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1.
Hernia ; 28(1): 199-209, 2024 Feb.
Article in English | MEDLINE | ID: mdl-37934377

ABSTRACT

PURPOSE: The objective of this retrospective study was to assess safety and comparative clinical effectiveness of laparoscopic inguinal hernia repair (LIHR) and robot-assisted inguinal hernia repair (RIHR) from multi-institutional experience in Taiwan. METHODS: Medical records from a total of eight hospitals were retrospectively collected and analyzed. Patients primarily diagnosed of inguinal hernia, recurrent inguinal hernia or incarceration groin hernia patients who either underwent laparoscopic or robot-assisted inguinal hernia repair between January 2018 and December 2022 were included in the study. Baseline characteristics, intra-operative and post-operative results were analyzed. To compare two cohorts, overlap weighting was employed to balance the significant inter-group differences. We also conducted subgroup analyses by state of a hernia (primary or recurrent/incarceration) and laterality (unilateral or bilateral) that indicated complexity of surgery. RESULTS: A total of 1,080 patients who underwent minimally invasive inguinal hernia repair from 8 hospitals across Taiwan were collected. Following the application of inclusion criteria, there were 279 patients received RIHR and 763 patients received LIHR. In the baseline analysis, RIHR was more often performed in recurrent/incarceration (RIHR 18.6% vs LIHR 10.3%, p = 0.001) and bilateral cases (RIHR 81.4 vs LIHR 58.3, p < 0.001). Suturing was dominant mesh fixation method in RIHR (RIHR 81% vs LIHR 35.8%, p < 0.001). More overweight patients were treated with RIHR (RIHR 58.8% vs LIHR 48.9%, p = 0.006). After overlap weighting, there were no significant difference in intraoperative and post-operative complications between RIHR and LIHR. Reoperation and prescription rates of pain medication (opioid) were significantly lower in RIHR than LIHR in overall group comparison (reoperation: RIHR 0% vs. LIHR 2.9%, p = 0.016) (Opioid prescription: RIHR 3.34 mg vs LIHR 10.82 mg, p = 0.001) while operation time was significantly longer in RIHR (OR time: RIHR 155.27 min vs LIHR 95.30 min, p < 0.001). CONCLUSIONS: This real-world experience suggested that RIHR is a safe, and feasible option with comparable intra-operative and post-operative outcomes to LHIR. In our study, RIHR showed technical advantages in more complicated hernia cases with yielding to lower reoperation rates, and less opioid use.


Subject(s)
Hernia, Inguinal , Laparoscopy , Robotic Surgical Procedures , Robotics , Humans , Analgesics, Opioid , Hernia, Inguinal/surgery , Hernia, Inguinal/etiology , Herniorrhaphy/adverse effects , Herniorrhaphy/methods , Laparoscopy/adverse effects , Laparoscopy/methods , Propensity Score , Retrospective Studies , Robotic Surgical Procedures/adverse effects , Robotic Surgical Procedures/methods , Treatment Outcome
2.
Harmful Algae ; 103: 102027, 2021 03.
Article in English | MEDLINE | ID: mdl-33980455

ABSTRACT

Research on harmful algal and cyanobacterial blooms (HABs and CHABs) has risen dramatically due to their increasing global distribution, frequency, and intensity. These blooms jeopardize public health, ecosystem function, sustainability and can have negative economic impacts. Numerous monitoring programs have been established using light microscopy, liquid chromatography coupled to mass spectrometry (LC-MS), ELISA, and spectrophotometry to monitor HABs/CHABs outbreaks. Recently, DNA/RNA-based molecular methods have been integrated into these programs to replace or complement traditional methods through analyzing environmental DNA and RNA (eDNA/eRNA) with techniques such as quantitative polymerase chain reaction (qPCR), fluorescent in situ hybridization (FISH), sandwich hybridization assay (SHA), isothermal amplification methods, and microarrays. These have enabled the detection of rare or cryptic species, enhanced sample throughput, and reduced costs and the need for visual taxonomic expertise. However, these methods have limitations, such as the need for high capital investment in equipment or detection uncertainties, including determining whether organisms are viable. In this review, we discuss the potential of newly developed molecular diagnosis technology based on Clustered Regularly Interspaced Short Palindromic Repeats/Cas proteins (CRISPR/Cas), which utilizes the prokaryotic adaptative immune systems of bacteria and archaea. Cas12 and Cas13-based platforms can detect both DNA and RNA with attomolar sensitivity within an hour. CRISPR/Cas diagnostic is a rapid, inexpensive, specific, and ultrasensitive technology that, with some further development, will provide many new platforms that can be used for HABs/CHABs biomonitoring and research.


Subject(s)
Clustered Regularly Interspaced Short Palindromic Repeats , Harmful Algal Bloom , Biological Monitoring , Ecosystem , In Situ Hybridization, Fluorescence
3.
Ann Oncol ; 29(4): 881-887, 2018 04 01.
Article in English | MEDLINE | ID: mdl-29481630

ABSTRACT

Background: There is no standard treatment after progression on second-line chemotherapy for metastatic breast cancer (MBC). We compared vinflunine with physician's choice of alkylating agent (AA) for patients with heavily pretreated MBC. Patients and methods: In this open-label phase III trial, patients with MBC were included if they had received at least two prior chemotherapy regimens for MBC and had received anthracycline, taxane, antimetabolite and vinca alkaloid therapy. Patients were no longer candidates for these chemotherapies because of resistance and/or intolerance. Patients were randomised to either vinflunine 280 mg/m2 intravenously every 3 weeks (q3w) or AA monotherapy q3w. Stratification factors were performance status, number of prior chemotherapy lines for MBC, disease measurability and study site. The primary end point was overall survival (OS). Results: A total of 594 patients were randomised (298 to vinflunine, 296 to AA). There was no difference between treatment arms in OS (hazard ratio 1.04, P = 0.67; median 9.1 months for vinflunine versus 9.3 months for AA), progression-free survival (hazard ratio 0.94, P = 0.49; median 2.5 versus 1.9 months, respectively) or overall response rate (6% versus 4%, respectively). However, the disease control rate was significantly higher with vinflunine than AA (44% versus 35%, respectively; P = 0.04). The most common adverse events (any grade) were haematological and gastrointestinal disorders and asthenia in both arms. The most common grade 3/4 adverse events were neutropenia (19% versus 11% with vinflunine versus AA, respectively) and asthenia (10% versus 4%). Conclusions: Vinflunine 280 mg/m2 q3w did not improve OS compared with the physician's choice of AA as third- or later-line therapy for MBC. Vinflunine demonstrated an acceptable safety profile, suggesting that vinflunine 320 mg/m2 merits evaluation. ClinicalTrials.gov: NCT01091168.


Subject(s)
Antineoplastic Agents, Alkylating/therapeutic use , Antineoplastic Agents, Phytogenic/therapeutic use , Breast Neoplasms/drug therapy , Neoplasm Metastasis , Vinblastine/analogs & derivatives , Adult , Aged , Antineoplastic Agents, Alkylating/adverse effects , Antineoplastic Agents, Phytogenic/adverse effects , Breast Neoplasms/pathology , Female , Humans , Middle Aged , Neoplasm Recurrence, Local/drug therapy , Quality of Life , Survival Analysis , Treatment Outcome , Vinblastine/adverse effects , Vinblastine/therapeutic use
4.
Phys Med Biol ; 60(15): 5995-6012, 2015 Aug 07.
Article in English | MEDLINE | ID: mdl-26183156

ABSTRACT

Monte Carlo simulations are used to calculate the relative biological effectiveness (RBE) of 300 MeV u(-1) carbon-ion beams at different depths in a cylindrical water phantom of 10 cm radius and 30 cm long. RBE values for the induction of DNA double strand breaks (DSB), a biological endpoint closely related to cell inactivation, are estimated for monoenergetic and energy-modulated carbon ion beams. Individual contributions to the RBE from primary ions and secondary nuclear fragments are simulated separately. These simulations are based on a multi-scale modelling approach by first applying the FLUKA (version 2011.2.17) transport code to estimate the absorbed doses and fluence energy spectra, then using the MCDS (version 3.10A) damage code for DSB yields. The approach is efficient since it separates the non-stochastic dosimetry problem from the stochastic DNA damage problem. The MCDS code predicts the major trends of the DSB yields from detailed track structure simulations. It is found that, as depth is increasing, RBE values increase slowly from the entrance depth to the plateau region and change substantially in the Bragg peak region. RBE values reach their maxima at the distal edge of the Bragg peak. Beyond this edge, contributions to RBE are entirely from nuclear fragments. Maximum RBE values at the distal edges of the Bragg peak and the spread-out Bragg peak are, respectively, 3.0 and 2.8. The present approach has the flexibility to weight RBE contributions from different DSB classes, i.e. DSB0, DSB+ and DSB++.


Subject(s)
Algorithms , Carbon Radioisotopes/toxicity , DNA Breaks, Double-Stranded , Radiation Dosage , Monte Carlo Method , Phantoms, Imaging , Relative Biological Effectiveness
5.
Appl Radiat Isot ; 97: 101-105, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25562679

ABSTRACT

The relative biological effectiveness (RBE) of high-energy protons has been well investigated, but estimates of RBE for lower-energy (<40MeV) protons are scarce. In the present work, measurements were made of the lineal energy spectra using a home-made miniature tissue-equivalent proportional counter for 15 and 30MeV protons from the TR 30/15 cyclotron. Monte Carlo simulations were made for the same spectra using the FLUKA code. These spectra were coupled to several biological models to evaluate the RBE for various biological endpoints.


Subject(s)
Proton Therapy , Radiometry/instrumentation , Radiotherapy, High-Energy , Cyclotrons , DNA Breaks, Double-Stranded , Humans , Linear Energy Transfer , Models, Biological , Monte Carlo Method , Radiometry/statistics & numerical data , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted/statistics & numerical data , Radiotherapy, High-Energy/statistics & numerical data , Relative Biological Effectiveness
6.
AJNR Am J Neuroradiol ; 36(3): 467-74, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25339652

ABSTRACT

BACKGROUND AND PURPOSE: Quantitative susceptibility mapping of the human brain has demonstrated strong potential in examining iron deposition, which may help in investigating possible brain pathology. This study assesses the reproducibility of quantitative susceptibility mapping across different imaging sites. MATERIALS AND METHODS: In this study, the susceptibility values of 5 regions of interest in the human brain were measured on 9 healthy subjects following calibration by using phantom experiments. Each of the subjects was imaged 5 times on 1 scanner with the same procedure repeated on 3 different 3T systems so that both within-site and cross-site quantitative susceptibility mapping precision levels could be assessed. Two quantitative susceptibility mapping algorithms, similar in principle, one by using iterative regularization (iterative quantitative susceptibility mapping) and the other with analytic optimal solutions (deterministic quantitative susceptibility mapping), were implemented, and their performances were compared. RESULTS: Results show that while deterministic quantitative susceptibility mapping had nearly 700 times faster computation speed, residual streaking artifacts seem to be more prominent compared with iterative quantitative susceptibility mapping. With quantitative susceptibility mapping, the putamen, globus pallidus, and caudate nucleus showed smaller imprecision on the order of 0.005 ppm, whereas the red nucleus and substantia nigra, closer to the skull base, had a somewhat larger imprecision of approximately 0.01 ppm. Cross-site errors were not significantly larger than within-site errors. Possible sources of estimation errors are discussed. CONCLUSIONS: The reproducibility of quantitative susceptibility mapping in the human brain in vivo is regionally dependent, and the precision levels achieved with quantitative susceptibility mapping should allow longitudinal and multisite studies such as aging-related changes in brain tissue magnetic susceptibility.


Subject(s)
Brain Mapping/methods , Brain , Magnetic Resonance Imaging/methods , Adult , Artifacts , Female , Humans , Magnetics , Male , Phantoms, Imaging , Reproducibility of Results
7.
Cancer Gene Ther ; 21(9): 389-96, 2014 Sep.
Article in English | MEDLINE | ID: mdl-25124811

ABSTRACT

Thymosin beta-4 (Tß4) is known to be involved in tumorigenesis. Overexpression of this polypeptide has been observed in a wide variety of cancers, including colorectal carcinoma (CRC). Accordingly, Tß4 has been proposed to be a novel therapeutic target for CRC, especially in its metastatic form. Although in vitro tumor-suppressive effects of Tß4 gene silencing mediated by small hairpin RNA (shRNA) have already been demonstrated, the in vivo efficacy of such an approach has not yet been reported. Herein, we demonstrated that infection with recombinant adenovirus expressing an shRNA targeting Tß4 markedly reduced the growth of and robustly induced apoptosis in CT-26 mouse CRC cells in culture. Additionally, tumors grown in nude mice from the CT-26 cells whose Tß4 expression already been downregulated by virus infection were also drastically reduced. Most importantly, significant growth arrest of tumors derived from the parental CT-26 cells was observed after multiple intratumoral injections of these viruses. Together, our results show for the first time that in vivo silencing of Tß4 expression by its shRNA generated after adenoviral infection can suppress CRC growth. These results further demonstrate the feasibility of treating CRC by a Tß4 knockdown gene therapeutic approach.


Subject(s)
Adenoviridae/genetics , Colorectal Neoplasms/genetics , Colorectal Neoplasms/pathology , Genetic Vectors/genetics , RNA, Messenger/genetics , RNA, Small Interfering/genetics , Thymosin/genetics , Actins/genetics , Actins/metabolism , Animals , Apoptosis/genetics , Cell Cycle/genetics , Cell Line, Tumor , Cell Transformation, Neoplastic/genetics , Colorectal Neoplasms/metabolism , Disease Models, Animal , Gene Knockout Techniques , Humans , Mice , RNA Interference , Transduction, Genetic , Tumor Burden/genetics , Xenograft Model Antitumor Assays
9.
Neoplasma ; 60(3): 290-4, 2013.
Article in English | MEDLINE | ID: mdl-23373998

ABSTRACT

Triple-negative breast cancer (TNBC) relapses more frequently than hormone receptor-positive subtypes and is often associated with poor outcomes. This retrospective study reviewed the pattern of distant metastasis with regard to survival in patients with TNBC. A total of 205 TNBC patients were analyzed. TNBC patients with lung metastases had the longest median post-metastatic OS (with 95% confidence interval) of 16.6 (10.3-22.9) months, followed by the bone, 16.3 (11.7-20.8) months, the liver, 8.9 (3.5-14.4) months, the pleura, 7.5 (2.8-12.3) months, and the brain, 4.3 (0.6-8.0) months. Kaplan-Meier plots indicated that TNBC patients with metastatic spread to brain, liver, and pleural had poorer post-metastatic OS rate than patients with lung metastases (p = 0.001, 0.004, and 0.029, respectively). Moreover, brain and liver metastases correlated significantly with poorer post-metastatic OS as compared to bone metastasis (p = 0.004 and 0.011, respectively). Route of first metastasis correlated significantly with survival of TNBC patients with brain metastases being the poorest survival indicator, followed by metastases to liver, pleura, bone, and lung.


Subject(s)
Bone Neoplasms/secondary , Brain Neoplasms/secondary , Breast Neoplasms/pathology , Liver Neoplasms/secondary , Lung Neoplasms/secondary , Adult , Aged , Aged, 80 and over , Bone Neoplasms/metabolism , Bone Neoplasms/mortality , Brain Neoplasms/metabolism , Brain Neoplasms/mortality , Breast Neoplasms/metabolism , Breast Neoplasms/mortality , Female , Humans , Immunoenzyme Techniques , Liver Neoplasms/metabolism , Liver Neoplasms/mortality , Lung Neoplasms/metabolism , Lung Neoplasms/mortality , Lymphatic Metastasis , Middle Aged , Neoplasm Staging , Prognosis , Receptor, ErbB-2/metabolism , Receptors, Estrogen/metabolism , Receptors, Progesterone/metabolism , Retrospective Studies , Survival Rate
10.
Anal Bioanal Chem ; 401(7): 2113-22, 2011 Oct.
Article in English | MEDLINE | ID: mdl-21847528

ABSTRACT

Surface modifications of microfluidic devices are of essential importance for successful bioanalytical applications. Here, we investigate three different coatings for quartz and poly(dimethylsiloxane) (PDMS) surfaces. We employed a triblock copolymer with trade name F(108), poly(L-lysine)-g-poly(ethylene glycol) (PLL-PEG), as well as the hybrid coating n-dodecyl-ß-D-maltoside and methyl cellulose (DDM/MC). The impact of these coatings was characterized by measuring the electroosmotic flow (EOF), contact angle, and prevention of protein adsorption. Furthermore, we investigated the influence of static coatings, i.e., the incubation with the coating agent prior to measurements, and dynamic coatings, where the coating agent was present during the measurement. We found that all coatings on PDMS as well as quartz reduced EOF, increased reproducibility of EOF, reduced protein adsorption, and improved the wettability of the surfaces. Among the coating strategies tested, the dynamic coatings with DDM/MC and F(108) demonstrated maximal reduction of EOF and protein adsorption and simultaneously best long-term stability concerning EOF. For PLL-PEG, a reversal in the EOF direction was observed. Interestingly, the static surface coating strategy with F(108) proved to be as effective to prevent protein adsorption as dynamic coating with this block copolymer. These findings will allow optimized parameter choices for coating strategies on PDMS and quartz microfluidic devices in which control of EOF and reduced biofouling are indispensable.


Subject(s)
Dimethylpolysiloxanes/chemistry , Microfluidic Analytical Techniques/instrumentation , Microfluidic Analytical Techniques/methods , Quartz/chemistry , Serum Albumin, Bovine/chemistry , Animals , Cattle , Electroosmosis , Kinetics , Surface Properties
11.
J Endocrinol Invest ; 34(11): 824-30, 2011 Dec.
Article in English | MEDLINE | ID: mdl-21613811

ABSTRACT

BACKGROUND: In thyroid cancer patients with multiple primary cancers, primary cancers tend to be more aggressive. AIMS: We analyzed multiple primary cancers in thyroid cancer patients and determined the differences between the incidence and the characteristics of primary cancers. MATERIALS AND METHODS: A total of 3070 patients with thyroid cancer underwent a thyroidectomy and follow-up examination at a single medical center. The times of diagnosis of the primary cancers were categorized as antecedent, synchronous, or subsequent to the diagnosis of thyroid cancer. RESULTS: After a mean follow-up period of 8.8 ± 0.5 yr, the presence of multiple primary cancers was histopathologically confirmed in 163 patients (5.3%). Patients with multiple primary cancers had a lower female-to-male ratio, an older mean age, advanced tumor-node-metastasis (TNM) stage, higher total mortality, and higher therapeutic radioactive iodide (131I) doses than patients without multiple primary cancers. Hematological malignancy and renal cell carcinoma, neither of which are among the 10 most common cancers observed in the general population of Taiwan, were the most common multiple cancers among women and men with thyroid cancer. Patient age, thyroid cancer tumor size, and thyroid cancer mortality in the antecedent, synchronous, and subsequent groups were not significantly different. CONCLUSIONS: Patients with multiple primary cancers in advanced stages had shorter disease-free survival period after treatment. Thyroid cancer patients with multiple primary cancers should be closely followed up for the occurrence of other secondary cancers in order to improve total mortality.


Subject(s)
Neoplasms, Multiple Primary/pathology , Thyroid Neoplasms/pathology , Thyroid Neoplasms/surgery , Adult , Aged , Disease-Free Survival , Female , Follow-Up Studies , Humans , Male , Middle Aged , Neoplasms, Multiple Primary/mortality , Thyroid Neoplasms/mortality , Thyroidectomy/trends
12.
Radiat Prot Dosimetry ; 143(2-4): 248-52, 2011 Feb.
Article in English | MEDLINE | ID: mdl-21169288

ABSTRACT

Radiobiological descriptions of cellular dosimetry and microdosimetry require both radiation dose and radiation quality. The lineal energy, defined as a ratio of the energy deposition by a particle in the biological target and the mean chord length of this target, is generally adopted to characterise the radiation quality. Most microdosimetry applications assume that the cell nucleus is the target region. Therefore, the lineal energy is obtained for the source (S) to target (T) geometry, T ← S, where S = cell surface, cytoplasm, cell nucleus and T = cell nucleus. The definition of lineal energy is based on the approximation that the particle mean pathlength is equal to target mean chord length. This approximation is valid for crossers of external irradiations. In the case of starters, insiders and stoppers of internal sources, particle pathlengths are always shorter than target chord lengths. Thus, the lineal energy does not reflect the specific energy deposition along particle path. In the present work, the specific energy deposition in a target is calculated using three distance parameters, i.e. target mean chord length, particle mean pathlength in the target and particle individual pathlength in the target. Monte Carlo calculations are performed for electrons of various energies and cells of different sizes. Results are analysed and discussed.


Subject(s)
Biological Assay/methods , Cell Physiological Phenomena/radiation effects , Models, Biological , Radiometry/methods , Algorithms , Animals , Computer Simulation , Dose-Response Relationship, Radiation , Electrons , Humans , Radiation Dosage
13.
Eur J Cancer Care (Engl) ; 19(2): 267-72, 2010 Mar.
Article in English | MEDLINE | ID: mdl-19709171

ABSTRACT

The terminal cancer patients increase needs for hospice care day by day. A new hospice consulting system has been developed in Taiwan to provide options for terminal cancer patients in choosing a suitable post-acute hospice care while a combined hospice care system is also given by the consulting team in the acute wards. Hereinafter is our report. From March 2005 to January 2006, 313 terminal cancer patients were analysed. These patients had signed consent forms for palliative treatment and had received consultations from the new hospice consulting system. Multivariate analysis showed that the home care patients had better performance status (P = 0.012), less shortness of breath (P = 0.006), less limbs swelling (P = 0.043), less flatulency (P = 0.000) and less constipation (P = 0.018). Among the 162 patients with regular follow-up, the symptoms/signs were significantly improved after intervention of consulting team in pain (P = 0.000), shortness of breath (P = 0.000), difficulty in sleeping (P = 0.002), nausea (P = 0.004), constipation (P = 0.008), changes in skin (P = 0.024) and adoption (P = 0.000). This new system had significant improvement in the terminal cancer patients' symptoms/signs control in acute wards and could contribute to the care quality of home care patients.


Subject(s)
Delivery of Health Care/methods , Neoplasms/therapy , Palliative Care/methods , Referral and Consultation , Adult , Aged , Aged, 80 and over , Decision Making , Female , Home Care Services , Hospice Care/psychology , Humans , Male , Middle Aged , Neoplasms/psychology , Palliative Care/psychology , Patient Satisfaction , Taiwan , Terminally Ill/psychology
14.
Phys Med Biol ; 54(19): 5847-60, 2009 Oct 07.
Article in English | MEDLINE | ID: mdl-19741277

ABSTRACT

A small animal irradiator is critical for providing optimal radiation dose distributions for pre-clinical animal studies. This paper focuses on the evaluation of using 6 or 18 MeV electron beams as small animal irradiators. Compared with all other prototypes which use photons to irradiate small animals, an electron irradiator has many advantages in its shallow dose distribution. Two major approaches including simulation and measurement were used to evaluate the feasibility of applying electron beams in animal irradiation. These simulations and measurements were taken in three different fields (a 6 cm x 6 cm square field, and 4 mm and 30 mm diameter circular fields) and with two different energies (6 MeV and 18 MeV). A PTW Semiflex chamber in a PTW-MP3 water tank, a PTW Markus chamber type 23343, a PTW diamond detector type 60003 and KODAK XV films were used to measure PDDs, lateral beam profiles and output factors for either optimizing parameters of Monte Carlo simulation or to verify Monte Carlo simulation in small fields. Results show good agreement for comparisons of percentage depth doses (

Subject(s)
Electrons , Radiotherapy/methods , Animals , Feasibility Studies , Mice , Mice, Inbred ICR , Molecular Imaging/instrumentation , Molecular Imaging/methods , Monte Carlo Method , Phantoms, Imaging , Radiation Dosage , Radiotherapy/instrumentation , Reproducibility of Results , Tomography, X-Ray Computed , Water
15.
J Phys Chem B ; 113(25): 8527-31, 2009 Jun 25.
Article in English | MEDLINE | ID: mdl-19485362

ABSTRACT

By means of time-resolved photoluminescence and photothermal techniques, after-effects from excited-state dynamics, energy migration, and conformational rearrangement of poly(9,9-di-n-octyl-2,7-fluorene) (PFO) and its homologues has been examined and interpreted with rotational potential maps from quantum mechanical calculations. Steady-state photoluminescence spectral changes and time-resolved photoluminescence measurements of oligofluorenes and PFO diluted in toluene suggest excited state ring torsion occurring within 30 ps of photoexitation. With all effects from internal conversion/intersystem crossing processes properly accounted for, we show that the conformational changes associated with this twisting motion can be quantitatively probed by means of photothermal methods. Results suggest mean torsion between neighboring fluorene units by ca. 40 degrees upon excitation, in agreement with the shift of rotational potential minimum from +/-40 degrees (and +/-140 degrees) in the ground state to +/-20 degrees (and +/-160 degrees) in the first excited singlet state according to results of quantum mechanical calculations.


Subject(s)
Fluorenes/chemistry , Absorption , Luminescence , Molecular Conformation , Photons , Rotation , Spectrometry, Fluorescence , Temperature
16.
Health Phys ; 96(6): 661-74, 2009 Jun.
Article in English | MEDLINE | ID: mdl-19430219

ABSTRACT

Red bone marrow is among the tissues of the human body that are most sensitive to ionizing radiation, but red bone marrow cannot be distinguished from yellow bone marrow by normal radiographic means. When using a computational model of the body constructed from computed tomography (CT) images for radiation dose, assumptions must be applied to calculate the dose to the red bone marrow. This paper presents an analysis of two methods of calculating red bone marrow distribution: 1) a homogeneous mixture of red and yellow bone marrow throughout the skeleton, and 2) International Commission on Radiological Protection cellularity factors applied to each bone segment. A computational dose model was constructed from the CT image set of the Visible Human Project and compared to the VIP-Man model, which was derived from color photographs of the same individual. These two data sets for the same individual provide the unique opportunity to compare the methods applied to the CT-based model against the observed distribution of red bone marrow for that individual. The mass of red bone marrow in each bone segment was calculated using both methods. The effect of the different red bone marrow distributions was analyzed by calculating the red bone marrow dose using the EGS4 Monte Carlo code for parallel beams of monoenergetic photons over an energy range of 30 keV to 6 MeV, cylindrical (simplified CT) sources centered about the head and abdomen over an energy range of 30 keV to 1 MeV, and a whole-body electron irradiation treatment protocol for 3.9 MeV electrons. Applying the method with cellularity factors improves the average difference in the estimation of mass in each bone segment as compared to the mass in VIP-Man by 45% over the homogenous mixture method. Red bone marrow doses calculated by the two methods are similar for parallel photon beams at high energy (above about 200 keV), but differ by as much as 40% at lower energies. The calculated red bone marrow doses differ significantly for simplified CT and electron beam irradiation, since the computed red bone marrow dose is a strong function of the cellularity factor applied to bone segments within the primary radiation beam. These results demonstrate the importance of properly applying realistic cellularity factors to computation dose models of the human body.


Subject(s)
Bone Marrow/radiation effects , Models, Biological , Adult , Algorithms , Biophysical Phenomena , Bone Marrow/diagnostic imaging , Humans , Male , Monte Carlo Method , Phantoms, Imaging , Photons/adverse effects , Photons/therapeutic use , Radiation Protection , Radiometry , Radiotherapy Dosage , Radiotherapy, High-Energy , Tomography, X-Ray Computed
17.
Radiat Prot Dosimetry ; 115(1-4): 530-5, 2005.
Article in English | MEDLINE | ID: mdl-16381780

ABSTRACT

This study compares the effective doses from a MIRD-type stylised model with those derived from the scaled-down version of the tomographic VIP-Man model for photon, electron, neutron and proton beams. The effective dose results from these two models show that they differ from each other within approximately 10% for common high-energy photon beams, within approximately 16% for neutrons, and within approximately 4% for high-energy proton beams. However, for low-energy protons and common electron beams, the effective doses can be different in >100%. It is concluded that the use of a single tomographic models will not improve the operational radiation protection dosimetry involving external beam exposures.


Subject(s)
Models, Biological , Radiation Protection/methods , Risk Assessment/methods , Software , Visible Human Projects , Whole-Body Counting/methods , Adult , Body Burden , Computer Simulation , Humans , Male , Relative Biological Effectiveness , Risk Factors , Tomography/methods
18.
Eur J Haematol ; 74(2): 152-7, 2005 Feb.
Article in English | MEDLINE | ID: mdl-15654907

ABSTRACT

Pulmonary function tests were performed in 20 patients with chronic myeloid leukemia before and after human leukocyte antigen-matched allogeneic sibling hematopoietic stem cell transplantation (HSCT) to identify any conditioning treatment effects on post-transplant function from January 1995 to December 2002. Of 20 patients, eight received non-myeloablative conditioning treatment and 12 received conventional myeloablative conditioning treatment. Pulmonary function tests including forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), and diffusion capacity for carbon monoxide (DLCO) were performed pretransplant, 6 and 12 months post-transplant. Possible pre-HSCT and post-HSCT risk factors were evaluated for association with pulmonary function. The results showed that myeloablative conditioning treatment had greater negative impact on FEV1, FVC, and DLCO than non-myeloablative conditioning therapy. We conclude that non-myeloablative allogeneic HSCT may apply a better transplant choice in patients who need special concern with post-transplant pulmonary function changes.


Subject(s)
Hematopoietic Stem Cell Transplantation , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/therapy , Lung/physiopathology , Respiratory Function Tests , Transplantation Conditioning , Adult , Forced Expiratory Volume , Humans , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/physiopathology , Middle Aged , Transplantation, Homologous
19.
J Comput Neurosci ; 19(3): 311-24, 2005 Dec.
Article in English | MEDLINE | ID: mdl-16502239

ABSTRACT

Learning-induced synchronization of a neural network at various developing stages is studied by computer simulations using a pulse-coupled neural network model in which the neuronal activity is simulated by a one-dimensional map. Two types of Hebbian plasticity rules are investigated and their differences are compared. For both models, our simulations show a logarithmic increase in the synchronous firing frequency of the network with the culturing time of the neural network. This result is consistent with recent experimental observations. To investigate how to control the synchronization behavior of a neural network after learning, we compare the occurrence of synchronization for four networks with different designed patterns under the influence of an external signal. The effect of such a signal on the network activity highly depends on the number of connections between neurons. We discuss the synaptic plasticity and enhancement effects for a random network after learning at various developing stages.


Subject(s)
Artificial Intelligence , Neural Networks, Computer , Neuronal Plasticity/physiology , Algorithms , Computer Simulation , Electrophysiology , Neural Pathways/cytology , Neural Pathways/physiology , Normal Distribution
20.
Health Phys ; 86(2): 174-82, 2004 Feb.
Article in English | MEDLINE | ID: mdl-14744051

ABSTRACT

A male human tomographic model was used to calculate values of energy imparted (epsilon) and effective dose (E) for monoenergetic photons (30-150 keV) in radiographic examinations. Energy deposition in the organs and tissues of the human phantom were obtained using Monte Carlo simulations. Values of E/epsilon were obtained for three common projections [anterior-posterior (AP), posterior-anterior (PA), and lateral (LAT)] of the head, cervical spine, chest, and abdomen, respectively. For head radiographs, all three projections yielded similar E/epsilon values. At 30 keV, the value of E/epsilon was approximately 1.6 mSv J(-1), which is increased to approximately 7 mSv J(-1) for 150 keV photons. The AP cervical spine was the only projection investigated where the value of E/epsilon decreased with increasing photon energy. Above 70 keV, cervical spine E/epsilon values showed little energy dependence and ranged between approximately 8.5 mSv J(-1) for PA projections and approximately 17 mSv J(-1) for AP projections. The values of E/epsilon for AP chest examinations showed very little variation with photon energy, and had values of approximately 23 mSv J(-1). Values of E/epsilon for PA and LAT chest projections were substantially lower than the AP projections and increased with increasing photon energy. For abdominal radiographs, differences between the PA and LAT projections were very small. All abdomen projections showed an increase in the E/epsilon ratio with increasing photon energy, and reached a maximum value of approximately 13.5 mSv J(-1) for AP projections, and approximately 9.5 mSv J(-1) for PA/lateral projections. These monoenergetic E/epsilon values can generate values of E/epsilon for any x-ray spectrum, and can be used to convert values of energy imparted into effective dose for patients undergoing common head and body radiological examinations.


Subject(s)
Anatomy, Cross-Sectional/methods , Models, Biological , Radiation Injuries/prevention & control , Radiation Protection/methods , Radiography , Radiometry/methods , Radiometry/standards , Risk Assessment/methods , Adult , Body Burden , Computer Simulation , Head/diagnostic imaging , Humans , Linear Energy Transfer , Male , Radiation Dosage , Radiography, Thoracic , Relative Biological Effectiveness , Spine/diagnostic imaging , United States , Whole-Body Counting/methods , X-Rays
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