Home About us Contact
|
Home About us Contact | ||
|
|
||
Own Laboratory (own + laboratory)
Selected AbstractsApplications of gold cluster compounds in immunocytochemistry and correlative microscopy: comparison with colloidal goldJOURNAL OF MICROSCOPY, Issue 3 2000J. M. Robinson In this review, we discuss the immunocytochemical literature with respect to a comparison between conventional colloidal gold and gold cluster compounds as immunoprobes. The relative advantages and disadvantages of each of these types of particle for immunocytochemical applications are discussed. We present results from our own laboratories and those of others on the comparison of these immunoprobes in selected experimental situations. These results show the use of gold cluster compounds at both light and electron microscope levels. At the ultrastructural level, gold cluster compounds have been used in pre-embedding labelling of cultured cells, and for labelling of ultrathin cryosections and freeze-fracture preparations. Recently, fluorescently tagged gold cluster compounds have become available. Using ultrathin cryosections of human neutrophils as a model system, we demonstrate that a single immunoprobe (i.e. a fluorescently tagged gold cluster compound) is a robust probe for correlative fluorescence and electron microscopy. [source] Facilitating Leiden's Cold: The International Association of Refrigeration and the Internationalisation of Heike Kamerlingh Onnes's Cryogenic LaboratoryCENTAURUS, Issue 3 2007Dirk VanDelft The International Association of Refrigeration (Association Internationale du Froid) was founded in January 1909. Right from the start, the Dutch physicist Heike Kamerlingh Onnes (1853,1926) played a major role in the new association, which brought together the science of low temperatures; the refrigeration industry; applications of cold to foodstuffs, trade, and transport; and relevant legislation. In July 1908, Kamerlingh Onnes became the first person to liquefy helium, making his Leiden cryogenic laboratory the coldest spot on earth. Because of this success, he was one of the big stars of the First International Congress of Refrigeration, held in October 1908, in Paris. As vice president of the association and chairman of the ,first committee', which dealt with the science of low temperatures, Kamerlingh Onnes was able to strengthen Leiden's position as the leading international centre for cryogenic research. His presentation at the Paris congress unleashed a stream of guest researchers to Leiden, where they enjoyed Kamerlingh Onnes's hospitality and were allowed to extend their research to much lower temperatures then could be reached in their own laboratories. The Association provided grants for young physicists to perform research ,relevant to cold technology' in Leiden's cryogenic laboratory. In practice, however, the Leiden program dealt only with basic research. In 1920, in the wake of World War I, the Association was transformed into the International Institute of Refrigeration (IIR). Kamerlingh Onnes, monsieur Zéro Absolu, maintained his key position. By stressing that the science of refrigeration had a golden future and that superconductivity, which was demonstrated in Leiden in 1911, would come to the aid of electrical engineers, Kamerlingh Onnes was able to secure the funding of his Leiden laboratory by the IIR. [source] The mechanisms that underlie glucose sensing during hypoglycaemia in diabetesDIABETIC MEDICINE, Issue 5 2008R. McCrimmon Abstract Hypoglycaemia is a frequent and greatly feared side-effect of insulin therapy, and a major obstacle to achieving near-normal glucose control. This review will focus on the more recent developments in our understanding of the mechanisms that underlie the sensing of hypoglycaemia in both non-diabetic and diabetic individuals, and how this mechanism becomes impaired over time. The research focus of my own laboratory and many others is directed by three principal questions. Where does the body sense a falling glucose? How does the body detect a falling glucose? And why does this mechanism fail in Type 1 diabetes? Hypoglycaemia is sensed by specialized neurons found in the brain and periphery, and of these the ventromedial hypothalamus appears to play a major role. Neurons that react to fluctuations in glucose use mechanisms very similar to those that operate in pancreatic B- and A-cells, in particular in their use of glucokinase and the KATP channel as key steps through which the metabolic signal is translated into altered neuronal firing rates. During hypoglycaemia, glucose-inhibited (GI) neurons may be regulated by the activity of AMP-activated protein kinase. This sensing mechanism is disturbed by recurrent hypoglycaemia, such that counter-regulatory defence responses are triggered at a lower glucose level. Why this should occur is not yet known, but it may involve increased metabolism or fuel delivery to glucose-sensing neurons or alterations in the mechanisms that regulate the stress response. [source] Interstrand crosslink inducing agents in pretransplant conditioning therapy for hematologic malignanciesENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 6 2010Benigno C. Valdez Abstract Despite successful molecularly targeted, highly specific, therapies for hematologic malignancies, the DNA interstrand crosslinking agents, which are among the oldest and least specific cytotoxic drugs, still have an important role. This is particularly true in stem cell transplantation, where virtually every patient receives conditioning therapy with a DNA-alkylating agent-based program. However, due to concern about serious additive toxicities with combinations of different alkylating drugs, the last several years have seen nucleoside analogs, whose cytotoxic action follows vastly different molecular pathways, introduced in combination with alkylating agents. The mechanistic differences paired with different metabolic pathways for the respective drugs have clinically translated into increased safety without appreciable loss of antileukemic activity. In this report, we review pre-clinical evidence for synergistic antileukemic activity when nucleoside analog(s) and DNA-alkylating agent(s) are combined in the most appropriate manner(s), without a measurable decrease in clinical efficacy compared with the more established alkylating agent combinations. Data from our own laboratory using combinations of fludarabine, clofarabine, and busulfan as prototype representatives for these respective classes of cytotoxic agents are combined with information from other investigators to explain how the observed molecular events will result in greatly enhanced synergistic cytotoxicity. We further present possible mechanistic pathways for such desirable cytotoxic synergism. Finally, we propose how this information-backed hypothesis can be incorporated in the design of the next generation conditioning therapy programs in stem cell transplantation to optimize antileukemic efficacy while still safeguarding patient safety. Environ. Mol. Mutagen., 2010. © 2010 Wiley-Liss, Inc. [source] Discovery of the hepatitis C virusLIVER INTERNATIONAL, Issue 2009Michael Houghton Abstract After nearly 6 years of intensive investigations between 1982 and 1988 in my laboratory at Chiron corporation, in which numerous molecular biological methods were used to investigate the viral aetiology of parenterally transmitted non-A, non-B viral hepatitis (NANBH), a single cDNA clone (5-1-1) was isolated that was shown to be derived from a new flavi-like virus, termed the hepatitis C virus (HCV). After screening hundreds of millions of bacterial cDNA clones derived from different liver and plasma samples obtained from experimentally infected chimpanzees, a single HCV clone was eventually isolated using a novel, blind immunoscreening method in which antibodies derived from a clinically diagnosed NANBH patient were used to identify a cDNA clone encoding an immunodominant epitope within HCV nonstructural protein 4. Its viral origin was demonstrated by its specific hybridization to a large single-stranded RNA molecule of ,10 000 nucleotides found only in NANBH-infected samples that shared distant sequence identity with flaviviruses. Further, HCV clone 5-1-1 was shown to be extrachromosomal and to encode an antigen eliciting antibody seroconversion only in NANBH-infected chimpanzees and humans. Subsequent work demonstrated that HCV was the principal cause of parenterally transmitted NANBH around the world, with an estimated 170 million global carriers and that blood screening tests detecting circulating HCV antibodies and viral RNA could effectively eradicate the transmission of transfusion-associated NANBH. Key viral-encoded enzymes essential to its life cycle are now the targets of vigorous, ongoing drug development activities, and the feasibility of successful vaccination strategies has been demonstrated using the valuable chimpanzee model, without which any progress on HCV would not have been possible. My colleagues and coworkers who made essential contributions to the discovery of HCV were George Kuo, who had his own laboratory at Chiron and who provided intellectual and practical input, Dan Bradley of the Centers for Disease Control and Prevention, who provided a large supply of well-characterized chimpanzee samples and knowledge of the NANBH field, and Qui-Lim Choo, in my own laboratory, who provided many years of outstandingly dedicated and precise molecular biology expertise. [source] New molecular methods to study gene functions in Candida infectionsMYCOSES, Issue 9-10 2002S. Theiß Candida; Molekulargenetik; Genfunktion; Genexpression; ABC-Transporter Summary.Candida albicans has become a model system for human pathogenic fungi in clinical research, mainly due to the increasing number of Candida infections. Molecular techniques to study C. albicans virulence properties have been improved over the last few years, despite difficulties in genetic manipulation of this fungus. Some of the recent achievements from our own laboratory or from other groups are described in this article. The molecular analysis of the recently identified ATP-dependent transporter Mlt1 using the green fluorescent protein (GFP) as reporter for protein localization and the dominant MPAR gene as a selection marker for gene inactivation provides an example for the study of gene functions in C. albicans. Zusammenfassung.Candida albicans ist für die klinische Forschung zu einem Modellsystem zur Untersuchung humanpathogener Pilze geworden, was nicht zuletzt auf die steigende Zahl an Candida -Infektionen zurückzuführen ist. Trotz der Schwierigkeiten, die eine genetische Manipulation dieses Pilzes mit sich bringt, konnten in den letzten Jahren molekularbiologische Techniken zur Erforschung der Virulenzfaktoren von C. albicans weiterentwickelt werden. Einige dieser neuen Methoden, zum Teil aus unserer Arbeitsgruppe, aber auch aus anderen Laboratorien, werden in diesem Artikel beschrieben. Zudem gibt die Analyse des kürzlich isolierten, ATP-abhängigen Transporters Mlt1 ein Beispiel für die Studie von Genfunktionen, wobei das GFP (green fluorescent protein) als Reporter für Proteinlokalisation und der dominante Selektionsmarkers MPAR zur Geninaktivierung verwendet wurden. [source] A pooled analysis of karyotypic patterns, breakpoints and imbalances in 783 cytogenetically abnormal multiple myelomas reveals frequently involved chromosome segments as well as significant age- and sex-related differencesBRITISH JOURNAL OF HAEMATOLOGY, Issue 6 2003Thérèse Nilsson Summary. The cytogenetic features (ploidy, complexity, breakpoints, imbalances) were ascertained in 783 abnormal multiple myeloma (MM) cases to identify frequently involved chromosomal regions as well as a possible impact of age/sex. The series included MM patients from the Mitelman Database of Chromosome Aberrations in Cancer and from our own laboratory. Hyperdiploidy was most common, followed by hypodiploidy, pseudodiploidy and tri-/tetraploidy. Most cases were complex, with a median of eight changes per patient. The distribution of modal numbers differed between younger and older patients, but was not related to sex. No sex- or age-related differences regarding the number of anomalies were found. The most frequent genomic breakpoints were 14q32, 11q13, 1q10, 8q24, 1p11, 1q21, 22q11, 1p13, 1q11, 19q13, 1p22, 6q21 and 17p11. Breaks in 1p13, 6q21 and 11q13 were more common in the younger age group. The most frequent imbalances were +,9, ,,13, +,15, +,19, +,11 and ,,Y. Trisomy 11 and monosomy 16 were more common among men, while ,X was more frequent among women. Loss of Y as the sole change and +,5 were more common in elderly patients, and ,,14 was more frequent in the younger age group. The present findings strongly suggest that some karyotypic features of MM are influenced by endogenous and/or exogenous factors. [source] | ||||||||||