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Biomedical subjects

E Ebert

Publications and source records attributed to E Ebert.

At least 19 recordsLinked to original sources
PubMed1999

Biphasic effects of melatonin on the propagation of excitation waves in the chicken retina.

The retinal spreading depression (SD) is a propagating wave in an excitable medium, the neuronal tissue of the retina. Its velocity is about 3 mm/min and it is accompanied by a variety of changes in the tissue, including electrical and optical events. The pronounced intrinsic optical signal (IOS) of the retinal SD makes it an extremely versatile tool for the investigation of the action of drugs on neuronal tissue and more specific on propagating excitation waves in neuronal tissue. Furthermore, in the last decade increasing evidence has been collected, which shows that SD waves are the basic mechanism of the aura in classical migraine. We have investigated the influence of melatonin on the propagation of retinal SD waves as it has been postulated to have protective effects on neuronal tissue. The results demonstrate that melatonin indeed slows down the retinal SD, however, only in a defined concentration range. Additionally, it changes the IOS of the wave.

Animals↗
PubMed1999

[Surgical treatment of cardiovascular manifestations of Marfan's syndrome].

Patients with Marfan's syndrome suffer mainly from the cardiovascular manifestations of the disease, in particular the acute dissection or rupture of the dilated aorta. Due to improved diagnostic and early surgical intervention the life expectancy of these patients could be considerably improved. However, rupture is still the most frequent and dissection the second frequent cause of death. Life threatening complications of aortic dissection are pericardial effusion, aortic insufficiency and malperfusion syndrome, due to obstruction of aortic branches. Dissection of the ascending aorta is treated by implantation of a valved conduit with reimplantation of the coronary arteries. Some surgeons favor the complete replacement of the ascending aorta with preservation of the aortic valve, although long-term results show some development of aortic insufficiency after this procedure. Based on the experience of the last years, most surgeons prefer the prophylactic replacement of the aorta in Marfan patients, i.e. before complications have occurred. A special treatment algorithm helps to define the indication for the operative treatment in different manifestations of the disease. The low mortality of the elective replacement of the ascending aorta in contrast to replacement in emergency cases speaks in favor of the early operative treatment. For the long-term prognosis of the patient a closed and continuous cardiologic surveillance is mandatory. The patient should be close to a center with the necessary diagnostic tools and with sufficient experience with the medical and surgical treatment, in order to further improve the life expectancy in the future.

Aortic Dissection↗
PubMed1999

Development and prevalidation of two different ELISA systems for the potency testing of Clostridium perfringens beta and epsilon-toxoid containing veterinary vaccines.

The potency testing of Clostridium perfringens mono- and multicomponent veterinary vaccines is currently performed with the mouse neutralisation test (MNT) to estimate levels of C. perfringens beta- and epsilon-antitoxin levels in the sera of rabbits immunised with the vaccine. Two in vitro methods based on monoclonal antibodies (mAb) have been developed for the determination of specific antibodies against C. perfringens beta-toxin (capture ELISA) and epsilon-toxin (competitive ELISA) in these sera. Both test systems show high specificity and good reproducibility. These ELISA procedures were used in addition to the routine batch potency test in mice (MNT) to determine beta- and epsilon-antitoxin levels in 523 samples of rabbit serum. There was good agreement between the rank order of sera determined in vivo and the rank order determined in vitro. Linear regression analysis gave correlation coefficients of 0.88 for the capture ELISA and 0.41 for the competitive ELISA, with a significance level of P < 0.01 in both cases. Furthermore, a prevalidation study was carried out in four laboratories to evaluate the transferability of the ELISA procedures and the interlaboratory reproducibility of the results. Three coded serum samples were tested several times. The results indicated that both ELISA systems are suitable candidates to replace the MNT used for the potency testing of beta- and epsilon-toxoid in mono- and multicomponent veterinary vaccines. However, these assays still need to be validated in an international collaborative study.

Animals↗
PubMed1999

Tegula function during free locust flight in relation to motor pattern, flight speed and aerodynamic output

Tegulae are complex proprioceptors at the wing base of locusts. Deafferentation of the tegulae causes a lack of specific phasic information related to the wing downstroke and the timing of the upstroke. Employing telemetry during free flight of the locust Schistocerca gregaria, we investigated the consequences of tegula ablation on free flight parameters including motor patterns (wingbeat frequency and the relationship between the activation of flight muscle antagonists), free flight speed and aerodynamic output. We investigated the role of the tegula pairs of both wings on the motor pattern generated in free-flying locusts. We show that the tegula organs are not essential for generating the motor patterns necessary for free flight. However, they are required for increasing the motor output to give additional effective lifting power during adaptive behaviour. We also investigated long-term changes in the free flight parameters after tegula ablation. The recovery of the adult flight system revealed in the present study suggests that there is adaptation to the loss of proprioceptive information; this argues for a full functional and behavioural recovery of the flight system of the locust under closed-loop conditions.

Journal Article↗
PubMed1997

Expression of cysteine protease inhibitors stefin A, stefin B, and cystatin C in human lung tumor tissue.

In human lung tumor tissue specimen (n = 73) concentrations of stefins A and B were found to be increased 2.0-fold (p < 0.01) and 1.3-fold (p < 0.01), respectively, as compared to matched normal tissue. Stefin A and B concentrations were higher in primary tumors than in secondary tumors, i.e. metastases from other organs to the lung (p < 0.01; p < 0.05, respectively). Cystatin C concentrations were rather low and did not differ between tumor and normal tissue. Both concentrations of stefins did not correlate with TNM stages. Stefin A was higher in squamous cell carcinoma than in adenocarcinoma (p < 0.01), while stefin B did not show such a difference. At investigation of a relationship between survival probability of patients with primary tumors it was found that increased stefin B concentrations and total cysteine-protease-inhibitory activities but not stefin A concentrations were positively correlated with survival probability. It is concluded that stefins A and B are major contributors to the cysteine protease inhibitory activity in primary lung tumors. Stefin B proved to be a prognostic factor, especially in squamous cell carcinoma.

Adolescent↗
PubMed1995

Chronic toxicity and carcinogenicity studies with the insecticide endosulfan in rats and mice.

The insecticide endosulfan was evaluated for chronic toxicity and carcinogenicity in long-term feeding studies in both Sprague-Dawley rats and NMRI mice. Dietary concentrations of the test substance were administered to rats at 0, 3, 7.5, 15 and 75 ppm and to mice at 0, 2, 6 and 18 ppm for 24 months each. In the rat study, only the treatment with the highest dose caused a significant reduction of body weight gains of the males and females at 75 ppm. The increased incidence of enlarged kidneys seen at autopsy at 75 ppm in females, and the slightly increased incidence of progressive glomerulonephrosis and slightly increased incidence of renal aneurysms seen histopathologically in the 75 ppm males, make the kidney the target organ in rats. On the basis of these findings a dietary concentration of 15 ppm is considered to be the no-observed-effect level (NOEL) in rats, equivalent to a daily test substance intake of 0.6 mg/kg body weight in males and 0.7 mg/kg body weight in females. In the mouse study, the treatment with 18 ppm caused a significant increase of mortality in the females and a slight (in the first third of the study, significant) reduction of body weight gain in males. Since there were no other substance-related findings, the dietary concentration of 6 ppm is considered to be the NOEL in mice, equivalent to a daily test substance intake of 0.84 mg/kg body weight in males and 0.97 mg/kg body weight in females. An evaluation of all relevant tumour data gained in both studies revealed no differences between control and treated groups. It was concluded, therefore, that endosulfan has no carcinogenic potential.

Administration, Oral↗
PubMed1995

Composition of TCR-CD3 complex in human intestinal intraepithelial lymphocytes: lack of Fc epsilon RI gamma chain.

Human intestinal intraepithelial lymphocytes (iIEL) are a unique population of predominantly CD8 alpha beta+, TCR alpha beta+ lymphocytes and, to a lesser extent, TCP gamma delta+ lymphocytes that proliferate poorly to anti-CD3 mitogenic signals but display significant cytolytic activity. Studies in mouse model systems have shown that the gamma chain of the high-affinity receptor for IgE (Fc epsilon RI gamma) may substitute for the zeta chain in the TCR-CD3 complex of iIEL. This has suggested that the functional properties of these cells may be associated with an altered composition of the TCR-CD3 complex. We therefore analyzed the TCR-CD3 complex of normal human iIEL. One- and two-dimensional non-reducing/reducing SDS-PAGE analysis of CD3 gamma, CD3 delta, CD3 epsilon, zeta and Fc epsilon RI gamma chain immunoprecipitates of cell surface radiolabeled proteins with subunit-specific antibodies revealed a TCR-CD3 complex without associated Fc epsilon RI gamma chains. Thus, normal human iIEL contain a TCR-CD3 complex that consists predominantly of zeta homodimers in association with the alpha beta TCR and CD3 gamma, delta and epsilon, similar to the majority of peripheral lymphocytes. This indicates that the distinct properties of human iIEL are not associated with substitutions of the Fc epsilon RI gamma chain in the TCR-CD3 complex.

Animals↗
PubMed1994

Glufosinate ammonium--some aspects of its mode of action in mammals.

The broad-spectrum herbicide glufosinate ammonium is a structural analogue of glutamate and acts in plants by inhibition of glutamine synthetase leading to a complete breakdown of ammonia metabolism. Owing to the structural analogy of glufosinate ammonium to glutamate, its effect on various glutamate-utilizing systems needed to be investigated in mammals. Although in laboratory animals glufosinate ammonium causes an inhibition of glutamine synthetase activity in different tissues, this inhibition led to slight increases of glutamate and ammonia levels at high sublethal and lethal doses only. After oral administration for 28 days, glufosinate ammonium had no effect on glutathione and carbohydrate metabolism and no effect on biosynthesis of non-essential amino acids in rats and dogs. Glufosinate ammonium does not interfere with various neurotransmitter receptors in vitro and does not influence the catecholamine neurotransmitter tissue concentrations after iv application. The results of these studies show that--in contrast to the plant metabolism--in mammals the inhibition of glutamine synthetase activity in various tissues does not lead to a breakdown of ammonia metabolism. The mammalian metabolism obviously compensates for this inhibition of glutamine synthetase activity by various other metabolic pathways. It is concluded that under the conditions of recommended use of glufosinate ammonium as an active ingredient in herbicides, a detrimental effect on the health of both users and consumers is extremely unlikely.

Administration, Oral↗
PubMed1993

Effects of bis(tri-n-butyltin)oxide in Japanese quail exposed during egg laying period: an interlaboratory comparison study.

The guideline no. 206 for testing of chemicals of the Organization for Economic Cooperation and Development (OECD) comprising an avian reproduction test using the Japanese quail (Coturnix coturnix japonica; Termminck and Schlegel 1849) as pair-hold test organisms has been applied in a version that reduced the treatment period to 6 weeks without any pretreatment. In the present study bis(tri-n-butyltin)oxide, C.A. No. 56-35-9 (tributyltin oxide, TBTO) was examined by five participants in an interlaboratory comparison test. A comparable regimen of dosing was performed by all participants starting either with 24 or 60 mg/kg TBTO in the feed and ending with 150 or 375 mg/kg. Within this dose range no signs of toxicity in adults were observed. Substance-related effects however were obvious with regard to egg production, fertility, hatching success, and survival of 14 day-old chicks. A clear dose dependency was given regarding effects on egg weight and on hatchability. The no-observed-effect concentrations for these two parameters was 60 mg/kg TBTO, characterizing these parameters as the most sensitive in this investigation. With the presented set of test parameters further aspects of subchronic toxicity in adults and chicks can be assessed as well as the validity of the performed test. Comparing the results for most test parameters consistency is obvious, thus confirming the applicability of the presented test guideline.

Animals↗
PubMed1992

Toxicology and hazard potential of trifluralin.

This paper reviews the results of toxicity studies conducted in laboratory animals to evaluate the safety of the herbicide trifluralin (TFL). The data show that TFL is slightly toxic following single oral exposure. Testing for embryotoxicity in rats and rabbits indicated no teratogenic potential, and many different mutagenicity tests showed that TFL was non-genotoxic. Subchronic and chronic toxicity testing in rats, mice and dogs indicated that TFL was haematotoxic (anaemia and methaemoglobinaemia), particularly in the dog, and slightly hepatotoxic. No-observed-effect levels of 4.8 and 41 mg/kg body weight/day, respectively, were determined in dogs and rats exposed chronically to TFL. Oncogenicity studies in rats and mice revealed no carcinogenic potential. Since the data for TFL indicated no mutagenic or other special toxicological risks, it is suggested that a safety factor of 100 could be used for the determination of the acceptable daily intake of TFL, which would be 0.05 mg/kg body weight/day.

Administration, Oral↗
PubMed1990

Summary of safety evaluation toxicity studies of glufosinate ammonium.

This article reviews the results of toxicity studies to evaluate the safety of the herbicide glufosinate ammonium (GLA) and its formulation (200 g/litre) in laboratory animals. The data show that GLA and its formulation are slightly toxic following oral exposure. In addition, the formulation induced GLA and its formulation are slightly toxic following oral exposure. In addition, the formulation induced slight dermal toxicity and eye irritation. Testing for teratogenicity in rats and rabbits indicated no teratogenic potential, and numerous mutagenicity tests showed GLA to be non-genotoxic. Chronic toxicity testing in rats and dogs yielded no-observable-effect levels of 2 and 5 mg/kg body weight/day, respectively. Oncogenicity studies in rats and mice revealed no carcinogenic potential. On the basis of these toxicity data it is concluded that this herbicide is safe under conditions of recommended use.

Aminobutyrates↗
PubMed1990

The dural shunt syndrome. I. Management of glaucoma.

The authors present four cases of the dural shunt syndrome in which shallowing of the anterior chamber or rubeosis developed. All patients were female, ranging in age from 66 to 79 years, exhibiting elevated intraocular pressure (IOP), decreased extraocular movements, injected tortuous episcleral vessels, and proptosis. The authors managed these four cases with laser iridotomy, gonioplasty, panretinal photocoagulation, or medical treatment. It is important to recognize associated findings in patients with shallow anterior chambers and elevated IOPs so that a diagnosis of a dural shunt is considered and appropriately treated. Theories on the mechanisms of increased IOP in the dural shunt syndrome and the management of various types of glaucoma in four different cases are reviewed.

Aged↗
PubMed1989

Increased scleral rigidity and age-related macular degeneration.

The coefficient of scleral rigidity of the eyes of 29 patients with age-related macular degeneration (ARMD) was significantly higher than the rigidity of 25 control patients, frequency matched for age. The data suggest that an increased scleral rigidity may be a significant risk factor for the development of the disorder.

Aged↗
PubMed1989

Growth of abused children. Contrasted with the non-abused in an urban poor community.

While the identification of a growth-retarded or otherwise undernourished child suggests a diagnosis of child abuse or neglect, it is not certain that abused children from poor communities are less well nourished than children living in similar environments. The setting of this study--day care centers in an urban poor city--provided an opportunity to make this comparison with appropriate community-based controls. Measures of height, weight, and weight/height (Body Mass Index (BMI] were compared for 196 children, 2 to 6 years of age, 53 of whom were victims of physical abuse. The data was adjusted for age, sex, and ethnicity using logistic regression analysis to determine occurrence of wasting (weight for height less than 5th percentile) and stunting (height for age less than 5th percentile). Significantly more abused children (16.3%) showed wasting as compared to non-abused (0.7%) with abused children 16.6 times more likely to show wasting than non-abused (95% confidence limits on the Odds Ratio 1.9-145.0). While 11.6 percent of abused children showed stunting compared to 5.6 percent of non-abused, this difference was not significant when the data was adjusted for demographic factors. The BMI (15.02 kg/m2) for abused children was significantly less than that (15.9 kg/m2) for non-abused children (F = 8.11; p = 0.0049). In the present study, significant wasting as seen in acute malnutrition was found among abused children at diagnosis, suggesting that within an urban poor community the growth of children so identified does differ from the growth of children who are not abused.

Child↗
PubMed1986

Defective interleukin-2 production and responsiveness by T cells in patients with chronic lymphocytic leukemia of B cell variety.

The present studies were designed to investigate the mechanism(s) of the defective T cell proliferative response to various stimuli in patients with B cell chronic lymphocytic leukemia B-CLL. In 14 patients with advanced B-CLL (stage III or IV) we found the T cell response in the autologous (auto) and allogeneic (allo) mixed lymphocyte reaction (MLR) to be 35.7% and 30% of the controls, respectively. Proliferation in the MLR depends upon the production of and response to interleukin 2 (IL 2), a T cell growth factor. IL 2 production in eight B-CLL patients was 22% of the control. The response to IL 2 was measured by the increase in the T cell proliferation in the MLR with the addition of IL 2. T cell proliferation in both the auto and allo MLR of CLL patients was significantly lower than in the controls after the addition of IL 2. The proliferative response of normal T cells to stimulation by CLL B cells was 50% of the control. This latter response was increased to control levels when cultures were supplemented with exogenous IL 2, suggesting that CLL B cells could stimulate IL 2 receptor generation in normal T cells in an allo MLR, but not IL 2 production. The presence of IL 2 receptors on activated T cells was directly determined using anti-Tac, a monoclonal antibody with specificity for the IL 2 receptor. Of the mitogen- or MLR-activated T cells in CLL patients, 6% and 10%, respectively, expressed Tac antigen, whereas identically stimulated control T cells were 60% and 47% Tac+, respectively. Our findings suggest that T cells in B-CLL are defective in their recognition of self or foreign major histocompatibility antigens as demonstrated by their impaired responsiveness in the MLR. Thus, these cells are unable to produce IL 2 or generate IL 2 receptors.

Antibodies, Monoclonal↗
PubMed1980

[Use of solubilization for the preparation of samples for determination of heavy metals in biological materials using atomic absorption spectrophotometry].

Solubilisation was tested for its suitability to prepare organic samples for metal determination. Flameless atomic-absorption spectrophotometry was used as test method. Copper, manganese, zinc, and chromium levels were determined from various organ systems of Wistar rat, in response to "normal" feeding of pelletised standard feed. A comparison between experimentally established concentrations, on the one hand, and literature data, on the other, suggested that solubilisation was applicable with good success to the preparation of samples from which to determine reliable values, in ppm and ppb, of the above elements.

Animal Feed↗
PubMed1980

[Control of trace elements in the rat using the heavy metal antidote "Unithiol" (sodium-2,3- dimercaptopropane sulfonate)].

The trace element balance in laboratory rats was found to be affected by somewhat lasting application of "Unitiol". Unambiguous decline of manganese, copper, and zinc concentrations was recorded from blood and liver. Complex fixation of copper was stronger than that of the other elements tested. No dose-dependent changes were observed with the experimental arrangement described. The chromium levels in all examined organs were affected but slightly or not at all. The proposal is made that long-term therapeutic use of chelate formers should be accompanied by properly balanced application of essential trace elements.

Animals↗