The triplet state of the FMO complex of the green sulfur bacterium Prosthecochloris aestuarii studied with single-crystal EPR

Triplet-electron paramagnetic resonance (EPR) spectra were obtained of single crystals of the FMO complex of the green sulfur bacterium Prostecochloris aestuarii. The experiments support the results presented in a previous paper (Louwe et al., J. Phys. Chem. 101 (1997) 11280), which showed that the experimental optical spectra of this pigment-protein complex are best reproduced by assuming that one bacteriochlorophyll (BChl 3) is energetically isolated and that this BChl is the triplet-carrying BChl of the FMO complex at cryogenic temperatures for low excitation density. When comparing the experimental and simulated data sets of the triplet-EPR spectra in single crystals, the best fit is obtained for two triplet states, one localized at BChl 3 and the other at BChl 1. The existence of two different triplet states is traced to the relatively high excitation power necessary to observe the small triplet-EPR signal of the FMO single crystals.     

Induction of T cell adhesion to extracellular matrix or endothelial cell ligands by soluble or matrix-bound interleukin-7

The putative effects of interleukin (IL)-7, operating in the context of extracellular matrix (ECM), on the adhesion of human T cells were examined. Recombinant human, IL-7 was found to bind ECM or fibronectin (FN) with IC50 values of 10-100 nM. Nanogram amounts of both soluble and, especially, FN- or ECM-bound IL-7, which differentially affected the morphologies of FN-adherent T cells, induced the adhesion of resting CD4+ and CD8+ T cells in dose-dependent and beta 1 integrin-dependent manners. Under static and flow conditions, soluble IL-7 also induced the binding of unstimulated T cells to vascular cell adhesion molecule-1, suggesting that this cytokine can also modulate integrin binding to endothelial cell ligands. The effects of affinity modulation by IL-7 of FN-specific beta 1 integrins depend on the presence of soluble FN, which inhibited T cell adhesion to FN induced by FN-bound IL-7 or by an integrin-specific affinity-modulating monoclonal antibody, but not by soluble IL-7 or phorbol 12-myristate 13-acetate. These findings provide an example of a major ECM integrin ligand, FN, which is capable of modulating its adhesive interactions with specific immune cells by associating with and presenting a cytokine in a bio-active state.     

The impact of true partnership between a university Level I trauma center and a community Level II trauma center on patient transfer practices

OBJECTIVE: To examine the effect of a clinical and administrative partnership with an academic urban Level I trauma center on the patient transfer practices at a suburban/rural Level II center. METHODS: Data for 2 years before affiliation (PRE) abstracted from inpatient charts and the trauma registry were compared with that for 2 years after (POST). The following data were collected: number of, reason for, and destination and demographics of transfers. Chi(2) test and t test analyses were used; p < 0.05 defined significance; data are mean +/- SEM. RESULTS: Transfer rate increased from 4% PRE to 6.9% (p = 0.001) POST with no significant difference in age, Glasgow Coma Scale score, Injury Severity Score, or Revised Trauma Score. Repatriation occurred in 12.8% POST (none PRE). The current Level I facility accepted 1.8% of all transfers PRE and 36.4% POST (p = 0.0001). PRE/POST rates by reason are as follows: pediatric, 14.6%/9.0% (p = 0.04); intensive care unit, 0.4%/1.7% (p = 0.13); complex orthopedic, 100%/0% (p = 0.005); vascular, 50%/0% (p = 0.008); spinal cord injury, 100%/100%; and ophthalmologic, 0%/100% (p = 0.005). CONCLUSIONS: In this experience of Level I/II partnership (1) transfer patterns were altered, (2) select patient cohort transfers decreased (pediatric, complex orthopedic, vascular), whereas others increased (aortic work-up), and (3) repatriation rates were low.     

Semi-automatic analysis of two-dimensional electrophoretic gels

A powerful technique, two dimensional gel electrophoresis, has recently become available for the analysis of biological material. This technique allows the proteins of a sample to be mapped on a two-dimensional polyacrylamide gel. The research outlined here involves a multi-disciplinary approach to the semi-automatic comparison of two gels of biologically similar materials. The aim of the project is to identify the significant differences between the gels and point them out to the electrophoresis expert. This job, when done by hand, can be time consuming, since the gels are distorted and can contain hundreds of protein spots. Automatic analysis of 2D gel separations has proved to be extremely difficult using statistical methods. Non-reproducibility of gel separations is also difficult to overcome using automatic systems. However, the human eye is extremely good at recognizing patterns in images, and human intervention in semi-automatic computer systems can reduce the computational complexity. This paper focuses on the intelligent knowledge-based systems aspects of the project, and in particular the work of the first author. The results demonstrate that the semi-automatic approach can produce reliable results quickly. Further work, beyond the scope of this paper, focuses on creating a database of gels for comparison.     

Model for the oxygenation of the YBa2Cu3O7−x 90K superconductor

A model incorporating the thermodynamic equilibrium oxygen content, oxygen in-diffusion, and oxide phases for the oxygenation of the YBa₂Cu₃O_7−x is described. For sintered polycrystals, grain growth and the resulting grain size distribution are included. The model is used to calculate the volume percent of each oxide phase for several processing conditions of sintered specimens and is compared with available results on the quantification of phases present. Such a comparison indicates that as the concentration of impurity phases increases so does the concentration of the less oxygenated 123 phases, suggesting that impurities coating 123 grains act as oxygen indiffusion barriers. The model is also used to investigate the uniformity of the oxygen content in large twinned and detwinned single crystals such as have been used for measuring superconductivity parameters.     

Oral topotecan given once or twice daily for ten days: a phase I pharmacology study in adult patients with solid tumors

The development of a highly sensitive method for detection of telomerase activity, telomeric repeat amplification protocol (TRAP), has provided knowledge on telomerase activity in normal and cancer tissues. Subsequent several modifications have been achieved, including an introduction of the internal standard and hybridization protection technique that leads to simplicity and improvement of reproducibility and linearity of this method, and application of TRAP to in situ analysis to identify the cells responsible for telomerase activity. As for measurement of telomere length, fluorescence in situ hybridization technique appeared to give an information of telomere length on an individual chromosome in contrast to analysis of terminal restriction fragment, a conventional method which can express mean telomere length of all chromosomes. Further methodological improvement in this field is ongoing and showing a new sight on cell mortality and immortality.     

Anomalous behavior of radiofrequency size effect signals in indium

Two types of anomalous behavior of radiofrequency size effect (RFSE) signals arising from the second-zone hole surface of indium have been observed. Both anomalies can be explained in terms of the overlapping of RFSE signals and can be resolved by slightly tilting the magnetic field with respect to the sample surface.     

Towards a New Taxonomy of Photosynthetic Bacteria: ADMR-Monitored Triplet Difference Spectroscopy of Reaction Center Pigment–Protein Complexes

Low-temperature (1.2 K) triplet-minus-singlet absorbance difference spectra of a number of photosynthetic bacteria, including members of almost all genera with the exception of Heliobacteriaceae, have been recorded by absorbance-detected magnetic resonance (ADMR). The spectra of the purple bacteria fall into two distinct classes. It is argued that these classes reflect the extent of delocalization of the primary donor triplet state over its two bacteriochlorophylls. The spectra from the green sulfur bacteria form a third class. In some cases, the bleaching of the long-wavelength primary donor absorption is split, or shows a strong shoulder at lower energy. This phenomenon is attributed to an intrinsic heterogeneity of the reaction center with regard to the precise configuration of the primary donor dimer. It is argued that the zero-field splitting parameters and the triplet-minus-singlet difference spectra may be used as a taxonomic tool.     

Five days of oral topotecan (Hycamtin), a phase I and pharmacological study in adult patients with solid tumours

Topotecan is a specific inhibitor to topoisomerase I. An oral formulation of topotecan is available with a bioavailability of 32-44% in humans. A phase I and pharmacological study of the oral formulation of topotecan administered daily for 5 days every 21 days was performed in adult patients with solid tumours to determine the maximum tolerated dose (MTD). Adult patients with a WHO performance status < or = 2 adequate haematological, hepatic and renal functions, with malignant solid tumours refractory to standard forms were entered into the study. Pharmacokinetics were performed on days 1 and 4 of the first course using a validated high performance liquid chromatographic assay. 29 patients entered the study, all patients were evaluable for toxicity and response. The doses studied in the 29 patients were 1.2, 1.8, 2.3, 2.7 mg/m2/day and a fixed dose of 4 mg/day without surface area adjustment. A total of 109 courses were given. Dose limiting toxicity (DLT) was reached at a dose of 2.7 mg/m2/day and consisted of CTC (NCI-Common Toxicity Criteria) grade IV granulocytopenia. The regimen was well tolerated. Non-haematological toxicities were mild, including fatigue, anorexia, nausea, vomiting and diarrhoea. A significant correlation was observed between the percentage decrease in white blood cells versus the area under the curve (AUC(t)) of topotecan lactone (R = 0.76 P < 0.01) which was modelled by a sigmoidal Emax function. The correlation coefficient between the absolute topotecan dose administered and the AUC(t) was R = 0.52 (P = 0.04). Pharmacokinetics of the fixed dose of 4 mg/day were comparable to the 2.3 mg/m2/day dose. DLT in this phase I study of five daily doses of oral topotecan every 21 days was granulocytopenia. The recommended dose for phase II studies is 2.3 mg/m2/day or alternatively, a fixed dose of 4 mg/day.