutive series of 188 patients (100 females) were operated for closure of a VSD. Temporary tricuspid valve detachment (TVD) was applied in 46 patients (24%) to enhance exposure of the defect using transatrial approach. Pre-operative baseline characteristics showed that the detached group was younger (0.79+/-1.8 vs 2.1+/-3.5 years, p=0.002) and had a lower weight (6.5+/-6.4 vs 10.0+/-11.0 kg, p=0.009). RESULTS: There was no difference in cross-clamp time (temporary TVD 36.2+/-11.3 vs non-temporary TVD 33.6+/-13.1 min, p=0.228). Postoperative echocardiography showed that 67 patients (36%) had trivial/minimal regurgitation, 10 patients (22%) from the temporary TVD group vs 57 patients (40%) from the non-detached group (p=0.02). There was no tricuspid stenosis. Hospital mortality comprised two patients (1%). One patient died due to a pulmonary hypertensive crisis and one in relation to an acute patch dehiscence for which an emergency reoperation was necessary. At first postoperative echocardiography no shunting was detected in 113 patients, trivial shunting in 73 and significant shunting in none. Multivariate logistic regression analysis revealed that weight at operation was a predictive factor for the occurrence of residual shunting (OR 0.95, C.I. 0.91-0.99). One patient with conduction disturbances needed a permanent DDD-pacemaker. Three patients were lost to follow-up. Mean follow-up time was 2.6 years (range 0.1-9.4). During follow-up no reoperations were necessary for closing a residual VSD. One patient died 7 months postoperative due to a bronchopneumonia. During follow-up in 37 (51%) of the 73 patients the trivial shunting disappeared spontaneously at a median time of 3.9 years. According to actuarial analysis all trivial shunting had disappeared at 8.4 years. CONCLUSION: Trivial residual shunting disappeared spontaneously at a median follow-up time of 3.9 years. During follow-up no patient needed to be reoperated for residual VSD. TVD proved to be a safe method to enhance the exposure of a VSD.

Methionine intake in rainbow trout (Oncorhynchus mykiss), relationship to cataract formation and the metabolism of methionine.

Young rainbow trout were given diets containing graded levels of methionine for 16 wk. Analysis of the weight gain and food efficiency data showed the methionine requirement to be not more than 0.76% of the diet (1.9% of dietary protein). Activities of regulatory enzymes of the transulfuration pathway, methionine adenosyltransferase and cystathionine synthase in trout liver were not altered by changes in methionine intake. Concentrations of free serine in liver and plasma of the trout were high at low levels of methionine intake but fell as dietary methionine increased. This implied decreased flux through cystathionine synthase at low methionine intakes. Large increases in liver and plasma taurine occurred at high methionine intakes, implying enhanced transulfuration activity. Liver ornithine decarboxylase activity was reduced at the lowest level of dietary methionine used but the activity of S-adenosylmethionine decarboxylase was unchanged. Eye lenses of the trout given these diets were examined by a scanning lens monitor. Analysis of focal length variability with this equipment demonstrated that, if abnormality of the lens is to be avoided, a higher concentration of dietary methionine (0.96% or 0.6% methionine + 0.36% cystine) is needed than that required to maximize growth.

Scanning laser measure of optical quality of the cultured crystalline lens.

An apparatus has been designed to automate the laser measuring technique and make it possible to monitor lens refractive function (spherical aberration) as well as change in lens transmittance during lens culture. A scanning laser beam (helium-neon) is used so that a number of beams pass through different spots on the lens to determine lens spherical aberration compared over time. Each refracted beam, received by two video cameras (X and Y directions), is digitized. The system first locates the optical centre of the lens by determining the beam position providing the least deflection for both the X and Y directions. The beam is then moved in predetermined steps on either side of the centre, and focal lengths are determined relative to the optic axis for each position. A measure of beam scatter is noted from post-refraction pixel excitation for each beam position. Improvements to the scanning laser system have led to greater accuracy and speed as well as to improved culture cells. Accuracy was increased by using high resolution (1 micron) stepping motors to move the scanning helium-neon laser. A new alignment process involving the superposition of the incident beam reflected on itself ensures that the incident beam is perpendicular to the lens equatorial axis. Scanning speed has been improved through a variety of hardware and software changes. Scanning time for a lens, including locating the optical centre and measuring focal length for 20 lens positions along the X and Y directions, takes about 60 seconds. Long-term studies on the degradation of lens optical performance frequency yield diffuse beams of very low intensity.(ABSTRACT TRUNCATED AT 250 WORDS)

Optical performance of the bovine lens before and after cold cataract.

Cold cataracts were induced in ten bovine lenses and then removed by warming. Cataracts first appeared at an average temperature of 11.7 degrees C. The cataracts appeared to be densest at an average temperature of 1.2 degrees C, while warming caused them to disappear completely at an average temperature of 16.4 degrees C. A computer-operated scanning laser system was used to measure the equivalent focal length and changes in relative transmittance before, during, and after the cataract was induced. In general the focal length profile (spherical aberration) that existed before cooling was recaptured on warming. Scatter values indicate that transmittance is not affected by the temporary cold cataract. Thus the optical performance of the bovine lens appears to be identical before and after cold cataracts are induced. We believe that these results indicate that the cataract has a supramolecular origin.

Lens optical quality is a direct function of lens sutural architecture.

We analyzed the structural and functional relationship between lens sutures and lens optical quality (focal length variability) by correlative scanning electron microscopy (SEM) and laser scan analysis. Twenty-two rabbit lenses (8 pigmented and 14 albino) were used in this study. Lenses were initially scanned by a low-power helium-neon laser beam that was passed either at an acute angle to a lens suture or along a lens suture. The results of laser scan analysis with the incident beam passed at an acute angle to a lens suture showed that generally, rabbit lenses were well corrected for spherical aberration. Subsequent SEM analysis showed that areas of lenses scanned that produced the least amount of focal variability were characterized by uniform fiber cells arranged in parallel, radial cell columns. In contrast, the results of laser scan analysis with the incident beam passed along a lens suture showed that there was significant focal length variability, i.e., spherical aberration at the lens sutures. Subsequent SEM analysis showed that the areas of lenses scanned that produced the greatest amounts of focal variability (lens sutures) were characterized by nonuniform fiber cell ends arranged as erratic suture branches in single growth shells and collectively as erratic suture planes formed between growth shells extending from the embryonic nucleus to the lens periphery. Furthermore, the amount of focal variability was directly proportional to the degree of structural disorder at the lens sutures. This is the first study to unequivocally show that the relationship between lens optical quality and specific parameters of lens morphology (lens sutures) can be quantified. These findings may help to elucidate the pathologic changes that lead to presbyopia and cortical cataractogenesis because these lenses are characterized by asymmetrical suture patterns and planes.

UV-B radiation and the optical properties of cultured bovine lenses.

The effect of UV-B radiation on the crystalline lens was examined by subjecting bovine lenses in culture to varying low exposures at 300 nm. Lens optical quality was monitored on a long-term basis (to 1000 hrs.) with an automated scanning laser system that recorded both change in relative scatter and focal length across each lens. Data were collected for 20 lens positions at each scan. Radiant exposure levels consisted of 0.5, 0.25, 0.125, 0.06 and 0.03 Jcm-2. Twenty irradiated lenses were compared to twelve untreated controls. All of the irradiated lenses showed changes in scatter and focal length relative to the controls. Most (about 75%) of the treated lenses showed significant increases in scatter (200-400%) and focal length (10-20%) at 40 to 60 hours after exposure. A similar time frame for lens damage was noted by visual inspection. Exposure to UV-B at the above doses did not affect culture longevity.

Effect of hydrogen peroxide, DL-propranolol, and prednisone on bovine lens optical function in culture.

Lens refractive function was monitored during long-term bovine lens culture experiments in which low concentrations of potentially damaging agents were added to the culture media. The agents tested were the drugs DL-propranolol and prednisone, and hydrogen peroxide. A computer-driven scanning laser system was used to monitor lens focal length during culture. The system consists of a scanning helium-neon laser beam, a television video camera, and a video frame digitizer. The system first locates the optical center of the lens, defined as the position of little or no refractive deviation of the beam. The laser scans the lens in small steps (0.05 mm), while the digitizer measures focal length for each beam position. A graphic profile of lens focal variation is plotted. A concentration of 0.1 mM hydrogen peroxide produces no significant change in lens focus after 315 hr of incubation. When the concentration is increased 10-fold (1.0 mM), lens focal ability is radically disturbed after 60 hr of incubation. Lenses incubated with prednisone (0.03 mM) for up to 525 hr show no difference in focal characteristics in comparison to control lenses. Propranolol in a concentration of 0.1 mM disrupts lens focal ability after 250 hr of incubation, whereas a higher concentration (1.0 mM) produces a similar effect after only 150 hr. These results indicate that lens refractive function is a sensitive measure of lens function during culture.

Bilateral experimental myopia in chicks.

Substantial amounts of myopia can be induced in chicks by depriving the eye of clear vision for a period of 2 weeks after hatching. Previous work has primarily involved unilateral visual deprivation. Experiments described here include bilateral visual deprivation involving an opaque goggle over one eye and a translucent goggle over the other. The results indicate that although myopia is induced bilaterally, the eye under the translucent goggle becomes more myopic than the contralateral eye or the unilateral deprivation condition. Lens focal characteristics are not affected by the level of myopia. The fact that deprivation of one eye can affect the refractive development of the contralateral eye has implications related to the question of central vs. peripheral neural control of refractive development.

The eye of the hooded seal, Cystophora cristata, in air and water.

Multiple refractive state measurements were made on a male and female hooded seal (Cystophora cristata) when the eyes were exposed to air and to water. The measures, made by conventional retinoscopy and by photorefraction, show that the seals are moderately hyperopic (2-3 diopters) in water and moderately myopic (2-4 diopters) in air. No significant astigmatism was noted in either medium. The absence of refractive state variation over time suggests that an accommodative mechanism is insignificant or absent, although histological study indicates that the ciliary muscle is well developed. Photokeratoscopy, carried out on two animals with two keratoscopic instruments, show that the cornea is relatively flat (30 mm, or about one-half the diameter of the eye). Furthermore the cornea is only slightly astigmatic (less than 1 diopter). The refractive power of the external corneal surface (in air), calculated from a measurement of corneal refractive index of 1.378, amounts to only 10 or 11 diopters. As in the typical fish eye, hooded seal lenses are spherical or nearly spherical in shape (24-23 mm), and have short focal lengths (30-32 mm). Focal measures for rays at varying distances from the lens center indicate that spherical aberration is well corrected. There is no indication in this seal species, of a previously reported adaptation involving a highly astigmatic cornea which together with a slit pupil can minimize the optical effect of movement from water to air.

Optical constancy of the chick lens during pre- and post-hatching ocular development.

Embryonic and post-embryonic development of the ocular lens is associated with the continual production of new secondary lens fibers by the mitotic activity of equatorial epithelial cells. This continual development affects lens size and shape and refractive index distribution. Study of embryonic lens optical function has been largely ignored. The optical characteristics of the developing chick lens, including paraxial and eccentric focal lengths, were measured during the embryonic period of development and up to 15 days after hatching. Measurements were made with an automated scanning laser system in which the video image of a helium-neon laser beam refracted by an excised lens in solution is digitized. Focal length is measured for beams moving in small steps on either side of that center. Measurements were made on excised lenses as well as with the lens in situ within the anterior segment of the eye. The results, collected from a study of a total of 80 lenses, indicates that embryo lenses at 6-7 days of incubation have long and very variable focal lengths. At the tenth embryo day, focal length drops by more than one-half and focal variations, between lenses and for different beam positions within a single lens, is reduced. Further measures for 14- and 17-day embryo lenses, as well as for lenses from hatchling and 5-, 10- and 15-day-old chicks, indicate that there is little change in focal length, either paraxially or for eccentric beam positions.(ABSTRACT TRUNCATED AT 250 WORDS)

Modelling cortical cataractogenesis. X. Evaluation of lens optical function by computer based image analysis using in vitro rat lens elevated glucose model.

As a model system rat lenses (Wistar) were isolated and cultured intact in medium M199 or M199 with 55 mM glucose. Glucose-stressed lenses developed opacities within 20 hours while control lenses remained clear. The comparative functionality of lenses was examined by two different video/computer-based imaging systems: one based on image analyses of laser light after transmission through the lens (Scanning Lens Monitor), and the other based on image analyses of the projection of white light transmitted through the lens (Kevex Image Analysis System). The combination of both methods detect changes in focal length and light scattering. On the basis of these results, these techniques can be used in animal studies for grading lenses by functional properties to complement morphologically based grading (slit-lamp) of cataracts provided by a veterinary pathologist.

Role of the lens and vitreous humor in the refractive properties of the eyes of three strains of goldfish.

Certain strains of goldfish are characterized by large bulging eyes which have been shown to be extremely myopic. Such myopia has been hypothesized to have its origin in enlargement of the posterior chamber of the eye. The focal length of the lens was found to be similar for paraxial and marginal lens zones in common, Chinese Black Moor and Celestial goldfish, thus providing indirect support of that hypothesis. Freeze-sectioning study of intraocular dimensions shows that the axial length of the vitreous chamber of the common goldfish eye is about 37% of total axial length. In contrast, it becomes more than 70% of axial length in Chinese Black Moors and Celestials. An examination of vitreous protein concentration indicates that ocular enlargement in Chinese Black Moors and in Celestials is related to an increase in vitreous quantity, and is accompanied by vitreous dilution. The fact that similar findings are reported in the case of experimental myopia in chicks, suggests the existence of a fundamental mechanism of refractive development for the vertebrate eye.

Experimentally induced myopia does not affect post-hatching development of the chick lens.

Myopia, as characterized by a large refractive error (e.g. -10.7 +/- 0.4 D), was induced in post-hatch chicks by a 14 day application of a goggle that was designed to blur the retinal image. In comparison to untreated eyes, the treated eye showed significant changes in wet eye weight and both axial and equatorial lengths. However, the lenses of myopic and non-myopic eyes were not significantly different in focal characteristics, light transmittance or total soluble protein content. Thus the lens neither contributes to, nor compensates for the large refractive error observed in experimentally induced myopia.

Computer assisted scanning laser monitor of optical quality of the excised crystalline lens.

We describe a technique, involving the projection of low power laser beams through excised lenses in solution, that makes it possible to measure photographically lens optical aberrations. Preliminary work indicates that the laser method can be used in combination with lens culture experiments as a means of monitoring changes in studies of lens biology. The goal of this research is the development of an effective in vitro optical monitor of ocular lenses in order to assist the study of the biochemistry of lens aging and cataractogenesis and be used as a sensitive toxicity measuring device.