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Biomedical subjects

G Arden

Publications and source records attributed to G Arden.

10 recordsLinked to original sources
PubMed2004

[Immune enhancing diet].

Immunonutrition contains nutritional elements which generally carry a positive effect on the immune system when given in large amounts. The main nutrients included in immunonutrition are: L-arginine, L-glutamine, nucleotides, and polyunsaturated fatty acids. Patients fed with immunonutrition had less infectious complications, were mechanically ventilated for shorter periods of time, and their hospitalization period was shorter. Mortality rates were generally not improved. In 2001, the U.S. Summit on Immune-Enhancing Enteral Therapy listed groups of patients who would benefit from immunonutrition. The article includes these recommendations. In conclusion, physicians should familiarize themselves with the issue of immunonutrition and consider using it in specific groups of hospital patients.

Amino Acids, Essential↗
PubMed1999

S-cone ERGs elicited by a simple technique in normals and in tritanopes.

PURPOSE: To measure changes in the relative spectral sensitivities of the dark adapted and light adapted ERG and thus to establish the possible contribution of rods to the 'blue cone' ERG elicited by flashes of blue light. BACKGROUND: Short wavelength stimuli in the light-adapted eye evoke small rounded b-waves which have been considered to be S-cone responses. We have recorded such responses from tritanopes, which called the assumptions into question. METHODS: Small ERGs were recorded to blue and green flashes. The stimulus was a Ganzfeld which employed light emitting diodes. ERGs were obtained in both the dark-adapted eye and after light adaptation to intense orange light (peak wavelength 610 nm). The change in sensitivity with light adaptation and the relative spectral sensitivity was determined from the voltage/log light intensity functions, using a 10 microV criterion. RESULTS: (1) peak times and changes in sensitivity did not help distinguish light-adapted rod from possible S-cone responses; (2) analysis of the change in the ratio of blue:green sensitivity from darkness to 4.4 log Td. 610 nm background suggests that in seven normal subjects, 90% or more of the ERG evoked by 440 nm flashes is generated by S-cones; (3) three tritanopes have insignificantly reduced S-cone responses. CONCLUSIONS: (1) clinical techniques used to isolate S-cone ERGs are appropriate; (2) there are at least two types of tritanope and in those we investigated, functional S-cones are probably displaced into the retinal periphery.

Adaptation, Ocular↗
PubMed1996

Colour contrast thresholds in congenital colour defectives.

The influence of congenital colour defects on a clinical computer test for equiluminous colour discrimination is studied. Differences in relative spectral sensitivity and changes in colour contrast discrimination are two distinct manifestations of the abnormal genes responsible for congenital red-green defects. The very simple and rapid method of the heterochromatic flicker brightness test acts like an anomaloscope and can be used to distinguish protan and deuteran defectives. The depth of the congenital colour defect can be quantified by the colour contrast threshold measured in equiluminous conditions along a single red-green axis identical for all types of red-green colour defectives. Colour contrast thresholds in tritan colour axes are not influenced by congenital red-green defects and therefore they are of extreme clinical interest to detect and quantify acquired colour defects, even in the presence of a previously unknown congenital red-green defect.

Color Perception Tests↗
PubMed1993

Mutations in the human retinal degeneration slow (RDS) gene can cause either retinitis pigmentosa or macular dystrophy.

Mutations in the RDS gene, which encodes the photoreceptor glycoprotein peripherin, have been sought in families with autosomal dominant retinal dystrophies. A cysteine deletion at codon 118/119 is associated with retinitis pigmentosa in one. Three families with similar macular dystrophy have mutations at codon 172, arginine being substituted by tryptophan in two and by glutamine in one. A stop sequence at codon 258 exists in a family with adult vitelliform macular dystrophy. These findings demonstrate that both retinitis pigmentosa and macular dystrophies are caused by mutations in RDS and that the functional significance of certain amino-acids in peripherin-RDS may be different in cones and rods.

Adult↗
PubMed1989

Papillo-renal syndrome. An inherited association of optic disc dysplasia and renal disease. Report and review of the literature.

A family is described in which the father and son had chronic renal disease of early onset and bilateral optic nerve dysplasia. A further son, known to have microphthalmos died of renal disease in childhood. Optic nerve changes included coloboma in the father and Handmann's optic nerve anomaly, a condition resembling the morning glory syndrome (M.G.S.), in the son. There was electrodiagnostic and visual field evidence of optic nerve dysfunction even where acuity was relatively unaffected. The son developed central serous retinopathy, a condition frequently encountered in association with optic nerve dysplasias, including M.G.S.

Adult↗
PubMed1988

Color vision testing with a computer graphics system: preliminary results.

We report a method for computer enhancement of color vision tests. In our graphics system 256 colors are selected from a much larger range and displayed on a screen divided into 768 x 288 pixels. Eight-bit digital-to-analogue converters drive a high quality monitor with separate inputs to the red, green, and blue amplifiers and calibrated gun chromaticities. The graphics are controlled by a PASCAL program written for a personal computer, which calculates the values of the red, green, and blue signals and specifies them in Commité Internationale d'Eclairage X, Y, and Z fundamentals, so changes in chrominance occur without changes in luminance. The system for measuring color contrast thresholds with gratings is more than adequate in normal observers. In patients with mild retinal damage in whom other tests of visual function are normal, this method of testing color vision shows specific increases in contrast thresholds along tritan color-confusion lines. By the time the Hardy-Rand-Rittler and Farnsworth-Munsell 100-hue tests disclose abnormalities, gross defects in color contrast threshold can be seen with our system.

Adult↗
PubMed1979

Measuring contrast sensitivity with gratings: A new simple technique for the early diagnosis of retinal and neurological disease.

The measurement of contrast sensitivity using gratings is a new clinical procedure which yields information about the functioning of the visual system. Previously, this type of information has not been readily obtainable in the clinical environment. This article includes the basic concepts of measuring contrast sensitivity with gratings and preliminary clinical results.

Evaluation Studies as Topic↗
PubMedDate not supplied

The separation of parallel visual systems by disease processes.

AIM: to investigate psychophysics and electrophysiology in disease states with altered retinal function. METHODS: determination of colour and luminance contrast sensitivity functions using computer controlled VDUs: recording of flash and pattern ERGs to short and long flashes of coloured lights under differing conditions of light adaptation: recording of pattern ERG. RESULTS: In melanoma-associated retinopathy (MAR) low spatial frequency temporal flicker loss occurs for achromatic Gaussians, but colour Gaussians are seen normally. Low spatial frequency luminance contrast sensitivity and motion losses are severe while red-green gratings are seen normally. In Cuban Tropical Amblyopia, achromatic luminance contrast sensitivity may be normal, in the presence of considerable losses of colour vision, to spatial frequencies as high as 32 c/degree. There are supernormal cone ERGs. CONCLUSIONS: these 2 conditions represent highly selective loss of 'M' and 'P' pathways respectively. Almost the entire 'bell shaped curve' normally represents M activity. In CTA, there may be a selective loss of the receptive field surrounds of P ganglion cells.

Color Perception↗