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PubMed2001

Effects of nicotinic antagonists on ocular growth and experimental myopia.

PURPOSE: To learn whether nicotinic cholinergic receptors modulate postnatal eye growth and influence the course of form-deprivation myopia. METHODS: One-week-old White Leghorn chicks wore a unilateral goggle to induce form-deprivation myopia. Other chicks were never goggled. Nicotinic antagonist drugs were administered by intravitreal injection, usually daily or every other day to the goggled eye or to one eye of never-goggled chicks. After 1 week, the eyes were studied by refractometry, A-scan ultrasonography, and caliper measurements. RESULTS: The relatively non-subtype-specific channel-blocking nicotinic antagonists chlorisondamine and mecamylamine each inhibited the development of form-deprivation myopia but with complex multiphasic dose responses. Chlorisondamine was the most effective. Mecamylamine, at the lowest tested doses, tended to stimulate the growth response and myopic refractive shift of goggle wearing. Methyllycaconitine competitively inhibits nicotinic receptors containing the alpha7 and alpha8 subunits, which are highly expressed in chick retina. It showed a less dramatic but still significant inhibitory effect on myopia. The effects of dihydro-beta-erythroidine, a competitive antagonist relatively selective for nicotinic receptors with alpha3 or alpha4 subunits and particularly for alpha3beta2-containing receptors, were the weakest and inhibited primarily axial elongation. Chlorisondamine but not mecamylamine also affected nongoggled eyes, inhibiting growth and shifting refraction toward hyperopia, but chlorisondamine also induced degenerative changes to the retinal pigment epithelium (RPE). CONCLUSIONS: Nicotinic receptors are involved in eye growth control. Nicotinic antagonists affect the development of form-deprivation myopia and perhaps the growth of nongoggled eyes. The differences in drug activity and multiphasic dose-response curves may reflect the complexity of nicotinic receptor subtypes associated with the eye and/or pharmacokinetic differences between the individual drugs. Although another tissue(s) cannot be completely excluded by these data, the site of action of these agents may be neural retina or RPE.

Animals↗
PubMed1975

[Some quantitative characteristics of the frog retinal rod outer segments].

Retinal rod outer segments in frogs were studied by means of light microscopy, refractometry, microspectrophotometry, and electron microscopy. Analysis of the data obtained shows that an unidentified substance, which makes up about 50% of outer segment dry weight, is lost during routine biochemical investigations. The protein parts of the rhodopsin molecules make up 85% of the outer segments proteins and 25% of outer segment dry weight. Rhodopsin molecules can be arranged in a square array with a unit cell side of about 7 nm on one side of each disk membrane. Lipids in a single membrane occupy only 2 nm, and disk membranes are strongly hydrated.

Animals↗
PubMed2001

[Biometric variation of the ocular globe in myopia].

GOAL: The study of correlation between myopia's pathogen and the biometrics variations of the different eye ball segments. MATERIAL AND METHOD: 64 patients were included in this study: 54 patients with myopia higher than--5 diopter and 10 patients with cataracta. All patients underwent a complete ocular examination including: visual acuity determination, ocular fundus examination, automatic refractometry, keratometry. Biometry was performed with an ultra-scan system. RESULTS: From 64 patients, 53 were with axial myopia, 1 with myopia induced by low corneal curvature radius and 10 patients with myopia induced by a high refractive index of the lens caused by cataract. In cases with axial myopia the axial length was high (26.1 mm) with a high vitreous length (20.78 mm). In cases with index myopia, only the lens thickness and the anterior chamber depth undergo biometrics variations. Curvature myopia is the result of the decrease of the corneal curvature radius. CONCLUSIONS: Axial myopia is that by far the most frequently form of myopia. In this case the increases in axial length is proportionally with the degree of myopia. Index myopia is produced by the increase of the refractive index of the lens in cataract. A low corneal curvature radius less frequently than the others produces curvature myopia.

Adolescent↗
PubMed1976

Objective evaluation of experimental ocular irritation.

After topically administered nitrogen mustard the irritative effect on the pupil, intraocular pressure, protein concentration of the aqueous humor and on the vessels of the iris and conjunctiva was quantified. The protein level in aqueous was determined by refractometry. The degree of hyperemia of conjunctiva and iris was determined by measuring the amount of Evans blue dye present in the tissue minutes after intravenous administration. A reproducible relationship was obtained using these methods to evaluate the degree of irritation produced by nitrogen mustard.

Animals↗
PubMed1990

[Aberrometry in the diagnosis of eye diseases].

Four methods (by means of Smirnova-Korniushina's aberrometer; with the help of aberroscope--Cherning's lattice; by presenting a figure of a cross; and by automatic refractometry through different portions of the pupil) were used for studying aberration of the optic system of the eye in 490 persons. Among them, 37 were healthy persons, 27--patients with ametropia of moderate degree, 24--with high myopia, 9--with astigmatism above 3.0 D, 16--with monocular diplopia, 327--with keratoconus, 7--with scars of the cornea, 21--with initial cataract, 47--after keratotomy. In norm and in ametropia to 6.0 D, a histogram of refraction distribution by the pupil has a small disperse and a pronounced peak, the Cherning's lattice is straight. In high myopia, the disperse of refraction increases, the peak is slightly pronounced, the lattice is curved along the margins. In astigmatism, the disperse of refraction is great, but there can be peaks. The whole lattice is curved. In monocular diplopia, two more peaks can be seen on the histogram. The lattice is greatly curved. In keratoconus, aberrometry without correction is possible only at the initial stage and shows a rather mixed picture. The histogram of refraction represents a low irregular row. In aberroscopy, the bands are greatly curved, frequently overstep the bounds of the frame that itself looses a form of a circle, becomes oval or polygonal. Contact correction improves the aberration picture considerably. In scars of the cornea, the lattice is distorted and infrequently repeats their forms. In initial cataract, the course of the bands becomes interrupted and rounded spots appear between them.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Effect of interleukin-2 on microvascular liquid and protein transport in the rat small intestine.

Interleukin-2 (IL-2), a glycoprotein lymphokine derived from activated T-lymphocytes displays potent anti-cancer properties but its therapeutic use has been limited by generalized tissue swelling. To shed light on the mechanism underlying this potentially life-threatening edematogenic syndrome, recombinant IL-2 or an equal volume of control solution (excipient or 5% dextrose) was administered to 88 adult, male Sprague-Dawley rats. Initially, rats were injected with 50,000 Cetus units (equal to 300,000 I.U.) of IL-2 intraperitoneally, either one-time ("acute" rats) or every eight hours for two or seven days ("chronic" rats). Thereafter, under pentobarbital anesthesia, the main mesenteric lymph duct was isolated, incised, and measurements made of intestinal lymph flow (JV) and the total protein content and protein fractions in lymph (L) and plasma (P) (refractometry and agarose gel electrophoresis, respectively). Final measurements were also carried out after superior mesenteric vein constriction to assess filtration-independent L/P total protein "washdown." After IL-2, JV and protein clearance (JV x L/P) were increased (p less than 0.001) while lymph and plasma total protein content and protein fractionation were unchanged. Protein washdown was also maintained. These data are not only inconsistent with bulk "plasma leak" from damaged capillaries, but in conjunction with previously demonstrated increased cardiac output and reduced systemic vascular resistance after IL-2 administration, the findings favor augmented microvascular surface exchange area from increased capillary perfusion as the primary mechanism underlying increased transcapillary liquid and protein flux. This conclusion conforms to the rapid reversal of edema in patients after cessation of IL-2 therapy.

Animals↗
PubMed1987

Clinical pathologic alterations in horses during a water deprivation test.

A 72-hour water deprivation test was performed in 12 horses to determine clinical pathologic changes. Reference values for electrolyte (X) clearance, expressed as a percentage of creatinine clearance (CLCR; %CLCRX), were also determined. A comparison was made between urine concentration measurement techniques. Results of %CLCRX determination in 12 horses before water deprivation were 0.034 +/- 0.095 %CLCRNa, 42.4 +/- 9.8 %CLCRK, 0.352 +/- 0.190 %CLCRCl, and 0.710 +/- 0.250 %CLCRP. During water deprivation, there was individual variation for electrolyte clearances, but Na excretion increased significantly (P less than 0.01) at 24 and 48 hours. After 48 hours' water deprivation, %CLCRNa decreased significantly, but was still greater than the initial clearance. Plasma protein was a better indicator of water deprivation (dehydration) in the horse than was PCV. Electrolyte concentrations in serum and urine were determined. Little significant (P less than 0.01) change in acid-base values was noticed after 72 hours' water deprivation. Urine osmolality (as determined by osmometry) was compared with sp gr (determined by refractometry) in determining urine concentration. Initially, sp gr correlated well with urine osmolality determinations, but this correlation decreased after 48 hours.

Animals↗
PubMed1985

Immunoglobulin transfer and weight gains in suckled beef calves force-fed stored colostrum.

Concentrations of immunoglobulins and total proteins in second-day post-partum serum samples of 62 beef calves from multiparous dams were measured by zinc sulphate turbidity, electrophoresis, radial immunodiffusion and refractometry. These results, together with health records and weight gains, were used to evaluate the practice of routinely force-feeding 1 L of stored colostrum to suckled beef calves immediately after birth. There was no apparent benefit from such force-feeding. It did not result in greater 48-hour serum immunoglobulin levels, nor did it improve weight gains at 42 days. None of the calves required treatment for neonatal disease, but one force-fed calf died from inhalation of regurgitated colostrum.

Animals↗
PubMed1971

Quantitation of serum lipoproteins by electrophoresis on agarose gel: standardization in lipoprotein concentration units (mg-100 ml) by comparison with analytical ultracentrifugation.

Lipoprotein electrophoresis on agarose gel has been modified to allow estimation of the absolute quantity of each fraction. The reproducibility of the method is illustrated by 12 determinations in a single day on serum from one normal subject: mean total dye uptake was 302 +/- 9 (sd "corrected dye units," and the percentages of beta-, pre-beta, and alpha-lipoprotein were 56.1 +/- 0.9, 29.1 +/- 0.4, and 14.8 +/- 0.7, respectively. Reproducibility over a period of 8 months was also demonstrated. Serum lipoproteins of five normal and 15 hyperlipidemic individuals determined by this technique were compared with values obtained by analytical ultracentrifugation. The correlation coefficients were: 0.993 for pre-beta-LP vs. VLDL, 0.978 for beta-LP vs. LDL, and 0.867 for alpha-LP vs. HDL. Lipoprotein values obtained by paper electrophoresis were also correlated with those of the analytical ultracentrifuge, but to a lesser degree (r = 0.956, 0.691, and 0.786, respectively). Values for LDL and VLDL which were measured by refractometry after preparative ultracentrifugation were very similar to those obtained from the analytical ultracentrifuge. Serum triglyceride concentration was highly correlated (r = 0.972) with the agarose values for pre-beta-LP; serum cholesterol concentration was correlated (r = 0.673) with beta-LP. It is proposed that the standard curves of the comparisons with the analytical ultracentrifugal values be used to convert the corrected dye units of electrophoresis on agarose gel to mg/100 ml of specific lipoprotein.

Adult↗
PubMed1978

An interlaboratory comparison of serum total protein analyses.

An analysis of the 1976 CAP Comprehensive Chemistry Survey of total serum proteins is presented. More than 2,000 laboratories contributed data in this survey. Estimation of total serum protein concentration by the biuret reaction remains the most widely used technic, followed by refractometry. Precision and accuracy data for a number of analytic systems and methods are presented. Precisions for the entire group are nearly comparable. A negative bias for total protein concentration was shown by the SMAC.

Blood Chemical Analysis↗
PubMed1982

The use of the laser light scattering for the molecular weight determination of membrane proteins in surfactants.

A method is described for the determination of the molecular weight of the protein moiety of protein surfactant complexes using of low angle laser light (633 nm) scattering in combination with high performance porous silica gel chromatography, precision differential refractometry and differential UV absorption was described. The calibration curves in sodium dodecyl sulfate (SDS) and in a non-ionic surfactant, octaethyleneglycol dodecyl ether, using several reference proteins yielded linear lines. Molecular weight of porin oligomers and monomers, an intrinsic membrance protein that forms the permeability channel in the outer membrane of Escherichia coli, were calculated and were found to be 109,000 and 36,300, respectively in SDS and that of oligomers in octaethy leneglycol dodecyl ether was 114,200. Similarly, the molecular weights of maltoporin oligomers and monomers, which form maltose-maltodextrin specific channels, appeared to be 148,500 and 48,200, respectively, in SDS and that of oligomers in octaethyleneglycol dodeclyl ether was 149,000.

Chromatography, Gel↗
PubMed1980

Hemoconcentration induced by surface hypothermia in infants.

The effects of surface hypothermia (25 degrees C) on arterial hematocrit value (by microcentrifuge) and plasma protein concentration (by refractometry) were studied in infants undergoing surface cooling for cardiac operations. To analyze in detail the mechanisms leading to the observed changes in patients, we performed parallel studies on normal dogs and permanently splenectomized dogs. In these dogs, measurements were also made of plasma volume (by 125I-albumin) and red cell volume (by 51Cr-erythrocytes). Arterial hematocrit value increased progressively during surface cooling in infants. Assuming that red cell volume remained constant and that the ratio of whole body red cell percentage to arterial hematocrit value during surface cooling in infants as in splenectomized dogs, we estimated percent changes in plasma volume in infants from arterial hematocrit data. The computed plasma volume decreased progressively as the body temperature was decreased. Since plasma protein concentration remained constant, the loss of plasma volume suggested a sequestration of whole plasma in portions of the circulatory bed and/or an extravasation of whole plasma into the interstitial space.

Animals↗
PubMed1978

[High-performance liquid chromatography in the determination of organic acids in wine].

We shall distinguish the case of non aromatic organic acids from that one of phenolic acids. In the first one, we have applied to wines a method used for fruit-juices by Palmer and List, 1973. After contact of the wine with a strong acid resin, its is injected on anion exchange resin Aminex A 25 precolumn (formiate form) which retains all the organic acids. The precolumn is washed with water to eliminate neutral components, then connected with the chromatographic column which contains the same resin. The different acids are eluted with a solution of natrium formiate at 70 degrees C. They are detected by differential refractometry (galacturonic, lactic, malic, succinic, tartric acids) and by ultraviolet at 254 nm (shikimic acid). Beside these compounds which are identified by their retention volumes, others not yet attributed peaks are detected. The limits of detection are 2 mg/l for shikimic acid, 30 mg/l for tartric acid and 15 mg/l for the others. Analysis time is about one hour. In the case of phenolic acids, we extract them from wine by diethyl ether after saturation with NaCl or by demixtion. The determination of phenolic acids is done on the ether extract or on the organic layer of the demixtion. Chromatography is obtained on octadecylsilanised column (RP 18) with solvent gradient (from 10% methanol in KH2PO4O,1 M pH 2,1 to 60% methanol in the same buffer) and detection in ultraviolet at 254 nm. The knowledge of recovery of acids by diethyl ether or by demixtion permits to obtain their concentrations in wine. The different so determinated phenolic acids are: gallic, 4 hydroxybenzoic, cafeic, vanillic, syringic and para coumaric acids. We have applied these methods to 32 wines for phenolic acids and 80 wines for non aromatic acids. Some results are presented in the case of 24 wines issued from Gamay and 8 wines from Pinot and it appears that tartric and shikimic acids have more important average concentrations in the former than in the latter.

Acetates↗
PubMed1993

[Apropos of preventive ophthalmologic interventions in the child population of compulsory school age. Authors' experience].

The results are reported of work carried out during the last five years by the Center of Social Ophthalmology, director Prof. G. Scuderi, which is part of the II Division of the Ophthalmologic Clinic of Rome University "La Sapienza" with the object of trying out together with territorial units a model of preventive intervention acting as a filter for specialized university facilities. In other words, already existing facilities and medical personnel were to be used and trained for specific methods and techniques. From 1985 through 1990, 787 children selected by ophthalmologic screening by school doctors among the compulsory school population of the RM 3 and 5 districts were seen and submitted to periodic checks. This cohort included children aged 5 to 14 without significant differences in sex distribution and with prevalence of the 8 to 10 year olds. Each subject was submitted to complete eye examination including refractometry and orthoptics, color vision, biomicroscopic and ophthalmoscopic examination. The principal findings show that about 36% of subjects examined have a natural vision of 11/10 while the high percentage of ametropia observed was mainly represented by astigmatism and hypermetropy, albeit of minor intensity. Strabismus was found in 2.79% and implied marked visual deficit that was often refractory to any type of treatment. In addition, the prevalence was determined of other abnormalities concerning eye motility, color vision and pathologies involving anterior segment and eyeground. In their conclusion, the authors stress the rarity of organic ocular pathology in children (mostly represented by inflammatory changes of the adnexes and conjunctiva) whereas amblyopia was one of the main causes of visual deficit in children. They stress the importance of early therapeutic intervention in order to allow complete visual rehabilitation. The results of the clinical model for prevention were excellent so that it can even be proposed for large scale prevention of amblyopia.

Adolescent↗
PubMedDate not supplied

[Intracapsular implantation of intraocular lenses in complicated cataracts].

A total of 75 patients with various types of cataracts, 35 of these (37 eyes) with complicated cataracts, were examined. Patients with a history of antiglaucoma surgery were not included in the study. Extracapsular extraction of complicated cataracts with intercapsular implantation and suture-free fixation of B. N. Alexeyev's IOL-IKB A004 were carried out after B. N. Alexeyev. The patients were examined using keratometry, ophthalmometry, visometry, echography and echobiometry, biomicroscopy, ophthalmoscopy, pupil test, tonometry, electron tonography, refractometry, gonioscopy, and entoptic phenomena. The results indicate the possibility of extracapsular cataract extraction with intracapsular implantation of IOLs after Alexeyev in patients with complicated cataracts. The incidence of intra- and postoperative complications in patients with complicated cataracts concomitant with myopia, glaucoma, uveitis, and diabetes mellitus did not differ from that in patients with uncomplicated cataracts concomitant with the same conditions. Moreover, the incidence of postoperative complications was far less in comparison with implantation of other lenses, as reported by some authorities.

Cataract↗
PubMedDate not supplied

[Structural transitions of serum proteins in solutions during high- and low-temperature dehydration].

Infrared and ultraviolet spectroscopy, potentiometric titration, and refractometry, as well as analysis of lysine, tryptophan, and tyrosine availability, and enzymic hydrolysis were used to establish that high-temperature and low-temperature dehydration of solutions of serum protein is accompanied by a rearrangement of its molecular structure, resulting in changes in the number of polar radicals and hydrophobic bonds, intermolecular and intramolecular interactions, and the formation of a new stable conformation. Comparison of the two methods of dehydration showed that cryoconcentration resulted in a greater accessibility of the protein molecule to chemical agents and proteolytic enzymes, whereas heating had an opposite effect.

Amino Acids↗
PubMed1997

[Computerized video-keratoscopic analysis and cataract surgery by phacoemulsification. Predictive calculation of the power of the intraocular implant].

PURPOSE: The authors present the results of a prospective study of 125 consecutive cases of phacoemulsification, performed by a single surgeon, to assess the benefit of computerised videokeratoscopy for the improvement of the predictive calculation of the power of intraocular lenses (IOL). METHODS: Preoperative keratometry was determined by means of 3 concurrent techniques, including automated kerato-refractometry (AKR 2000, Nidek) and videokeratoscopy by TMS-1 (Tomey) and CAS-1 (EyeSys). The results of the IOL calculation by these 3 methods was compared postoperatively to the power of the actual IOL yielding emmetropia as calculated by the optical method based on the postop, refraction at the various time-points. RESULTS: Simulated values obtained with videokeratoscopy significantly reduced the refractive error at 1 postop, week (p = 0.001), one month (p = 0.002) and 3 months (p = 0.002) for the CAS1 and at 3 months (p = 0.002) for the TMS1, as compared to values obtained with conventional automated keratometry. The refractive error was significantly reduced with the CAS1 at one month (p = 0.001) and 3 months (p = 0.019) as compared to TMS1. CONCLUSION: The determination of the anterior curvature of the entrance pupil by videokeratoscopy significantly improves the predictive calculation of the IOL power.

Aged↗