Visual reproduction

Decreases in performance on tests that measured intelligence (a similarities test) and memory (digit span and visual reproduction tests) were observed in chloralkali workers exposed for an average of 16.9 years to low levels of mercury when compared to an age-matched control group (Piikivi et al. 1984). 

Roberts et al. evaluated proprioception in two groups of patients with ACL deficiency with different severity of symptoms [44]. Their symptomatic patients had a higher threshold to TTDPM in their injured side in a flexion trial from 20° (median of 1.5° versus median of 0.5°) and in an extension trial from 40° (median of 1.0° versus median of 0.5°) than the asymptomatic patients did. No differences were found in the other threshold, active or visual reproduction tests. They coti-cluded that patients with severe ACL deficiency symptoms have inferior proprioceptive ability in some measurements compared with patients with good knee function. Their findings indicate that proprioceptive deficits might influence the outcome of an ACL injury treated non-operatively. 

In many cases the simple visual reproduction of the actual situation is not sufficient because complicated procedures must be exercised or information from senses other than vision must be processed. In such casestraining with simulators is often successful. However, in contrast to programmed learning, some basic knowledge is generally a prerequisite for training in simulators and complex behavior patterns are learned. 

In certifying audio and audio-visual material and promotional material on databases, interactive systems and the Internet, companies must ensure that a written transcript of the material is certified including reproductions of any graphs, tables and the like that appear in it. In the event of a complaint, a copy of the written material will be requested. 

The activity of vitamin A is related to vision process, tissue differentiation, growth, reproduction, and the immune system. A deficiency of this micronutrient mainly leads to visual problems, impaired immune function, and growth retardation in children. Hypervitaminosis could lead to hepatotoxicity, affect bone metabolism, disrupt lipid metabolism, and teratogenicity [417]. The isomerization of P-carotene, due to technological processes in foods, leads to a reduction of the vitamin A activity it is therefore important to analyze it. 

This notion, that reproduction is a consequence of the internal logic of life, can be visualized in Figure 8.3 (see also Luisi, 1996), which is an extension of the drawing of our Green Man (Figure 2.1) discussed in Chapter 2. It represents the various modes of existence of a minimal autopoietic system. This system is defined by a semi-permeable membrane formed by only one component S that allows the entrance of the nutrient A, which is transformed inside the system into S, the... 

Methylmercury intoxication affects mainly the central nervous system and results in paresthesias, ataxia, hearing impairment, dysarthria, and progressive constriction of the visual fields. Signs and symptoms of methylmercury intoxication may first appear several weeks or months after exposure begins. Methylmercury is a reproductive toxin. High-dose prenatal exposure to methylmercury may produce mental retardation and a cerebral palsy-like syndrome in the offspring. Low-level prenatal exposures to methylmercury have been associated with a risk of subclinical neurodevelopmental deficits. 

Van Vugt DA (1990) Influences of the visual and olfactory systems on reproduction. Semin Reprod Endocrinol, 8 1-7. 

Reproduction Retinol and retinal are essential for normal repno duction, supporting spermatogenesis in the male and preventing fetal resorption in the female. Retinoic acid is inactive in maintain ing reproduction and in the visual cycle, but promotes growth and differentiation of epithelial cells thus, animals given vitamin A only as retinoic acid from birth are blind and sterile. 

Vitamin A is necessary for growth and reproduction, resistance to infection, maintenance and differentiation of epithelial tissues, stability and integrity of membrane structures, and the process of vision. In terms of the last function, vitamin A is a component of rhodopsin or visual purple, a photosensitive pigment in the eye that is needed for vision in dim light. An early mild clinical symptom of vitamin A deficiency is night blindness a severe deficiency of this fat-soluble vitamin results in xerophthalmia, an eye condition leading to blindness. 

Unusual features of vitamin A as observed by some investigators include (1) decreases serum cholesterol in large-quantity administration (chicks) (2) dietary protein required to mobilize liver reserves of vitamin A (3) decreased quantities in tumors (4) coenzynre Q10 accumulates in A-deficient rat liver (5) Ubichromenol-50 accumulation in A-deficient rat liver (6) retinoic acid functions as vitamin A except for visual and reproductive functions (7) anti-infection properties and anti-allergic properties (8) decreases basal metabolism (9) detoxification of poisons in the liver aided by vitamin A and (10) vitamin A is involved in triose —> glucose conversions. 

Retinoic acid (vitamin A acid), in which the alcohol group has been oxidized, shares some but not all of the actions of retinol. Retinoic acid is ineffective in restoring visual or reproductive function in certain species in which retinol is effective. Flowever, retinoic acid is very potent in promoting growth and controlling differentiation and maintenance of epithelial tissue in vitamin A-deficient animals. Indeed, all-trans-retinoic acid (tretinoin) appears to be the active form of vitamin A in all tissues except the retina, and is 10- to 100-fold more potent than retinol in various systems in vitro. Isomerization of this compound in the body yields 13-n.v-rctinoic acid (isotretinoin), which is nearly as potent as tretinoin in many of its actions on epithelial tissues but may be as much as fivefold less potent in producing the toxic symptoms of hypervitaminosis A. 

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