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Biomedical subjects

A Müller

Publications and source records attributed to A Müller.

At least 487 records · Page 27Linked to original sources
PubMed1989

[Parameters of nitrogen metabolism for male broilers of Tetra 82 descent].

In several growth and N-balance experiments with male broilers of the genotype Tetra 82 the course of live weight and parameters of N-metabolism were investigated. Semi-synthetic feed mixtures of different protein concentration but equal protein quality (protein mixture: 70% soybean meal and 30% fish meal) were used in the trials. Data from N-balance investigations were reckoned up in the N-turnover model from Gebhardt (1963). The course of maximum (N-balance plus endogenous N-loss) capacity in dependence on live weight was regressive calculated. Based on this regression a possibility of calculation of efficiency depended protein and amino acid requirement for the whole fattening period in dependence on live weight, protein intake and protein quality (A.b) was illustrated.

Age Factors↗
PubMed1989

Peripheral QCT: a low-risk procedure to identify women predisposed to osteoporosis.

A low-risk procedure is described for the precise quantitation of changes of trabecular and cortical bone density at peripheral measuring sites. The method is based on quantitative computed tomography (QCT). Bone parameters are calculated for a sample volume common to all examinations of a patient. This is achieved by matching stacks of tomograms according to the cross sectional area of the bone measured. With the help of a special-purpose CT system the described procedure enables a reproducibility for trabecular and cortical bone parameters of 0.3% (1 SD) at a local radiation dose of 0.1 mSv (10 mrem). The method was used to assess the individual changes in bone density of 39 perimenopausal women during an observation period of 2 to 3 years. The results are grouped according to their menstrual state. Regularly menstruating women experience minute or no changes in bone density. After menopause the interindividual differences are considerable: some women lose bone excessively, others remain relatively stable. The frequency distribution of the rate of bone loss appears to be bimodal. Hence women can be classified in fast losers and slow losers. We conclude that the rate of bone loss may be most helpful in the identification of those women predisposed to osteoporosis.

Disease Susceptibility↗
PubMed1989

Oxygen affinity of haemoglobin modulates cerebral blood flow in premature infants. A study with the non-invasive xenon-133 method.

Low cerebral blood flow (CBF) is thought to cause ischaemic brain lesions in premature infants, but a normal outcome has also been observed. Low oxygen affinity of haemoglobin and high arterial oxygen content, independently, reduce CBF under normal, physiological conditions. Transfusions lower the amount of fetal haemoglobin [HbF] and therefore the oxygen affinity of premature babies. In 47 premature babies (range of gestational age 25-34 weeks, birthweight 740-1370 g), CBF was measured with the i.v. Xenon 133 method on days 1, 3 and 7. The relative amount of fetal haemoglobin [HbF] was used as a marker of oxygen affinity of haemoglobin and the haematocrit as representing the arterial oxygen content. A significant influence of [HbF] on CBF was found on days 1, 3 and 7 in ultrasonographically normal babies (n = 13). In babies with subependymal and/or intraventricular haemorrhage (n = 15), this correlation was significant only on day 3 and in those with abnormal intraparenchymal echodensities (n = 19) only on day 7. The correlation between haemoglobin concentration and CBF was not significant. Multiple regression analysis showed a significant influence of [HbF] on CBF independent of haematocrit, pCO2 and blood pressure. It appears that, after blood transfusion, normal babies, and to a lesser extent those with haemorrhages are able to lower their CBF according to the actual oxygen affinity of blood. However, low CBF (less than 10 ml/100 g/min) in non-transfused babies was often associated with later development of cystic periventricular leukomalacia.)

Blood Gas Analysis↗
PubMed1989

[Improving the reproducibility of bone marrow culture by means of a salt-conditioned medium as a definite source of colony-stimulating activity].

Bone-marrow stem cell culture allows an insight into the regulatory system of normal and disturbed haemopoiesis. However, the prerequisite for it is that defined conditions of cultures are created. One step in this direction is the application of conditional media as a source of colony stimulating activity. The capacity of various conditioned media to stimulate proliferation and differentiation of human bone-marrow cells was examined and compared with the traditional feeder technique. In this respect the addition of 15% of umbilical cord conditioned medium proved to be well suited to achieve reproducible results.

Bone Marrow Cells↗
PubMed1989

Status of allogeneic bone marrow transplantation in childhood in the GDR.

Of 25 HLA-identical, MLC negative transplants 10 patients had acute lymphoblastic leukaemia (ALL), 8 acute nonlymphoblastic leukaemia (ANLL), 3 severe aplastic anaemia, 2 malignant histiocytosis, 1 patients neuroblastoma and 1 Fanconi anaemia. 3 HLA nonidentical, MLC positive transplants were performed, two children had malignant infantile osteopetrosis and 1 child had a severe combined immunodeficiency disease. Patients with ALL and ANLL received cyclophosphamide and single dose total body irradiation. 3 patients received fractionated TBI. The results for the allogeneic group overall indicate that the actuarial disease free survival rate is 0.62. 16 of 25 patients are in continuous complete remission (CCR) periods of 3-78 months posttransplant. All three transplanted children with severe aplastic anaemia alive disease-free for periods of 21-81 months. 10 patients with ALL were transplanted (2 in first remission for high risk ALL, 8 in second remission). 7 of 10 patients are alive and disease-free (CCR rate 0.67). 8 patients underwent BMT for ANNL while in first remission in 7 patients and in third partial remission in 1 patient. 4 of 8 patients are alive and disease-free for periods of 25-56 months (CCR rate 0.50). 1 patient with neuroblastoma stage IV survives 24 months, 1 child with Fanconi anemia died on day +25 of GVHD and septicaemia. 1 of the 2 patients transplanted for malignant histiocytosis relapsed 3 months posttransplant, 1 patient is alive and disease-free 5 months posttransplant. In none of the HLA-nonidentical and MLC positive transplantations T-cell depleted marrow engrafted.

Adolescent↗
PubMed1989

Transplantation of major AB0-incompatible bone marrow: removal of red cells by dextrane sedimentation.

The elimination of erythrocytes by dextran sedimentation is a useful method to prevent haemolytic complications after AB0-incompatible bone marrow transplantation. The procedure presented here lasts only 1.5-2 hours, is high reproducible and safe in respect of infections. The mean recovery of nucleated cells amounted to 94%. The contamination with erythrocytes is low (recovery 1.1%). We have never seen haemolytic reactions during 7 AB0-incompatible bone marrow transplantations.

ABO Blood-Group System↗
PubMed1989

[Erythropoietin--a review].

Erythropoietin is one of the members of the growth factor family. It is a glycoprotein. The sialic acid residues of the carbohydrate part prevent the elimination of the molecule from the circulation. The protein moiety is responsible for its biological activity. The main locus of synthesis of erythropoietin is the kidney, but there exist different concepts about its exact localisation. Most of the erythroid cells will be influenced by erythropoietin, except of the erythrocytes, which do not bind this factor. Besides short latency effects like the stimulation of the hemoglobin synthesis, there also occur long latency effects like the stimulation of the synthesis of different membrane proteins.

Animals↗
PubMed1989

[The conditions and clinical feasibility of technics of bone marrow stem cell culture].

The clonal culture of bone marrow cells is a usefull method for the investigation of the normal and the disturbed haemopoiesis. In the field of bone marrow purging for autologous bone marrow transplantation and T-cell elimination for GVHD-prophylaxis, the bone marrow culture is used to control the bone marrow processing. The use of pure CSF-preparations and cell separators make this technique well reproducible.

Bone Marrow Cells↗
PubMed1989

Vascular relaxing effects of bumetanide.

Bumetanide reduced basal tension of resting carotid arteries as well as tonic contraction elicited by 36 mM of KCl, KNO3 and 0.1 mM norepinephrine but had little effect on phasic response to norepinephrine and angiotensin II. Bumetanide was much more active against norepinephrine than KCl, KNO3 and its effect was not reduced by propranolol. These findings establish a distinction between bumetanide and the Ca antagonists, which do not affect basal tension but selectively inhibit potassium (K+) contracture. On the contrary, this compound resembles the nitrocompounds in that vascular relaxation does not require the integrity of endothelium but is abolished by methylene blue. These two common traits support the view that the increased synthesis of cyclic GMP secondary to guanylate cyclase activation may be directly involved in the vasodilating properties of the drug.

Angiotensin II↗
PubMed1989

[Resorption and biotransformation of model substances in primary idiopathic hemochromatosis (siderophilia)].

In 12 patients with primary idiopathic haemochromatosis absorption and biotransformation were measured by model substances. Aim of the investigation was the correlation of the biotransformation of the liver with the degree of liver injury and the clinical picture. We determined in patients and compared with control group: elimination of metamizol in urine, absorption and elimination of caffeine in serum, serum concentrations and elimination of sulfamethazin in urine, absorption of xylose, - In patients with haemochromatosis accompanied with slight liver damage only demethylation of metamizol was slackened. In patients with higher degree of liver damage the elimination of metamizol as well as of caffeine was decreased. Because of the high percentage of slow acetylators in the patient group metabolism of sulfamethazine is decreased. - There was no correlation between iron loading of the organism, absorption of xylose and biotransformation of the model substances.

Adult↗
PubMed1989

[Application of information technology in orthodontics. 1. Necessity, possibilities and prospects for use of task-orientated computers, for example the PC 1715].

There is an urgent need to make use of modern information technology with fourth generation computers, which is also relevant to orthodontic practice. Properties of the PC 1715--small, user-friendly and cost-effective--make it seem particularly suited to this purpose. Possible areas of application and technical parameters are described.

Computers↗
PubMed1989

[The effect of chronic aluminum loading on lysosomal enzymes in serum and organ homogenates. Methodologic aspects].

The influence of aluminium administration both on the lysosomes and on the activity of DNA-dependent enzymes in rats with intact kidney function or following partial nephrectomy was investigated. The elevation in free N-acetyl-beta-D-glucosaminidase in connection with a decrease of latent beta-NAG-level in liver, spleen and kidneys may be supposed a dose dependent aluminium damage of the lysosomes. Moreover, the decrease of free and total beta-glucuronidase in the liver and spleen could be caused by a selective inhibition of synthesis of this enzyme.

Acetylglucosamine↗
PubMed1989

Multicentric primaries and residual tumor masses following wide excision in breast cancer: a basis for irradiation.

In the Department of Gynecology and Obstetrics 131 modified radical mastectomies were carried out in patients with invasive breast cancer eligible for breast conserving therapy between 1978 and 1981. The technique of plastination was used for the first time in a complete histological investigation of the breast specimens. In all cases segmental resections with a rim of crossly normal tissue around the primary of at least 2 cm were simulated. Residuals of the primary in vicinity of the resection margin were found in 19.1% and multicentric tumor foci in 24.4% of all cases in the remaining breast. In 8.4% of the patients the residuals extended more than 3 cm beyond the resection margin. The volumes of the residuals were significantly larger than the volumes of the multicentric foci (p = 0.004). According to these results a 2 cm rim of grossly normal tissue should be resected with the primary tumor. A reexcision is to be recommended in cases with resection margins that are histologically not free of tumors. Considering the difficulty of a total histologic examination of the whole resection margin a boost dose should be supplemented. The extension of the residuals requires a boost field covering one third up to one half of the normal sized breast.

Breast Neoplasms↗
PubMed1988

Characterization of complex gramicidin monolayers by light reflection and Fourier transform infrared spectroscopy.

The reflectivities of monomolecular films of water-insoluble fatty alcohols and fatty acid methyl esters are measured at the air/water interface. A correlation between chain length and reflectivity of the monofilm is established which agrees with calculated values derived from a theoretical model. The correlation is used to estimate thickness of a monolecular film of gramicidin A. Fourier transform infrared (FTIR) spectroscopy is applied to transferred mixed layers of ion-channel-forming gramicidin A and dioctadecyldimethylammonium bromide in order to evaluate the structure of gramicidin. Transfer conditions for these monofilms are elaborated. Results of the reflection method and FTIR spectroscopy demonstrate that gramicidin exists as double-stranded beta-helix inside the monolayer at a lateral pressure similar to that found in biomembranes.

Fourier Analysis↗
PubMed1988

Activation of phosphofructokinase 2 by insulin in cultured hepatocytes without accompanying changes of effector levels or cAMP-stimulated protein kinase activity ratios.

Activation of glycolysis by insulin in cultured adult rat hepatocytes is accompanied by an activation of phosphofructokinase 2 (PFK 2). PFK 2 activation might be caused by insulin-dependent changes of (a) metabolite levels, (b) basal and (c) Br8cAMP-stimulated cAMP-dependent protein kinase activity; this problem was investigated. 1. Cells cultured with 0.1 nM insulin for 48 h exhibited a low glycolytic rate and low fructose 2,6-bisphosphate [Fru(2,6)P2] levels. Addition of insulin increased Fru(2,6)P2 and Fru(1,6)P2 levels sequentially which points to PFK 2 as first target enzyme of insulin action. 2. Concentrations of Glc6P, Fru6P, phosphoenolpyruvate, glycerol 3-phosphate and citrate, which modulate PFK 2/fructose 2,6-bisphosphatase 2 activity, were not altered by insulin. 3. Activation of PFK 2 by insulin occurred without changes in the levels of total and protein-bound cAMP. Bound cAMP amounted to about 14% of total cAMP. 4. Insulin neither decreased the basal dissociation state of the cAMP-dependent protein kinase nor lowered the sensitivity of the kinase towards cAMP in cell extracts. 5. Addition of the phosphodiesterase-resistant Br8cAMP to the cultures increased cAMP levels 3-4-fold, elevated the protein kinase activity ratio from 0.14 to 0.6 and decreased the Fru(2,6)P2 level and the rate of glycolysis. When Br8cAMP and insulin were given together, insulin was capable of counteracting Br8cAMP in that it activated glycolysis and PFK 2 and elevated the Fru(2,6)P2 level; however, it did not decrease the elevated protein kinase activity ratio. It is concluded that insulin presumably does not activate PFK 2 through changes in cAMP and effector levels or through inhibition of cAMP-dependent protein kinase dissociation. The data support the hypothesis that insulin may act via activation of PFK 2 phosphatase.

Animals↗