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PubMed2004

Diffuse aggressive lymphoma.

The aggressive non-Hodgkin's lymphomas can be cured in more than half of the cases. However, there has been great variation in the results reported from individual clinical Phase II trials. This variation in result can be attributed to unrecognized heterogeneity in this group of diseases. Recent clinical and molecular studies have enabled us to define more homogenous population in which new therapies can be studied. For patients with advanced stages of diffuse large B cell lymphoma, a new standard of therapy exists. For patients with localized aggressive non-Hodgkin's lymphomas, heterogeneity in patient selection prevents us from defining a new standard of care. Finally, in mantle cell lymphoma, new opportunities in drug discovery may permit advances in the treatment of this uniformly fatal malignancy. In Section I, Dr. Richard Fisher reviews the development of combination chemotherapy for patients with advanced stage diffuse large B cell lymphoma. Because of great heterogeneity in patients enrolled in Phase II studies, large randomized Phase III studies were required in the 1980s to define CHOP has the standard of care. This heterogeneity has now been defined carefully in the international prognostic factor index and more recently by gene array studies. It will now need to be incorporated prospectively into studies or retrospectively analyzed to understand clinical trial results. The addition of rituximab to CHOP has now been demonstrated to improve survival in two large Phase III studies in elderly patients. A recently presented study in younger patients suggests a similar benefit. Thus CHOP/rituximab has become the established standard of care for all patients with advanced stage diffuse large B cell lymphoma. Other concepts being evaluated to further improve on these results include: dose intensification; initial treatment with chemotherapy plus allogeneic stem cell transplantation; and infusional chemotherapy. Finally, the status of the treatment for relapsed patients will be defined. In Section II, Dr. Thomas Miller defines the treatment for limited stage aggressive non-Hodgkin's lymphoma. Randomized trials have demonstrated the critical importance of initial chemotherapy for treatment of these patients. The amount of chemotherapy given needs to be increased for patients with bulky tumors. In most circumstances radiotherapy after the completion of chemotherapy has been shown to be advantageous. A modification of the international prognostic factor index for patients with early stage disease is presented to permit comparisons among different populations. Recently reported early-stage studies need to be analyzed in terms of the heterogeneity of the patients involved to understand the reported results. The addition of monoclonal antibodies, as well as radioimmunotherapy, are being tested in an effort to improve on the results for the poor prognosis patients. In Section III, Dr. Owen O'Connor describes the pathology immunophenotype and natural history of mantle cell lymphoma. Conventional treatment strategies with combination chemotherapy achieved objective responses in approximately half of the patients but no significant impact on survival. The addition to rituximab to CHOP chemotherapy or other treatment strategies appears to improve the remission rate; however, no major changes in survival have also been reported. Excellent single institution results have been reported with HyperCVAD plus rituximab regimen, which is currently being tested in a national cooperative group trial. The most excitement in this field currently relates to the variety of new agents which appear to have significant activity in relapsed patients with mantle cell lymphoma. This includes the proteosome inhibitor, bortezomib, which is shown to have approximately a 50% response rate with some CRs and reasonable durability in early single institution Phase II studies. Larger national multi-center trials are ongoing. In addition, agents such as thalidomide, flavopiridol, and piroxantrone will be reviewed.

Antibodies, Monoclonal↗

PubMed1976

Respiratory response to airway occlusion in infants: sleep state and maturation.

The progressive respiratory response to occlusion of the airway at FRC was measured in a group of full-term and premature human infants. The sleep state of the full-term infants was shown to affect the response primarily through variations in the phase of thoracic and abdominal movements. The weakest responses were seen in those infants who demonstrated parodoxical respiration prior to occlusion. Most infants developed paradoxical respiratory movements after occlusion, but this did not affect the strength of the load-compensatory response. An increase in response related to both gestational and postnatal age was observed. This increase could not be accounted for by variations in the amount of paradoxical and in-phase respiration and thus may represent an increase in the sensitivity of infants to chemical stimuli with maturation.

Aging↗

PubMed1987

Evaluation of a modeling system for S-phase estimation in breast cancer by flow cytometry.

Using software programs provided by Coulter Electronics, we have developed an analysis system that would address problems encountered in DNA flow cytometric analysis of heterogeneous solid tumor populations, especially where the G2-M phase of the diploid population contaminates the S-phase of the aneuploid population, causing an overestimation of cells in S phase. We used the PARA 1 and PARA 2 programs in concert and developed three analysis models: (a) for euploid tumors; (b) for hyperdiploid tumors with overlapping populations; and (c) for near-diploid aneuploid tumors. Our purpose in this paper is to determine the limits and reproducibility of this analysis system with an emphasis on tumors with overlapping populations. Aliquots of frozen, pulverized breast tumor tissue (50 to 100 mg), routinely used in the steroid receptor assay, were used for routine flow cytometric measurement of the DNA index and S-phase fraction. To determine the accuracy of the analysis when overlapping populations were present, we mixed an aneuploid breast cancer cell line with human blood lymphocytes in varying ratios. A 10% mixture of aneuploid cells, the lowest mixture tested, still allowed analysis results within 95% confidence limits. Reproducibility of the system was assessed on frozen breast tumor tissue by intra- and interassay variation studies measuring cell cycle parameters and coefficient of variation of the G0-G1 peak width. Within any sample the amount of variation (+/- 2 SD) for the G0-G1 value was +/- 4.40 for intraassay and +/- 4.60 for interassay, and the amount of variation for S phase was +/- 3.0 and +/- 3.2 for intraassay and interassay, respectively. There was no difference in the variation of estimates for G2-M (+/- 2.6 for both intra- and interassay). In this study, the coefficient of variation of the G0-G1 peak greater than 5% was defined as unacceptable for accurate analysis, with the conclusion that S-phase fractions in aneuploid tumors can be routinely analyzed in human breast tumor biopsies despite tumor cell heterogeneity.

Aneuploidy↗

PubMed2006

Application of a column selection system and DryLab software for high-performance liquid chromatography method development.

This paper describes a strategy for the development of chromatographic methods for drug candidates based upon the use of simple MS compatible mobile phases and optimization of the chromatographic selectivity through variations of the stationary phase and mobile phase pH. The strategy employs an automated column selection system and a series of HPLC columns, varying in hydrophobicity and silanol activity, in combination with DryLab software to develop chromatographic methods for the separation of mixtures of bupivacaine and its metabolites; acidic, basic, and neutral compounds; and atenolol, nitrendipine, and their degradation products.

Atenolol↗

PubMed2000

Rapid liquid chromatographic method for simultaneous determination of tetracyclines antibiotics and 6-epi-doxycycline in pharmaceutical products using porous graphitic carbon column.

A rapid and selective high performance liquid chromatographic (HPLC) method has been developed for the separation and determination of five commercially used tetracyclines. The chromatography was performed on a porous graphitic carbon (PGC) column, using 0.05 M potassium phosphate buffer (pH 2.0)--acetonitrile (40 + 60) as the mobile phase and ultraviolet detection at 268 nm. The method permits the simultaneous determination of oxytetracycline, metacycline, chlortetracycline and doxycycline as well as the separation of one of their common impurities (6-Epi-doxycycline) in bulk powder and pharmaceutical preparations with detection limits of 0.5-2 microg ml(-1) and recoveries of 98.9-100.5%. Correlation coefficients for calibration curves in the range of 5-50 microg ml(-1) were greater than 0.999 for all tetracyclines. The within- and between-day precision was determined for both retention times and peak area. It is suggested that the proposed HPLC-PGC method should be used for routine quality control and dosage form assay of tetracyclines in pharmaceutical preparations. The chromatographic behaviour of the five tetracyclines was examined under variable mobile phase compositions, the results revealed that elution order and selectivity were dependent on the buffer agent used. Comparison between retentions obtained with PGC and with silica-based stationary phase (ODS), showed similar variations of the capacity factors with the mobile phase composition, but with a different elution order.

Chromatography, High Pressure Liquid↗

PubMed1998

Variations of rat brain calmodulin content in dark and light phases: effect of pentylenetetrazol-induced kindling.

Calmodulin (CaM) through activation of CaM-kinase II may be involved in the molecular mechanisms underlying the epileptogenic processes. Some evidence suggests that kindling responses change across the day-night cycle. In order to test if kindling stimulation modifies CaM content, we measured CaM concentrations in amygdala, hippocampus and hypothalamus obtained from control and kindled rats during light and darkness. Male Wistar rats (250-300 g), were injected i.p. with Pentylenetetrazol (PTZ) (35 mg/kg/24 h). Once chemical kindling was established, rats were sacrificed by decapitation at 10:30 a.m. and 01:30 a.m. The brains were obtained, and the amygdala, hippocampus and hypothalamus dissected. CaM content was measured in the cytosol and membrane fractions by radioimmunoassay. We found a significant increase in CaM content in cytosol and membrane fractions of both control and kindled rats during the dark phase. No significant differences in CaM concentrations were observed between control and experimental rats, whether during the light or the dark phase. The data suggest a well defined photoperiodic variation in CaM concentrations in limbic structures, despite the neuronal excitability produced by kindling. In addition, the observed CaM increases during the dark time may be related to a protective mechanism against enhanced sensitivity to seizures observed during the night.

Amygdala↗

PubMed1993

Lifelong learning of physicians: contributions of different educational phases to practice performance.

This pilot study was designed to find out where and when in their education physicians thought they had acquired the competencies they used in their daily practices five years after completion of their formal training. Specifically, the study sought physicians' views about the relative contributions of seven major phases of medical education (i.e., preclinical, clinical, "practice phases 1 and 2," specialty training, formal continuing education, and independent learning) to their practice performances. In 1991, the authors distributed a questionnaire to 330 physicians participating in a continuing medical education course in Germany, asking them about the relative contributions of these educational phases to their practice performances. A total of 141 (43%) returned questionnaires, of which 114 were suitable for evaluation. Specialty education was believed to have contributed most to the physicians' daily practices, with a median contribution of 20%. Practice-based independent learning, in which 38% participated in groups, contributed, with a median of 18%, and was superior to formal continuing education, with a median of 5%, and to university education, 15%. The frequency distribution of the percentages allotted to the seven phases showed great variation. Thirty-four respondents stated that they had not gained appreciably from preclinical education or formal continuing education but that the other five phases had contributed 50% to 90% of the knowledge and skills they used in their practices.

Clinical Competence↗

PubMed1992

Differences in auditory performance between monaural and dichotic conditions. I: masking thresholds in frozen noise.

Thresholds of a 5-ms, 1-kHz signal were determined in the presence of a frozen-noise masker. The noise had a flat power spectrum between 20 Hz and 5 kHz and was presented with a duration of 300 ms. The following interaural conditions were tested with four listeners: Noise and signal monaural at the same ear (monaural condition, NmSm), noise and signal identical at both ears (diotic condition, NoSo), noise identical at both ears and signal monaural (dichotic condition, NoSm) and uncorrelated noise at the two ears and signal monaural (NuSm). The signal was presented at a fixed temporal position with respect to the frozen noise in all measurements and thresholds were determined for different starting phases of the carrier frequency of the signal. Variation of the carrier phase strongly influenced the detection in the diotic condition and the masked thresholds varied by more than 10 dB. The pattern of thresholds for the monaural condition was less variable and the thresholds were generally higher than for the diotic condition. The monaural-diotic difference for specific starting phases amounted to as much as 8 dB. Comparison measurements using running noise maskers revealed no such difference. This relation between monaural and diotic thresholds was further investigated with eight additional subjects. Again, monaural and diotic thresholds in running noise were identical, while in frozen noise, diotic thresholds were consistently lower than monaural thresholds, even when the ear with the lower NmSm threshold was compared. For the starting phase showing the largest monaural-diotic difference, the thresholds for NoSm lay between the monaural and the diotic values. At other starting phases, the NoSm threshold was clearly lower than both the NmSm and the NoSo threshold. One possible explanation of the observed monaural-diotic differences relates to contralateral efferent interaction between the right and the left hearing pathway. A prediction based on this explanation was verified in a final experiment, where frozen-noise performance for NmSm was improved by simultaneously presenting an uncorrelated running noise to the opposite ear.

Acoustic Stimulation↗

PubMed1999

Spectral quantitation by principal component analysis using complex singular value decomposition.

Principal component analysis (PCA) is a powerful method for quantitative analysis of nuclear magnetic resonance spectral data sets. It has the advantage of being model independent, making it well suited for the analysis of spectra with complicated or unknown line shapes. Previous applications of PCA have required that all spectra in a data set be in phase or have implemented iterative methods to analyze spectra that are not perfectly phased. However, improper phasing or imperfect convergence of the iterative methods has resulted in systematic errors in the estimation of peak areas with PCA. Presented here is a modified method of PCA, which utilizes complex singular value decomposition (SVD) to analyze spectral data sets with any amount of variation in spectral phase. The new method is shown to be completely insensitive to spectral phase. In the presence of noise, PCA with complex SVD yields a lower variation in the estimation of peak area than conventional PCA by a factor of approximately 2. The performance of the method is demonstrated with simulated data and in vivo 31P spectra from human skeletal muscle.

Analysis of Variance↗

PubMed2005

Ultrasound phase-contrast transmission imaging of localized thermal variation and the identification of fat/tissue boundaries.

We present a new ultrasound technique for registering localized temperature changes in soft tissues. Conversely, small temperature changes may be induced in order to image tissue layers. The concept is motivated by the search for a compact, low cost method for guiding noninvasive thermal therapies; however its utility may extend to a wide range of imaging problems such as tumour imaging in the breast. This method combines ultrasound transmission imaging, planar projection techniques and phase-contrast theory. After outlining the theoretical foundation of the technique, its feasibility is tested by simulating localized heating within homogeneous tissue layers. Success of this imaging method is evaluated as a function of the ultrasound-imaging wavelength for a Gaussian-shaped heated region over the frequency range from 0.1 to 2 MHz. Furthermore we simulate two-dimensional image reconstruction from a receiving array. We conclude that thermal phase-contrast imaging in tissues is plausible for detecting the treatment spot in thermal therapies while operating at frequencies below 1 MHz. Additionally, it may also be possible to use the method for noninvasive thermometry. However, thermometry would require operation at higher frequencies at the tradeoff of increased attenuation and higher sensitivity to scattering, which needs to be further explored.

Body Temperature↗

PubMed2004

Broadband phase correction of FT-ICR mass spectra via simultaneous excitation and detection.

In typical Fourier transform ion cyclotron resonance (FT-ICR) mass spectra, temporally dispersed excitation and the delay between excitation and detection result in continuous variation of signal phase with frequency in the detected time-domain ion signal. The complex frequency-domain spectrum of such a signal is a linear combination of absorption- and dispersion-mode spectral components with corresponding asymmetric peaks. For this reason, magnitude-mode spectral display is usually employed to yield a phase-independent uniform and symmetrical peak shape at the expense of spectral resolution. In this work, we implement simultaneous excitation and detection to enable Fourier deconvolution to recover absorption-mode spectra for both low- and high-field FT-ICR instruments. These spectra yield resolving power improvement factors approaching the maximum theoretical limit of 2.0, as well as reduction in frequency assignment errors relative to conventional magnitude-mode spectra. The Fourier deconvolution procedure has the additional benefit of correcting for spectral variation resulting from nonuniform power distribution over the excitation bandwidth and the potential benefit of providing useful diagnostic information for interpretation of experimental performance.

Journal Article↗

PubMed2000

An improved broadband decoupling sequence for liquid crystals and solids.

Recently we developed an efficient broadband decoupling sequence called SPARC-16 for liquid crystals ¿J. Magn. Reson. 130, 317 (1998). The sequence is based upon a 16-step phase cycling of the 2-step TPPM decoupling method for solids ¿J. Chem. Phys. 103, 6951 (1995). Since then, we have found that a stepwise variation of the phase angle in the TPPM sequence offers even better results. The application of this new method to a liquid crystalline compound, 4-n-pentyl-4'-cyanobiphenyl, and a solid, L-tyrosine hydrochloride, is reported. The reason for the improvement is explained by an analysis of the problem in the rotating frame.

Crystallization↗

PubMed2005

Responses to selection on male-phase duration in Chamerion angustifolium.

Protandry (when male function precedes female) can enhance fitness by reducing selfing and increasing pollen export and outcrossed siring success. However, responses to selection on protandry may be constrained by genetic variation and correlations among floral traits. We examined these potential constraints in protandrous Chamerion angustifolium (Onagraceae) by estimating genetic variation in male-phase duration and associated floral traits using a paternal half-sib design and selection experiment. Narrow-sense heritability of male-phase duration was estimated as 0.23 (SE +/- 0.04) and was positively correlated with floral display. The selection experiment shortened male-phase duration 0.8 SD from the parental average of 17.0 h and lengthened it by 2.0 SD. Furthermore, fixed floral longevity caused a negative association between male- and female-phase durations. These results suggest that selection on male-phase duration is not limited by genetic variation. However, changes in male-phase duration may influence pollinators through correlated changes in floral display and reduced opportunities for pollen receipt during female phase.

Analysis of Variance↗

PubMed1991

Does Fourier phase shift correlate with conduction delay in bundle branch block?

Fourier analysis of radionuclide ventriculography is adept at qualitatively demonstrating interventricular conduction delay in bundle branch block. In this study of eighteen patients, there is a considerable individual variation when the phase delay is expressed as an absolute conduction delay (milliseconds). Much of this variability persists after curve representation by the Fourier function has been optimized. It is suggested that this variability is due to differences in the shape of the right and left ventricular time-activity curves, reflecting differences in contraction and relaxation in the two ventricles. Such differences may be more pronounced in some subjects than others. These results suggest that absolute conduction delay cannot be reliably achieved by this method.

Bundle-Branch Block↗

PubMed2004

Daily variation in cellular content of UV-absorbing compounds mycosporine-like amino acids in the marine dinoflagellate Scrippsiella sweeneyae.

Sudden exposure experiments to high PAR (photosynthetically available radiation) or high PAR+UVR (ultraviolet radiation) were conducted for the marine dinoflagellate Scrippsiella sweeneyae acclimated to either low PAR or high PAR to determine the induction of cellular mycosporine-like amino acid (MAA) in relation to photosynthesis status. When the exposure to high PAR (30.8 Wm(-2)) was provided at different time in the light period for S. sweeneyae acclimated to low PAR (7.7 Wm(-2)) which suppressed photosynthesis, S. sweeneyae could enhance the induction of MAA but it only occurred in the first half of the light period. When UVR exposure was provided for the culture acclimated to high PAR which enhanced photosynthesis, cellular MAA content did not increase during the entire light period, but displayed daily variation similar to the control for two and half days. Daily variation of cellular MAA content did not synchronized with that of cell volume and cellular chlorophyll a content. The individual MAAs also revealed similar daily variations with different phase, which increased for a few hours in the beginning of the light period, except for cellular palythine content. Thus the total cellular MAA content revealed daily variation with changing the relative composition within a few hours. As one of the biological protective strategies against harmful UVR in sunlight, the daily vertical migration in the bloom forming dinoflagellates might be accompanied by the daily variation of cellular MAA content for a photosynthesis at daytime.

Animals↗

PubMed1996

The effect of number of histogram events on reproducibility and variation of flow cytometric proliferation measurement.

Sources of variation in synthesis phase fraction (SPF) calculation were studied, and the number of histogram events was found to be an important quality control consideration. Six cell cycle models (CCMs) for histograms composed of 1,000 to 20,000 events were compared. All CCMs were cytometer based, or available in Multicycle (MC) software. The experiment consisted of five consecutive acquisitions, on the same day, of the same propidium iodide (PI) stained sample of T24 human cell line, at each of nine "landmarks" between 1,000 and 20,000 events. The authors found (1) all CCMs evaluated required > or = 5,000 events for accurate, reproducible SPF; and (2) in the 5,000-20,000 event range the MC models provided the most accurate, reproducible SPF values. Therefore, histogram-dependent curve fitting models may enhance clinical applications of FCM proliferation measurements. The authors conclude that histogram rejection criteria for S-phase analysis should be established, and that two-color multiparametric DNA analysis "live" gating with tissue specific markers may assure acquisition of sufficient events for accurate SPF.

Carcinoma, Transitional Cell↗

PubMed1999

Hyaluronic acid grafted with poly(ethylene glycol) as a novel peptide formulation.

Hyaluronic acids (HA) grafted with poly(ethylene glycol) (PEG) (PEG-g-HA) were synthesized. The materials characterization, enzymatic degradability and peptide (insulin) release from solutions of the copolymers were examined. Distribution of bioactive peptides within the polymer chain is well-known for combinations of PEG and polysaccharides as aqueous polymer two-phase systems. Insulin was preferentially partitioned into the PEG phase in a PEG/HA solution system. Enzymatic degradation of the copolymers was strongly dependent on the PEG content. Thermal analysis revealed that PEG-g-HA exhibited a variation in phase-separated structures depending on the PEG content. The solution of PEG-g-HA enabled insulin to remain in the PEG moieties dispersed in the HA matrix. Leakage of insulin from the copolymers was dependent upon the PEG content. Leakage rate of insulin from copolymer containing between 7 and 39% by weight of PEG were similar. A dramatic increase in leakage rate occurred when the PEG content was increased to greater than 39% by weight. It is considered that the loaded insulin was partitioned into the PEG moieties and became entangled with the PEG chains. The conformational change of insulin was effectively prevented in PEG-g-HA solutions, although insulin was denatured in storage of both phosphate buffered solution and HA solution. Such a heterogeneous-structured polymeric solution may be advantageous as an injectable therapeutic formulation for ophthalmic or arthritis treatment.

Biodegradation, Environmental↗

PubMed1993

[A study on the integration of fetal behavior and the development of association between parameters evaluated].

To evaluate the development of the fetal behavioral state with reference to the association of the fetal parameters we selected, we simultaneously monitored fetal heart rate (FHR), fetal movement (FM), fetal eye movement (FEM) and fetal breathing movement (FBM). These various parameters were monitored with 2 ultrasonographic real time scanners and a doppler device to monitor fetal movement. We assessed the convergence and integration of these four parameters to evaluate the association rate (AR). FHR with a variation in excess of 3 min. was interpreted as the active phase (A), and reduced variation in excess of 3 min. as the inactive phase (I). When FM and FEM were observed in the 1 min. window of A, we labeled this A3, and when FBM was present in more than 10% of the 1 min. window, we labeled it A4. A3/A = AR-A3% and A4/A = AR-A4% was calculated. A similar calculation was done for I, without FM and FEM in the 1 min. window of I (I3) and when FBM was present less than 10% of 1 min. (I4), allow derivation AR-I3% and AR-I4%. A discrete separation of synchrony in A and asynchrony in I can be seen to develop as the fetus matures, and we feel that this may be a valuable tool in the evaluation of fetal central nervous system development in utero.

Central Nervous System↗