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Broome EJ, Brown DL, Mitchel RE. Adaptation of human fibroblasts to radiation alters biases in DNA repair at the chromosomal level. Int J Radiat Biol 1999; 75:681-90. [PMID: 10404997 DOI: 10.1080/095530099140014] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
PURPOSE To determine whether adaptation to ionizing radiation biases repair of radiation-induced chromosomal breaks. MATERIALS AND METHODS Normal human fibroblasts were radiation-adapted by exposure to 10 cGy of gamma-radiation. FISH probes for chromosomes 2, 4, 7, 18 and 19 were used to determine the chromosomal origin of the DNA in micronuclei resulting from a subsequent 4Gy exposure of these cells, and corresponding non-adapted cells. RESULTS Compared with 4 Gy exposed but non-adapted cells, the radiation-adapted cells subsequently exposed to 4 Gy showed an overall decrease in the frequency of micronuclei. However, the micronuclei that did form in the adapted cells had a decreased frequency of DNA originating from chromosomes 2 and 18, an increased frequency of DNA from chromosome 19 and no change in frequency of DNA from chromosomes 4 and 7. CONCLUSIONS Adaptation to radiation increased the overall cellular repair of radiation-induced chromosomal breaks, but also created a repair bias such that some chromosomes were preferentially repaired or discriminated against, while the repair of others was unbiased.
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Edep ME, Guarneri EM, Teirstein PS, Phillips PS, Brown DL. Differences in TIMI frame count following successful reperfusion with stenting or percutaneous transluminal coronary angioplasty for acute myocardial infarction. Am J Cardiol 1999; 83:1326-9. [PMID: 10235089 DOI: 10.1016/s0002-9149(99)00094-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The Thrombolysis In Myocardial Infarction (TIMI) flow grade achieved in the infarct-related artery (IRA) during reperfusion therapy for acute myocardial infarction (AMI) is directly related to myocardial salvage. Recently, several series have demonstrated the safety of stenting in AMI and documented a larger postprocedure luminal diameter than that found at angioplasty, although no study has compared the effect of PTCA and stenting in AMI on flow characteristics of the IRA. The residual stenosis and the number of frames required to opacify standardized angiographic landmarks normalized for vessel length (corrected TIMI frame count) or compared with flow in a corresponding normal coronary artery (TIMI frame count index) were determined for the IRA of 39 patients who underwent angioplasty or stenting for AMI. Baseline characteristics were similar for the 20 patients who underwent stenting and the 19 patients who underwent percutaneous transluminal coronary angioplasty. After intervention, the luminal diameter was greater (3.24 vs 2.09 mm, p <0.0001) and the residual stenosis was less (-9.4% vs. 26.7%, p <0.0001) after stenting than after percutaneous transluminal coronary angioplasty. These changes in vessel geometry were associated with a lower corrected TIMI frame count (16.1 vs 30.7, p <0.002) and a lower TIMI frame count index (0.68 vs 1.3, p <0.002). Thus, stenting in AMI is associated with a greater postprocedure luminal diameter and improvement in coronary blood flow as measured by the TIMI frame count method.
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Talley JJ, Bertenshaw SR, Brown DL, Carter JS, Graneto MJ, Koboldt CM, Masferrer JL, Norman BH, Rogier DJ, Zwwifel BS, Seibert K. 4,5-Diaryloxazole inhibitors of cyclooxygenase-2 (COX-2). Med Res Rev 1999; 19:199-208. [PMID: 10232649 DOI: 10.1002/(sici)1098-1128(199905)19:3<199::aid-med1>3.0.co;2-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A series of methysulfonyl or sulfonamido substituted 4,5-diaryloxazole were prepared and evaluated for their ability to inhibit the inducible form of cyclooxygenase (COX-2) in vitro and in vivo. Several unique substitution patterns were identified that led to potent and selective inhibitors of COX-2. In general, 2-trifluoromethly-4,5-diaryloxazoles substituted with a methylsulfonyl or sulfonamido group were particularly potent inhibitors. One of the more potent compounds with a selectivity for COX-2 of about 800 fold was 4b (SC-299). SC-299, a highly fluorescent molecule, may be useful for spectroscopic studies on preferential inhibitor binding to COX-2.
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Brown DL. Disparate effects of the 1989 Loma Prieta and 1994 Northridge earthquakes on hospital admissions for acute myocardial infarction: importance of superimposition of triggers. Am Heart J 1999; 137:830-6. [PMID: 10220631 DOI: 10.1016/s0002-8703(99)70406-0] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Most occurrences of presumed triggers of acute myocardial infarction (AMI) do not actually trigger an AMI. The relation between vulnerability to development of AMI and timing of triggers of AMI is poorly understood. The 1989 Loma Prieta earthquake struck the San Francisco Bay Area at 5:04 PM during a period of relatively reduced circadian vulnerability to AMI. The 1994 Northridge earthquake awakened citizens of Los Angeles at 4:31 AM, also during a period of otherwise reduced vulnerability to AMI, but superimposed the stress of the earthquake upon the known stress of awakening. Study of times of onset of natural disasters and their effect on precipitation of AMI may provide insight into the physiology of triggering. This study was designed to compare the triggering ability of 2 similarly intense earthquakes that occurred singly or superimposed upon another trigger. METHODS AND RESULTS California discharge records were analyzed from the week before, the day of, and the 6 days after the Loma Prieta and Northridge earthquakes and the same dates of control years for total admissions, AMI admissions, and congestive heart failure admissions. There was no statistically significant increase in AMI admissions in the San Francisco Bay Area on the day of the Loma Prieta earthquake compared with the days before or after the earthquake or compared with the same day in 1990. In contrast, there was a 110% increase in admission rate for AMI in Los Angeles County on the day of the Northridge earthquake compared with the average of the 7 days before the earthquake (z = 4.349, P <.001). Similarly, there was a >80% increased risk of admission for AMI on the day of the Northridge earthquake in 1994 compared with the same date in 1995 (relative risk 1.828, 95% confidence intervals 1.289 to 2.592). CONCLUSIONS Extreme emotional stress superimposed on the stress of awakening results in enhanced triggering of AMI. When emotional stress occurs at less vulnerable periods, there is no significant increase in incidence of AMI.
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Broome EJ, Brown DL, Mitchel RE. Fluorescence in situ hybridization of micronuclei in binucleate fibroblasts: a protocol for cytoplasm preservation. Biotechniques 1999; 26:610-2, 614. [PMID: 10343894 DOI: 10.2144/99264bm03] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Dolling JA, Boreham DR, Brown DL, Raaphorst GP, Mitchel RE. Cisplatin-modification of DNA repair and ionizing radiation lethality in yeast, Saccharomyces cerevisiae. Mutat Res 1999; 433:127-36. [PMID: 10102039 DOI: 10.1016/s0921-8777(98)00069-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cis-diamminedichloroplatinum II (cisplatin) is a DNA inter- and intrastrand crosslinking agent which can sensitize prokaryotic and eukaryotic cells to killing by ionizing radiation. The mechanism of radiosensitization is unknown but may involve cisplatin inhibition of repair of DNA damage caused by radiation. Repair proficient wild type and repair deficient (rad52, recombinational repair or rad3, excision repair) strains of the yeast Saccharomyces cerevisiae were used to determine whether defects in DNA repair mechanisms would modify the radiosensitizing effect of cisplatin. We report that cisplatin exposure could sensitize yeast cells with a competent recombinational repair mechanism (wild type or rad3), but could not sensitize cells defective in recombinational repair (rad52), indicating that the radiosensitizing effect of cisplatin was due to inhibition of DNA repair processes involving error free RAD52-dependent recombinational repair. The presence or absence of oxygen during irradiation did not alter this radiosensitization. Consistent with this result, cisplatin did not sensitize cells to mutation that results from lesion processing by an error prone DNA repair system. However, under certain circumstances, cisplatin exposure did not cause radiosensitization to killing by radiation in repair competent wild type cells. Within 2 h after a sublethal cisplatin treatment, wild type yeast cells became both thermally tolerant and radiation resistant. Cisplatin pretreatment also suppressed mutations caused by exposure to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), a response previously shown in wild type yeast cells following radiation pretreatment. Like radiation, the cisplatin-induced stress response did not confer radiation resistance or suppress MNNG mutations in a recombinational repair deficient mutant (rad52), although thermal tolerance was still induced. These results support the idea that cisplatin adducts in DNA interfere with RAD52-dependent recombinational repair and thereby sensitize cells to killing by radiation. However, the lesions can subsequently induce a general stress response, part of which is induction of RAD52-dependent error free recombinational repair. This stress response confers radiation resistance, thermal tolerance, and mutation resistance in yeast.
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Brown DL. Absence of thrombotic thrombocytopenic purpura following coronary stenting in the ticlopidine era. Am J Cardiol 1999; 83:640-1. [PMID: 10073887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Brown DL, Cole BF, Arrick BA. Re: Multifactorial analysis of differences between sporadic breast cancers and cancers involving BRCA1 and BRCA2 mutations. J Natl Cancer Inst 1999; 91:90-1. [PMID: 9890178 DOI: 10.1093/jnci/91.1.90a] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Brown DL, Smith DJ. Bacterial colonization/infection and the surgical management of pressure ulcers. OSTOMY/WOUND MANAGEMENT 1999; 45:109S-118S; quiz 119S-120S. [PMID: 10085981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The purpose of this paper is to review the current recommendations and guidelines for the care and treatment of pressure ulcers with specific reference to the control of infection within these wounds and surgical management. After reviewing the literature published between May 1993 and April 1998, it is our contention that no significant changes in the clinical management of this problem are warranted. This may signal the need for further study in this area. Recommendations for the optimal care of clean and infected pressure ulcers are included.
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Ziser A, Plevak DJ, Wiesner RH, Rakela J, Offord KP, Brown DL. Morbidity and mortality in cirrhotic patients undergoing anesthesia and surgery. Anesthesiology 1999; 90:42-53. [PMID: 9915311 DOI: 10.1097/00000542-199901000-00008] [Citation(s) in RCA: 275] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Patients with cirrhosis have a reduced life expectancy. Anesthesia and surgery have been associated with clinical decompensation in patients with cirrhosis. METHODS The authors retrospectively reviewed the records of all patients with the diagnosis of cirrhosis who underwent any surgical procedure under anesthesia at their institution between January 1980 and January 1991 (n = 733). Univariate and multivariate analyses were used to identify the variables associated with perioperative complications and short- and long-term survival. RESULTS The perioperative mortality rate (within 30 days of surgery) was 11.6%. The perioperative complication rate was 30.1%. Postoperative pneumonia was the most frequent complication. Multivariate factors that were associated with perioperative complications and mortality included male gender, a high Child-Pugh score, the presence of ascites, a diagnosis of cirrhosis other than primary biliary cirrhosis (especially cryptogenic cirrhosis), an elevated creatinine concentration, the diagnosis of chronic obstructive pulmonary disease, preoperative infection, preoperative upper gastrointestinal bleeding, a high American Society of Anesthesiologists physical status rating, a high surgical severity score, surgery on the respiratory system, and the presence of intraoperative hypotension. CONCLUSION Risk factors have been identified for patients with cirrhosis who undergo anesthesia and surgery.
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Wilson JL, Brown DL, Wong GY, Ehman RL, Cahill DR. Infraclavicular brachial plexus block: parasagittal anatomy important to the coracoid technique. Anesth Analg 1998; 87:870-3. [PMID: 9768785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
UNLABELLED Infraclavicular brachial plexus block is a technique well suited to prolonged continuous catheter use. We used a coracoid approach to this block to create an easily understood technique. We reviewed the magnetic resonance images of the brachial plexus from 20 male and 20 female patients. Using scout films, the parasagittal section 2 cm medial to the coracoid process was identified. Along this oblique section, we located a point approximately 2 cm caudad to the coracoid process on the skin of the anterior chest wall. From this point, we determined simulated needle direction to contact the neurovascular bundle and measured depth. At the skin entry site, the direct posterior insertion of a needle will make contact with the cords of the brachial plexus where they surround the second part of the axillary artery in all images. The mean (range) distance (depth along the needle shaft) from the skin to the anterior wall of the axillary artery was 4.24 +/- 1.49 cm (2.25-7.75 cm) in men and 4.01 +/- 1.29 cm (2.25-6.5 cm) in women. Hopefully, this study will facilitate the use of this block. IMPLICATIONS We sought a consistent, palpable landmark for facilitation of the infraclavicular brachial plexus block. We used magnetic resonance images of the brachial plexus to determine the depth and needle orientation needed to contact the brachial plexus. Hopefully, this study will facilitate the use of this block.
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Sodja C, Brown DL, Walker PR, Chaly N. Splenic T lymphocytes die preferentially during heat-induced apoptosis: NuMA reorganization as a marker. J Cell Sci 1998; 111 ( Pt 16):2305-13. [PMID: 9683626 DOI: 10.1242/jcs.111.16.2305] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We are investigating nuclear events during apoptosis in mouse splenic lymphocytes cultured immediately after isolation (controls) or after heat treatment (42 degreesC, 30 minutes), and have found that hyperthermia increased the level of apoptosis to double that of spontaneous apoptosis in controls within 6 hours. Immunolabelling for Nuclear Mitotic Apparatus Protein (NuMA) suggested that splenocytes were responding heterogeneously to the heat treatment. Whereas all nuclei in controls and about half of nuclei in heat-treated samples showed the usual diffuse nucleoplasmic labelling, 40–60% of nuclei in heated samples also contained numerous bright spots. We then examined whether the heterogeneity in NuMA organization might be an indication of a differential response of B and T lymphocytes to hyperthermia, and whether the presence of NuMA spots is related to the apoptotic process. NuMA labelling of heated fractionated splenocyte populations showed that 90% of nuclei in T-enriched cultures (less than or equal to 4% IgG+ cells), but only 25% of nuclei in B-enriched samples (less than or equal to 80% IgG+ cells), contained spots. As well, 2 hours after heat treatment of unfractionated cultures, greater than or equal to 90% of nuclei that were accumulating DNA strand breaks, as detected by TUNEL, exhibited NuMA spots. These data indicate that cells with NuMA spots are targetted for, or have initiated, the death program. Since most T cells, but few or no B cells, were spotty after heating, we conclude further that hyperthermia induces apoptosis preferentially in splenic T lymphocytes. The observation that the proportion of T cells was, on average, threefold greater in control than in heated samples after 24 hours in culture reinforces this conclusion.
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Korbin CD, Brown DL, Welch WR. Paraovarian cystadenomas and cystadenofibromas: sonographic characteristics in 14 cases. Radiology 1998; 208:459-62. [PMID: 9680576 DOI: 10.1148/radiology.208.2.9680576] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To describe the sonographic features of paraovarian cystadenomas. MATERIALS AND METHODS We searched the computerized pathology and radiology databases for cases of histopathologically proved paraovarian cystadenomas from January 1993 through December 1996 in which preoperative sonography had also been performed. Fourteen paraovarian cystadenomas or cystadenofibromas were identified in 14 patients aged 20-57 years. Sonographic and pathologic findings were correlated. RESULTS Three of the masses appeared as simple cysts sonographically. Of the remaining 11 masses, nine had solid nodular areas within the cyst; three had septations; and four had a thick wall, an irregular wall, or both at sonography. At sonography, four masses were thought to arise outside the ovary, four were erroneously thought to arise in the ovary, and the location was uncertain in six. CONCLUSION Paraovarian cystadenomas are cystic masses that usually contain one or more small solid nodules and occasionally contain septations.
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Gelczer RK, Charboneau JW, Hussain S, Brown DL. Complications of percutaneous ethanol ablation. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 1998; 17:531-533. [PMID: 9697961 DOI: 10.7863/jum.1998.17.8.531] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Percutaneous ethanol injection therapy performed with sonographic visualization is a steadily growing therapeutic method that can be used in the ablation of solid and cystic masses in a variety of anatomic locations. Ethanol has been used for many years as an angiographically administered agent for vascular embolization of tumors such as hepatic and renal neoplasms. It was first used as a percutaneously injected agent for the sclerosis of renal cysts. Local infiltration or intravascular injection of ethanol leads to cell death by causing cell membrane lysis, protein denaturation, and vascular occlusion. Because of the initial success in the sclerosis of renal cysts, percutaneously injected ethanol is now used in the ablation of hepatic cysts and solid tumors, such as hepatocellular carcinomas. As a treatment agent, ethanol combines the benefits of being widely available, inexpensive, efficacious, and relatively easy to administer. Optimal results require that the radiologist have considerable experience in ultrasonographic scanning techniques and facility with percutaneous needle insertion under real-time visualization. Alternatively, the radiologist may choose CT as a method to visualize needle placement. Percutaneous ethanol injection therapy usually is an effective alternative to conventional surgical resection of liver lesions and has a low complication rate. We present two patients in whom hypotensive complications occurred during percutaneous ethanol injection therapy and discuss the likely causative mechanisms.
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Abstract
Borderline or equivocal sonographic findings in the fetal heart are occasionally encountered. Echogenic foci in the ventricles, small pericardial effusions, and mild discrepancy in ventricular size are three such problematic findings. The significance of each of these findings, as currently understood, will be discussed in this article.
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Brown DL, Schneider DL, Colbert R, Guss D. Influence of insurance coverage on delays in seeking emergency care in patients with acute chest pain. Am J Cardiol 1998; 82:395-8. [PMID: 9708677 DOI: 10.1016/s0002-9149(98)00338-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The time required to decide to seek medical care for acute chest pain is the major modifiable component in the process of care delivery. This study demonstrates that prehospital delay in the setting of acute chest pain was related to the type of health insurance.
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Brown DL, Doubilet PM, Miller FH, Frates MC, Laing FC, DiSalvo DN, Benson CB, Lerner MH. Benign and malignant ovarian masses: selection of the most discriminating gray-scale and Doppler sonographic features. Radiology 1998; 208:103-10. [PMID: 9646799 DOI: 10.1148/radiology.208.1.9646799] [Citation(s) in RCA: 169] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To determine the gray-scale and Doppler sonographic features that best enable discrimination between malignant and benign ovarian masses and develop a scoring system for accurate diagnosis with these features. MATERIALS AND METHODS Gray-scale and Doppler sonographic features of 211 adnexal masses were correlated with the final diagnosis; the most discriminating features for malignancy were selected with stepwise logistic regression. RESULTS Twenty-eight masses were malignant and 183 benign. All masses with a markedly hyperechoic solid component or no solid component were benign. For masses with a nonhyperechoic solid component, additional features that allowed statistically significant discrimination of benignity from malignancy were, in decreasing order of importance, (a) location of flow at conventional color Doppler imaging, (b) amount of free intraperitoneal fluid, and (c) presence and thickness of septations. A scoring formula that made use of values based on the logistic regression equation had an area under the receiver operating characteristic curve of 0.98 +/- 0.01. The cutoff score with the highest accuracy had a sensitivity of 93% and specificity of 93%. CONCLUSION A solid component is the most statistically significant predictor of a malignant ovarian mass. A multiparameter scoring system that uses three gray-scale and one Doppler feature, developed by means of stepwise logistic regression, has high sensitivity and specificity for predicting malignancy.
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Brown DL, Smith TL, Knepper LE. Evaluation of five primitive reflexes in 240 young adults. Neurology 1998; 51:322. [PMID: 9674840 DOI: 10.1212/wnl.51.1.322] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Dolling JA, Boreham DR, Brown DL, Mitchel RE, Raaphorst GP. Modulation of radiation-induced strand break repair by cisplatin in mammalian cells. Int J Radiat Biol 1998; 74:61-9. [PMID: 9687976 DOI: 10.1080/095530098141735] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
PURPOSE To investigate the repair of ionizing radiation-induced DNA lesions in human skin fibroblasts in the presence of cisplatin-DNA adducts and to determine the persistence of DNA repair inhibition by cisplatin. MATERIALS AND METHODS Normal human fibroblasts (AG 1522) treated with cisplatin were exposed to 4 Gy 60Co gamma-radiation and assayed for repair of radiation-induced damage under growth-permissive conditions. DNA damage was measured by the fluorescence analysis of DNA unwinding (FADU) and cytokinesis-blocked micronucleus assays. RESULTS Rejoining of strand breaks caused by 4 Gy radiation in cells without cisplatin pre-treatment appeared to be biphasic with an initial fast component (up to 15 min of repair time) followed by a slower component, and was completed by 90 min. Cisplatin treatment (10 microg/ml, 30 min) immediately before irradiation had no effect on the fast rejoining component, but inhibited the slow component (p<0.01). The same cisplatin treatment 24 h prior to irradiation inhibited both slow and fast components (p<0.01). In contrast, decreasing the cisplatin exposure to 1.0 microg/ml for 30 min, 24h prior to irradiation, resulted in an increased amount of strand break repair at each time point measured compared with irradiated control cells. This mild cisplatin treatment (95% survival) also resulted in a reduction of radiation-generated micronuclei indicating an adaptive response. CONCLUSIONS Cisplatin used in combination with ionizing radiation can produce differential cellular responses depending upon the severity of the cisplatin treatment and the time interval between cisplatin and radiation exposures.
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Vaillant AR, Müller R, Langkopf A, Brown DL. Characterization of the microtubule-binding domain of microtubule-associated protein 1A and its effects on microtubule dynamics. J Biol Chem 1998; 273:13973-81. [PMID: 9593747 DOI: 10.1074/jbc.273.22.13973] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To determine how MAP1a interacts with microtubules we expressed several 6myc-tagged MAP1a fragments in P19 EC and HeLa cells. Confocal immunofluorescence microscopy showed that the fragment consisting of amino acids (aa) 1-281 of MAP1a did not bind while the fragment consisting of aa 1-630 did, indicating that the region of MAP1a between aa 281 and 630 contains a microtubule-binding domain. Deletion of the basic repeats from aa 336-540 did not result in loss of microtubule binding, suggesting that the regions flanking the basic repeats can bind MAP1a to microtubules. These observations were confirmed using an in vitro microtubule binding assay. The levels of acetylation and detyrosination of polymerized microtubules were assessed by quantitative dot blotting in cells expressing MAP1a fragments or MAP2c. Compared with untransfected cells, the polymerized tubulin in cells expressing full-length MAP1a was more acetylated and detyrosinated, but these increases were smaller than those seen in cells expressing MAP2c. Consistent with this, the microtubules in MAP2c expressing cells were more resistant to colchicine than those in cells overexpressing MAP1a. These data implicate aa 281-336 and/or 540-630 of MAP1a in microtubule binding and suggest that MAP1a is less able to stabilize microtubules than MAP2c.
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Di Salvo DN, Benson CB, Laing FC, Brown DL, Frates MC, Doubilet PM. Sonographic evaluation of the placental cord insertion site. AJR Am J Roentgenol 1998; 170:1295-8. [PMID: 9574605 DOI: 10.2214/ajr.170.5.9574605] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Velamentous and marginal umbilical cords are uncommon abnormalities of placental cord insertion that can entail significant fetal risk. We undertook this investigation to assess the ability of prenatal sonography to reveal abnormal insertions of the umbilical cord into the placenta. SUBJECTS AND METHODS Forty-six patients had both prenatal sonographic evaluation of the placental cord insertion site and postnatal pathologic examination. Distance from the insertion site to the nearest placental edge was categorized by sonography and pathology as normal if greater than 1 cm and abnormal if less than or equal to 1 cm. Sonographic and pathologic findings were compared. RESULTS Thirty-eight singleton and eight twin pregnancies, for a total of 54 cord insertions, were studied. Of the 43 sonographically normal insertions, 38 had normal pathologic findings, and the remaining five insertions had abnormal pathologic findings (all marginal cord insertions). All 11 insertions that showed abnormality on sonography were abnormal on pathologic examination (seven marginal and four velamentous insertions). Sonography was able to reveal a difference between the two types of abnormal insertions in only a single patient, in whom the cord insertion changed from marginal to velamentous during a 7-week interval. Sonography had an overall sensitivity of 69% (11/16), a specificity of 100% (38/38), and an accuracy of 91% (49/54) for revealing abnormal placental cord insertion sites. CONCLUSION Targeted sonographic examination of the placental site of umbilical cord insertion will reveal abnormal placental cord insertions, although distinguishing the specific type of abnormal insertion may require the use of color Doppler imaging.
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