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Dry matter and crude protein degradability of four parasitic plants (mistletoes) associated with browse trees in Botswana.

Four parasitic plants (Tapinanthus lugardii, Erianthenum ngamicum, Viscum rotundifolium and Viscum verrucosum) associated with browse trees in Botswana were evaluated for the degradability of their dry matter (DM) and crude protein (CP). All these plants have high levels of crude protein, ranging from 144.5 to 163.4 g/kg DM, with a significant (p < 0.001) difference in crude protein content between the plants. The rate of degradation of DM was highest for V. rotundifolium (0.197 h(-1)) and lowest for E. ngamicum (0.031 h(-1)). The two Viscum species had the highest effective DM degradability at an outflow rate of 0.05%. The rate of degradation of crude protein was highest for V. rotundifolium (0.144 h(-1)) and lowest for T. lugardii (0.0346 h(-1)). The effective degradability (ED) of crude protein was highest for V. rotundifolium at 0.03 and 0.05 h(-1) outflow rates. T. lugardii and E. ngamicum had an apparently low effective degradability, but this may result from an association of their protein with tannins, which would be able to supply amino acids in the small intestine after dissociation due to the abomasal pH.

Animal Feed↗

Conformer selection and differential restriction of ligand mobility by a plant lectin--conformational behaviour of Galbeta1-3GlcNAcbeta1-R, Galbeta1-3GalNAcbeta1-R and Galbeta1-2Galbeta1-R' in the free state and complexed with galactoside-specific mistletoe lectin as revealed by random-walk and conformational-clustering molecular-mechanics.

To study conformational parameters of ligands before and after complex formation with the galactoside-binding agglutinin of Viscum album L. (VAA) in solution, combined computer-assisted random walk molecular mechanics (RAMM) calculations extended by conformational clustering analysis (CCA), molecular dynamics (MD) simulations as well as two-dimensional rotating-frame nuclear Overhauser effect (ROE) and two-dimensional nuclear Overhauser effect (NOE) spectroscopy NMR experiments were employed. Derivatives of the naturally occurring disaccharides Galbeta1-3GlcNAcbeta1-R and Galbeta1-3GalNAcbeta1-R as well as of a synthetic high-affinity binding partner, i.e. the disaccharide Galbeta1-2Galbeta1-R', were chosen as ligands in this study. The disaccharides displayed inherent flexibility in the valley of the global minimum between phi/psi combinations of (40 degrees/60 degrees) and (40 degrees/-60 degrees). Calculations of the de-N-acetylated sugars revealed that presence of this group did not markedly influence the distribution of low-energy conformers in the phi, psi, epsilon plot. Occupation of side minima at phi/psi (180 degrees/0 degrees) or (0 degrees/180 degrees) is either unlikely or low according to the results of MD simulations and RAMM calculations extended by CCA. Notably, these side minima define conformations which are not stable during a MD simulation. Transitions to other minima occur already a few picoseconds after the start of the simulation. NMR experiments of the free-state ligand confirmed the validity of the data sets obtained by the calculations. Following the description of the conformational space in the free-state NMR experiments were performed for these disaccharides complexed with VAA. They yielded two interresidual contacts for Galbeta1-3GlcNAcbeta1-R and Galbeta1-2Galbeta1-R'. The ligand conformations in the complex did not deviate markedly from those of a minimum conformation in the free state. One- and two-dimensional transferred nuclear Overhauser enhancement (TRNOE) experiments at different mixing times excluded the influence of spin-diffusion effects. When the NOE build-up curves in the three studied cases were compared, the residual mobility of the penultimate carbohydrate unit of Galbeta1-3GalNAcbeta1-R was observed to be higher than that of the respective hexopyranose unit of the other two bound ligands. Due to the availability of the conformational parameters of Galbeta1-2Galbeta1-R' in association with a galectin, namely the beta-galactoside-binding protein from chicken liver, it is remarkable to note that this ligand displays different conformations in the binding sites of either the plant or the animal lectin. They correspond to local energy-minimum conformations in the phi,psi, epsilon plot and substantiate differential conformer selection by these two lectins with identical nominal monosaccharide specificity.

Binding Sites↗

Prevention of 20-methylcholanthrene-induced sarcoma by a mistletoe extract, Iscador.

Iscador, an extract from the semi-parasitic plant Viscum album, was found to inhibit 20-methylcholanthrene-induced carcinogenesis in mice. Intraperitoneal administration of Iscador (1 mg/dose) twice weekly for 15 weeks could completely inhibit 20-methylcholanthrene-induced sarcoma in mice and protect these animals from tumour-induced death. Iscador was found to be effective even at lowered doses. After administration of 0.166, 0.0166 and 0.00166 mg/dose 67, 50 and 17% of animals respectively did not develop sarcoma.

Animals↗

A national survey of the complications of endometrial destruction for menstrual disorders: the MISTLETOE study. Minimally Invasive Surgical Techniques--Laser, EndoThermal or Endorescetion.

OBJECTIVES: To study the frequency of complications of endometrial resection and ablation for menstrual disturbances and the influence of the experience of the operators. DESIGN: Prospective survey with additional retrospective reporting by theatre staff. SETTING: 300 National Health Service and independent hospitals in the United Kingdom (excluding Scotland). POPULATION: 10,686 women registered by 690 doctors (1-222 cases/doctor) from April 1993 to October 1994. METHODS: Mailings were sent to relevant medical and non medical staff at every hospital to ascertain who performed the operations. These doctors were asked to complete a questionnaire detailing their previous experience. Completed patient registration forms were returned each month. Theatre contacts returned lists of cases reported in theatre registers. MAIN OUTCOME MEASURES: Perioperative, post-operative and delayed complications by method of surgery and experience of operator. RESULTS: Two directly related deaths were reported. Laser and rollerball ablations were associated with least operative and post-operative complications. Combined loop and rollerball diathermy was associated with a higher rate, but with fewer immediate operative complications than loop resection alone. Endometrial thinning agents were not associated with decreased complications. Fibroids were associated with increased operative haemorrhage. Early post-operative complication rates ranged from 0.77% to 1.51%. Six-week follow up in 82.5% of the women revealed few complications (1.25% to 4.58%). Increasing operative experience was associated with fewer uterine perforations in the loop resection alone group (chi 2 for trend, P < 0.001), but had no effect on operative haemorrhage in any group. CONCLUSIONS: These procedures were used widely in 1993 to 1994 with low morbidity and mortality. The techniques may be relatively easily learned in the apprenticeship system without compromising safety. Combined diathermy resection appears safer than loop resection alone, but laser and rollerball ablation were safest.

Adult↗

Formation of lactose-resistant aggregates of human platelets induced by the mistletoe lectin and differential signaling responses to cell contact formation by the lectin or thrombin.

Human platelets afford a suitable and physiologically relevant model to study receptor-dependent cell aggregation and ensuing biosignaling reactions. Since cell surface glycoconjugates can serve as ligands in recognitive protein--carbohydrate interactions, it is of interest to investigate the reactivity of such epitopes for a plant lectin and the elicited intracellular responses. Therefore, the galactose-specific lectin (Viscum album agglutinin, VAA) was employed as a tool for this purpose. It was found that VAA induced platelet aggregation at a concentration of 2.5 microgram/ml using 2.5. 108 cells/ml, composed of the formation of both lactose-sensitive (Lac+) and lactose-resistant (Lac-) intercellular contacts. Lac- aggregates were formed only by metabolically active platelets of about 70% of the samples from the group of studied volunteers. The requirement of metabolic activity for formation of these contacts which no longer depend on lectin--ligand recognition was underscored by the lack of their appearance in the presence of metabolic inhibitors such as nordihydroguaiaretic acid, trifluoperazine, N-ethylmaleimide and menadione. With respect to biosignaling, the effective aggregation of platelets did not affect the basal level of Ca2+ in cells and reduced the rate of the menadione-dependent generation of H2O2. In parallel series platelet aggregation induced by bovine thrombin (0.03 U/ml) triggered an increase in the cytoplasmic Ca2+ level and an enhancement of the H2O2 generation. Overall, these results imply metabolically controlled post-binding reactions which strengthen the lectin-induced cell association and demonstrate differential responses with respect to the Ca2+ level and H2O2-generation between lectin- or thrombin-mediated aggregation of human platelets.

Animals↗