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At least 343 records · Page 19Linked to original sources
PubMed1986

Genetic-molecular basis for a simple Drosophila melanogaster somatic system that detects environmental mutagens.

We have developed a simple, objectively scorable test for the mutagenicity of chemical compounds which can be fed Drosophila melanogaster. The test depends upon the somatic reversion of the X chromosome, recessive eye color mutation, white-ivory (wi) to wild type (w+). Reversions are scored as clones of w+ facets in the wi eyes of eclosing adults. To increase the sensitivity, a tandem quadruplication containing four wi mutations was synthesized. Thus, in homozygous females eight wi mutations are potentially revertible. Six mutagenic compounds, all alkylating agents, all gave positive results at several concentrations tested. Molecular analysis demonstrates that the induced reversions, germinal and somatic, are associated with the loss of 2.9-kilobase DNA duplicated in the wi mutation.

Animals↗
PubMed2003

Automatic spatial coding of perceived gaze direction is revealed by the Simon effect.

In a typical Simon task, the (irrelevant) spatial position of the stimulus interferes with the processing of the salient characteristic (e.g., color). We used the Simon effect to investigate the automatic processing of gaze cues. We show that a simple drawing of schematic eyes automatically generates a spatially defined code of gaze direction. Although completely irrelevant to the task, direction of gaze influenced reaction times in a spatially selective two-choice discrimination based on eye color. Moreover, in one experiment employing an orthogonal manipulation of stimulus position and gaze direction, we found that coding of gaze direction is independent of stimulus spatial coding. Our finding of a "gaze-direction Simon effect" is congruent with the hypothesis that gaze direction is coded by a specialized mechanism.

Adult↗
PubMedDate not supplied

Investigation of blood flow velocity by color Doppler imaging in nonischemic central retinal vein occlusion with collateral veins.

PURPOSE: To study the blood flow velocity in the central retinal vein after the resolution of non-ischemic central retinal vein occlusion (CRVO) with optociliary vein (OCV). METHODS: Eleven patients and 22 healthy volunteers were studied. Indocyanine green (ICG) angiography was used to investigate the choroidal veins in the affected eyes. Color Doppler imaging was used to measure the blood velocity in the central retinal artery and vein in the 11 affected and 22 healthy eyes. RESULTS: Indocyanine green angiography verified the formation of retinochoroidal collaterals in all the affected eyes. The velocity in the central retinal vein was significantly lower in the affected eyes. CONCLUSIONS: The results indicate that the collaterals are important routes of extraretinal outflow of retinal venous blood. It is recommended in the investigation of CRVO by color Doppler imaging to perform ICG angiography to determine if retinochoroidal collateral veins have been formed.

Aged↗
PubMed1991

Genotoxicity testing with the somatic white-ivory system in the eye of Drosophila melanogaster.

The white-ivory test in Drosophila melanogaster is designed to detect chemically induced reversions of the sex-linked, recessive unstable eye-color mutation white-ivory to the wild-type form. After exposure of larvae reversions are detectable as clones of red facets in the eye of newly enclosed adult flies. Tester strains containing a quadruplication of the white-ivory gene on the X-chromosome(s) were used. In a strain with males carrying 4 copies of the gene and females carrying 8 copies of the gene, spontaneous reversions occurred proportional to the gene copy number. In contrast to this, chemically induced reversions occurred only 1.36 times more frequently in females (carrying 8 copies of the gene) than in males (carrying 4 copies). Since chemicals inducing different lesions in DNA (bleomycin, cyclophosphamide, daunomycin, diethyl sulfate and 7,12-dimethylbenz[a]anthracene) did induce statistically significant frequencies of reversions the test appears to be capable of detecting a wide variety of genotoxic chemicals with different modes of action. The recombinogen strychnine did not induce reversions.

Animals↗
PubMed1997

Performance of a color indicator in a disinfecting solution for the maintenance of soft contact lenses.

An experimental study of Allergan's Oxysept Comfort system was performed by measuring the slight reddish hue that appears in the disinfecting solution, indicating to the users that their lenses are again ready to be worn. The temporal evolution of the color of the solution has been measured under standardized conditions and analyzed in the CIELAB system, from the perspective of the typical threshold discrimination of the human eye. Color differences between neutralized and non-neutralized solutions occurred in an appropriate direction of the color space to enhance discrimination and were clearly perceptible by normal observers (greater than 9.7 +/- 1.2 CIELAB units). Colorimetric analyses have been used to draw conclusions regarding observers with defective color vision. The color of the solution changes abruptly, approximately 25 min after the neutralization process begins, and remains nearly constant after about 60 min, this agreeing well with the temporal evolution of the hydrogen peroxide concentration.

Color↗
PubMed1987

Tryptophan metabolism in tsetse flies and the consequences of its derangement.

Literature comparing salmon and wild type Glossina morsitans morsitans and that comparing tan and wild type Glossina palpalis palpalis is reviewed. New information is presented on behaviour and biochemistry of salmon and wild type G. m. morsitans. The eye color mutants result from two lesions in the tryptophan to xanthommatin pathway: lack of tryptophan oxygenase in G. m morsitans and failure to produce or retain xanthommatin in eyes (but not in testes) of G. p. palpalis. The salmon allele in G. m. morsitans is pleiotropic and profoundly affects many aspects of fly biology including longevity, reproductive capacity, vision, vectorial capacity and duration of flight, but not circadian rhythms. The tan allele in G. p. palpalis has little effect upon the biology of flies under laboratory conditions, except that tan flies appear less active than normal. Adult tsetse flies metabolize tryptophan to kynurenine which is excreted; fluctuations in activities of the enzymes producing kynurenine suggest this pathway is under metabolic control.

Animals↗
PubMed1997

The objective measure of color vision in primary open angle glaucoma.

PURPOSE: To objectively evaluate the clinical application of color pattern reversal visual evoked potential (CPR-VEP) on primary open angle glaucoma (POAG). METHODS: CPR-VEP and FM 100-hue test were performed in 31 eyes with POAG and 33 normal eyes. Color pattern stimulation was presented by color monitor controlled by computer program. The reversal rate of the stimulating pattern was 2 Hz and the spatial frequency of the stimulating was 0.53 cycle/degree. The color stimulating pattern include White/Black, Red/Black, Green/Black, Blue/Black, Yellow/Black, Red/Green and Blue/Yellow. RESULTS: CPR-VEP P1 latencies were obviously prolonged in POAG group in comparison with normal control group in equiluminance. All CPR-VEP P1 amplitudes, except Blue/Black P1 amplitude, show no differences between POAG group and normal control group. CONCLUSION: P1 latencies of all CPR-VEP and P1 amplitude of Blue/Black CPR-VEP were parameters for identifying acquired dyschromatopsia caused by POAG. The results showed nonselective damages in color channels and luminance channel in POAG. CPR-VEP is helpful in detecting acquired dyschromatopsia.

Adolescent↗
PubMed1997

[Etiological and clinical characteristics of infectious optic neuritis].

Fifty-one patients with infectious optic neuritis (ION) with no associated choroidal or retinal involvement were studied in relation to the etiologic agents, and to the epidemiological and clinical features to look up features which could be used to distinct them from the demyelinating optic neuritis (DON) which have a well-known tendency to convert to multiple sclerosis. Bilateral involvement was found in 23 patients (45.1%), simultaneously in 18 cases. Sex distribution was 2M:1F. The ages ranged from 1 to 82 years (median 34.8); 1/3 of the patients were younger than 20 and 1/3 were 50 years of age or older. Syphilis was found in 19 patients being the single most common etiology, whereas viral infections were found in 41.2% of the cases. Visual acuity was severely damaged in most patients and was worse than 20/200 in 57.3% of the involved eyes. Color vision was affected in 91.8%. Visual field defects were found in 92.2%, with predominance of the central defects (40.7%). The optic disc was abnormal in 90.5% of the eyes. This study clearly demonstrates that ION and DON have distinct epidemiological and clinical features. The awareness of these differences may help clinicians to follow different paths for the correct diagnosis and appropriate treatment and prognostic orientation of their patients.

Adolescent↗
PubMed1997

Albinism due to transposable element insertion in fish.

The i locus of the medaka fish, Oryzias latipes, is responsible for tyrosinase expression, and several mutant alleles have been identified. The genotype i1/i1 exhibits a complete albino phenotype, having pale orange-red skin and red eyes. This mutant lacks in vivo tyrosinase activity. The genotype i4/i4, on the other hand, shows a quasi-albino phenotype with skin as bright as that of i1/i1 but with red-wine-colored eyes. At the light microscope level, reduced pigmentation is observed both in the skin and eyes of this mutant. The tyrosinase genes for the i1 and the i4 alleles were cloned and sequenced, and compared with that of the wild-type tyrosinase gene. The i1 allele was found to contain a 1.9-kb transposable element in the 1st exon, and the i4 allele was found to contain a 4.7-kb transposable element in the 5th exon. Both i1 and i4 are alleles that were found in a commercial breeding population. The insertion of a transposable element thus appears to constitute a natural cause of mutations that cause albinism in this organism.

Albinism↗
PubMed2005

Bilateral acute depigmentation of the iris.

PURPOSE: To report on five cases of unusual bilateral stromal depigmentation of the iris and pigment dispersion masquerading as uveitis. METHODS: We describe the clinical features of five consecutive patients who presented with acute depigmentation of the iris stroma between June and October 2003. RESULTS: Four patients were female, one was male. Age at presentation ranged from 15 to 25 years. Presenting symptoms were sudden-onset ocular discomfort and red eye in four patients and change of eye color in one patient. All patients had bilateral involvement, with a symmetrical diffuse depigmentation of the iris stroma in three cases and patchy areas of iris depigmentation in two. Other common features were mild ciliary injection (seven eyes), Krukenberg spindle (seven eyes), circulating pigment in the anterior chamber (eight eyes), and heavy pigment deposition in the angle (ten eyes). No eyes had iris transillumination defects, inflammatory keratic precipitates or inflammatory cells in the anterior chamber. Systemic laboratory work-up was unrewarding in all cases, and PCR analysis of the aqueous humor for HSV1 and 2 was negative in one patient. Four patients were treated with a short course of topical corticosteroids and three with oral acyclovir. One patient was lost to follow-up. The remaining four patients were followed up for 6-19 months with a stable clinical picture. CONCLUSION: In contrast to pigment dispersion syndrome, pigment seemed to be released from iris stroma in the five cases described here. Although patchy depigmentation of the iris resembled the lesions seen in herpetic iridocyclitis in two of the patients, symmetrical bilateral involvement and lack of intraocular inflammation were the differentiating features. The patients described here could represent a new entity or an unusual presentation of herpetic eye disease.

Acute Disease↗
PubMed2004

Are patients with psoriasis susceptible to the classic risk factors for actinic keratoses?

BACKGROUND: An increased prevalence of benign solar damage (eg, facial wrinkles) but not neoplastic lesions was observed among patients with psoriasis who were exposed to Dead Sea climatotherapy compared with controls. OBJECTIVES: To compare the prevalence of actinic keratosis in psoriatic patients and controls and to assess whether known risk factors behave similarly in both groups. DESIGN: Multicenter cross-sectional study. SETTING: Dermatology clinics in 4 participating Israeli hospitals and at a Dead Sea clinic. PARTICIPANTS: Adult subjects (n = 460) with plaque-type psoriasis were recruited from the Israel Psoriasis Association (volunteer sample) and from dermatology clinics (convenience sample). The control group (n = 738) consisted of nonimmunosuppressed patients attending these clinics for benign conditions unrelated to sun exposure, such as atopic or contact dermatitis. MAIN OUTCOME MEASURES: Prevalence and distribution of actinic keratoses and odds ratios associated with skin, hair, and eye color and propensity or history of sunburn adjusted for age, ethnicity, and sun exposure. RESULTS: Actinic keratoses were observed in 200 controls (27%) and 51 subjects (11%) (P<.001). This increased prevalence occurred in both sexes, participants aged 35 years or older, all ethnic groups, smokers, and nonsmokers. The anatomical distribution of lesions did not substantially differ between subjects and controls. In multivariate analysis, psoriasis conferred a protective effect (odds ratio, <1), as did dark skin, dark eyes, and a history of severe sunburn in childhood. However, significant interactions were observed between psoriasis and hair color as well as psoriasis and propensity to sunburn, whereby a linear association was observed for controls but not for patients with psoriasis. CONCLUSIONS: Psoriasis confers protection against actinic keratosis. Hair color and propensity to sunburn exert differential effects among psoriatic patients and controls.

Adult↗
PubMed1984

Abnormal central visual pathways in the brain of an albino green monkey (Cercopithecus aethiops).

The visual pathways of an albino green monkey have been studied electrophysiologically and by autoradiographic methods. The monkey had a white coat and pink eyes; it had a strabismus and a nystagmus. When comparisons were made with normal macaque and green monkeys, several abnormalities could be defined. In the retina there was no foveal pit. A whole mount preparation showed a central area of high ganglion cell density in which the ganglion cells were significantly larger than the most central ganglion cells of a normal monkey. More peripheral retinal areas showed an apparently normal distribution of ganglion cell sizes and packing densities. Within the optic tract the number of uncrossed retinofugal fibers was less than normal, the part of the tract that represents central vision showing almost no uncrossed component. The uncrossed input to the lateral geniculate nucleus and to the superior colliculus was similarly reduced. Regions normally receiving ipsilateral afferents from the central retina were innervated exclusively by crossed afferents. The pathways to the magnocellular geniculate layers showed a more extensive abnormality than did the pathways to the parvicellular layers. Not only were the afferents to the geniculate layers abnormal, but the laminar pattern in the nucleus was also clear than normal in some parts of the nucleus, and there were a number of abnormal laminar fusions. Within the visual cortex it was possible to demonstrate a normal mapping of the contralateral visual field through the contralateral nasal retina and through the peripheral parts of the ipsilateral temporal retina. The central parts of the temporal retina mapped abnormally in the contralateral visual cortex, so that there was a monocular map of the central parts of the visual field forming as a mirror reversal of the normal map. The normal map of the contralateral hemifield formed columns that alternated with the abnormal map of the ipsilateral hemifield. The peripheral parts of the visual field were represented as ocular dominance columns, demonstrable electrophysiologically and also by the transneuronal transport of 3H-proline.

Animals↗
PubMed1981

The effects of molybate, tungstate and lxd on aldehyde oxidase and xanthine dehydrogenase in Drosophila melanogaster.

The effects of dietary sodium molybdate and sodium tungstate on eye color and aldehyde oxidase and xanthine dehydrogenase activities have been determined in Drosophila melanogaster. Dietary sodium tungstate administration has been used as a screening procedure to identify two new lxd alleles. Tungstate administration results in increased frequencies of "brown-eyed" flies in lxd stocks and a coordinate decrease in AO and XDH activities in all genotypes tested. The two new lxd alleles affect AO and XDH in a qualitatively but not quantitatively similar fashion to the original lxd allele. AO and XDH activity and AO-CRM levels appear much more sensitive to mutational perturbations of this gene-enzyme than do XDH-CRM levels in the genotypes tested.

Aldehyde Dehydrogenase↗
PubMed1996

The effect of low level acoustic stimulation on susceptibility to noise in blue- and brown-eyed young human subjects.

OBJECTIVE: The aim of this study was to investigate the influence of pigmentation on the reduction in temporary noise-induced threshold shift (TTS) due to low level acoustic stimulation (LLAS). A pigmentation-dependent LLAS effect on TTS could be interpreted as a strial melanocyte involvement in LLAS. It could not be explained by cochlear sensorineural structure changes only. DESIGN: Teenagers were classified according to eye color (n = 6 + 6) and exposed to music at 70 dBA 6 h per day for 9 days (LLAS). TTS was measured before, during, and after the LLAS period. RESULTS: It was shown that LLAS reduced TTS significantly more in blue-eyed than in brown-eyed subjects. The difference in TTS remained for at least 1 wk after the cessation of LLAS. CONCLUSIONS: It is suggested that the observed difference in LLAS effect is due to strial melanocyte differences in free radical defense. It is also possible that other cochlear antioxidant enzyme systems, responsible for inactivation of harmful oxygen radicals and simultaneously involved in melanin synthesis such as the thioredoxin reductase/thioredoxin electron transfer system are activated.

Acoustic Stimulation↗
PubMed1989

Cyclosporine in Behçet's disease resistant to conventional therapy.

Cyclosporine (cyclosporine A) at 7 to 16 mg/kg/day was administered for eight to 18 months to four patients with Behçet's disease with bilateral panuveitis resistant to the combination of prednisone, colchicine, and chlorambucil. Visual acuity was maintained or improved in all eyes. Color vision also improved significantly. A dramatic and significant decrease of the chronic vitreous haze occurred within the first two weeks of therapy and persisted until the end of the study. Retinal inflammation, including hemorrhages, exudates, edema, and fluorangiographic abnormalities, decreased progressively in all eyes. The severity of the anterior and posterior acute attacks also decreased significantly. This study suggests that cyclosporine is beneficial for the treatment of refractory and severe Behçet's disease, but its side effects require careful follow-up.

Adult↗
PubMedDate not supplied

Orange: a plumage color mutation accompanied by semi-lethality in Japanese quail.

A new plumage color mutant, orange, in Japanese quail (Coturnix japonica) was characterized by the same plumage pattern as in the wild type but with diluted pigmentation on the whole body. Light reddish-brown and light black are predominant instead of heavy brown and heavy black in the wild type. Although the eye color of the adult orange mutant was somewhat similar to that of the wild type, it showed a reddish color when held to the light. Fertility of the orange mutant was normal (97.8%), but hatchability was significantly lower than that of the wild type (72.8% versus 93.5%) because of the increased prehatching mortality. Moreover, posthatch mortality within 5 weeks of age was greatly increased in the orange mutant over that of the wild type (60.4% versus 8.4%). Genetic analysis revealed that the mutant plumage is controlled by an autosomal recessive gene. There is a possibility that the orange is homologous to the previously reported cinnamon mutation.

Animals↗