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101.
Dmitri Artemov Zaver M. Bhujwalla Ross J. Maxwell John R. Griffiths Ian R. Judson Martin O. Leach Jerry D. Glickson 《Magnetic resonance in medicine》1995,34(3):338-342
The anticancer agent temozolomide labeled with 13C (8-Carbamoyl-3-13C-methylimidazo-[5,1-d]-1,2,3,5-tetrazin-4-(3H)-one), was noninvasively detected in subcutaneous RIF-1 tumors by a selective cross polarization 13C NMR method, at a field strength of 9.4T. Pharmacokinetics of the drug, at a dose of 150 mg/kg, were determined for intravenous and intraperitoneal modes of administration (three animals per mode). The half-life of the drug in the tumors was approximately 60 min. The uptake and clearance of the drug, however, varied significantly between individual hosts, for both modes of administration. These results demonstrate the feasibility of obtaining pharmacokinetics of anticancer agents for individual tumors without the need for a label that might modify drug activity (e.g., fluorine). The variability of the in vivo measurements, even within the same tumor model, demonstrates the necessity of directly monitoring the tumor to evaluate drug pharmacokinetics. 相似文献
102.
103.
Martin Klomp Peter M. Van den Bergh Frits J. H. Harinck 《Child & youth care forum》1997,26(5):343-355
In child and youth care in the Netherlands, systematic planning of treatment is more and more considered to be a condition
for effective and well founded treatment. Although workers are convinced of the benefits of treatment plans, treatment planning
is not yet a natural and integrated part of residential care. There are several pressure points. In this article a model of
treatment planning will be presented that contributes to an answer to these pressure points. The theoretical bases and the
practical implications of this model will be discussed. 相似文献
104.
105.
Characterization and isolation of SOB2, a human sperm protein with a potential role in oocyte membrane binding 总被引:2,自引:1,他引:1
Lefevre A; Martin Ruiz C; Chokomian S; Duquenne C; Finaz C 《Molecular human reproduction》1997,3(6):507-516
G12 monoclonal antibody (mAb), one of a library of constructed mAb directed
against human sperm proteins, was found by immunoperoxidase staining to
label the post-acrosomal and neck regions of fixed human cauda epididymal
and ejaculated spermatozoa. Epithelium and fluid of caput epididymis were
strongly labelled while there was no staining on testis and efferent ducts.
Western lot analysis revealed that G12 antibody reacted with proteins of
17.5, 18 and 19 kDa in human spermatozoa. This pattern seems to be specific
for mature human spermatozoa, as it has not been observed either in other
human tissues tested, or in spermatozoa from different animals. SOB2, the
corresponding protein, was isolated from NP40-extracted human spermatozoa
by using preparative electrophoresis, followed by isoelectrofocusing
according to its isoelectric point of 6.4 G12 Fab fragments strongly
inhibited binding of human spermatozoa to zona-free hamster oocytes (up to
86% inhibition at 200 micrograms/ml). Impairment of binding was dependent
on the concentration of purified G12 immunoglobulin (Ig)G1, and significant
even at 10 micrograms/ml. There was no inhibitory effect of G12 antibody on
sperm motility parameters or triggering of the acrosome reaction and it did
not inhibit binding to human zona pellucida. These results indicate that
SOB2 is likely to participate in membrane oocyte binding, and my be
potential candidate for the development of a contraceptive vaccine.
相似文献
106.
Voltage dependence of the pattern and frequency of discrete Ca2+ release events after brief repriming in frog skeletal muscle
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Michael G. Klein Alain Lacampagne Martin F. Schneider 《Proceedings of the National Academy of Sciences of the United States of America》1997,94(20):11061-11066
Applying a brief repolarizing pre-pulse to a depolarized frog skeletal muscle fiber restores a small fraction of the transverse tubule membrane voltage sensors from the inactivated state. During a subsequent depolarizing test pulse we detected brief, highly localized elevations of myoplasmic Ca2+ concentration (Ca2+ “sparks”) initiated by restored voltage sensors in individual triads at all test pulse voltages. The latency histogram of these events gives the gating pattern of the sarcoplasmic reticulum (SR) calcium release channels controlled by the restored voltage sensors. Both event frequency and clustering of events near the start of the test pulse increase with test pulse depolarization. The macroscopic SR calcium release waveform, obtained from the spark latency histogram and the estimated open time of the channel or channels underlying a spark, exhibits an early peak and rapid marked decline during large depolarizations. For smaller depolarizations, the release waveform exhibits a smaller peak and a slower decline. However, the mean use time and mean amplitude of the individual sparks are quite similar at all test depolarizations and at all times during a given depolarization, indicating that the channel open times and conductances underlying sparks are essentially independent of voltage. Thus, the voltage dependence of SR Ca2+ release is due to changes in the frequency and pattern of occurrence of individual, voltage-independent, discrete release events. 相似文献
107.
Mark L. Laudenslager Maria L. Boccia Christy L. Berger Mary M. Gennaro-Ruggles Britta McFerran Martin L. Reite 《Developmental psychobiology》1995,28(4):199-211
Many behavioral, immunological, and physiological consequences of brief maternal separation in bonnet (Macaca radiata) and pigtail monkeys (Macaca nemistrina) have been documented. However, the impact of social separation on plasma cortisol and growth hormone is unknown for these particular species. In the present study, the behavioral and endocrinological consequences of a 2-week maternal separation in socially housed infant bonnet and pigtail monkeys were followed. In seven pairs (separated and matched control) of bonnet and six pairs of pigtail infants, plasma was obtained under baseline, separated, and reunion conditions twice weekly for the duration of the study. Blood samples were obtained from both infants of the pair in approximately 10 min. Plasma total cortisol, free cortisol, and growth hormone were measured in these samples. Focal animal behavioral observations were made on all subjects twice daily throughout the study period. In both species, total cortisol and free cortisol rose immediately following maternal separation in comparison to the matched nonseparated controls and returned to basal levels (e.g., that of matched non-separted controls) following reunion with the mother. In contrast, plasma growth hormone rose only in the pigtail infants over a time course that peaked around the time of reunion. Multiple regression techniques indicated for the first week of separation, in the separated but not control subjects, that mean plasma free and total cortisol was positively related to distress behaviors (vocalization and postural slouch) observed during this week and negatively related to social behaviors (play and proximity to others) noted during the same period. In contrast, plasma growth hormone was related to both species and sex of the subjects but unrelated to behavioral variables. © 1995 John Wiley & Sons, Inc. 相似文献
108.
The cellular and regional distribution of glutathione (GSH) and GSH-related enzyme systems involved in cellular defense against reactive oxygen species and electrophilic xenobiotics in the nervous system has been extensively studied. However, little is known about the subcellular distribution of GSH systems in brain tissue and cultured neural cells. The present study investigates the distribution of mitochondrial and cytosolic GSH and GSH-related enzymes in cultured cerebellar astrocytes and granule cells, and compares them with levels in the adult rat cerebellum. Cytosolic GSH levels and cytosolic activities of glutathione reductase (GR), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) in astrocytes were 57, 153, 245, and 92% higher than those found in granule cells, respectively. In contrast, granule cells contained significantly higher mitochondrial GSH levels than astrocytes. Granule cells also demonstrated comparable mitochondria/cytosolic concentrations of GSH and GR, GPX and GST activities to those observed in the cerebellar tissue, whereas ratios in astrocytes were markedly lower. Although in vitro treatments with 100 μM ethacrynic acid depleted both cytosolic and mitochondrial GSH in cultured astrocytes and granule cells in a time-dependent fashion, cellular GSH in granule cells was more resistant to the GSH-depleting agent than astrocytes. These results suggest that although GSH and GSH-related enzymes are abundant in cytosolic compartments of astrocytes, mitochondrial pools are relatively small. Since brain mitochondria are sites of significant hydrogen peroxide generation, the mitochondrial localization of GSH and its associated enzymes in neural cells provide important defenses against toxic oxygen species in the nervous system. Differences in subcellular distribution of GSH systems in individual neural cell types may provide a basis for selective cellular and/or subcellular expression of neurotoxicity. 相似文献
109.
110.
Martin Woodhead 《Early child development and care》1990,58(1):129-141
There is now a substantial body of American research evidence demonstrating that early education programmes can have major long term effects right through into adult life. Cost-benefit analysis has enabled the data to be transformed into a compelling case for public financial investment. But insufficient attention has been paid to explaining how a short term preschool programme could have such enduring effects. The effects are best understood by applying a transactional model which shows how processes in the school and community transformed and amplified short term effects into long term outcomes. Adopting a transactional model modifies the messages for policy. The results of evaluations carried out in one society may not apply in another. In some school systems there may be more effective strategies than early education for improving educational prospects. 相似文献