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Biomedical subjects

R Jäger

Publications and source records attributed to R Jäger.

At least 55 records · Page 3Linked to original sources
PubMed1992

The visual forebrain and eating in pigeons (Columba livia).

The contribution of forebrain structures to the control of visually guided eating behaviors was studied using a technique for reversible 'visual decerebration'. The procedure is based upon the fact that structures in the thalamus and telencephalon receive their visual inputs primarily from the contralateral eye. When the eye contralateral to the ablated hemisphere is occluded, the remaining eye has unilateral access to these structures. When the eye ipsilateral to the ablated hemisphere is occluded, the bird is functionally decerebrate; i.e., visual processing by the remaining eye is restricted to structures caudal to the forebrain. The performance of normal and hemispherectomized subjects under binocular and monocular (unilateral, decerebrate) viewing conditions was compared on tests of ingestive efficiency, identification, conditioned peck localization, and grasping. In normal subjects, differences between right and left eye were not significant on any of these tasks. In hemispherectomized subjects, monocular performance on the first three tasks depended critically upon which eye was occluded. In the decerebrate condition (i.e., when the eye opposite the ablated hemisphere was used) performance on the identification, ingestive efficiency and peck localization tasks was significantly degraded, but grasping was unimpaired. We conclude that the brain structures critical for the visuomotor control of grasping lie caudal to the forebrain.

Animals↗
PubMed1992

Coexpression of CD4 and CD8 on mitogen-activated peripheral blood T cells from children with asthma: possible involvement of interleukin 4.

Mononuclear cells were isolated from the peripheral blood of 28 asthmatic and 18 healthy children aged 3 to 16 years. The cells were stimulated with phytohemagglutinin for 96 hours. Activated cells were detected microscopically by MTT staining. Expression of cell surface antigens was detected by indirect immune fluorescence using CD4-specific and CD8-specific monoclonal antibodies. Results indicate an enhanced expression of CD8 on mitogen-activated T cells from asthmatic children compared with cells from healthy controls (median 43% versus 27%). Further experiments revealed that CD8 is coexpressed with CD4 on activated lymphocytes. Coexpression is significantly enhanced with lymphocytes from asthmatic patients compared with normal controls. In addition, interleukin 4 is able to enhance this coexpression with lymphocytes from healthy but not asthmatic children suggesting an in vivo preactivation of lymphocytes from asthmatic patients with interleukin 4.

Adolescent↗
PubMed1991

Enhanced superoxide generation by eosinophils from asthmatic children.

In 21 asthmatic children, aged 2-19 years, and 11 age-matched controls purified (purity greater than 75%) peripheral blood eosinophils and neutrophils (purity greater than 95%) were stimulated with phorbol myristate acetate (44 ng/ml) for 30 min at 37 degrees C. The superoxide generation was determined as well as the superoxide dismutase inhibitable cytochrome c reduction. Eosinophils obtained from asthmatic patients displayed a significantly higher O2- generation (p less than 0.01) when compared to neutrophils from the same patients or to eosinophils and neutrophils from healthy controls. Preincubation with human recombinant granulocyte macrophage colony stimulating factor for 30 min or platelet-activating factor for 10 min resulted in augmented O2- generation by eosinophils from control, but not from asthmatic children, indicating a possible in vivo priming of eosinophils in asthma.

Adolescent↗
PubMed1991

[Inter- and intra-individual variability of pharmacokinetic parameters for contraceptive steroids].

Serum levels of ethinylestradiol (E2) and levonorgestrel (LNG) have been determined in 10 volunteers of similar age after administration of 1 tablet of the oral contraceptives Gravistat and Ediwal, respectively, each containing 0.05 mg E2 and 0.125 mg LNG, using a cross over design. The studies were carried out at intervals of 4 weeks, within the follicular phase of the menstrual cycle and under standardized conditions. Wide variations were observed between the women in the calculated pharmacokinetic parameters, while there was a relatively close correspondence between the intra-individually obtained values, except for one case.

Adult↗
PubMed1990

Visuomotor feeding perturbations after lateral telencephalic lesions in pigeons.

Pigeons with lesions of the lateral part of the telencephalon, visual Wulst, and fronto-archistriatal tract were compared with sham-operated controls in 2 procedures. In one of them the time it took the pigeons to grasp and eat a certain number of grains was recorded. In the other experiment the number of grains was counted that the pigeons consumed out of a mixture of grains and pebbles within a fixed time interval. Only the pigeons with lateral telencephalic lesions were impaired. While in the first experiment the lateral ablated birds improved with time there was no recovery of performance in the second experiment.

Afferent Pathways↗
PubMed1990

Wallstent endoprostheses for the relief of prostatic urethral obstruction in high risk patients.

Twenty-one patients with prostatic urethral obstruction who were unfit for surgery were treated with self-expandable stainless steel endoprostheses inserted under fluoroscopic guidance. The procedure was technically successful in all patients, although in one case a second stent was required 2 months later. One patient developed a urethral stricture in the 12-16 month follow up period. One case of epididymoorchitis and one case of septicaemia after stenting were treated successfully with antibiotics. Endoprostheses represent a satisfactory alternative to prostatectomy in high-risk patients.

Aged↗
PubMed1990

Amino Acid Transport across the Tonoplast of Vacuoles Isolated from Barley Mesophyll Protoplasts : Uptake of Alanine, Leucine, and Glutamine.

Mesophyll protoplasts from leaves of well-fertilized barley (Hordeum vulgare L.) plants contained amino acids at concentrations as high as 120 millimoles per liter. With the exception of glutamic acid, which is predominantly localized in the cytoplasm, a major part of all other amino acids was contained inside the large central vacuole. Alanine, leucine, and glutamine are the dominant vacuolar amino acids in barley. Their transport into isolated vacuoles was studied using (14)C-labeled amino acids. Uptake was slow in the absence of ATP. A three- to sixfold stimulation of uptake was observed after addition of ATP or adenylyl imidodiphosphate an ATP analogue not being hydrolyzed by ATPases. Other nucleotides were ineffective in increasing the rate of uptake. ATP-Stimulated amino acid transport was not dependent on the transtonoplast pH or membrane potential. p-Chloromercuriphenylsulfonic acid and n-ethyl maleimide increased transport independently of ATP. Neutral amino acids such as valine or leucine effectively decreased the rate of alanine transport. Glutamine and glycine were less effective or not effective as competitive inhibitors of alanine transport. The results indicate the existence of a uniport translocator specific for neutral or basic amino acids that is under control of metabolic effectors.

Journal Article↗
PubMed1990

[Pharmacokinetics of ethinyl estradiol following the administration of combination contraceptive preparations].

A radioimmunoassay for ethinylestradiol (EE2) which was developed in the pharmacological department of VEB Jenapharm has been modified and fully validated. It was the purpose of the present study to extend the still limited data concerning EE2-serum levels after a single and repeated ingestion of combination pills with different doses of EE2. 10 volunteers aged 17-25 years with normal body weight and length received a single tablet of either Gravistat (0.05 mg ethinylestradiol + 0.125 mg levonorgestrel) or Minisiston (0.03 mg ethinylestradiol + 0.125 mg levonorgestrel). 11 other women were involved into the study after ingestion of the 21st tablet of a contraceptive cycle. Peak serum levels which were significantly higher in the Gravistat- than in the Minisiston-group were observed 90 to 120 minutes after the oral administration. Detectable EE2 levels were determined in all volunteers after 24 hours. Pharmacokinetic data showed pronounced interindividual variations. Whereas the mean 24 hours levels of EE2 increased progressively during the treatment cycles, kinetic values obtained at the end of the cycle exhibited a significantly higher level than those after ingestion of a single dose. Area under curve (AUC) was calculated by the trapezoidal rule with the aid of a compartment free model.

Adolescent↗
PubMed1989

[The behavior of cytoplasmic progesterone receptors in the cycling endometrium and the effect of hormonal contraceptives].

Concentration of cytosolic progesterone receptor (PR) was measured by means of an exchange procedure in the endometria of 80 women. Investigations carried out in 35 normal menstruating females showed a gradual increase of PR during the preovulatory and immediate postovulatory phases, decreasing to the lowest level at the end of the cycle. Measurements in endometrial samples obtained from women on combined hormonal contraceptives demonstrated a significant decline of PR concentration in the periovulatory phase resulting in a flattening of the sinusoid PR concentration curve. The stronger down regulation effect of the preparation containing 1.5 mg of dienogest is due to the higher progestogenic efficacy of dienogest in the respective dosage. We consider the down regulation phenomenon a useful means among others to characterize the progestogenic potency of a steroid.

Adult↗
PubMed1988

Biochemical effects of methyl chloride in relation to its tumorigenicity.

The biochemical effects of methyl chloride were investigated in tissues of F-344 rats and B6C3F1 mice (both sexes). Activities of GST were 2-3 times higher in livers of male B6C3F1 mice, compared with those of female mice, and with rats of both sexes. In kidneys GST activities of (male) mice were about 7 times lower than those found in livers. The activity of FDH was higher in livers of mice (both sexes) than in those of rats. No obvious sex difference was found in livers of rats and mice with respect to FDH. In kidneys, however, (minor) differences in FDH activities occurred between male and female B6C3F1 mice (4.7 vs. 3.1 nmol/min per mg). Sex differences of FDH activity in kidneys were not observed in F-344 rats. The microsomal transformation (by cytochrome P-450) of methyl chloride and S-methyl-L-cysteine to formaldehyde in tissues of B6C3F1 mice occurred preferentially in the liver. More formaldehyde was produced in liver microsomes of male, compared to those of female mice. Kidney microsomes metabolized methyl chloride to formaldehyde much less than liver microsomes. After a single exposure of mice of both sexes to 1000 ppm methyl chloride no elevation in formaldehyde concentrations was observed in livers and kidneys ex vivo. The determination of DNA lesions, using the alkaline elution technique, revealed no DNA-protein crosslinks in kidneys of male B6C3F1 mice after exposure to methyl chloride (1000 ppm, 6 h day-1, 4 days) and gave only minor evidence of single-strand breaks. Lipid peroxidation (production of TBA reactive material), induced by single exposure to methyl chloride (1000 ppm, 6 h), was very pronounced in livers of male and female mice. Smaller increases in peroxidation were observed in the kidneys of exposed mice. The theory that renal tumors observed in male mice after chronic exposure of the test animals to high (1000 ppm) concentrations of methyl chloride, are evoked by intermediates and in situ produced formaldehyde is proven unlikely by our results.

5-Methylcytosine↗
PubMed1988

Levels of plasminogen activator inhibitor in patients with angina pectoris.

Levels of plasminogen activator inhibitor type 1 (PAI) were measured in 180 patients with angina pectoris (148 males and 32 females, age range 29 to 70 years). An age-matched normal population served as a control. PAI was determined by a functional titration assay, its activity was expressed as arbitrary units (AU). PAI levels were significantly (P less than 0.005) higher in patients with angina (24.3 +/- 10.3 AU/ml) than in normals (20.4 +/- 4.6 AU/ml). PAI levels were unrelated to sex or age in both the patient and the control groups. Plasma triglyceride levels were correlated to PAI in patients and in normals. Patients with a history of previous myocardial infarction (n = 114) had similar PAI levels as patients without infarction (24.2 +/- 11.1 AU/ml as compared to 24.4 +/- AU/ml). It is concluded that PAI levels are elevated in patients with coronary heart disease, whether myocardial infarction has taken place or not.

Adult↗
PubMed1986

[Combination of bilateral idiopathic necrosis of the femoral and humeral heads--initial report of a syndrome].

The authors report on a patient of 31 years of age with bilateral necroses of the head of the femur and of the humerus. Internistic and neurological examinations did not yield any pointer to an existing symptomatic bone necrosis, so that this case--not described in literature so far--represents an aseptic, idiopathic necrosis of both femoral and humeral heads. The findings obtained with plain radiography, computed tomography, selective angiography of the femoral head and magnetic resonance tomography are presented.

Adult↗
PubMed1984

Lateral telencephalic lesions affect visual discriminations in pigeons.

The importance of the lateral telencephalon of the pigeon for visual performance was examined. Lesions in this area markedly impaired both the acquisition and the retention of instrumentally learned hue, intensity and pattern discriminations. Comparable lesions of the thalamofugal visual projection in the dorsoanterior telencephalon did not have an appreciable effect. Laterally lesioned pigeons showed only a minor, non-significant impairment in an instrumental auditory discrimination task. These results generally agree with findings of other authors on domestic chicks but disagree with previous work on pigeons. The visual discrimination performance of laterally lesioned subjects improved gradually over the course of days and weeks without specific experience being necessary, and after 3 months the recovery was virtually complete. The effect of lateral telencephalic lesions is discussed in connection with known visual projections within the avian endbrain and their relationship with other functional systems.

Animals↗
PubMed1984

[Experimental conditions for embolization treatment of renal hypertension].

An experimental study was carried out on 146 rats with hypertension in order to determine whether the intensive collateral circulation which develops in reno-vascular hypertension is responsible for the high failure rate following clinical embolisation. Ethibloc embolisation, which fills the capillaries, is as effective as nephrectomy, whereas ligature of the renal artery fails to affect the hypertension.

Animals↗
PubMed1983

[CT findings in calcified pseudotumors in hemodialysis patients].

Three patients undergoing haemodialysis, who had extensive calcified pseudo-tumours, were examined by computer tomography. In two patients bone destruction was present, which was obscured by the calcification on conventional radiographs. In one patient an abscess in the vicinity of the pseudo-tumour was discovered by CT. CT enables exact localisation of the calcified areas to be achieved and aids therapy.

Abscess↗