The calcium binding capacity of polycarboxylates

It can be shown both theoretically and experimentally that calcium carbonate forms during the titration of polycarboxylates by calcium with carbonate as the indicator, and that the calcium carbonate is dispersed by the polycarboxylate. If the dispersing capacity of the polymer exceeds the level of calcium carbonate present, the precipitation of the calcium salt of the polymer is observed as the end point. If the quantity of carbonate is increased to a level greater than that of the dispersing capacity of the polymer, the precipitation of calcium carbonate is observed as the end point, and we term the result of this titration the “calcium carbonate dispersing capacity.”     

Prevention of necrotizing enterocolitis in extremely low birth weight infants by IgG feeding?

Oral immunoglobulin has been described as preventing necrotizing enterocolitis(NEC) in preterm infants. To prevent NEC in extremely low birth weight infants (ELBW), we have carried out oral IgG prophylaxis since April 1991. The efficacy of this prophylaxis was examined in a study comparing historical cohorts. ELBW infants delivered in the Department of Obstetrics and Gynaecology of the University of Ulm and treated until day 28 in the level III intensive care nursery, Division of Neonatology, University of Ulm were included. Cohort 1, born between 1.1.1988 and 31.3.1991, received no oral IgG and served as a control [n = 84, gestational age: median 26 weeks, range 24-34; birth weight: 811 g, 490-990], cohort 2, born between 1.4.1991 and 31.12.1995 [n= 137, gestational age: 26 weeks, 22-32; birth weight: 760 g, 362-995], received 6 x 100 mg/kg human IgG (Beriglobin) orally on days 1-28. NEC, stage 2a and higher according to the modified classification of Bell, was observed in 9 of 84 (10.7%) infants of cohort 1 and in 11 of 137 (8%) infants of cohort 2 until day 28. The difference did not reach statistical significance (P = 0.63 Fisher's exact test). CONCLUSION: In this historical cohort study, ELBW infants were not protected against NEC by oral IgG. The present published evidence does not allow recommendation of oral human IgG administration in preterm infants as a prophylactic measure against NEC.     

Esophageal scintigraphy of Zenker''s diverticula before and after diverticulotomy]

To assess the role of insulin in the development of obesity induced by antipsychotic drugs, a glucose tolerance test was conducted in 40 female rats during the peak of sulpiride-induced weight gain and in 40 vehicle-treated animals. The glucose area under the curve did not differ between the groups (P = 0.24), however, the area under the insulin curve was significantly decreased by sulpiride (55.2 +/- 2.8 versus 115.6 +/- 18.9, P = 0.007). The results suggest that insulin resistance and hyperinsulinaemia are not involved in the excessive weight gain observed in this animal model of drug-induced obesity. Alternatively, the insulin-dampened response observed in the sulpiride-treated rats may be related to increased insulin sensitivity, which may promote weight gain as proposed by Ravussin (1995).     

Dextrorphan, but not dextromethorphan, exerts weak antidystonic effects in mutant dystonic hamsters

The effects of dextromethorphan and its metabolite dextrorphan on severity of dystonia were examined in mutant dystonic hamsters, an animal model of idiopathic paroxysmal dystonia, in which recent examinations have shown antidystonic effects of selective N-methyl-D-aspartate (NMDA) receptor antagonists. Dextromethorphan and dextrorphan are non-competitive NMDA receptor antagonists which additionally exhibit affinity for sigma receptors. Dextrorphan (20 and 40 mg/kg i.p.) significantly retarded the progression of dystonia at the higher dose, whereas dextromethorphan (20, 40, 60 mg/kg i.p.) failed to exert any antidystonic effects even at high doses which caused severe effects. The lack of antidystonic efficacy of dextromethorphan may be related to its higher affinity to sigma receptors compared with dextrorphan.     

Structural changes are associated with soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor complex formation

SNAP-25, syntaxin, and synaptobrevin play a key role in the regulated exocytosis of synaptic vesicles, but their mechanism of action is not understood. In vitro, the proteins spontaneously assemble into a ternary complex that can be dissociated by the ATPase N-ethylmaleimide-sensitive fusion protein and the cofactors alpha-, beta-, and gamma-SNAP. Since the structural changes associated with these reactions probably form the basis of membrane fusion, we have embarked on biophysical studies aimed at elucidating such changes in vitro using recombinant proteins. All proteins were purified in a monomeric form. Syntaxin showed significant alpha-helicity, whereas SNAP-25 and synaptobrevin exhibited characteristics of largely unstructured proteins. Formation of the ternary complex induced dramatic increases in alpha-helicity and in thermal stability. This suggests that structure is induced in SNAP-25 and synaptobrevin upon complex formation. In addition, the stoichiometry changed from 2:1 in the syntaxin-SNAP-25 complex to 1:1:1 in the ternary complex. We propose that the transition from largely unstructured monomers to a tightly packed, energetically favored ternary complex connecting two membranes is a key step in overcoming energy barriers for membrane fusion.     

Application of thermomechanical treatment on medium-carbon microalloyed steels continuously cooled from forging temperature

In the high-production-drop-forging of parts for automobile and truck engines the classical quench and tempering (QT) of low-alloyed steels is nowadays - in a lot of plants in Europe - substituted by direct continuous cooling (CC) of microalloyed steels without the necessity of additional heat treatment and expensive straightening as well as stress relieving cycles. Nevertheless, there are some limitations on strength and toughness achievable by this technique. On two commercial medium-carbon (0.3%C) steels microalloyed with vanadium or vanadium and titanium, modified deformation parameters were applied. The mechanical properties, determined by the tensile test, can be improved by decreasing the deformation temperature. Nevertheless, the values of yield strength (resp. 0.2%-proof stress) as well as reduction of area remain inferior to those after QT of the same steels.     

Intrinsic stress and preferred orientation in TiN coatings deposited on Al using plasma immersion ion implantation assisted deposition

TiN coatings were deposited on Al substrates using the plasma immersion ion implantation and deposition (PIIIAD) technique, employing a filtered Ti cathodic arc in a nitrogen atmosphere. Negative pulsed bias voltages between 0 to −4.0 kV were applied with varying duty cycles, at a constant time-averaged bias. Stress measurements using X-ray diffraction reveal an increase and then a decrease in the intrinsic compressive stress at increasing on-time bias. A bias-dependent preferred orientation of TiN is observed, i.e. {111}, {200} and {220} at low bias and predominantly {200} at higher bias. The hardness reduces from 29 GPa at lower bias to 20 GPa at higher bias. Thus, the time averaged energy of ion bombardment does not uniquely determine the properties of the growing coating, which can be adjusted by the on-time substrate bias applied for very short durations. A simplified subplantation model of stress development is formulated for the case of pulsed bias, the predictions of which are in reasonable agreement with the experimental data.     

Experimental studies on the suitability of human mesothelial cells for seeding vascular prostheses: shear stress resistance in vitro

This investigation forms part of a study on the suitability of human omentum mesothelial cells (HOMES) as an alternative to endothelial cells (EC) for seeding vascular grafts. Isolated HOMES were grown in primary culture and characterized by their morphology (light microscopy and scanning electron microscopy (SEM)), as well as by fluorescence-activated cell sorting (FACS) and immunocytochemistry. The latter two methods showed cells which were positive for smooth muscle-type actin and cytokeratin, but negative for factor VIII-related antigen. HOMES were grown to confluence on glass with or without a fibronectin coating. Controlled shear stress was applied for up to 30 min using a plate and cone rheometer at 20 dynes/cm². These dynamic culture conditions led to loss of only occasional cells. The most marked alterations seen on SEM were some cell elongation, marked raising of the nucleus and loss of luminal cytoplasmic microvilli. Time-lapse video microscopy revealed that shear stress also increased the spreading capacity of some cells. Similar experiments with venous endothelial cells gave a shearing off of a confluent monolayer. This investigation shows the marked shear-stress resistance of HOMES, a pre-requisite for their use to seed vascular prostheses.     

Adenoid cystic cancer of the breast. Case report and meta-analysis of the literature

Adenoid-cystic carcinoma of the breast is considered a rare entity with a comparatively favourable prognosis. We report the case of a 58 year old woman and review another 150 cases published to date in the pertinent literature. The clinical course and outcome of 99 patients was evaluated by meta-analysis. Recurrence-free ten-year survival was calculated at 85.1 percent following mastectomy and at 45.7 percent after breast-conserving therapy (p < 0.05). Six of ten local recurrences and 7 of 8 distant metastases occurred 5 years or later after initial treatment. It is concluded that patients with adenoid-cystic carcinoma of the breast should be treated by primary mastectomy and extended follow-up is recommended.     

Analysis of the lithuanian final energy consumption with respect to economic changes

The development of energy consumption in Lithuania is investigated on the basis of realistic economic scenarios. The aim is to provide reasonable projections of final energy consumption for selected demand sectors. The main parameters determining consumption are the gross national product (GNP) and the real price for energy. The influences of price level and economic activity during preceding periods are evaluated by using multiple regressions with a quasi-dynamic model. Insofar as these mechanisms cannot be detected for Lithuania, experiences with other former centrally-planned economies, which have already turned into kinds of market economies, are applied to make realistic projections for the transitory period. The underlying scenarios for the GNP and price developments are taken from official Lithuanian projections, but they have been adjusted to allow for the most recent development. The results of the quasi-dynamic model are compared with the official final energy-demand projections to provide policy advice for a proper restructuring of the energy system.