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Biomedical subjects

H Benning

Publications and source records attributed to H Benning.

9 recordsLinked to original sources
PubMed1995

Therapeutic range in transscleral contact cyclophotocoagulation.

Laser contact cyclophotocoagulation (CP) increasingly replaces noncontact CP and cryotherapy as it produces less damage to the conjunctiva and sclera. However, the optimal wavelength and protocol for treatment have not yet been firmly established. We used a contact continuous-wave (cw)-Nd:YAG laser at 1064 nm (Meridian-Microruptor III) with a bare fiber. A total of 30 freshly enucleated porcine eyes with brown irides were treated within 12 h of enucleation. The intraocular pressure was kept at 35-40 mmHg with an infusion system. The fiber was placed at a 1.5-mm distance from the limbus perpendicularly to the scleral surface, and applications were made using power levels ranging from 1.0 to 10.0 W for exposure periods of 0.5, 0.7, 1.0, 1.5, 2.0, 3.0, and 4.0 s. A just-visible whitening of the ciliary body was defined as a minimal effect, a complete whitening without loss of ciliary structures was defined as a medium effect, and a complete whitening with loss of ciliary structures was defined as a maximal effect. Supramaximal "pop" effects could be identified by the typical sound and the destruction of the ciliary body. Pop effects originate from a sudden overheating, which leads to the formation of small gas bubbles. Using an exposure duration of 0.5 s, no pop effect or maximal effect was observed. For longer exposure periods the therapeutic range decreased continuously (3.7 +/- 2.7 W for 0.5 s, 0.3 +/- 0.3 W for 4.0 s).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[The prognosis of arterial occlusions of the eye].

Central retinal artery occlusion is caused by embolism or changes in blood rheology and viscosity. In the past, different concepts of treatment were introduced. Main princip is to improve microcirculation by increasing the pressure of perfusion, the diameter of retinal vessels or decreasing blood viscosity. Success of therapy depends on the age of artery occlusion and the rate of persisting retinal perfusion. The different concepts of therapy and their results are discussed.

Combined Modality Therapy↗
PubMed1994

[Color duplex ultrasound findings in patients with endocrine orbitopathy].

UNLABELLED: Color Doppler imaging makes it possible for the first time to assess the blood flow velocity of orbital vessels. Especially in Graves disease, with its increase of orbital contents, this technique allows detection of changes in the perfusion of retrobulbar arteries and veins. We examined 23 patients (19 female, 4 male, average age 47.9 years) with thyroid ophthalmopathy using color Doppler imaging. Central retinal artery and vein, posterior ciliary arteries, vortex veins, superior orbital vein and ophthalmic artery were located and their Doppler spectra analysed. Results were compared with observations recorded in a control group consisting of 105 healthy volunteers. The thicknesses of extraocular muscles were measured echographically. RESULTS: There was no significant difference in blood flow velocity in central retinal artery and vein, posterior ciliary arteries and vortex veins between patients with Graves disease and the control group. The maximal blood flow velocity in superior orbital vein was significantly decreased (P = 0.01 on right eye, P = 0.04 on left eye). There was a slight correlation between reduced venous outflow in the superior orbital vein and the severity of the disease (r = 0.52 on right eye, r = 0.5 on left eye). CONCLUSION: Color Doppler imaging is a new, noninvasive technique that could be used to examine patients with thyroid ophthalmopathy. Reduced venous outflow may contribute to exophthalmus by creating perivenous edema and consequent swelling of orbital fat.

Adult↗
PubMed1988

Metabolism of ether glycolipids with potentially antineoplastic activity by Ehrlich ascites tumor cells.

Ehrlich ascites tumor cells were incubated in vitro with rac-1-O-[1'-14C]octadecyl-2-O-methylglycero-3-beta-D-glucopyranosi de for 24 h. The potentially antineoplastic ether glycolipid was rapidly metabolized by the cells to radioactive 1-O-octadecyl-2-O-methylglycerol (70 pmol/10(6) cells per h) and further acylated to 1-O-octadecyl-2-O-methyl-3-acylglycerols. Incubation of Ehrlich ascites cells with synthetic rac-1-O-[1'-14C]octadecyl-2-O-methyl-3-palmitoylglycerol showed that this metabolite is reconverted by deacylation to 14C-labeled 1-O-octadecyl-2-O-methylglycerol. The latter compound or a metabolite derived therefrom may be the 'toxic principle' of both the ether glyceroglycolipids and ether glycerophospholipids having a 1-O-alkyl-2-O-methylglyceryl moiety, as suggested by Unger et al. (J. Natl. Cancer Inst. 78 (1987) 219-222).

Animals↗
PubMed1985

Ether glycerolipids: novel substrates for studying specificity of enzymes involved in glycerolipid biosynthesis in higher plants.

Ether glycerolipids, predominantly alkylacylglycerols and alkylacylglycerophosphocholines, are synthesized in photomixotrophic rape (Brassica napus) suspension cells from various exogenous monoalkylglycerols. The stereospecific distribution of acyl moieties was studied in these ether glycerolipids with regard to chain-length and degree of unsaturation of alkyl moieties and compared with the distribution of acyl moieties in the corresponding endogenous acyl glycerolipids. The results show the following: (1) Alkylacylglycerophosphocholines replaced up to one-half of the corresponding physiological membrane lipids, i.e. diacylglycerophosphocholines, without changing the total amount of cholineglycerophospholipids as compared to untreated cells. (2) The composition of acyl moieties in total lipids of rape cells was practically unaltered by fatty acids derived via oxidative cleavage from the various alkyl moieties of either glycerolipids. (3) In 1-O-alkyl-2-acylglycerols derived from exogenous alkylglycerols and in endogenous 1,2-diacylglycerols compositions of acyl moieties were found to be different indicating that different pathways were operative in the biosynthesis of these two neutral glycerolipids. (4) Enzymes involved in synthesizing molecular species of 1-O-alkyl-2-acylglycerophosphocholines or 2-O-alkyl-1-acylglycerophosphocholines as well as 1,2-diacylglycerophosphocholines showed similar specificities with regard to chain-length and degree of unsaturation of both alkyl and corresponding acyl moieties. Thus, ether glycerolipids formed by plant cells from exogenous alkylglycerols are suitable metabolites for studying the specificity of enzymes involved in the biosynthesis of glyerolipids.

Chemical Phenomena↗
PubMed1984

Metabolism of orally administered alkyl beta-glycosides in the mouse.

The metabolism of octyl beta-D-[U-14C]glucoside, ]1-14C]dodecyl beta-D-maltoside and [1-14C]hexadecyl beta-D-glucoside was studied after oral administration to mice. The beta-glycosidic bond was rapidly hydrolyzed in intestine and liver. The cleavage products, sugars and long-chain alcohols, entered the pathways of lipid and carbohydrate metabolism. It appears that alkyl beta-glycosides are suitable as additives in food and feed.

Animals↗