3,314 research outputs found

    Biological properties of adriamycin bound to biodegradable polymeric carriers

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    Three different conjugates having adriamycin (ADR) bound to the side chain carboxyl groups of high-molecular weight poly (¿--glutamic acid) (PGA) either directly or by interpolation of GlyGly and GlyGlyGlyLeu spacers, respectively, were compared with respect to immunogenicity and cytotoxicity in mice as well as release of drug by lysosomal enzymes. The cytotoxic efficacy of a single i.p. dose of each conjugate (5 mg ADR-equiv./kg) against L1210 leukemia cells implanted i.p. in DBA2 mice was studied by monitoring the survival time, the body weight and the number of long-term survivors (LTS). PGA-GlyGlyGlyLeu-ADR and PGA-GlyGly-ADR significantly enhanced the mean survival time (MST) of treated animals compared with the untreated control group (T/C 148¿149%) as did free ADR (T/C 147%). The tetrapeptide-spacer containing conjugate effected the presence of LTS at day 50 (2/5) as did free ADR (1/5).\ud \ud The secondary antibody response of the drug conjugates elicited in A/J mice after repeated dosage (125 ¿g/mouse) at day 0, 14 and 28 was evaluated at day 35 using the ELISA technique. IgG titers varied from a very low value (PGA-GlyGlyGlyLeu-ADR) to moderately high levels (PGA-ADR, PGA-GlyGly-ADR) which are 2¿3 orders of magnitude below that obtained for the strong immunogen bovine IgG. The data suggest that certain parts on the surface of the conjugates are immunogenic.\ud \ud The release of extractable low-molecular weight products from the conjugates mediated by lysosomal enzymes was analyzed using reversed-phase HPLC. The release profile of ADR as well as Gly-ADR, Leu-ADR or GlyLeu-ADR was determined. The total amount of ADR released after 77 h was 3.6% for PGA-GlyGlyGly-Leu-ADR, 1.0% for PGA-GlyGly-ADR and 0.5% for PGA-ADR. With all conjugates unidentified products were produced.\ud \ud It is proposed that the mechanism of action of the polymeric conjugates under in vivo conditions may be due to pinocytic capture followed by lysosomal degradation with release of ADR

    Use of a scoring technique to assess the effect of field variability on yield of pearl millet grown on three alfisols in Niger.

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    Within-field spatial variability of pearl millet (Pennisetum glaucum) was studied at three different sites on Alfisols in Niger. Grain yields in fields on a North-South gradient were 8-383, 2-1343, 7-815 kg/ha, with a coefficient of variation of 61, 55, and 53%, respectively. Variability was explained by soil chemical factors for only 5 to 28%. A simple method of scoring millet growth for individual hills a few weeks before harvest was tested by measuring yield variability in a field as an alternative for expensive soil chemical analyses. The median score value explained 25, 67, and 8% of the variability for the same gradient, respectively. As a verification step, map pattern comparisons of millet grain and straw yields with median score values gave low taxonomic distances (0.01-1.7), indicating significant similarities in variability. The hill scoring method is an appropriate tool to identify millet grain and straw yield variability

    Studies on the Mechanisms of Microbial Adaptation to the Physical Environment

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    The environmental factors which affect humans and other animals also influence the microorganisms which are such an important part of our ecology. Some of the microorganisms are very closely associated with animals, living in the digestive tract and synthesizing essential nutrients for the host. For these microbes, most external physical changes are of little consequence, because they are well shielded by the animals' homeostatic systems. The vast majority of microorganisms, however, live free in nature, especially in the soil and oceans. It has been estimated that the upper 15 cm of a fertile soil may contain over 4000 kg of bacteria and fungi per hectare. These organisms are responsible for degrading the complex molecules of plants and animals when they die, eventually producing simple organics, carbon dioxide, and inorganics, which are then used for the next cycle of plant growth. It is believed that over 90 % of the biologically produced carbon dioxide results from the metabolic activity of bacteria and fungi. In addition to recycling plant nutrients, soil bacteria also provide new nutrients through 'fixation' of atmospheric nitrogen into ammonia and nitrate, the forms which can be used by plants. Microorganisms so have an enormous capacity for detoxifying both natural and man-made poisons. All of these functions of microorganisms are essential to the operation of the material cycles on Earth. This is true of all locations on the planet, regardless of the climate or other environmental factors. In fact, one of the most impressive attributes of microorganisms is their ability to adapt to every stable environment on Earth. These include such extremes as polar regions, hot springs, water saturated with salt, mountain tops, ocean depths, acid and alkaline waters, deserts, intense radioactivity, soil and water contaminated with toxic chemicals or petroleum, and areas devoid of oxygen

    ICU at home, with the use of mobile IC unit services:intensive care goes that extra mile

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    In this report we describe a patient with a long ICU stay because of severe Guillain Barré syndrome. Treatment was patient-centred and Mobile ICU facilities were used to facilitate an ICU at home for one day. Early focus on individual needs and wishes and close communication with and within ICU treatment teams can help to improve the long-term consequences of ICU admission. Research on which interventions are effective and most cost-effective need to be performed

    A Systematic Review of the Effects of Hyperoxia in Acutely Ill Patients:Should We Aim for Less?

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    Introduction. Despite widespread and liberal use of oxygen supplementation, guidelines about rational use of oxygen are scarce. Recent data demonstrates that current protocols lead to hyperoxemia in the majority of the patients and most health care professionals are not aware of the negative effects of hyperoxemia. Method. To investigate the effects of hyperoxemia in acutely ill patients on clinically relevant outcomes, such as neurological and functional status as well as mortality, we performed a literature review using Medline (PubMed) and Embase. We used the following terms: hyperoxemia OR hyperoxemia OR [“oxygen inhalation therapy” AND (mortality OR death OR outcome OR survival)] OR [oxygen AND (mortality OR death OR outcome OR survival)]. Original studies about the clinical effects of hyperoxemia in adult patients suffering from acute or emergency illnesses were included. Results. 37 articles were included, of which 31 could be divided into four large groups: cardiac arrest, traumatic brain injury (TBI), stroke, and sepsis. Although a single study demonstrated a transient protective effect of hyperoxemia after TBI, other studies revealed higher mortality rates after cardiac arrest, stroke, and TBI treated with oxygen supplementation leading to hyperoxemia. Approximately half of the studies showed no association between hyperoxemia and clinically relevant outcomes. Conclusion. Liberal oxygen therapy leads to hyperoxemia in a majority of patients and hyperoxemia may negatively affect survival after acute illness. As a clinical consequence, aiming for normoxemia may limit negative effects of hyperoxemia in patients with acute illness

    WASP-4b Arrived Early for the TESS Mission

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    The Transiting Exoplanet Survey Satellite (TESS) recently observed 18 transits of the hot Jupiter WASP-4b. The sequence of transits occurred 81.6 ±\pm 11.7 seconds earlier than had been predicted, based on data stretching back to 2007. This is unlikely to be the result of a clock error, because TESS observations of other hot Jupiters (WASP-6b, 18b, and 46b) are compatible with a constant period, ruling out an 81.6-second offset at the 6.4σ\sigma level. The 1.3-day orbital period of WASP-4b appears to be decreasing at a rate of P˙=12.6±1.2\dot{P} = -12.6 \pm 1.2 milliseconds per year. The apparent period change might be caused by tidal orbital decay or apsidal precession, although both interpretations have shortcomings. The gravitational influence of a third body is another possibility, though at present there is minimal evidence for such a body. Further observations are needed to confirm and understand the timing variation.Comment: AJ accepte
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