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Biomedical subjects

C Ohrloff

Publications and source records attributed to C Ohrloff.

At least 91 records · Page 5Linked to original sources
PubMed1983

Lens metabolism and aging: enzyme activities and enzyme alterations in lenses of different species during the process of aging.

Extensive investigations on the metabolism of animal lenses over the life span indicate various changes that, regarded collectively, suggest a decrease in metabolic energy. A factor analytic interpretation and discussion of these results indicate that enzyme modifications might be one of the fundamental causes of the age-related changes in lens metabolism. Detailed investigations on the kinetic and physicochemical properties of certain enzymes of the carbohydrate breakdown in lenses of different ages verify this assumption. Since the changes observed are found mostly in the lens nucleus protein neosynthesis no longer takes place, posttranslational modifications appear to be responsible.

Aging↗
PubMed1983

Fructose, fructose 1-phosphate, and glyceraldehyde breakdown in carbohydrate metabolism.

Recent investigations showed that all enzymes that are involved in the catabolism of fructose via fructose 1-phosphate (F-1-p) are present in the bovine lens. The present studies were performed to provide information regarding the extent to which fructose, F-1-p and glyceraldehyde (GA) are actually catabolized via this pathway, and how they increase the lactate, alpha-glycerophosphate and glycerol concentrations. Incubation was performed with a homogenate of bovine lens equator. F-1-p, and particularly fructose + ATP, considerably increased lactate and alpha-glycerophosphate concentrations, while the glycerol concentration remained unchanged compared to controls. Lactate formation through GA was not observed; while small amounts of glycerol and alpha-glycerophosphate are formed, it seems that the major part is transformed to glycerate. The results show that the further breakdown of lenticular fructose occurs via F-1-p and that the phosphorylated C3 fragments (dihydroxyacetone phosphate) are transferred to the energy metabolism, which is not the case with GA.

Animals↗
PubMed1983

Studies of lens enzyme activities in relation to cataract type and plasma constituents.

The specific activities of glutathione reductase (GR), EC 1.6.4.2, and aldolase, (ALD) EC 4.1.2.13, were determined in the homogenates of 60 cataractous lenses. Concentrations of certain plasma constituents and the morphological types of cataract of the patients were known. Investigations were aimed at establishing a possible correlation between enzyme activities and plasma constituents as well as between the specific activities of GR and ALD and type of cataract. A correlation between the specific activity of GR and the urea content of the blood could be identified. Results also indicated a relationship between the decrease in GR activity and the formation of cortical cataracts.

Alkaline Phosphatase↗
PubMed1982

[Experiences with the 1st 1400 posterior chamber lens implantations after phacoemulsification].

Since May 1979 the authors have performed 3000 posterior chamber lens implantations; the purpose of this report is to present interim data on the first 1400 cases. The mean age of the patient was 69 years; lens power was determined biometrically, and the diopter range of the implant lenses was between 10 and 30 D. Postoperatively 93.7% of the patients had a visual acuity of 0.5 or better, 70% between 0.8 and 1.0. Serious complications, such as corneal edema, lens luxation and expulsive choroidal hemorrhage have not occurred so far; slight complications such as decentration of the lens, secondary, glaucoma and synechiae have seldom been observed and have reacted favorably to therapy.

Aged↗
PubMed1982

Investigations of the enzymes involved in the fructose breakdown in the cattle lens.

By introducing fructose into the glycolysis, it is possible to stimulate ATP formation. As is the case in animal experiments, in human lenses, too, the first step in the phosphorylation to fructose-1-phosphate via the enzyme ketohexokinase. The present investigation deals with the question whether enzymes present in the lens are responsible for the further steps in fructose degradation. Particularly the aldolase isoenzyme C splits fructose-1-phosphate into glyceraldehyde and dihydroxyacetone phosphate in the same way as in glucose catabolism. Dihydroxyacetone phosphate can further be directly degraded and thus utilized to ATP formation. From glyceraldehyde, glycerol (aldose reductase) or glycerate (aldehyde dehydrogenase) can be formed. The presence of triosekinase, which phosphorylates glyceraldehyde directly to glyceraldehyde-3-phosphate, could only be determined in the lens tissue of young animals. The presence of glycerokinase (glycerol leads to glycerophosphate) could not be verified. Thus, in the lens tissue 1 ATP molecule net per fructose molecule can be formed. In older age, the glucose breakdown is limited by hexokinase and phosphofructokinase, so that the glucose, after transformation via the sorbitol pathway to fructose, can also be utilized for the energy metabolism.

Aging↗
PubMed1981

[Recurrent corneal swelling accompanying intermittent hemodialysis in terminal kidney failure (author's transl(].

Typical eye changes in dialysis patients, which have been attributed to an osmotic disequilibrium, are elevated IOP, retinal edema or detachment, and cataract. This paper reports on a 66-year-old aphakic patient on intermittent hemodialysis, who developed corneal changes that may also be consequential to a disequilibrium. During hemodialysis treatments she repeatedly developed corneal swellings and bullous detachment of the corneal epithelium. These changes were always reversible during the period between treatments. Examination with the reflecting microscope demonstrated an endothelial cell density of 600/mm2, which is assumed to be the threshold density capable of maintaining corneal integrity under normal conditions, but is inadequate under the osmotic stress induced by hemodialysis. Methods of treatment are discussed.

Aged↗
PubMed1981

[Influence of local application of isoptomax eye drops on neuromuscular transmission].

The muscle-relaxing effect of antibiotics, particularly that of aminoglycosides and polymyxins after oral, intravenous, intramuscular and local application is described. After local application of Isoptomax eye drops, one patient suffered from relaxation of the muscular system of the neck and throat. The phenomenon did not recede until several hours after therapy was discontinued. The mechanism of action is described and a possible treatment discussed with reference to the relevant literature.

Dexamethasone↗
PubMed1978

Experimental cataracts in rats due to tryptophan-free diet.

A tryptophan-free diet induces posterior subcapsular cataracts and reversible corneal opacities in young Wistar rats. Compared to the controls there is a significant decrease of body weight, lens fresh weight, and water-soluble lens protein. Protein separation by isoelectric focusing shows diminished alpha-, beta-, and gamma-crystallin fractions. If tryptophan is restored to the diet after 24 days, new clear lens fibers are laid down again, indicating that the mechanism of protein synthesis has not been permanently damaged by tryptophan-deficiency.

Animals↗
PubMed1977

[Determination of the KM-value of the fumarase (E.C. 4.2.1.2) with bencyclan-hydrogenfumarate as the substrate (author's transl)].

The Michaelis-Menten constant for fumarase (E.C. 4.2.1.2) has been determined by measuring the enzyme activity by the spectrophotometric method of Racker, which depends on the formation or disappearance of the double bond of fumaric acid. When using Na2-fumarate or bencyclan hydrogenfumarate (Fludilat), respectively, as a substrate, a KM-value of 1.3 X 10(-3) M was found for both substances. In a linked assay where the formation of NADH in the reaction of fumarate leads to malate leads to oxaloacetate was used as a parameter for the reaction rate, a KM-value of 1.35 X 10(-3) M was found.

Animals↗
PubMed1977

Action of bencyclane-hydrogen-fumarate on the carbohydrate metabolism of bovine lens homogenates.

1-Benzyl-1-(3-dimethylaminopropoxy)cycloheptane (bencyclane-hydrogen-fumarate; Fludilat) in a concentration of 10-2 M effects an increase in the O2 consumption and the formation of CO2 in a 10% bovine lens homogenate. This effect is even increased if the glucose-substrate supply is raised from 25 mM to 37 mM. Investigations on the concentrations at ATP, ADP and AMP show that bencyclane is able to stabilize the physiologic distribution pattern of the three free adenine nucleotides. Further, the observed changes in the distribution pattern indicated that the fumaric acid rest of bencyclane may serve as a substrate for this reaction in the same way as fumarate.

Adenosine Diphosphate↗
PubMed1976

[Aging of the lens and cataract (author's transl)].

Lens opacities in old patients are usually classified as "senile cataracts". Since there are very distinct morphologic types of opacities it is evident that we have to deal with different types of triggers in discussing the cataractogenesis. A great variety of risk factors might act as triggers for the development of opacities in aged people, and there is no doubt that among them age changes of lens metabolism are the most important. These age induced changes of lens metabolism do not only influence the energy level of lens metabolism (energy concept of lens transparency), the trigger may as well be located within the protein synthesizing system or the processes responsible for maintaining normal protein conformation, further, an exogenous intoxication may also occur. Lack of normal human lenses of all ages suited for metabolic research and an undefined classification for instance, coloration of the cataractous lens) makes biochemical research with respect to the pathogenesis of senile cataracts almost impossible. Animal models (naphthalene cataract, tryptophane-deficiency, X-irradiation) suited for the purpose may well support the basic research of this subject, even if we have to assume certain species differences of lens metabolism.

Aging↗