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Huang WF, Tsai YW, Hsiao FY, Liu WC. Changes of the prescription of hormone therapy in menopausal women: an observational study in Taiwan. BMC Public Health 2007; 7:56. [PMID: 17439639 PMCID: PMC1871579 DOI: 10.1186/1471-2458-7-56] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Accepted: 04/17/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND To evaluate the impact of the 2002 Women's Health Initiative (WHI) study results on the prescription of menopausal hormone therapy (MHT) to treat menopause-related symptoms in Taiwan. METHODS This retrospective study participant data collected from women interviewed in 2001 Taiwan's National Health Interview Survey (NHIS) and the National Health Insurance (NHI) outpatient claims for women being treated for menopause-related symptoms. We compared prescriptions made for MHI to women seeking outpatient treatment for menopause-related symptoms before and after the publication of the 2002 WHI to study its effect of prescription behavior in Taiwan. There was one dichotomous outcome variable, which was whether MHT was prescribed or not in an outpatient visit to treat menopause-related symptoms. RESULTS Our study included 504 women 45 years old or above whose outpatient visits for menopause-related symptoms were covered by National Health Insurance in 2002. In total, these 504 women made 2549 outpatient visits to be treated for these symptoms. The proportion of outpatient visits in which MHT was prescribed dropped from 83.0% (n = 1,155) before WHI to 73.0% (n = 844) after WHI. We found a decrease in likelihood that women would be prescribed MHT for menopause-related symptoms after the release of the WHI report (OR = 0.36, 95% CI = 0.25 to 0.52, p < 0.05). Gynecologists and obstetricians are more likely to prescribe MHT than physicians with other medical specialties (5.34; 95% CI = 3.45 to 8.26, p < 0.05). Women with college level educations or higher became less likely to be prescribed MHT (Model 2; OR 0.30; 95% CI 0.11-0.83), and academic medical centers became less likely to prescribe MHT than other medical care institutions (Model 3; OR 0.15; 95% CI 0.34-0.63). CONCLUSION The WHI report caused a substantial decline in the use of MHT to treat menopause-related symptoms in Taiwan. It was found to exert most of its influence in patients with higher educations, physicians with specialties other than gynecologists and obstetricians, and academic medical centers.
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Wu IC, Chow NH, Cheng PN, Liu WC, Young KC, Chang WL, Chen CY, Tseng KC, Chang TT. Characterization of viral kinetics in patients with hepatitis B e antigen-positive chronic hepatitis B. J Med Virol 2007; 79:663-9. [PMID: 17457902 DOI: 10.1002/jmv.20822] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
A study was conducted during a 1 year follow-up to characterize the viral kinetics in hepatitis B e antigen (HBeAg)-positive chronic hepatitis B and to develop a model of predicting the probability of spontaneous HBeAg seroconversion. Fifty-seven patients with HBeAg-positive chronic hepatitis B were enrolled with monthly follow-ups from three Phase III clinical trial placebo groups. According to serial viral loads, 30 patients (52.6%) with the stationary pattern maintained stable HBV DNA levels with fluctuations of less than 1.5 log copies/ml. Twenty patients (35.1%) with the declining pattern exhibited a spontaneous decline of more than 1.5 log copies/ml without a following rebound of at least 1.5 log copies/ml. The remaining seven patients (12.3%) had the wavering pattern. Both declining and wavering patterns, when compared with the stationary pattern, had significantly higher hepatic necroinflammation in terms of ALT and Knodell scores at the baseline and peak ALT levels during the follow-up period. The declining pattern had a significantly better clinical outcome in terms of the lowest final HBV DNA and a reduction in the necroinflammatory score after 1 year. Furthermore, the declining pattern had a favorable HBeAg seroconversion rate (40%) compared with the wavering (14.3%) and stationary patterns (0%). A regression equation, incorporating simultaneous serum bilirubin, ALT, and HBV DNA levels, predicted the probability of HBeAg seroconversion with a sensitivity of 76.8% and a specificity of 74.7%. In conclusion, different viral kinetic patterns in patients with chronic hepatitis B implicate distinct clinical significance and immunologic perspective.
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Chang SY, Sheng WH, Lee CN, Sun HY, Kao CL, Chang SF, Liu WC, Yang JY, Wong WW, Hung CC, Chang SC. Molecular epidemiology of HIV type 1 subtypes in Taiwan: outbreak of HIV type 1 CRF07_BC infection in intravenous drug users. AIDS Res Hum Retroviruses 2006; 22:1055-66. [PMID: 17147490 DOI: 10.1089/aid.2006.22.1055] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In Taiwan, sexual transmission is responsible for most HIV-1 infections with two dominant subtypes, subtype B and CRF01_AE, distributing among homosexual and heterosexual groups, respectively. Recently, intravenous drug use has become an emerging route of HIV-1 transmission and contributed to a significant increase of HIV-1 infection. To characterize the HIV isolates responsible for the outbreak among intravenous drug users (IDUs), phylogenetic analysis was performed to analyze the protease/RT sequences amplified from HIV-1-infected IDUs at National Taiwan University Hospital and Taipei City STD Control Center. CRF07_BC, which is circulating in northern China, was demonstrated to account for the majority of HIV-1 infection in IDUs in the past 2 years. Although these Taiwanese CRF07_BC sequences shared the same breakpoint positions as those described in the CRF07_BC reference sequences, they formed a unique cluster in the phylogenetic tree, suggesting they originated from a founder virus. This finding was further supported by the relative low genetic diversity and unique sequence features. Our results demonstrated the emergence of CRF07_BC and its association with the HIV-1 outbreak among IDUs between 2004 and 2005 in Taiwan. This finding not only helps us to have a better understanding of the HIV evolution in Asia, but also has important implications for vaccine design in the future.
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Liu WC, Mizokami M, Buti M, Lindh M, Young KC, Sun KT, Chi YC, Li HH, Chang TT. Simultaneous quantification and genotyping of hepatitis B virus for genotypes A to G by real-time PCR and two-step melting curve analysis. J Clin Microbiol 2006; 44:4491-7. [PMID: 17021067 PMCID: PMC1698380 DOI: 10.1128/jcm.01375-06] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Both the viral titer and the genotype significantly determine clinical outcomes and responses to antiviral treatment in chronic hepatitis B virus (HBV) infection. A method was developed for large-scale A-to-G genotyping with simultaneous viral quantification. The assay was run on a LightCycler instrument using hybridization probes. The genotype was determined from the melting points of the probes in a two-step manner. Set 1 amplicons differentiated genotypes B, E, and F from A, C, D, and G and simultaneously quantified viremia by real-time PCR. Melting curve analysis using the set 2-1 amplicon or the set 2-2 amplicon reaction mixture was then used to differentiate these genotype groups into single genotypes. HBV DNA quantification was consistent with that of the Amplicor assay and linear in a range from 10(2) to 10(13) copies/ml. By comparison with the restriction fragment length polymorphism method, 92.3% of 441 samples were accurately genotyped by the current assay. The method should be useful for genotyping and quantification of HBV DNA in areas where all genotypes exist.
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155
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Liu WC, Chen HH, Hsieh WH, Chang CH. Linking watershed and eutrophication modelling for the Shihmen Reservoir, Taiwan. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2006; 54:39-46. [PMID: 17302303 DOI: 10.2166/wst.2006.834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The Shihmen Reservoir, located in northern Taiwan, features the second storage volume of impoundments on the island. The watershed of the Shihmen Reservoir has been subjected to serious pollutants due to anthropogenic interference. This study applies a watershed model, BASINS, to simulate the flow and nutrients loads from the watershed. BASINS then drives the CE-QUAL-W2 model for water quality predictions in the reservoir. The watershed modelling results are compared with field data. They reveal that significant nutrient loads were generated from the watershed during storms. The model calibration and verification were achieved with water surface elevation, temperature, and water quality constituents including nutrients, dissolved oxygen, and chlorophyll a in the reservoir using the eutrophication model.
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Liu WC, Jenkins C, Shaw DJ, Matthews L, Pearce MC, Low JC, Gunn GJ, Smith HR, Frankel G, Woolhouse MEJ. Modelling the epidemiology of Verocytotoxin-producing Escherichia coli serogroups in young calves. Epidemiol Infect 2005; 133:449-58. [PMID: 15962551 PMCID: PMC2870268 DOI: 10.1017/s0950268804003644] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We investigate the epidemiology of 12 Verocytotoxin-producing Escherichia coli (VTEC) serogroups observed in a calf cohort on a Scottish beef farm. Fitting mathematical models to the observed time-course of infections reveals that there is significant calf-to-calf transmission of VTEC. Our models suggest that 40% of all detected infections are from calf-to-calf transmission and 60% from other sources. Variation in the rates at which infected animals recover from infection by different VTEC serogroups appears to be important. Two thirds of the observed VTEC serogroups are lost from infected calves within 1 day of infection, while the rest persist for more than 3 days. Our study has demonstrated that VTEC are transmissible between calves and are typically lost from infected animals in less than 1 week. We suggest that future field studies may wish to adopt a tighter sampling frame in order to detect all circulating VTEC serogroups in similar animal populations.
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Abstract
There are a number of different non-operative interventions which aim to control moderate adolescent idiopathic scoliosis (AIS) from progression. Clinicians may find difficulties in the selection of appropriate interventions for AIS. A comprehensive literature review was carried out to study all contemporary non-operative interventions, it was noted that rigid spinal orthoses apparently give more curve control; however, it would compromise the patient's quality of life via those inevitable factors--physical constraint, poor acceptance and psychological disturbance. There is a trend to develop more effective, acceptable and user-friendly interventions. Under such an aspiration, the theories and clinical evidence of different interventions should be developed along the clinical pathway of early intervention with reliable indicators/predictors, patient's active participation, dynamic control mechanism, holistic psychological and psychosocial considerations, and effective and long-lasting outcome.
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Young KC, Lindsay KL, Lee KJ, Liu WC, He JW, Milstein SL, Lai MMC. Identification of a ribavirin-resistant NS5B mutation of hepatitis C virus during ribavirin monotherapy. Hepatology 2003; 38:869-78. [PMID: 14512874 DOI: 10.1053/jhep.2003.50445] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
Ribavirin (RBV), a guanosine analogue, has been suggested to exert an antiviral action against hepatitis C virus (HCV) by causing lethal mutations and suppressing RNA polymerase in vitro, but the mechanism of its clinical therapeutic effects is currently unknown. To test the hypothesis that RBV could act both as an RNA mutagen and inhibit viral RNA synthesis in vivo, we studied the evolution of the nucleotide sequences of HCV RNA at the nonstructural (NS) 5B region in patients receiving RBV, placebo, or interferon alfa (IFN-alpha) monotherapy. The RBV group showed a slightly more accelerated evolution rate of HCV RNA quasispecies than either the IFN-alpha or placebo group. RBV caused preferentially A-to-G and U-to-A mutations. Interestingly, an NS5B amino acid 415 Phe-to-Tyr (F415Y) mutation emerged in all (5 of 5) patients infected with HCV genotype 1a during the RBV treatment. Subsequently, the parental 415F strain reemerged in some patients after the treatment was discontinued. The effect of the amino acid substitution at NS5B415 on HCV RNA replication was then investigated using an HCV subgenomic replicon in Huh7 cells. We showed that treatment of replicon cells with RBV reduced the HCV RNA level of NS5B415F replicon, but not NS5B415Y, in a dose-dependent manner. Thus, NS5B F415Y mutation represents an RBV-resistant variant. The 3-dimensional modeling and structure analysis of NS5B protein revealed that the 415th amino acid is located at the P helix region of the thumb subdomain, which may interact with the minor groove of the template-primer duplex in the putative RNA-binding cleft. In conclusion, RBV could work as a weak mutagen for HCV RNA in HCV-infected patients. Furthermore, the selection of an RBV-resistant variant with a single amino acid substitution in NS5B suggested that RBV may directly interact with HCV RNA polymerase, thus interfering with its enzymatic activity.
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Bai YM, Lin CC, Chen JY, Liu WC. Therapeutic effect of pirenzepine for clozapine-induced hypersalivation: a randomized, double-blind, placebo-controlled, cross-over study. J Clin Psychopharmacol 2001; 21:608-11. [PMID: 11763010 DOI: 10.1097/00004714-200112000-00012] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The objective of this study was to investigate the efficacy of pirenzepine in the treatment of clozapine-induced hypersalivation. Pirenzepine is reported to counteract hypersalivation by its selective antagonistic activity on the M4-muscarinic receptor, which is stimulated by clozapine. Twenty patients with clozapine-induced hypersalivation underwent a random-order, double-blind, placebo-controlled, cross-over trial which lasted 8 weeks each for the pirenzepine and placebo investigations, with a 4-week washout period in between. The severity of hypersalivation was assessed using an objective measure: saliva production monitored through the diameter of wetted surface on tissue paper placed over the patient's pillow. Our study showed that pirenzepine had no significant therapeutic effect on hypersalivation compared with placebo, suggesting that hypersalivation induced by clozapine might have a neurobiological basis other than the M4-muscarinic receptor.
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160
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Holodny AI, Schwartz TH, Ollenschleger M, Liu WC, Schulder M. Tumor involvement of the corticospinal tract: diffusion magnetic resonance tractography with intraoperative correlation. J Neurosurg 2001; 95:1082. [PMID: 11765829 DOI: 10.3171/jns.2001.95.6.1082] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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161
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Ren J, Ge L, Li Y, Bai J, Liu WC, Si XM. Detection of circulating CEA molecules in human sera and leukopheresis of peripheral blood stem cells with E. coli expressed bispecific CEAScFv-streptavidin fusion protein-based immuno-PCR technique. Ann N Y Acad Sci 2001; 945:116-8. [PMID: 11708464 DOI: 10.1111/j.1749-6632.2001.tb03871.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In this study, a method called bispecific CEAScFv-streptavidin fusion protein-based immuno-PCR technique will be tested experimentally. The application of the bispecific fusion protein-based immuno-PCR technique has the significant advantage that it can be readily applied in the clinical setting, as well as tested as a potential screening tool in high-risk populations of certain types of cancer.
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162
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Christodoulou C, DeLuca J, Ricker JH, Madigan NK, Bly BM, Lange G, Kalnin AJ, Liu WC, Steffener J, Diamond BJ, Ni AC. Functional magnetic resonance imaging of working memory impairment after traumatic brain injury. J Neurol Neurosurg Psychiatry 2001; 71:161-8. [PMID: 11459886 PMCID: PMC1737512 DOI: 10.1136/jnnp.71.2.161] [Citation(s) in RCA: 211] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVES To examine patterns of brain activation while performing a working memory task in persons with moderate to severe traumatic brain injury (TBI) and healthy controls. It is well established that working memory is an area of cognition that is especially vulnerable to disruption after TBI. Although much has been learned about the system of cerebral representation of working memory in healthy people, little is known about how this system is disrupted by TBI. METHODS Functional magnetic resonance imaging (fMRI) was used to assess brain activation during a working memory task (a modified version of the paced auditory serial addition test) in nine patients with TBI and seven healthy controls. RESULTS Patients with TBI were able to perform the task, but made significantly more errors than healthy controls. Cerebral activation in both groups was found in similar regions of the frontal, parietal, and temporal lobes, and resembled patterns of activation found in previous neuroimaging studies of working memory in healthy persons. However, compared with the healthy controls, the TBI group displayed a pattern of cerebral activation that was more regionally dispersed and more lateralised to the right hemisphere. Differences in lateralisation were particularly evident in the frontal lobes. CONCLUSIONS Impairment of working memory in TBI seems to be associated with alterations in functional cerebral activity.
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Chiu HJ, Wang YC, Liou JH, Chao CH, Lee H, Tsai KY, Liu WC. Serotonin 6 receptor polymorphism in schizophrenia: frequency, age at onset and cognitive function. Neuropsychobiology 2001; 43:113-6. [PMID: 11287786 DOI: 10.1159/000054876] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The relative abundance of serotonin 6 receptor (5HT6) in some limbic regions and the high affinity of some antipsychotics for 5HT6 suggest that the 5HT6 gene might play a role in the pathogenesis of schizophrenic disorders. A recent study reported an association between a C267T polymorphism of the 5HT6 gene and schizophrenia. In order to test whether the 5HT6 gene plays a role in the pathogenesis of schizophrenic disorders, patients (n = 148) and control subjects (n = 160) were genotyped for 5HT6. We also investigated the relationship between genotypes and patients' age at onset and cognitive function in schizophrenic patients. Cognitive function in the patients was evaluated by the Mini-Mental State Examination (MMSE). The results demonstrated no significant differences in genotype or allele frequencies between controls and patients. In the patient group, age at onset and MMSE score did not differ significantly among the three 5HT6 genotpyes. The results of this study suggest that the 5HT6 C267T polymorphism plays no major role in susceptibility to the development of schizophrenia and is not related to cognitive impairment or age at onset in schizophrenic patients. Further studies of the relation between 5HT6 polymorphism and the symptoms and the therapeutic response in schizophrenic patients may help to elucidate the role of 5HT6 in the pathogenesis of schizophrenia.
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Liu WC, Hsu MH, Kuo AY. A modeling study of water quality in main channel and estuarine wetland. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2001; 36:641-660. [PMID: 11460322 DOI: 10.1081/ese-100103751] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A simple computation framework is applied to include estuarine wetland and their interaction with main channels in estuarine modeling. The concept and the model implementation of the scheme are explained using a vertical two-dimensional model of estuarine hydrodynamics and water quality. The model was applied to the Tanshui River estuary and Kuan-Du wetland. The model is calibrated and verified by the available measured data. Simulations are also conducted for various upstream freshwater discharges to predict water quality in the main channel and estuarine wetland. The results show that the inclusion of estuarine wetland in a water-quality model not only provides a framework for computing water-quality conditions but also accounts for the interaction between wetland and main channel. The model provides a useful tool for environmental planning, protection and proposed wetland restoration works.
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Hartman VN, Miller MA, Clayton DF, Liu WC, Kroodsma DE, Brenowitz EA. Testosterone regulates alpha-synuclein mRNA in the avian song system. Neuroreport 2001; 12:943-6. [PMID: 11303765 DOI: 10.1097/00001756-200104170-00016] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Alpha-synuclein is a small, highly conserved protein in vertebrates that has been linked to several neurodegenerative diseases. The avian song control system is one of the model systems in which the protein was independently discovered. Alpha-synuclein is dynamically regulated in the song system during song learning, a process in which sex steroids play a central role. We compared alpha-synuclein mRNA expression in the brains of 12 adult male chipping sparrows (Spizella passerina) treated with either testosterone or blank s.c. implants. We saw pronounced upregulation of alpha-synuclein mRNA in, as well as an increase in the volume of, the song control nucleus area X in response to exogenous testosterone. To our knowledge this is the first report of steroid regulation of synuclein gene expression in any model system.
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167
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Wiese C, Gauny SS, Liu WC, Cherbonnel-Lasserre CL, Kronenberg A. Different mechanisms of radiation-induced loss of heterozygosity in two human lymphoid cell lines from a single donor. Cancer Res 2001; 61:1129-37. [PMID: 11221843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Allelic loss is an important mutational mechanism in human carcinogenesis. Loss of heterozygosity (LOH) at an autosomal locus is one outcome of the repair of DNA double-strand breaks (DSBs) and can occur by deletion or by mitotic recombination. We report that mitotic recombination between homologous chromosomes occurred in human lymphoid cells exposed to densely ionizing radiation. We used cells derived from the same donor that express either normal TP53 (TK6 cells) or homozygous mutant TP53 (WTK1 cells) to assess the influence of TP53 on radiation-induced mutagenesis. Expression of mutant TP53 (Met 237 Ile) was associated with a small increase in mutation frequencies at the hemizygous HPRT (hypoxanthine phosphoribosyl transferase) locus, but the mutation spectra were unaffected at this locus. In contrast, WTK1 cells (mutant TP53) were 30-fold more susceptible than TK6 cells (wild-type TP53) to radiation-induced mutagenesis at the TK1 (thymidine kinase) locus. Gene dosage analysis combined with microsatellite marker analysis showed that the increase in TK1 mutagenesis in WTK1 cells could be attributed, in part, to mitotic recombination. The microsatellite marker analysis over a 64-cM region on chromosome 17q indicated that the recombinational events could initiate at different positions between the TK1 locus and the centromere. Virtually all of the recombinational LOH events extended beyond the TK1 locus to the most telomeric marker. In general, longer LOH tracts were observed in mutants from WTK1 cells than in mutants from TK6 cells. Taken together, the results demonstrate that the incidence of radi-ation-induced mutations is dependent on the genetic background of the cell at risk, on the locus examined, and on the mechanisms for mutation available at the locus of interest.
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Holodny AI, Schulder M, Liu WC, Wolko J, Maldjian JA, Kalnin AJ. The effect of brain tumors on BOLD functional MR imaging activation in the adjacent motor cortex: implications for image-guided neurosurgery. Radiology 2001; 248:971-8. [PMID: 11003273 DOI: 10.1148/radiol.2483071280] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND PURPOSE Functional MR (fMR) imaging data coregistered to a neurosurgical navigation system have been proposed as guides for the resection of brain tumor in or adjacent to eloquent cortices. The purpose of this study was to compare data obtained from the side of the brain affected by tumor with the contralateral side and to determine if there are physiological limitations of fMR imaging in accurately determining the location of the primary motor cortex. METHODS Ten patients with tumors in or directly adjacent to the motor cortex were studied with fMR imaging (finger-tapping paradigm). fMR imaging data were analyzed using multiple R values. These data were coregistered to a real-time intraoperative neurosurgical navigation system. RESULTS Significant variability of motor cortex activation patterns was noted among individual patients. The activation volumes on the side of the tumor were significantly smaller compared with the contralateral side for all tumors not previously resected (0.66+/-0.47). This was most pronounced in glioblastomas (0.27+/-0.21). We propose that these differences were caused by a loss of autoregulation in the tumor vasculature of glioblastomas and venous effects. CONCLUSION Notwithstanding the differences noted, the motor cortex was identified successfully in all patients. This was confirmed by intraoperative physiological identification of the motor cortex and a lack of postoperative neurologic deficit.
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Holodny AI, Ollenschleger MD, Liu WC, Schulder M, Kalnin AJ. Identification of the corticospinal tracts achieved using blood-oxygen-level-dependent and diffusion functional MR imaging in patients with brain tumors. AJNR Am J Neuroradiol 2001; 22:83-8. [PMID: 11158892 PMCID: PMC7975563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Diffusion-weighted MR imaging was used to delineate the corticospinal tract (CST) successfully and to depict its relationship to adjacent brain tumors. The CST was defined by a method by which it seems possible to delimit the distance from the CST to the main tumor mass and to show displacement and infiltration of the tract by the neoplasia. This information cannot be gathered from routine anatomic MR imaging.
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Liu WC, Houde-Walter SN, Veasey DL, Peskin AP. Design and optimization of a diode-pumped fiber-coupled yb:er glass waveguide laser. APPLIED OPTICS 2000; 39:6165-6173. [PMID: 18354624 DOI: 10.1364/ao.39.006165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
An adaptive simulated annealing optimization algorithm is used to derive laser rate equation and waveguiding models with which the best design for a diode-pumped fiber-coupled, Yb:Er glass waveguide laser can be determined. Material parameters that correspond to commercially available laser-glass and diode-pump sources are used in this study. Given a continuous-wave 300-mW pump at 977 nm, approximately 48 mW of power at 1540 nm can be coupled into the LP(01) mode of an optical fiber. Fabrication and alignment tolerance analyses are presented.
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Schulder M, Vega J, Narra V, Jacobs A, Kalnin A, Lange G, Liu WC. Functional magnetic resonance imaging and radiosurgical dose planning. Stereotact Funct Neurosurg 2000; 73:38-44. [PMID: 10853096 DOI: 10.1159/000029749] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To assess the effect of functional magnetic resonance imaging (fMRI) on stereotactic radiosurgical (SRS) dose planning. METHODS Patients included those undergoing SRS whose lesions were in or near areas that could be identified with fMRI. After processing, an fMR scan was registered to the anatomic scan, and this dataset was registered to a stereotactic CT scan. The imaged functional areas were contoured along with standard anatomical targets. Dose planning was done at first with the functional volumes rendered invisible; the plans were then adjusted as needed using the functional targets. Doses were measured using a dose-volume histogram tool. RESULTS SRS was performed in 12 patients, 1 of whom also underwent SRT. Functional volumes studied included motor cortex in 8 patients, visual in 6 and language in 3; a total of 33 functional targets were imaged. Prescription doses ranged from 12 to 22.5 Gy (mean 19.5 Gy), and the maximum dose to functional volumes from 8 cGy to 18.5 Gy (mean 2.9 Gy). In 6 patients, arc adjustment using functional targets yielded a >50% reduction in dose to at least one functional volume; in all patients, the dose reduction to 50 and 75% of functional volumes averaged 4% (12 cGy) and 13% (30 cGy), respectively, while the reduction of maximal dose averaged 24% (50 cGy). CONCLUSIONS fMRI can be used in SRS to reduce irradiation of eloquent brain using standard prescription doses. Appropriate arc adjustment may allow for escalation of the dose to the targeted lesion.
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Schulder M, Holodny A, Liu WC, Gray A, Lange G, Carmel PW. Functional magnetic resonance image-guided surgery of tumors in or near the primary visual cortex. Stereotact Funct Neurosurg 2000; 73:31-6. [PMID: 10853094 DOI: 10.1159/000029747] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To assess the accuracy of functional magnetic resonance imaging (fMRI) of the primary visual cortex in patients undergoing surgery for tumors in the occipital lobe. METHODS Two patients with nondominant occipital lobe tumors were studied, one with a solitary lung metastasis and another with radiation necrosis after radiosurgery for a low-grade astrocytoma. At surgery, visual evoked potentials (VEPs) were stimulated using Light-emitting-diode goggles and recorded using cortical grids placed immediately after brain exposure. The location of the peak VEP was compared to that predicted by the registered functional scan. RESULTS In each case, the epicenter of visual activation as represented on the registered fMRI corresponded to the site of peak VEP recording. Prediction error for the visual cortex, measured in patient 1, was 1.0 mm. Visual confirmation showed the registration in the second patient to be accurate as well. CONCLUSION As previously demonstrated for sensorimotor fMRI, visual fMRI accurately predicts the location of the primary visual cortex. Additional confirmation is expected with more clinical experience.
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Holodny AI, Schulder M, Liu WC, Wolko J, Maldjian JA, Kalnin AJ. The effect of brain tumors on BOLD functional MR imaging activation in the adjacent motor cortex: implications for image-guided neurosurgery. AJNR Am J Neuroradiol 2000; 21:1415-22. [PMID: 11003273 PMCID: PMC7974044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/1999] [Accepted: 03/02/2000] [Indexed: 02/17/2023]
Abstract
BACKGROUND AND PURPOSE Functional MR (fMR) imaging data coregistered to a neurosurgical navigation system have been proposed as guides for the resection of brain tumor in or adjacent to eloquent cortices. The purpose of this study was to compare data obtained from the side of the brain affected by tumor with the contralateral side and to determine if there are physiological limitations of fMR imaging in accurately determining the location of the primary motor cortex. METHODS Ten patients with tumors in or directly adjacent to the motor cortex were studied with fMR imaging (finger-tapping paradigm). fMR imaging data were analyzed using multiple R values. These data were coregistered to a real-time intraoperative neurosurgical navigation system. RESULTS Significant variability of motor cortex activation patterns was noted among individual patients. The activation volumes on the side of the tumor were significantly smaller compared with the contralateral side for all tumors not previously resected (0.66+/-0.47). This was most pronounced in glioblastomas (0.27+/-0.21). We propose that these differences were caused by a loss of autoregulation in the tumor vasculature of glioblastomas and venous effects. CONCLUSION Notwithstanding the differences noted, the motor cortex was identified successfully in all patients. This was confirmed by intraoperative physiological identification of the motor cortex and a lack of postoperative neurologic deficit.
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Haan S, Hoekema N, Poniatowski S, Liu WC, Eberly J. Directional correlation in direct and sequential double ionization of model atoms. OPTICS EXPRESS 2000; 7:29-38. [PMID: 19404366 DOI: 10.1364/oe.7.000029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We discuss directional dependence in the time development of spatial wavefunctions, which includes jet formation, for two-electron model atoms exposed to intense laser fields. Two competing scenarios for double ionization are evident: (1) both electrons emerge simultaneously from the core region and on the same side of the nucleus, and (2) the electrons detach on opposite sides but not simultaneously. The importance of the electron-electron repulsion contribution to the competing processes is investigated for various laser intensities.
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Liu WC, Schulder M, Narra V, Kalnin AJ, Cathcart C, Jacobs A, Lange G, Holodny AI. Functional magnetic resonance imaging aided radiation treatment planning. Med Phys 2000; 27:1563-72. [PMID: 10947259 DOI: 10.1118/1.599022] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Functional MRI (magnetic resonance imaging) allows one to noninvasively identify various eloquent cortices in the brain. The integration of cortical activation information into radiosurgical treatment planning may provide an alternative to prevent or minimize radiation damage to eloquent cortex. A novel approach of directly integrating the fMRI (functional magnetic resonance imaging) brain map into treatment planning is proposed. Three brain tumor patients have been studied using this method with motor and/or visual paradigms. Brain activation was demonstrated in eloquent cortex at the precentral gyrus (motor area) and medial occipital lobe (visual area). The activation maps were transferred to a treatment planning workstation, (XKnife), and 3D (three-dimensional) activation maps were generated and co-registered to a 3D CT (computed tomography) anatomical data set, which provided the calibration localizer, for treatment planning. Radiosurgery was designed based on both functional and structural information by the medical team consisting of a radiation oncologist, a neurosurgeon and a physicist. The average maximum dose for the tumor was 2113 cGy. The average maximum dose for tissue surrounding the tumor was 1600 cGy. The average dose with fMRI information to the eloquent cortex was 163.4 cGy over three patients, while without fMRI information it was 240.5 cGy. The average percentage dose reduction over three patients is 32%. The results suggest that using this method can reduce the dose to the eloquent cortex. This approach provides the physician with additional information for treatment planning and may spare the patient unnecessary radiation exposure to adjacent eloquent cortices.
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Holodny AI, Kisza PS, Contractor S, Liu WC. Does a herniated nucleus pulposus contribute significantly to a decrease in height of the intervertebral disc? Quantitative volumetric MRI. Neuroradiology 2000; 42:451-4. [PMID: 10929308 DOI: 10.1007/s002340000319] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
A lumbar intervertebral disc with a herniated nucleus pulposus (HNP) often exhibits a decrease in the height of the intervertebral space. Our purpose was to ascertain whether the loss of volume of an HNP is sufficient to cause a perceptible decrease in the height of the intervertebral space. MRI of 44 patients with 51 HNPs were reviewed. The volumes of the herniated material and of the intervertebral discs were calculated for every level from L1-2 to L5-S1. The average volume of the HNP was 503 +/- 301 mm3. The average volumes of all 220 intervertebral discs and of the 127 normal-appearing discs were 14,442 +/- 4200 mm3 and 17,476 +/- 2885 mm3 respectively. The average volume of the HNP represented 3.5% of the parent disc. An average HNP caused a decrease in intervertebral space height of 0.35 mm (0.56 pixels). Therefore, the loss of the volume of the HNP does not cause a significant decrease in the intervertebral space height. The average calculated decrease in the disc height is less than that reported in normal diurnal variation.
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Sait SM, Liu WC, Thompson DJ, Godfray HC, Begon M. Invasion sequence affects predator-prey dynamics in a multi-species interaction. Nature 2000; 405:448-50. [PMID: 10839538 DOI: 10.1038/35013045] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ecologists seek to understand the rules that govern the assembly, coexistence and persistence of communities of interacting species. There is, however, a variety of sequences in which a multi-species community can be assembled--unlike more familiar one- and two-species systems. Ecological systems can exhibit contrasting dynamics depending on initial conditions, but studies have been focused on simple communities initiated at different densities, not on multi-species communities constructed in different sequences. Investigations of permanence and convergence in ecological communities have been concerned with the flux of whole species (presence or absence) but have not addressed the central issues concerning the dynamics exhibited by individual species in particular interactions. Here we examine data for replicated three-species systems and demonstrate that the dynamic trajectories of both a predator and its prey within the system are determined by the sequence in which it is constructed, and that for one construction-sequence alternative dynamic patterns are possible.
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Maniker A, Liu WC, Marks D, Moser K, Kalnin A. Positioning of vagal nerve stimulators: technical note. SURGICAL NEUROLOGY 2000; 53:178-81. [PMID: 10713198 DOI: 10.1016/s0090-3019(99)00176-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Vagal nerve stimulation has become an important treatment for patients with intractable seizure disorders. Many of these patients will require magnetic resonance imaging (MRIs) of the brain after the stimulator has been implanted to monitor underlying neurologic conditions. Functional MRI (fMRI) is also being used in the evaluation of epilepsy. With the current recommended implant techniques the magnetic field of the MRI will deactivate the pulse generator while the patient is in the supine position for the scan. A simple change in positioning of the pulse generator will help to avoid deactivating the device during an MRI. This will avoid exposing the patient to lengthy time periods with a deactivated stimulator and also allow for the performance of fMRIs and any other MRI scans needed to monitor underlying neurologic conditions. METHODS A working model of the NeuroCybernetic Prosthesis (NCP) pulse generator was assessed with an oscilloscope and LED light connected to it that related activation of the generator while in the MRI. This simulation was performed with the device alone, in multiple positions. Then patients with implanted devices who could personally confirm the activation of their stimulators were also studied. RESULTS A pulse generator placed with the electrode inputs parallel to the long axis of the body was not deactivated by the magnetic field of the MRI when the patient was in the supine position. CONCLUSION Changing the implant position of a vagal nerve stimulator pulse generator will help to prevent deactivation of the device while in the MRI, allowing for the performance of fMRIs while not exposing the patient to lengthy time periods with a deactivated vagal nerve stimulator.
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Liu WC, Kwak BK, Kim KN, Kim SY, Woo JJ, Chung DJ, Hong JH, Kim HS, Lee CJ, Shim HJ. Tuberculous aneurysm of the abdominal aorta: endovascular repair using stent grafts in two cases. Korean J Radiol 2000; 1:215-8. [PMID: 11752958 PMCID: PMC2718204 DOI: 10.3348/kjr.2000.1.4.215] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Tuberculous aneurysm of the aorta is exceedingly rare. To date, the standard therapy for mycotic aneurysm of the abdominal aorta has been surgery involving in-situ graft placement or extra-anatomic bypass surgery followed by effective anti-tuberculous medication. Only recently has the use of a stent graft in the treatment of tuberculous aortic aneurysm been described in the literature. We report two cases in which a tuberculous aneurysm of the abdominal aorta was successfully repaired using endovascular stent grafts. One case involved is a 42-year-old woman with a large suprarenal abdominal aortic aneurysm and a right psoas abscess, and the other, a 41-year-old man in whom an abdominal aortic aneurysm ruptured during surgical drainage of a psoas abscess.
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Wolansky LJ, Finden SG, Chen J, Hanna R, Holodny AI, Ahmad I, Liu WC, Contractor S. Optimization of gray/white matter contrast with fast inversion recovery for myelin suppression: a comparison of fast spin-echo and echo-planar MR imaging sequences. AJNR Am J Neuroradiol 1999; 20:1653-7. [PMID: 10543636 PMCID: PMC7056192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
We compared two MR imaging sequences, fast inversion recovery for myelin suppression (FIRMS) and echo-planar FIRMS (EP-FIRMS), for depicting gray/white matter contrast. In 18 patients, the frequency bandwidth (BW) was optimized for each sequence; in nine patients, the BW was held constant. In the BW-optimized group, the mean contrast-to-noise ratio (C/N) was three times higher with the FIRMS sequence. In the BW-constant group, the mean C/N was 27% higher with the EP-FIRMS sequence; however, geometric distortion degraded the EP-FIRMS images excessively. For optimal gray/white contrast, FIRMS appears to be the superior pulse sequence.
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Mosier K, Patel R, Liu WC, Kalnin A, Maldjian J, Baredes S. Cortical representation of swallowing in normal adults: functional implications. Laryngoscope 1999; 109:1417-23. [PMID: 10499047 DOI: 10.1097/00005537-199909000-00011] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Dysphagia of neurogenic or postsurgical origin presents management and therapeutic challenges to the otolaryngologist. Improvements in management and therapeutic approaches may be facilitated by understanding how the central nervous system controls swallowing. The purpose of this investigation was to utilize functional magnetic resonance imaging to determine patterns of cortical activity during swallowing in normal, healthy adult subjects. STUDY DESIGN Functional magnetic resonance imaging (fMRI) was performed on eight healthy adult subjects using conventional BOLD (blood oxygenation level dependent) techniques. METHODS Subjects performed three different swallowing tasks including dry and bolus swallows, and performed a control finger movement task. Statistical maps of cortical activation were generated using a cross-correlation analysis. One-way and two-way ANOVA statistical analyses were performed to compare activated areas among the different tasks and to determine the effects of task sequence. RESULTS Activation during the three swallowing tasks occurred in the primary motor cortex, primary somatosensory cortex, and other cortical and subcortical sites. Cortical representation of swallowing and finger movement followed somatotopic maps. Differential distribution of cortical activation was observed for the different swallowing tasks. CONCLUSIONS Activation of the primary motor and somatosensory cortices, as well as other sensory-motor areas, occurs with swallowing in normal adults. Differential distribution of cortical activity with different swallowing tasks suggests differential functional organization for different swallowing tasks. Understanding these mechanisms may facilitate improved management and therapeutic intervention for neurogenic and postsurgical dysphagia.
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Wolansky LJ, Rajaraman V, Lum C, Park K, Fiorito TF, Patel S, Liu WC, Wedmid A. Water-suppression MRI: role in the evaluation of osseous lesions. Clin Imaging 1999; 23:319-26. [PMID: 10665351 DOI: 10.1016/s0899-7071(99)00157-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The efficacy of chemical shift based water-suppression MRI in the evaluation of bone marrow lesions has not been previously reported. T1-weighted images without and with water suppression were compared in five patients with 16 lesions. There was a significant improvement in the contrast-to-noise ratio (from 4.32 to 5.95, P < 0.01) and contrast ratio (from 1.71 to 5.69, P < 0.004) with water suppression. Water suppression may be useful clinically by increasing the conspicuity of bone marrow lesions.
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Mosier KM, Liu WC, Maldjian JA, Shah R, Modi B. Lateralization of cortical function in swallowing: a functional MR imaging study. AJNR Am J Neuroradiol 1999; 20:1520-6. [PMID: 10512240 PMCID: PMC7657739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
BACKGROUND AND PURPOSE While functional MR imaging and other techniques have contributed to our knowledge of functional brain localization, these methods have not been extensively applied to the complex and incompletely understood task of swallowing. We used functional MR imaging to investigate motor cortex activity during swallowing in healthy human adults. METHODS Eight subjects were imaged on a 1.5-T MR system using blood oxygen level-dependent contrast mechanisms. Subjects performed three swallowing tasks and a finger-tapping task. Areas of activation in the cortex and subcortical areas were tabulated, and a laterality index, defined as LI = [sigmas left - sigmas right]/[sigmas left + sigmas right] x 100, was computed for the three tasks. RESULTS Activation was observed in the primary motor and sensory cortices, motor processing and association areas, and subcortical sites. This activity was dominant for one hemisphere with left hemispheric dominance more prevalent among the subjects. Right hemispheric dominance, however, showed stronger lateralization than the left hemisphere. CONCLUSION Our data indicate that specific sites in the motor cortex and other cortical and subcortical areas are activated with swallowing tasks and that hemispheric dominance is a feature of swallowing under these conditions. In addition, we demonstrate the utility of functional MR imaging in the study of the cortical representation of swallowing and suggest a role for functional MR imaging in the diagnosis of dysphagia of cerebral origin.
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Liu WC, Kowarz MW. Vector diffraction from subwavelength optical disk structures: two-dimensional modeling of near-field profiles, far-field intensities, and detector signals from a DVD. APPLIED OPTICS 1999; 38:3787-3797. [PMID: 18319986 DOI: 10.1364/ao.38.003787] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Rigorous two-dimensional vector-diffraction patterns of a focused beam incident on an optical disk, specifically, a digital versatile disk (DVD), are examined both in the near field and in the far field. An efficient finite-difference frequency-domain method is developed for calculating the electromagnetic fields in the neighborhood of subwavelength dielectric and metallic structures. The results of vector-diffraction theory are compared with those of scalar-diffraction theory for pressed DVD features that consist of pits or of bumps. The sum (data) and difference (tracking) signals from a split photodetector are also calculated for different disk features and for different polarizations. The subwavelength features of a DVD result in considerable vector-diffraction effects both in the near-field profiles and in the detector signals, depending not only on the polarization of illumination but also on whether the features are pits or bumps. This paper provides important insight into the vector-diffraction effects encountered in high-density optical data storage systems.
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Abstract
When, where and from whom young songbirds learn their songs have been controversial issues in the study of song development. We chose to study some of these issues in two migratory and closely related songbirds, the chipping sparrow, Spizella passerina, and field sparrow, Spizella pusilla. Nestlings of both species were collected in western Massachusetts and hand-reared in the laboratory. There, juveniles were placed in separate cages and assigned to one of three rooms; in each room were eight young chipping sparrows, eight young field sparrows and two adult tutors of each species, arranged so that most of the young males were adjacent to adult tutors of the same species. During mid-winter, adult tutors were moved from one room to another, so that the young birds heard different song types from different tutors during their hatching year and the following spring. From spectral analysis of our extensive tape recordings, we found that most juvenile males imitated the songs of their hatching-year tutors but then gradually modified their songs to match more closely either their adult tutors or other pupils the next spring. One chipping and one field sparrow clearly imitated a new song syllable from a spring live tutor; that is, these yearling males learned songs by 'instruction'. Other sparrows improvised extensively, and one chipping sparrow learned a field sparrow's song syllable. Our results reveal great individual variation in how songs are developed, and we expect similar flexibility among birds in nature. Copyright 1999 The Association for the Study of Animal Behaviour.
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Holodny AI, Schulder M, Liu WC, Maldjian JA, Kalnin AJ. Decreased BOLD functional MR activation of the motor and sensory cortices adjacent to a glioblastoma multiforme: implications for image-guided neurosurgery. AJNR Am J Neuroradiol 1999; 20:609-12. [PMID: 10319970 PMCID: PMC7056038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/1998] [Indexed: 02/12/2023]
Abstract
A patient with a glioblastoma multiforme and mild sensorimotor deficits had significantly less activation of the motor and sensory cortices on the side with the tumor than on the contralateral side on blood oxygen level-dependent (BOLD) functional MR images. This difference, which may be due to pressure effects or loss of vascular autoregulation, should be considered in preoperative planning in which BOLD functional MR imaging is used to identify eloquent cortices to be avoided during brain tumor surgery.
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Wolansky LJ, Chong S, Liu WC, Kang E, Simpson SW, Karimi S, Akbari H. Single-shot echo-planar imaging of multiple sclerosis: effects of varying echo time. Neuroradiology 1999; 41:163-6. [PMID: 10206157 DOI: 10.1007/s002340050724] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Our aim was to determine the relative merits of short and long echo times (TE) with single-shot echo-planar imaging for imaging cerebral lesions such as multiple sclerosis. We examined seven patients with clinically definite multiple sclerosis were imaged at 1.5 T. Patients were scanned with spinecho, single-shot echo-planar imaging, using TEs of 45, 75, 105, and 135 ms. Region of interest (ROI) measurements were performed on 36 lesions at or above the level of the corona radiata. The mean image contrast (IC) was highest (231.1) for a TE of 45 ms, followed by 75 ms (218.9), 105 ms (217.9), and 135 ms (191.6). When mean contrast-to-noise ratios (C/N) were compared, the value was again highest (29.7) for TE 45 ms, followed by 75 ms (28.9), 105 ms (28.5), and 135 ms (26.3). In a lesion-by-lesion comparison, TE 45 ms had the highest IC and C/N in the largest number of cases (50 % and 47.2 %, respectively). IC and C/N for TE 45 ms were superior to those of 75 ms in 64% and 58%, respectively. These results support the use of relatively short TEs for single-shot echo-planar imaging in the setting of cerebral lesions such as multiple sclerosis.
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Liu WC, Sanchez-Monroy D. Prevalence of back discomfort and estimates of back load in two manufacturing facilities. THE ANNALS OF OCCUPATIONAL HYGIENE 1998; 42:549-56. [PMID: 9838868 DOI: 10.1016/s0003-4878(98)00067-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
This study evaluated the association between the prevalence of back discomfort and estimates of back load posed by nine jobs in two manufacturing facilities. Prevalence of back discomfort experienced was estimated through self-administered questionnaires. A total of 266 questionnaires were distributed to workers randomly selected from nine jobs in two factories. Workers were asked to rate on a 0-5 scale the discomfort level they experienced in the back for a one-month period before and at the time of the survey. The return rate for each job ranges from 57% to 100%. Overall, 14.5% of the survey respondents experienced some discomfort in the back. With the assistance of a checklist, nine supervisors rated each task of the job they supervised by the magnitude of the force (low, moderate, or high) and by the duration, (less than 30% time, 30% to 50% time, and greater than 50% time) that workers typically spent in awkward back postures, such as back flexion, extension, twisting, and lateral bending. An additional total back load estimate was provided independently by an ergonomist. Logistic regression analysis found a positive association between the back discomfort prevalence observed in the present study and the load estimates both by the ergonomist and by task information based on back twisting. Significant concordance was found between the ergonomist's load estimates and the supervisors' estimate of the duration of twisted back. This study demonstrated not only that a checklist approach could provide useful task information for deriving exposure estimates, but also that exposure estimate for a job could be derived from its constituent tasks. Though in this study it was the supervisor who utilized the checklist to estimate the back loads, there is no reason why experienced workers could not use the checklist to provide similar estimates. A large-scale study should be conducted to improve the design of this checklist approach.
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Schulder M, Maldjian JA, Liu WC, Holodny AI, Kalnin AT, Mun IK, Carmel PW. Functional image-guided surgery of intracranial tumors located in or near the sensorimotor cortex. J Neurosurg 1998; 89:412-8. [PMID: 9724115 DOI: 10.3171/jns.1998.89.3.0412] [Citation(s) in RCA: 166] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT The purpose of this study was to evaluate the efficacy of noninvasive preoperative functional imaging data used in an interactive fashion in the operating room. The authors describe a method of registering preoperative functional magnetic resonance (fMR) imaging localization of sensorimotor cortex with a frameless stereotactic surgical navigation device. METHODS The day before surgery, patients underwent blood oxygen level-dependent fMR imaging while performing a finger-tapping motor paradigm. Immediately afterward an anatomical stereotactic MR image was acquired. Raw fMR imaging data were analyzed offline at a separate workstation, and the resulting functional maps were registered to a high-resolution anatomical scan. The fused functional-anatomical images were then downloaded onto a surgical navigation computer via an ethernet connection. At surgery, the brain was exposed in the standard fashion, and the sensorimotor cortex was identified by direct cortical stimulation, the use of somatosensory evoked potentials, or both. This localization was then compared with that predicted by the registered fMR study. Thirteen procedures were performed in 12 patients. The mean registration error was 2.2 mm. The predicted location of motor and/or sensory cortex matched that found on intraoperative mapping in all 12 patients tested. Maximal tumor resection was accomplished in each case and no new permanent neurological deficits resulted. CONCLUSIONS Compared with conventional brain mapping techniques, fMR image-guided surgery may allow for smaller brain exposures, localization of the language cortex with the patient under general anesthesia, and the mapping of multiple functional sites. The scanning equipment used in this method may be more readily available than for other functional imaging techniques such as positron emission tomography or magnetoencephalography.
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Schulder M, Maldjian JA, Liu WC, Mun IK, Carmel PW. Functional MRI-guided surgery of intracranial tumors. Stereotact Funct Neurosurg 1998; 68:98-105. [PMID: 9711702 DOI: 10.1159/000099909] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We describe a technique of registering functional magnetic resonance image (fMRI) data sets with the anatomical images used for intraoperative navigation. Three patients with supratentorial tumors were studied, 2 with astrocytomas and 1 with a meningioma. The day before surgery, a functional blood-oxygen-level-dependent MR scan was done. During the same imaging session, an anatomic stereotactic MR scan was performed. The raw data were reconstructed off line on a workstation, and the fMR maps were then registered to the anatomic studies using image header information. Fused images were then transferred to the navigational workstation over an Ethernet connection. At surgery, brain exposure was performed in a standard manner. In each case, the registered scans accurately localized the motor and/or sensory cortex. No new permanent neurological deficits resulted from surgery. The potential advantages of fMRI-guided surgery include: (1) smaller brain exposures; (2) localization of language cortex under general anesthesia; (3) mapping of multiple functional sites, with decreased time and increased case of surgery.
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Liu WC, Kowarz M. Vector diffraction from subwavelength optical disk structures: Two-dimensional near-field profiles. OPTICS EXPRESS 1998; 2:191-197. [PMID: 19377601 DOI: 10.1364/oe.2.000191] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
An efficient finite-difference frequency-domain method is developed for calculating electromagnetic fields in the neighborhood of subwavelength dielectric and metallic structures. The method is used to investigate two-dimensional near-field and far-field patterns of a focused beam diffracted from an optical disk, specifically from a DVD (Digital Versatile Disk). It is shown that the polarization of illumination has a significant impact on diffraction patterns as expected and that scalar theory does not provide an accurate analysis of diffraction from a DVD.
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Liu WC, Hwang CB, Cheng RK, Wu RS, Hui YL, Tan PP. Unexpected left endobronchial intubation in a case of Turner's syndrome. ACTA ANAESTHESIOLOGICA SINICA 1997; 35:253-6. [PMID: 9553243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Patients with Turner's syndrome present a multiplicity of cardiovascular and airway abnormalities. We describe a case of Turner's syndrome with pericardial effusion who experienced an inadvertent endobronchial intubation due to displacement of the endotracheal tube immediately after the pericardial drainage. A sudden increase of airway pressure and decrease of oxygen saturation in the presence of breathing sound audible via the chest piece placed on the left hemithorax first misled us to call our attention to sputum impaction. No sputum was obtainable from airway suction. Inadvertent bronchial intubation was highly suspected at the post-anesthesia room when a decrease of right side breathing sound was noted together with a progressive fall of oxygen saturation. Emergent chest x-ray confirmed the diagnosis. It was thought that the mishap took place early in the act of or following the pericardial drainage. Our case serves as evidence once again to emphasize the possibility of endobronchial intubation due to displacement of endotracheal tube during anesthesia and the importance of monitoring to guard against inadvertent bronchial intubation, particularly in patients with associated problems such as Turner's syndrome with huge pericardial effusion.
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Jiang ZC, Su YL, Deng YF, Sun W, Liu WC, Wei DM, Yan JY, Yao YL. The chromosomal effect of birchen dust as determined by the micronucleus test. BIOMEDICAL AND ENVIRONMENTAL SCIENCES : BES 1997; 10:396-401. [PMID: 9448921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In a wood processing factory, the measured air concentration of birchen dust was 1.26 +/- 0.41 mg/m3, and the micronucleus frequency of peripheral blood lymphocytes in 83 workers exposed to wood dust was 1.13 +/- 2.83/1000, which was significantly higher (P < 0.01) than that of control group (0.51 +/- 1.41/1000). The number of exposed workers with positive micronucleus test was 9.6%, which was higher than that of control group (4.5%), but the difference was not significant (P > 0.05). The micronucleus test in mice treated with water extracts of unsteamed and unbaked birchen dust showed that the micronucleus frequencies in all treated groups were significantly higher than that of control group (P < 0.01) and there was also a dose response correlation (r = 0.96, P < 0.0005). The results of steamed and baked birchen dust extracts were significantly lower than those of the unsteamed and unbaked ones at the same doses (P < 0.001). This suggests that when the birchen dust is steamed at the temperature of 100 degrees C for 24 h or baked at the temperature of 80 degrees C, its inducing effect in micronucleus test could be lowered.
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Maldjian JA, Schulder M, Liu WC, Mun IK, Hirschorn D, Murthy R, Carmel P, Kalnin A. Intraoperative functional MRI using a real-time neurosurgical navigation system. J Comput Assist Tomogr 1997; 21:910-2. [PMID: 9386283 DOI: 10.1097/00004728-199711000-00013] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A 42-year-old-man had focal left hand motor seizures. MR studies demonstrated a right posterior frontal brain tumor. Functional MRI was performed, localizing the motor cortex posterior to the lesion. The functional images were integrated with a neurosurgical navigation computer. A real-time intraoperative display of the anatomic and functional images was produced, registered to a neurosurgical probe. Excellent correlation was demonstrated between the functional maps and invasive electrophysiologic mapping performed at the time of craniotomy.
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195
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Maldjian JA, Liu WC, Hirschorn D, Murthy R, Semanczuk W. Wavelet transform-based image compression for transmission of MR data. AJR Am J Roentgenol 1997; 169:23-6. [PMID: 9207495 DOI: 10.2214/ajr.169.1.9207495] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVE The purpose of this study was to develop an effective, inexpensive teleradiology image-transmission system for transfer of MR studies using wavelet transform image compression. CONCLUSION We describe an efficient system for implementing teleradiology capability for transmission of diagnostic MR images. The system uses the wavelet transform to achieve greater than 90% image compression, with standard modern transmission times of less than 5 sec per compressed image. The method is inexpensive and can be implemented using commonly available workstation and MR scanner capabilities.
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196
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Wolansky LJ, Chiang PK, Liu WC, Gonzales RN, Holodny AL, Baker SR. Fast inversion recovery for myelin suppression (FIRMS). A new magnetic resonance pulse sequence. J Neuroimaging 1997; 7:176-9. [PMID: 9237438 DOI: 10.1111/jon199773176] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Fast inversion recovery for myelin suppression is a new magnetic resonance sequence with the ability to increase gray-white matter contrast. This can improve the definition of normal anatomical structures.
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197
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Hwang CB, Hui YL, Liu WC, Chu KK, Wang YL, Ho AC. Absorption of irrigating fluid during transcervical resection of endometrium--a report of two cases. ACTA ANAESTHESIOLOGICA SINICA 1997; 35:45-50. [PMID: 9212481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
It has been recognized for many years that the use of hypotonic solution for the irrigation of the bladder cavity during transurethral resection of the prostate (TURP) may result in hyponatremia and water intoxication due to rapid and excessive absorption of the solution from the exposed prostatic bed, the clinical manifestation of which is termed "TURP syndrome". A similar condition termed "female TURP syndrome" following hysteroscopic transcervical endometrial resection (TCR) has been reported. Since the frequency of TCR continues to increase the increased rate of "TCR syndrome" would come in its wake. Here, we present two cases who developed severe hyperglycemia and hyponatremia while underwent TCR with 10% dextrose in water as the irrigation fluid and the same time emphasize the potential risk of this complication.
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198
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Tao PL, Liu WC, Tsuei YS, Cheng CY. The role of vasopressin on the effect of U-50,488 to block the development of morphine tolerance and physical dependence. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 1997; 355:281-7. [PMID: 9050024 DOI: 10.1007/pl00004944] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
U-50,488, a selective kappa-opioid receptor agonist, has been reported to inhibit the development of antinociceptive tolerance to morphine in mice, rats and guinea pigs, but the mechanism involved in this action remains unknown. Since U-50,488 has been reported to suppress the plasma vasopressin level, we investigated the role of vasopressin with U-50,488 in the male Sprague Dawley rat in this study. Animals (230-270 g) were chronically treated with morphine (10 mg/kg, i.p.) twice a day for 6 days in order to induce tolerance to antinociceptive effect measured by tail-flick test. Withdrawal symptoms were precipitated by naloxone (10 mg/kg, i.p.) on day 7. U-50,488 (i.p.) or AVP (i.p. or i.c.v.) or U-50,488 and AVP was (were) coadministered with chronic morphine to investigate their effects on morphine tolerance and dependence. We found that coadministration of 8 mg/kg U-50,488 (i.p.) with morphine almost completely block morphine tolerance and partially block withdrawal symptoms. In contrast, coadministration of AVP (0.3 microgram/kg, i.p., or 0.01 microgram, i.c.v.) with morphine and U-50,488, the effects of U-50,488 to block morphine tolerance and dependence were reversed. In addition, treatment of AVP antagonist (dPTyr(Me)AVP, 0.5 microgram/kg, i.p. or 0.5 microgram, i.c.v.) has the similar effect as U-50,488 to block morphine tolerance. In summary, the effect of U-50,488 to block morphine tolerance and dependence may relate to its inhibitory effect on AVP release.
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199
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Kuang L, Yang DJ, Inoue T, Liu WC, Wallace S, Wright KC. Percutaneous intratumoral injection of cisplatin microspheres in tumor-bearing rats to diminish acute nephrotoxicity. Anticancer Drugs 1996; 7:220-7. [PMID: 8740729 DOI: 10.1097/00001813-199602000-00012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Poly(D,L-lactide) microspheres loaded with cisplatin (PLA-CDDP MS) were prepared by a solvent evaporation technique for direct intratumoral injection. The microspheres, 50-100 microns, containing 40.04% of cisplatin produce sustained release in vitro. PLA-CDDP MS (6 mg/kg body weight of cisplatin) suspensions were injected intratumorally into mammary tumors in rats. Cisplatin solution (6 mg/kg body weight) was injected either intratumorally or intraperitoneally in two groups. After treatments, the tumor size decreased in each of the groups as a function of time. Sixteen days post-injection, the tumors had either disappeared or significantly shrunk. PLA-CDDP MS had a similar antitumor effect compared with cisplatin aqueous solution. Blood urea nitrogen, serum creatinine and histopathology examinations revealed that the renal toxicity in the PLA-CDDP MS group was significantly less than in the control groups. These results indicate that intratumoral injection of PLA-CDDP MS maintains anticancer potency and reduces acute renal toxicity.
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200
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Zhuang K, Li WD, Liu WC. Fertility by rapidly activated sperm from epididymis. Chin Med J (Engl) 1994; 107:594-5. [PMID: 7805443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
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