Fish eye

Theory and Equipment. Many diseases of the human body can be identified by visual appearance. Tumors in the upper gastrointestinal (GI) tract, for example, possess a characteristic salmon pink color (3). The presence of such a color can be an indication of disease. Endoscopy is the medical imaging tool used to detect such colors in the inside of hoUow internal organs such as the rectum, urethra, urinary bladder, stomach, colon, etc. An endoscope is the instmment used to perform endoscopy. Endoscopic imaging involves the production of a tme color picture of the inside of the human body using lenses and either hoUow pipes, a fiber optic bundle, or a smaU CCD camera. AU three use a large field-of-view, sometimes referred to as a fish eye, lens to aUow a 180° field of view. 

Endoscopes containing a CCD camera replace the fiber optic bundle with a smaU monochrome CCD chip at the focal point of the fish eye lens (4). 

Use well-designed, specialized polymer dissolution systems wherever possible (such as those from the U.S. Filter, Inc. subsidiary, Strandco ), especially for emulsion polymers, rather than simple dissolving tanks and mixers with propeller-type impellers. This prevents undissolved lumps of polymer (fish-eyes) and the breakdown of polymer chains. Always install a strainer to prevent possible pump clogging. 

Famiiiai aipha-iipoprotein deficiency Tangier disease Fish-eye disease Apo-A-i deficiencies All have low or near absence of HDL. Tendency toward hypertriacylglycerolemia as a result of absence of apo C-ll, causing inactive LPL. Low LDL levels. Atherosclerosis in the elderly. 

Fig. 4. Fish eye burning in cracking catalyst beads. Appearance after partial bum-off (top), and coke concentration versus radius in beads for successive stages of buro-off (bottom) for three temperature regions (a) low, (b) intermediate, (c) high.

LCAT catalyzes the transfer of a preferentially unesterified fatty acid from the sn-2 position of phosphatidylcholine to the 3/i-hydroxy group of cholesterol, and thereby produces lysophosphatidylcholine and a cholesteryl ester [50]. Depending on the mutation in the LCAT gene, homozygous or compound heterozygous patients present with one of two clinical phenotypes, classical LCAT deficiency or fish-eye disease [58, 85]. Classical LCAT deficiency is caused by a broad spectrum of missense and non-sense mutations that interfere with the synthesis or secretion or affect the catalytic activity of LCAT [10]. Fish-eye disease is caused by a limited number of missense point mutations that alter the surface polarity, and thereby interfere with the binding of the enzyme to apoA-I containing lipoproteins [77]). 

Biochemically, both patients with classical LCAT deficiency and fish-eye disease present with very low levels of HDL cholesterol (< 0.3 mmol/1), although some pa-... 

LCAT acts preferentially on lipids transported by HDL (so-called a-LCAT activity), but also on lipids transported by apoB-containing lipoproteins (so-called jS-LCAT activity) [58, 85]. In practice, LCAT activity is measured either as the activity required to esterify radioactive cholesterol that has been exogenously incorporated into native HDL or into artificial HDL-like particles (a-LCAT activity) or which has been equilibrated with endogenous lipoproteins of the plasma sample (cholesterol esterification rate, CER) [21, 58, 85]. Several variations of these assays have been reported, some of which are available as commercial test kits (e.g., Roar Biomedical, New York, USA). In addition, LCAT concentration can be determined by either laboratory-made tests or by a commercial ELISA kits [57]. However, the decrease in LCAT concentration is difficult to judge since it also decreases secondary to HDL deficiency due to causes other than LCAT deficiency. Plasma from patients with LCAT deficiency fails to esterify radioactive cholesterol provided by any substrate. By contrast, plasmas of patients with fish-eye disease show a near-normal cholesterol ester-fication rate but have a selective inability to esterify radioactive cholesterol provided to plasma with native HDL or reconstituted HDL (a-LCAT activity) [58, 85]. 

Patients with classical LCAT deficiency fail to esterify cholesterol in any substrate and hence have both an undetectable or very low cholesterol esterification rate and a-LCAT activity. Patients with fish-eye disease usually have a normal cholesterol esterification rate and a selective a-LCAT deficiency. 

Patients with classical LCAT deficiency show an increased proportion of unesterified cholesterol in plasma (80-100%). By contrast, the plasma from patients with fish-eye disease has a slightly elevated proportion of unesterified cholesterol (up to 70%). 

Funke H, Eckardstein A von, Pritchard PH, Albers JJ, Kastelein JJ, Droste C, Assmann G (1991) A molecular defect causing fish eye disease an amino acid exchange in lecithin-cholesterol acyltransferase (LCAT) leads to the selective loss of alpha-LCAT activity. Proc Natl Acad Sci U S A 88 4855-4859... 

Santamarina-Fojo S, Hoeg J, Assmann G, Brewer HJ (2000) Lecithin cholesterol acyltrans-ferase deficiency and fish-eye disease. In Scirver C, Beaudet A, Sly E, Valle D (eds) The Metabolic and Molecular Bases of Inherited Disease, 8th edn. McGraw-Hill, New York, pp 2817-2833... 

Recently a detailed study has been made of the methods required to obtain spectra of micro and ultra-micro amounts of sample 117). A focussing micro-illuminator is used for the detection of 1-10 micrograms of samples. Often, one can obtain the spectrum of impurities like fish-eyes in plastics by merely punching a hole the size of the imperfection in a masking material like cardboard and run the spectrum until the signal-to-noise level has reached a sufficient value to make an identification of the impurity. One can carry out a similar measurement in regions where the impurity appears to be absent and subtract the two spectra to enhance the spectra of the impurity relative to the more dominant polymer. 

In these packages, visible imperfections generated at the time of molding, e.g., discoloration, fish eyes, rough surface, etc., are significant problems that need to be addressed. Thus, several improvements in the process of producing an EVOH have been proposed. 

Fish eye - A thin elongated void in a calendered sheet. A surface imperfection. Not detrimental to service life. 

Charge the water to a mixing vessel and start agitation. Charge the Macol TD-12 and mix until dissolved and free of "fish eyes." Charge the ramaining ingredients and mix until clear. 

Charge the ingredients in the sequence given above and mix until clear and free of "fish eyes. ... 

Film Appearance. It is important to minimize film imperfections or defects when LDPE is blown into film. The common defects are arrow-heads, pinpoint gels, gels or fish eyes , and oxidized gels or colored specks. 

The allusion to "rings full of eyes," in verse 18, is very true to fact, for the Work at one stage appears to be made literally of rings, or strata, set full of eyes - "fishes eyes," one writer calls them. ( Remora ). From the phenomenal spectacle, the ancient Greek mystics invented the "Argus-eyed monster" - the creature with a hundred eyes, while the Hindu Rishis saw it as the image of Krishna, reflected in a thousand Gopis. 

Dunlap, W. C., Williams, D. M., Chalker, B., and Banaszak, A., Biochemical photoadaptation in vision UV-absorbing pigments in fish eye tissues, Comp. Biochem. Physiol., 93B, 601, 1989. 

C4. Carlson, L. A., and Philipson, B., Fish-eye disease. A new familial condition with massive corneal opacities and dyslipoproteinemia. Lancet 1, 921-924 (1979). 

F18. Forte, T. M., and Carlson, L. A., Electron microscopic structure of serum lipoproteins from patients with fish eye disease. Arteriosclerosis 4, 130—137 (1984). 

On any calender line there are several possible sources of contamination, the first being the raw materials used. In most resins there will be a small number of discoloured grains, which are accepted up to a specified level. On occasions a manufacturer s equipment fails and produces resin with more than normal contamination of this kind. Some particles may not be discoloured but may fail to disperse and so cause small lumps in the film (known in clear films as fish eyes ). On the other hand, lumps may not necessarily be attributable to faults in the resin—they can arise also from poor dispersion of plasticizer, or from degradation taking place at some stage in the process. 

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