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Fleming ND, Westin SN, Meyer LA, Shafer A, Rauh-Hain JA, Onstad M, Cobb L, Bevers M, Fellman BM, Burzawa J, Bhosale P, Zand B, Jazaeri A, Levenback C, Coleman RL, Soliman PT, Sood AK. Correlation of surgeon radiology assessment with laparoscopic disease site scoring in patients with advanced ovarian cancer. Int J Gynecol Cancer 2020; 31:92-97. [PMID: 33154095 DOI: 10.1136/ijgc-2020-001718] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 10/13/2020] [Accepted: 10/15/2020] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Radiographic triage measures in patients with new advanced ovarian cancer have yielded inconsistent results. OBJECTIVE To determine the correlation between surgeon radiology assessment and laparoscopic scoring by disease sites in patients with newly diagnosed advanced stage ovarian cancer. METHODS Fourteen gynecologic oncology surgeons from a single institution performed a blinded review of pre-operative contrast-enhanced CT imaging from patients with advanced stage ovarian cancer. Each of the patients had also undergone laparoscopic scoring assessment, between April 2013 and December 2017, to determine primary resectability using the validated Fagotti scoring method, and assigned a predictive index value score. Surgeons were asked to provide expected predictive index value scores based on their blinded review of the antecedent CT imaging. Linear mixed models were conducted to calculate the correlation between radiologic and laparoscopic score for surgeons individually, and as a group. Once the model was fit, the inter-class correlation and 95% CI were calculated. RESULTS Radiology review was performed on 20 patients with advanced stage ovarian cancer who underwent laparoscopic scoring assessment. Surgeon faculty rank included assistant professor (n=5), associate professor (p=4), and professor (n=5). The kappa inter-rater agreement was -0.017 (95% CI -0.023 to -0.005), indicating low inter-rater agreement between radiology review and actual laparoscopic score. The inter-class correlation in this model was 0.06 (0.02-0.21), indicating that surgeons do not score the same across all the images. When using a clinical cut-off point for the predictive index value of 8, the probability of agreement between radiology and actual laparoscopic score was 0.56 (95% CI 0.49 to 0.73). Examination of disease site sub-scales showed that the probability of agreement was as follows: peritoneum 0.57 (95% CI 0.51 to 0.62), diaphragm 0.54 (95% CI 0.48 to 0.60), mesentery 0.51 (95% CI 0.45 to 0.57), omentum 0.61 (95% CI 0.55 to 0.67), bowel 0.54 (95% CI 0.44 to 0.64), stomach 0.71 (95% CI 0.65 to 0.76), and liver 0.36 (95% CI 0.31 to 0.42). The number of laparoscopic scoring cases, tumor reductive surgery cases, or faculty rank was not significantly associated with overall or sub-scale agreement. CONCLUSIONS Surgeon radiology review did not correlate highly with actual laparoscopic scoring assessment findings in patients with advanced stage ovarian cancer. Our study highlights the limited accuracy of surgeon radiographic assessment to determine resectability.
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Affiliation(s)
- Nicole D Fleming
- Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Shannon N Westin
- Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Larissa A Meyer
- Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Aaron Shafer
- Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Jose Alejandro Rauh-Hain
- Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Michaela Onstad
- Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Lauren Cobb
- Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Michael Bevers
- Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Bryan M Fellman
- Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Jennifer Burzawa
- Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, University of Washington, Seattle, Washington, USA
| | - Priya Bhosale
- Department of Diagnostic Imaging, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Behrouz Zand
- Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Amir Jazaeri
- Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Charles Levenback
- Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Robert L Coleman
- Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Pamela T Soliman
- Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Anil K Sood
- Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
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Arias-Moreno AJ, Hosseini HS, Bevers M, Ito K, Zysset P, van Rietbergen B. Validation of distal radius failure load predictions by homogenized- and micro-finite element analyses based on second-generation high-resolution peripheral quantitative CT images. Osteoporos Int 2019; 30:1433-1443. [PMID: 30997546 PMCID: PMC6614386 DOI: 10.1007/s00198-019-04935-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 03/05/2019] [Indexed: 12/15/2022]
Abstract
UNLABELLED This study developed a well-standardized and reproducible approach for micro-finite element (mFE) and homogenized-FE (hFE) analyses that can accurately predict the distal radius failure load using either mFE or hFE models when using the approaches and parameters developed in this study. INTRODUCTION Micro-FE analyses based on high-resolution peripheral quantitative CT (HR-pQCT) images are frequently used to predict distal radius failure load. With the introduction of a second-generation HR-pQCT device, however, the default modelling approach no longer provides accurate results. The aim of this study was to develop a well-standardized and reproducible approach for mFE and hFE analyses that can provide precise and accurate results for distal radius failure load predictions based on second-generation HR-pQCT images. METHODS Second-generation HR-pQCT was used to scan the distal 20-mm section of 22 cadaver radii. The sections were excised and mechanically tested afterwards. For these sections, mFE and hFE models were made that were used to identify required material parameters by comparing predicted and measured results. Using these parameters, the models were cropped to represent the 10-mm region recommended for clinical studies to test their performance for failure load prediction. RESULTS After identification of material parameters, the measured failure load of the 20-mm segments was in good agreement with the results of mFE models (R2 = 0.969, slope = 1.035) and hFE models (R2 = 0.966, slope = 0.890). When the models were restricted to the clinical region, mFE still accurately predicted the measured failure load (R2 = 0.955, slope = 1.021), while hFE predictions were precise but tended to overpredict the failure load (R2 = 0.952, slope = 0.780). CONCLUSIONS It was concluded that it is possible to accurately predict the distal radius failure load using either mFE or hFE models when using the approaches and parameters developed in this study.
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Affiliation(s)
- A J Arias-Moreno
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, De Zaale, Groene Loper 15, 5612AP, Eindhoven, The Netherlands
- Department of Mechanics and Production, Autonomous University of Manizales, Antigua Estación del Ferrocarril, Manizales, Caldas, Colombia
| | - H S Hosseini
- Institute for Surgical Technology and Biomechanics, University of Bern, Stauffacherstrasse 78, 3014, Bern, Switzerland
| | - M Bevers
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, De Zaale, Groene Loper 15, 5612AP, Eindhoven, The Netherlands
| | - K Ito
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, De Zaale, Groene Loper 15, 5612AP, Eindhoven, The Netherlands
| | - P Zysset
- Institute for Surgical Technology and Biomechanics, University of Bern, Stauffacherstrasse 78, 3014, Bern, Switzerland
| | - B van Rietbergen
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, De Zaale, Groene Loper 15, 5612AP, Eindhoven, The Netherlands.
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Abstract
A discrete reaction-diffusion model was used to estimate long-term equilibrium populations of a hypothetical species inhabiting patchy landscapes to examine the relative importance of habitat amount and arrangement in explaining population size. When examined over a broad range of habitat amounts and arrangements, population size was largely determined by a pure amount effect (proportion of habitat in the landscape accounted for >96% of the total variation compared to <1% for the arrangement main effect). However, population response deviated from a pure amount effect as coverage was reduced below 30%-50%. That deviation coincided with a persistence threshold as indicated by a rapid decline in the probability of landscapes supporting viable populations. When we partitioned experimental landscapes into sets of "above" and "below" persistence threshold, habitat arrangement became an important factor in explaining population size below threshold conditions. Regression analysis on below-threshold landscapes using explicit measures of landscape structure (after removing the covariation with habitat amount) indicated that arrangement variables accounted for 33%-39% of the variation in population size, compared to 27%-49% for habitat amount. Thus, habitat arrangement effects became important when species persistence became uncertain due to dispersal mortality.
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Affiliation(s)
- Curtis H Flather
- U.S. Department of Agriculture Forest Service, Rocky Mountain Research Station, Fort Collins, Colorado 80526, USA
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Said HK, Bevers M, Butler CE. Reconstruction of the pelvic floor and perineum with human acellular dermal matrix and thigh flaps following pelvic exenteration. Gynecol Oncol 2007; 107:578-82. [DOI: 10.1016/j.ygyno.2007.08.063] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2007] [Revised: 08/02/2007] [Accepted: 08/09/2007] [Indexed: 11/30/2022]
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Slomovitz BM, Ramirez PT, Frumovitz M, Soliman PT, Bevers M, Coleman RL, Levenback C. Electrothermal bipolar coagulation for pelvic exenterations. Gynecol Oncol 2006; 102:534-6. [PMID: 16483643 DOI: 10.1016/j.ygyno.2006.01.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2005] [Revised: 01/03/2006] [Accepted: 01/12/2006] [Indexed: 10/25/2022]
Abstract
OBJECTIVES The morbidity associated with pelvic exenteration is high; however, patients undergoing this procedure have no other curative treatment options. Excessive blood loss is a common complication of this procedure. We evaluated whether use of an electrothermal bipolar coagulator (LigaSure Atlas, ValleyLab, Boulder, Colorado, USA) during pelvic exenteration is safe and whether it reduces intraoperative blood loss, intraoperative blood transfusion requirements, and length of hospital stay. METHODS Between September 2003 and January 2005, 12 patients underwent pelvic exenteration (total, anterior, or posterior) performed using the electrothermal bipolar coagulator. Estimated blood loss, transfusion requirements, length of hospital stay, and complications necessitating reoperation were evaluated. RESULTS The mean age was 55 years (range, 30-77), the mean estimated blood loss was 1931 ml (range, 1300-1500 ml), the mean number of units of packed red blood cells transfused intraoperatively was 3.4 U (range, 2-12 U), the mean operative time was 609 min (range, 400-940 min), and the mean length of hospital stay was 19.9 days (range, 7-27). There were no intraoperative complications related to the electrothermal bipolar coagulator use. None of the patients had any complications necessitating reoperation. CONCLUSIONS Use of the electrothermal bipolar coagulator device during pelvic exenteration is safe and may decrease blood loss and the number of units of blood that must be transfused intraoperatively.
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Affiliation(s)
- Brian M Slomovitz
- Department of Gynecologic Oncology, The University of Texas M. D. Anderson Cancer Center, 1155 Pressler Boulevard, Unit 1362, Houston, TX 77030, USA
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Frumovitz M, Slomovitz BM, Singh DK, Broaddus RR, Abrams J, Sun CC, Bevers M, Bodurka DC. Frozen section analyses as predictors of lymphatic spread in patients with early-stage uterine cancer1. J Am Coll Surg 2004; 199:388-93. [PMID: 15325608 DOI: 10.1016/j.jamcollsurg.2004.05.258] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2004] [Revised: 04/29/2004] [Accepted: 05/03/2004] [Indexed: 11/24/2022]
Abstract
BACKGROUND Many gynecologic oncologists use intraoperative frozen section (IFS) assessment of histologic grade and depth of myometrial invasion (DOI) as predictors of final grade and stage in women with endometrial cancer. This clinical decision method has never been critically examined. STUDY DESIGN We retrospectively reviewed charts of patients with a preoperative diagnosis of uterine endometrioid adenocarcinoma and an intraoperative frozen section assessment of histologic grade and depth of myometrial invasion. Intraoperative predictors combining intraoperative frozen section assessment of histologic grade and depth of myometrial invasion were established and compared with final grade and surgical stage. We then modeled the risks of pelvic and paraaortic lymph node metastases for each predictor. RESULTS There were 129 patients who met inclusion criteria. Thirty-six patients had the IAG1 predictor; 17 (47%) were stage IAG1 on final pathology. Ten patients had the IAG2 predictor; 3 (30%) were stage IAG2 on final pathology. Thirty-four patients had the IBG1 predictor; 18 (53%) were stage IBG1 on final pathology. Forty-nine patients had the IBG2 predictor; 34 (69%) were stage IBG2 on final pathology. Our decision models predict that the IAG1 predictor has a 1% risk of paraaortic and a 2% risk of pelvic lymph node metastases. The IAG2 and IBG1 predictors have a 2% risk of paraaortic and a 4% risk of pelvic lymph node metastases. The IBG2 predictor has a 2% risk of paraaortic and a 6% risk of pelvic lymph node metastases. CONCLUSIONS The combination of intraoperative frozen section analysis for histologic grade and depth of myometrial invasion does not correlate well with final pathologic grade and stage. Data from our models suggest a significant risk of lymph node spread even for patients with seemingly low-risk disease. Until better markers of lymphatic spread exist, we recommend complete surgical staging of all patients with endometrial cancer.
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Affiliation(s)
- Michael Frumovitz
- Department of Gynecologic Oncology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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8
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Abstract
OBJECTIVE The aim of this study was to determine the effectiveness and toxicity of monthly treatment with intravenous paclitaxel for women with advanced or recurrent uterine papillary serous carcinoma (UPSC). METHODS Consenting women with histologically confirmed advanced (FIGO stage III or IV) or recurrent UPSC were treated on an Institutional Review Board approved protocol of a 24-h intravenous infusion of 200 mg/m(2) of paclitaxel every 3 weeks. Both measurable and nonmeasurable disease cases were enrolled. Treatment was continued until disease progression, patient intolerance, or (in women with nonmeasurable disease) completion of six courses. RESULTS Twenty patients received from 1 to 11 cycles of therapy. Two women died of disease after 1 cycle of therapy and were not evaluable for response. Among 13 women with measurable tumor receiving 2 or more cycles of therapy, 4 had a complete clinical response and 6 had a partial response (objective response rate, 77%). The median time to progression was 7.3 months (range, 2-21 months). All 3 remaining patients with measurable disease had stable disease for a median of 6 months. The 5 patients without evaluable disease received 5 to 6 cycles of adjuvant paclitaxel. Three developed recurrence (range, 4-10 months; median, 7.2 months). Neutropenia was the major toxicity. Eleven of the 20 patients required G-CSF support, and 9 were hospitalized for neutropenic fever. One woman had reversible cardiac symptoms, which might have been related to paclitaxel treatment. At the time of analysis (mean follow-up, 23 months; range, 4.3-59.9 months), 13 women had died of disease, 4 were alive with disease, and 2 were disease free. All 3 disease-free patients had been treated for nonmeasurable advanced stage disease. CONCLUSION Paclitaxel appears to have excellent activity in the treatment of advanced or recurrent UPSC, an uncommon but aggressive malignancy. Longer survival appears to be more common among women with small-volume disease.
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Affiliation(s)
- L Ramondetta
- Department of Gynecologic Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas, 77030, USA.
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Verschraegen CF, Levenback C, Vincent M, Wolf J, Bevers M, Loyer E, Kudelka AP, Kavanagh JJ. Phase II study of intravenous DX-8951f in patients with advanced ovarian, tubal, or peritoneal cancer refractory to platinum, taxane, and topotecan. Ann N Y Acad Sci 2001; 922:349-51. [PMID: 11193920 DOI: 10.1111/j.1749-6632.2000.tb07062.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- C F Verschraegen
- Secion of Gynecologic and Medical Therapeutics, Department of Gynecology Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
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Moon C, Verschraegen CF, Bevers M, Freedman R, Kudelka AP, Kavanagh JJ. Use of docetaxel (Taxotere) in patients with paclitaxel (Taxol) hypersensitivity. Anticancer Drugs 2000; 11:565-8. [PMID: 11036959 DOI: 10.1097/00001813-200008000-00007] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Anaphylaxis or significant hypersensitivity reaction is one of the most catastrophic potential complications of chemotherapy. There is a 2-5% risk of hypersensitivity with paclitaxel, a commonly used chemotherapeutic agent for various cancers. Three patients, who developed hypersensitivity to paclitaxel infusion, received docetaxel without allergic reactions. Docetaxel may therefore be an alternative treatment for patients with paclitaxel hypersensitivity.
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Affiliation(s)
- C Moon
- Department of Internal Medicine Specialities, University of Texas MD Anderson Cancer Center, Houston 77030, USA
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Donato ML, Gershenson D, Ippoliti C, Wharton JT, Bast RC, Aleman A, Anderlini P, Gajewski JG, Giralt S, Molldrem J, Ueno N, Lauppe J, Korbling M, Boyer J, Bodurka-Bevers D, Bevers M, Burke T, Freedman R, Levenback C, Wolf J, Champlin RE. High-dose ifosfamide and etoposide with filgrastim for stem cell mobilization in patients with advanced ovarian cancer. Bone Marrow Transplant 2000; 25:1137-40. [PMID: 10849525 DOI: 10.1038/sj.bmt.1702421] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
High-dose chemotherapy combined with autologous peripheral blood stem cell transplantation has shown promise as treatment for recurrent or persistent epithelial ovarian cancer. We evaluated the stem cell mobilization regimen of high-dose ifosfamide plus etoposide in 32 patients with epithelial ovarian cancer, who had a positive second-look laparatomy or recurrent disease. Ifosfamide was given at 10 g/m2 by continuous i.v. from days 1 to 3. Etoposide was given at 150 mg/m2 every 12 h for six doses on days 1-3. Filgrastim was given at 10 microg/kg/d s.c. from day 5 until the completion of peripheral blood stem cell harvest. Fourteen of 32 patients had measurable or evaluable disease before mobilization therapy and were assessed for response. In nine (64%) of the 14 patients, treatment response was demonstrated, and these patients received a second cycle of mobilization therapy. The target CD34+ cell dose (>8 x 106 cells/kg) was achieved with a median of one apheresis (range 1-5). A median of 25.1 (range 8.0-122.5) x 106 CD34+ cells/kg body weight was collected. Non-hematologic toxicity was limited to grade 2 renal dysfunction in one patient and grade 2 hepatic dysfunction in three patients. In this patient group, high-dose ifosfamide plus etoposide with filgrastim support was well tolerated, lead to successful stem cell harvest and had antitumor activity.
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Affiliation(s)
- M L Donato
- Department of Blood and Marrow Transplantation, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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Paccamonti DL, Pycock JF, Taverne MA, Bevers M, Van Der Weijden GC, Gutjahr S, Schams D, Blouin D. PGFM response to exogenous oxytocin and determination of the half-life of oxytocin in nonpregnant mares. Equine Vet J 1999; 31:285-8. [PMID: 10454085 DOI: 10.1111/j.2042-3306.1999.tb03818.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We investigated the half-life of oxytocin in reproductively normal mares and the prostaglandin response after oxytocin administrations. Mares were given oxytocin, 10 or 25 iu, i.v., on the day of, or 2 days after, ovulation, and frequent jugular blood samples were collected for analysis of oxytocin and Prostaglandin F metabolite (PGFM) by RIA. Neither dose of oxytocin nor day of treatment affected the half-life of the exogenous oxytocin, which was determined to be 6.8 min. A significant increase in PGFM was observed within 6 min of oxytocin administration and peak values were observed within 10 min. PGFM response after oxytocin administration on the day of ovulation appeared elevated compared to the response 2 days after ovulation.
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Affiliation(s)
- D L Paccamonti
- Department of Herd Health and Reproduction, University of Utrecht, The Netherlands
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Hof J, Hull Sieg C, Bevers M. Spatial and temporal optimization in habitat placement for a threatened plant: the case of the western prairie fringed orchid. Ecol Modell 1999. [DOI: 10.1016/s0304-3800(98)00176-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Abstract
We examine habitat size, shape, and arrangement effects on populations using a discrete reaction-diffusion model. Diffusion is modeled passively and applied to a cellular grid of territories forming a coupled map lattice. Dispersal mortality is proportional to the amount of nonhabitat and fully occupied habitat surrounding a given cell, with distance decay. After verifying that our model produces the results expected for single patches of uniform habitat, we investigate heterogeneous and fragmented model landscapes. In heterogeneous single-patch systems near critical patch size, populations approach Gaussian spatial distributions with total population constrained by the capacity of the most limiting cell. In fragmented habitat landscapes, threshold effects are more complex and parametrically sensitive. The results from our experiments suggest the following: the ability to achieve persistence in hyperdispersed patchy habitats by adding similarly fragmented patches requires meeting threshold reproduction rates; persistent metapopulations in which no local population is individually persistent appear when dispersal distances and reproduction rates are both high, but only within narrow parameter ranges that are close to extinction thresholds; successful use of stepping-stone patches to support metapopulation systems appears unlikely for passively diffusing species; elongated patches offer early colonization advantages, but blocky patches offer greater population resilience near extinction thresholds. A common theme running through our findings is that population viability estimates may depend on our ability to determine when population and habitat systems are approaching extinction threshold conditions.
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Affiliation(s)
- M Bevers
- Rocky Mountain Research Station, USDA Forest Service, 240 West Prospect Road, Fort Collins, Colorado, 80526, USA
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Kemp B, Soede NM, Kankofer M, Bevers M, Taverne MA, Wensing T, Noordhuizen JP. Influence of linoleic/linolenic acid ratio in the diet of periparturient cattle on plasma concentrations of PGF2 alpha metabolite and placental expulsion rate. Theriogenology 1998; 49:571-80. [PMID: 10732036 DOI: 10.1016/s0093-691x(98)00008-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Forty-eight cows Holstein Friesian x Dutch Friesian (HF x DF) were randomly assigned to 2 groups fed 1 of 2 diets (isocaloric and isonitrogenous but different in linoleic/linolenic acid ratio) from 4 wk before expected parturition until 7 d after calving. Effects of the diet on plasma linoleic/linolenic acid ratio, plasma PGFM levels and placental explusion rate were studied. Dietary treatment resulted in significant differences in linoleic/linolenic acid ratio in blood plasma (1.00 +/- .22 vs 4.41 +/- .53). The placental expulsion rate was not significantly different between the 2 treatment groups. Plasma PGFM levels, as analyzed for 28 cows from 30 d before parturition until 1.5 d after parturition, were similar for the diets. Cows with a longer placental expulsion rate had lower PGFM levels at parturition (for instance, placental expulsion rate shorter (n = 11) and longer (n = 17) than 6 h, 1248 vs 2965 pg/ml, residual standard deviation 1185 pg/ml, P < 0.01). The results show that the dietary linoleic/linolenic acid ratio can influence the plasma linoleic/linolenic acid ratio without affecting the placental expulsion rate or plasma PGFM levels around parturition.
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Affiliation(s)
- B Kemp
- Wageningen Institute of Animal Sciences, Wageningen Agricultural University, The Netherlands
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17
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Meijer JC, Trudeau VL, de Jong FH, Bevers M, Noordhuizen-Stassen EN, Wensing CJ. Absence of direct effects of GnRH on testicular steroid secretion in the ram. J Reprod Fertil 1989; 86:517-24. [PMID: 2668522 DOI: 10.1530/jrf.0.0860517] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Effects of GnRH, administered via the testicular artery, on testicular steroidogenesis were studied in rams during the non-breeding season. Concentrations of testosterone and 17-hydroxyprogesterone in testicular venous blood showed similar profiles which were identical for GnRH-treated (0.5 ng infused over 60 min or 25 ng injected) and control testes. Increases of testicular venous concentration of both hormones were only marginally reflected in peripheral venous concentrations. Peripheral administration of hCG (200 i.u., i.v.) stimulated testosterone secretion to a larger extent than 17-hydroxyprogesterone secretion in 10/11 rams, GnRH-treated and control testes showing identical responses. High testicular venous concentrations of both hormones after administration of GnRH were paralleled by increased concentrations of endogenous LH. These LH peaks were evoked by 25 ng GnRH in 7/8 rams. The observed effects of GnRH treatment on testicular steroid secretion thus cannot be considered to be the result of direct stimulation of steroidogenesis by GnRH.
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Affiliation(s)
- J C Meijer
- Department of Functional Morphology, Faculty of Veterinary Medicine, University of Utrecht, The Netherlands
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Taverne M, Bevers M, Bradshaw JM, Dieleman SJ, Willemse AH, Porter DG. Plasma concentrations of prolactin, progesterone, relaxin and oestradiol-17 beta in sows treated with progesterone, bromocriptine or indomethacin during late pregnancy. J Reprod Fertil 1982; 65:85-96. [PMID: 7077605 DOI: 10.1530/jrf.0.0650085] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Pregnant gilts (3/group) were given no treatment, 10 mg bromocriptine twice daily by mouth, from Day 111 of pregnancy to 1 day post partum, 25 mg progesterone s.c. at 6-h intervals from Days 111 to 116 inclusive or 400 mg indomethacin by mouth at 6-h intervals from Day 111 to 116 inclusive. Before spontaneous delivery maternal plasma prolactin and relaxin concentrations started to rise almost simultaneously between 58 and 47 h before the first piglet and both hormones reached peak values when the plasma progesterone concentration had started to decline rapidly (approximately 21-23 h). Suppression of prolactin levels by bromocriptine prevented the onset of lactation completely but had no obvious influence on changes of the other hormone concentrations and the course of parturition. Progesterone treatment delayed the onset of expulsion of the piglets but did not delay the simultaneous increase in prolactin and relaxin concentrations. These changes in hormone levels were prevented by indomethacin treatment but occurred essentially unchanged when the treatment was ended. The results support the concept that parturition in the pig is preceded by a biphasic increase of plasma prostaglandin levels.
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