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Biomedical subjects

E Bühler

Publications and source records attributed to E Bühler.

At least 19 recordsLinked to original sources

Ethical and legal aspects of enteral nutrition.

European ethical and legal positions with regard to EN vary slightly from country to country but are based on a common tradition derived from Graeco Roman ideas, religious thought and events of the 20th century. The Hippocratic tradition is based on 'beneficience' (do good) and 'non-maleficience' (do no harm). Religious thinking is based upon the presumption of providing food and drink by whatever means unless burden outweighs benefit. The concept of 'autonomy' (the patients right to decide) arose following in the decades after the Second World War and is enshrined in Human Rights law. The competent patient has the right to participate in decision making and to refuse treatment although the doctor is not obliged to give treatment which he or she considers futile or against the patient's interests. The incompetent patient is protected by law. The fourth principle is that of 'justice' i.e. equal access to healthcare for all. The law regards withholding and withdrawing treatment as the same. It also defines the provision of food and drink by mouth as basic care and feeding by artificial means as a medical treatment. It requires doctors to act in the best interests of the patient.

Decision Making↗

Concurrent quantification of cellular cholesterol, cholesteryl esters and triglycerides in small biological samples. Reevaluation of thin layer chromatography using laser densitometry.

Absolute specificity and high accuracy is required for the quantitation of cholesterol, cholesteryl esters and triglycerides in small biological samples, particularly in a limited number of cells. Both can be achieved through thin-layer chromatography and molybdatophosphoric acid staining, while the shortcomings of traditional spot detection are overcome by laser densitometry. The major advantage of the proposed technique is the concurrent assay of nanogram quantities of cholesterol, cholesteryl esters and triglycerides. Our assay is at least ten-fold more sensitive than common thin-layer chromatography-based techniques and at least four-fold more sensitive than common enzymatic methods. The present low-cost assay is highly reproducible and may be particularly suitable for the routine lipid analysis of a 10% aliquot of relatively small tissue and cell samples, equivalent, for instance, to > or = 10(4) human monocytes.

Cholesterol↗

Altered switch in lipid composition during T-cell blast transformation in the healthy elderly.

Decreased mitogen responsiveness of lymphocytes during aging correlates inversely with membrane microviscosity, which reflects an altered lipid composition. Therefore, we addressed the question, whether age-related alterations of lipid metabolism affect the switch in lipid composition during formation of blasts. Membrane lipids and fatty acids of peripheral blood lymphocytes from SENIEUR protocol compatible ("healthy") elderly donors (66-77 yr) and young controls (18-30 yr) were quantified after incubation with or without the mitogen phytohaemagglutinin. The blastic change in membrane lipid composition was different for young controls with respect to cholesterol, phosphatidylethanolamine, total phospholipids, as well as several fatty acids. Moreover, the age-related alterations in the switch of membrane lipids and fatty acids were significantly correlated with a decreased mitogen response. Thus, the alterations in membrane reorganization during blast formation of lymphocytes from the elderly point to a disturbed cellular lipid homeostasis with possible impact on the age-related reduction in immune function.

Adolescent↗

Lung hypoplasia and severe pulmonary hypertension in an infant with double heterozygosity for spondyloepiphyseal dysplasia congenita and achondroplasia.

A rare instance of double heterozygosity for spondyloepiphyseal dysplasia congenita and achondroplasia is presented. Despite midface hypoplasia, thorax deformity and lung hypoplasia, the child survived the neonatal period. Severe pulmonary hypertension, already present at birth, led to right heart failure and death at the age of 1 year.

Achondroplasia↗

Low density lipoprotein for oxidation and metabolic studies. Isolation from small volumes of plasma using a tabletop ultracentrifuge.

A rapid method is described for the isolation of small volumes of plasma low density lipoprotein (LDL) free of plasma protein contaminants using the TL-100 Tabletop Ultracentrifuge (Beckman). The isolation of LDL was achieved by a 25 min discontinuous gradient density centrifugation between the density range of 1.006 and 1.21 g/ml, recovery of LDL by tube slicing followed by a 90 min flotation step (d = 1.12 g/ml). The purity of LDL and apolipoprotein B100 (apo B100) were monitored by agarose electrophoresis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), radial immunodiffusion and micropreparative fast protein liquid chromatography (FPLC). The ability of LDL oxidation was assessed by following absorbance at 234 nm after addition of copper ions. The functional integrity of the isolated LDL was checked by clearance kinetics after injection of [125I]-labelled LDL in estrogen-treated rats. The additional purification step led to LDL fractions free of protein contamination and left apo B100, alpha-tocopherol and beta-carotene intact. The LDL prepared in this way was free of albumin, as evident from analytic tests and from its enhanced oxidative modification by copper ions. Used for analytical purposes, this method allows LDL preparations from plasma volumes up to 570 microliters. This method is also convenient for metabolic studies in small animals, especially those relating to the determination of kinetic parameters of LDL in which LDL-apo B100 has to be specifically radiolabelled.

Animals↗

Depletion of plasma vitamin C but not of vitamin E in response to cardiac operations.

The whole-body inflammatory response produced by cardiopulmonary bypass is an important cause of perioperative morbidity after cardiac operations. This inflammatory response produces reactive oxygen species and other cytotoxic substances, such as the cytokines. The generation of reactive oxygen species might deplete principal antioxidant micronutrients, that is, vitamins C and E and the carotenoids. Therefore, we have investigated the time course of the plasma concentrations of vitamins C and E and the carotenoids in 18 patients undergoing coronary bypass operations after randomization for previous vitamin E supplementation (300 mg dl-alpha-acetyl-tocopherol 3 times daily for 4 weeks) or placebo. Supplementation with alpha-tocopherol doubled the lipid-standardized plasma vitamin E concentration to 63.7 +/- 14.5 mumol/L when compared with that of the control subjects (31.2 +/- 9.0 mumol/L) before the operation. The plasma concentrations of vitamin C (36.0 +/- 19.0 mumol/L and 44.0 +/- 21.7 mumol/L, respectively) and of the carotenoids were not statistically different between the two groups at baseline. The absolute plasma concentrations of both vitamin E and the carotenoids decreased during and after cardiopulmonary bypass, but after correction for hemodilution the plasma concentrations of vitamin E and the carotenoids showed no decrease. The vitamin E concentrations in the erythrocytes did not change either. In contrast, the plasma concentration of vitamin C decreased in all subjects within 24 hours after the operation by roughly 70%. Correction for hemodilution still revealed a significant decrease in plasma vitamin C that persisted in most patients up to 2 weeks. In conclusion, the vitamin E and the carotenoid plasma concentrations are of no major concern during and after cardiac operations. In contrast, the serious depletion of vitamin C may deteriorate the defense against reactive oxygen species-induced injury during cardiac operations.

Ascorbic Acid↗

Molecular genetic analysis of Turkish cystic fibrosis patients.

The cystic fibrosis (CF) gene was recently cloned and a three basepair deletion removing phenylalanine 508 from the coding region was identified as the mutation on the majority of cystic fibrosis chromosomes. The frequency of this mutation varies among different geographic locations. In this study we analysed 25 Turkish families and have found the relative frequency of the delta F508 (DF508) mutation to be 20.37%. This is similar to that reported in other Middle Eastern countries and contrasts with the considerably higher frequencies encountered in Northern Europe and North America. Molecular analysis of the two nucleotide binding folds (NBFs) of the cystic fibrosis transmembrane conductance regulator (CFTR) gene with direct sequencing, has also shown that the other defined mutations in these regions of the gene do not occur in the CF patients from the Turkish population. One patient presenting with severe clinical features was determined to be a compound heterozygote for the mutations delta F508/1677delTA.

Alleles↗

A high-density-lipoprotein receptor appears to mediate the transfer of essential fatty acids from high-density lipoprotein to lymphocytes.

It has been shown previously that a specific high-density lipoprotein (HDL) receptor exists on human lymphocytes that recognizes apoprotein (apo) A1 as its ligand, and may be responsible for utilization of HDL lipids to respond optimally to mitogenic stimulation when cultured in serum-free medium supplemented with HDL. To clarify further the relationship between various HDL lipids used by lymphocytes and HDL receptor activity, the lipid composition of the cells and the regulation of HDL and low-density lipoprotein (LDL) receptors on freshly isolated lymphocytes and mitogen-activated T-blasts after treatment with lipoproteins, liposomes or fatty acids were investigated. Our data show that the linear increase in cell proliferation correlates with the presence of HDL in fatty-acid-free culture medium in the concentration range of HDL receptor saturation. Decreased binding/uptake of dioctadecylindocarbocyanine (DiI)-fluorescence-labelled HDL by freshly isolated lymphocytes was observed in the presence of unlabelled HDL in 4-day culture, whereas T-blast binding/uptake was down-regulated by preincubation not only with HDL but also with LDL. T-blasts pretreated with HDL showed increased cellular contents of phosphatidylcholine, oleic acid (C18:1,n-9) and linoleic acid (C18:2,n-6), which are essential for optimal proliferation of mitogen-stimulated lymphocytes. Furthermore, DiI-HDL binding on lymphocytes was down-regulated by up to 20% (resting T cells) and 50% (T-blasts) when cultured in the presence of apoA1-phosphatidylcholine liposomes (T-blasts only), oleic acid or linoleic acid, but not by stearic acid (C18:0). The results indicate that HDL provide lymphocytes with essential fatty acids, which in turn regulate HDL receptor activity.

Adult↗

Arrangement of DYZ1 and DYZ2 repeats on the human Y-chromosome: a case with presence of DYZ1 and absence of DYZ2.

The composition of Yq-heterochromatin is dominated by the two repetitive sequences DYZ1 (4000 copies) and DYZ2 (2000 copies). Probes derived from these sequences can be used for sex determination and the structural analysis of aberrant Y-chromosomes. Using such probes Schmid et al., have recently proposed a regular interspersion of the two sequences in a ratio of 2:1 over the entire Yq12 chromosome region. By Southern analysis we investigated the DNA of a normal male, cytogenetically negative for Yq-heterochromatin. Applying the same probes as used by Schmid et al., only a small amount of DYZ1 material could be detected. The case presented indicates the presence of DYZ1 only in the Yq11-Yq12 junction region and excludes DYZ2 from any function relevant for normal male development.

Blotting, Southern↗

Correlation of lymphocyte lipid composition membrane microviscosity and mitogen response in the aged.

Healthy aged and young blood donors were investigated for the role of membrane lipid composition in the age-related increase in membrane microviscosity and decline of mitogen responsiveness. Membrane microviscosity was shown to correlate positively with membrane cholesterol/phospholipid molar ratios, which were significantly elevated in the elderly. A positive correlation also was confirmed between lymphocyte membrane microviscosity, which was measured using the probe 1,6-diphenyl 1,3,5-hexatriene, and phytohemagglutinin responsiveness of cells from the same donor. Using stepwise regression statistical analysis, the variables age, cholesterol, cholesterol/total phospholipid and phosphatidyl ethanolamine/phosphatidyl choline molar ratios were all shown to have a significant positive influence on membrane microviscosity, whereas total phospholipids had a negative effect. No statistically significant difference was seen in content of any single saturated or unsaturated fatty acid between young and old donors. After pooling, however, the proportion of all unsaturated fatty acids was significantly higher in cells from the elderly as a consequence of an increase of n-6 and n-3 polyunsaturated fatty acids. Changes in lipid composition and physical properties of lymphocyte plasma membranes may, therefore, be responsible (at least partially) for the diminution of immune reactivity in old age.

Adult↗

Plasma vitamin E and beta-carotene concentrations during radiochemotherapy preceding bone marrow transplantation.

Blood from 19 patients was examined for the essential antioxidants alpha-tocopherol and beta-carotene before, during, and after bone marrow transplantation (BMT). Marrow ablation and immunosuppression for BMT conditioning was achieved by treatment with high-dose chemotherapy, mostly combined with total body irradiation. All patients required total parenteral nutrition beginning 1 wk before BMT. After conditioning therapy the concentration of absolute and lipid-standardized alpha-tocopherol and beta-carotene in plasma decreased significantly, presumably as a result of an enhanced breakdown of these antioxidants. The loss of these lipid-soluble antioxidants has to be considered as a possible cause for early posttransplant organ toxicity.

Adolescent↗

[Fertility and Turner mosaicism syndrome].

Six patients with a Turner mosaicism are reported. All six women were investigated for sterility or infertility. Four of six patients had a total of nine pregnancies: six abortions, one stillbirth, two normal children. The literature contains reports of 17 pregnancies in 10 women with 45.X karyotype and 106 pregnancies in 48 women with mosaicism. Miscarriages, stillbirths and malformations were common. These women need special counselling and in case of a pregnancy amniocentesis is indicated. We discuss the pathogenesis of reduced fertility with Turner patients and explain the problems related to the cystogenetic diagnosis of the Turner-Mosaic Syndrome.

Abortion, Spontaneous↗

Decreased essential antioxidants and increased lipid hydroperoxides following high-dose radiochemotherapy.

The blood from 19 patients having bone marrow transplantation was examined for the essential antioxidants alpha-tocopherol and beta-carotene as well as lipid hydroperoxides before, at and after bone marrow transplantation (BMT). Conditioning therapy, preceding BMT in order to achieve marrow ablation and immunosuppression, consists of high-dose chemotherapy which is mostly combined with total body irradiation (TBI). In order to see a possible difference between patients with and without additional TBI, we divided the patients up into two groups; patients receiving TBI (RT+) and patients without TBI (RT-). All patients required total parenteral nutrition beginning one week prior to BMT. After conditioning therapy plasma levels of absolute and lipid-standardized alpha-tocopherol and beta-carotene decreased in both groups, presumably as a result of an enhanced breakdown of these antioxidants. The loss of these lipid-soluble antioxidants has to be considered as a possible cause for early post-transplant toxicity. Lipid hydroperoxides increase significantly in the group of patients with additional TBI, whereas the other group, receiving no additional TBI, showed no significant change. We suggest high-dose supplementation of essential antioxidants for patients undergoing BMT.

Adolescent↗

Linkage relationships and allelic associations of the cystic fibrosis locus and four marker loci.

The linkage relationships between the cystic fibrosis (CF) locus and four marker loci (MET-H, MET-D, D7S8 and D7S16), allelic associations between these loci and the extent of informativity at these marker loci were investigated in a sample of 206 families with at least one child affected by CF. The data were contributed by 11 laboratories from Europe and Israel. The maximum lod scores and recombination frequency estimates (luminal diameter) (and confidence limits of luminal diameter) were: 18.3 at luminal diameter = 0.007 (0.001-0.038) for CF vs. MET, 11.0 at luminal diameter = 0.016 (0.001-0.068) for CF vs. D7S8, and 5.7 at luminal diameter = 0.0 (0.0-0.064) for CF vs. D7S16. A gene order of CF-MET-D7S8 was best supported by the data, but its preference to the order D7S8-CF-MET is mainly based on one single family. There are significant allelic associations between CF, MET, D7S8 and D7S16; these allelic associations affect the risk of random individuals to be carriers of CF.

Alleles↗

Increase of gingival hydroxyproline and proline by improvement of ascorbic acid status in man.

The 4-hydroxyproline and proline content of periodontal tissue was measured in 24 adult volunteers with initially low and partially even deficient plasma vitamin C values, before and after peroral supplementation with 70 mg ascorbic acid daily for six weeks. The latter caused a statistically significant rise and normalization respectively of plasma ascorbic acid and simultaneously a statistically significant increase of the hydroxyproline and proline in periodontal tissue (p less than 0.01) but not before the plasma vitamin C level was above 0.9 mg/dl. The optimal plasma vitamin C level which was associated with the highest hydroxyproline and proline content in periodontal tissue ranged between 1.00-1.30 mg/dl corresponding to the total daily dietary ascorbic acid intake of about 100 mg.

Adult↗