Publications by authors named "William A Bennett"

11 Publications

  • Page 1 of 1

Absence of neurotoxicity with medicinal grade terbutaline in the rat model.

Reprod Toxicol 2011 May 22;31(4):447-53. Epub 2011 Jan 22.

Department of Obstetrics and Gynecology, University of Mississippi Medical Center, Jackson, MS 39216-4505, USA.

To evaluate neurological effects of terbutaline, rats were injected with saline, terbutaline (Sigma or American Pharmaceutical Partners (APP™)) at 0.5 mg/kg-d or 10 mg/kg-d between postnatal days (PND) 2-5 or 11-14. Brains collected 24 h after last injection were used to determine corpus-callosum thickness, Purkinje cell and neuronal number in the cerebellum. Ambulation, distance traveled, resting time and time on rotarod were analyzed. Terbutaline (both doses/grades at PND 11-14) decreased corpus-callosum thickness. Ambulation time was significantly decreased in the 10 mg/kg-d (Sigma) and 0.5 mg/kg-d of terbutaline (APP™) (PND 2-5) juvenile-rats and 10 mg/kg-d-Sigma adult-rats, 0.5 mg/kg-d APP™ (PND 11-14) adult-rats. Resting time was increased in both doses of APP™ (PND 2-5) in juvenile-rats, 10 mg/kg-d Sigma adult-rats. 10 mg/kg-d-Sigma (PND 2-5) decreased distance traveled in adult-rats. 0.5 mg/kg-d-Sigma (PND 2-5 and PND 11-14) decreased the time spent on rotarod (30 RPM) in adult-rats. Sigma terbutaline Sigma had 2× as much free base compared to APP™. In conclusion, APP™ terbutaline did not have a deleterious effect on the developing rat brain.
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http://dx.doi.org/10.1016/j.reprotox.2011.01.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3970845PMC
May 2011

Roles of hCG in Advancing Follicular Growth to Ovulation after Concurrent Injections of PGF(2α) and GnRH in Postpubertal Holstein Heifers Bearing a CL.

Vet Med Int 2010 Dec 1;2010:394236. Epub 2010 Dec 1.

Department of Agriculture, Alcorn State University, 1000 ASU Drive, Box 750, Alcorn State, MS 39096, USA.

A study was conducted to test the hypothesis that injecting Gonadotropin-releasing hormone (GnRH) concurrently with Prostaglandin F2 alpha (PGF(2α)) followed by an injection of human Chorionic Gonadotropin (hCG), would advance follicular growth to ovulation in Holstein heifers bearing a corpus luteum (CL). After manual examination of the CL, group 1 (PGF; n = 12) received an injection of PGF(2α) (25 mg, im). Group 2 (PGF + GnRH; n = 13) received an injection of GnRH (100 μg, im) immediately after an injection of PGF(2α). Group 3 (PGF + GnRH + hCG; n = 12) received concurrent injections of PGF(2α) and GnRH followed with hCG (1500 IU, im) two days later. Follicular size and day of ovulation were monitored by daily ultrasonographic examination from days 1 to 10. Blood was collected on days-7, 0 (PGF(2α) administration), 2, and 7. Progesterone was not different (P > .05) on days-7, 0, and 2 between the experimental groups. However, it was higher (P < .005) in the PGF + GnRH + hCG group on day 7 compared to PGF + GnRH heifers, but not significantly higher than the PGF. Additionally, heifers in the PGF + GnRH + hCG group ovulated earlier (P < .05) than heifers in the PGF + GnRH and the PGF group. This data indicates that hCG advances follicular growth to ovulation in spite of high levels of progesterone when injected 48 h after concurrent treatments of GnRH and PGF(2α) on heifers bearing a CL.
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http://dx.doi.org/10.4061/2010/394236DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2995931PMC
December 2010

Bayesian change point analysis of abundance trends for pelagic fishes in the upper San Francisco Estuary.

Ecol Appl 2010 Jul;20(5):1431-48

Australian Centre for Biodiversity, School of Biological Sciences, Monash University, Melbourne 3800, Australia.

We examined trends in abundance of four pelagic fish species (delta smelt, longfin smelt, striped bass, and threadfin shad) in the upper San Francisco Estuary, California, USA, over 40 years using Bayesian change point models. Change point models identify times of abrupt or unusual changes in absolute abundance (step changes) or in rates of change in abundance (trend changes). We coupled Bayesian model selection with linear regression splines to identify biotic or abiotic covariates with the strongest associations with abundances of each species. We then refitted change point models conditional on the selected covariates to explore whether those covariates could explain statistical trends or change points in species abundances. We also fitted a multispecies change point model that identified change points common to all species. All models included hierarchical structures to model data uncertainties, including observation errors and missing covariate values. There were step declines in abundances of all four species in the early 2000s, with a likely common decline in 2002. Abiotic variables, including water clarity, position of the 2 per thousand isohaline (X2), and the volume of freshwater exported from the estuary, explained some variation in species' abundances over the time series, but no selected covariates could explain statistically the post-2000 change points for any species.
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http://dx.doi.org/10.1890/09-0998.1DOI Listing
July 2010

Analysis of pelagic species decline in the upper San Francisco Estuary using multivariate autoregressive modeling (MAR).

Ecol Appl 2010 Jul;20(5):1417-30

Australian Centre for Biodiversity, School of Biological Sciences, Monash University, Melbourne 3800, Australia.

Four species of pelagic fish of particular management concern in the upper San Francisco Estuary, California, USA, have declined precipitously since ca. 2002: delta smelt (Hypomesus transpacificus), longfin smelt (Spirinchus thaleichthys), striped bass (Morone saxatilis), and threadfin shad (Dorosoma petenense). The estuary has been monitored since the late 1960s with extensive collection of data on the fishes, their pelagic prey, phytoplankton biomass, invasive species, and physical factors. We used multivariate autoregressive (MAR) modeling to discern the main factors responsible for the declines. An expert-elicited model was built to describe the system. Fifty-four relationships were built into the model, only one of which was of uncertain direction a priori. Twenty-eight of the proposed relationships were strongly supported by or consistent with the data, while 26 were close to zero (not supported by the data but not contrary to expectations). The position of the 2 per thousand isohaline (a measure of the physical response of the estuary to freshwater flow) and increased water clarity over the period of analyses were two factors affecting multiple declining taxa (including fishes and the fishes' main zooplankton prey): Our results were relatively robust with respect to the form of stock-recruitment model used and to inclusion of subsidiary covariates but may be enhanced by using detailed state-space models that describe more fully the life-history dynamics of the declining species.
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http://dx.doi.org/10.1890/09-1724.1DOI Listing
July 2010

Integrating contaminant responses in indicator saltmarsh species.

Mar Environ Res 2006 Jul 15;62 Suppl:S317-21. Epub 2006 Apr 15.

University of California Davis, Bodega Marine Laboratory, Bodega Bay, CA, USA.

A challenge in environmental management is to provide both methodology and a framework for assessing effects of pollutants in resident species and then applying the findings to management. The Pacific Estuarine Ecosystem Indicator Research (PEEIR) consortium advocates the development of an integrated portfolio of techniques using indicator species selected for various habitat types. We developed such a portfolio for California salt marsh ecosystems and evaluated the feasibility of our approach in management applications. PEEIR is employing a suite of biomarker responses in two indigenous species, the lined shore crab (Pachygrapsus crassipes) and the longjaw mudsucker (Gillichthys mirabilis). Detrimental effects such as apoptosis, endocrine disruption, and ovarian tumors have been observed in G. mirabilis at a site where toxicity test responses were relatively low. With P. crassipes, developmental abnormalities and several markers of decreased reproductive performance were quantified at the same site. Multivariate statistical techniques are used to examine the relationships between the responses and multiple contaminant and natural stressors. For the fish, findings are related to population-level parameters using dynamic energy budget (DEB) models.
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http://dx.doi.org/10.1016/j.marenvres.2006.04.011DOI Listing
July 2006

Hypertension produced by reductions in uterine perfusion in the pregnant rat: role of tumor necrosis factor-alpha.

Hypertension 2005 Oct 6;46(4):1022-5. Epub 2005 Sep 6.

Department of Physiology and Obstetrics/Gynecology, University of Mississippi Medical Center, Jackson, MS 39216-4505, USA.

Inflammatory cytokines such as tumor necrosis factor (TNF)-alpha are elevated in preeclamptic women and are thought to be an important link between placental ischemia and endothelial dysfunction. The purpose of this study was to determine the role of TNF in mediating hypertension in response to chronic reductions in uterine perfusion (RUPPs) in pregnant rats. Arterial pressure was significantly higher in RUPP rats (138+/-1 mm Hg) than in pregnant rats (107+/-1 mm Hg). Serum TNF-alpha levels in the RUPP rats were 17+/-4 pg/mL compared with 8+/-1 pg/mL in normal pregnant rats. To determine the long-term effects of a 2- to 3-fold elevation in plasma TNF-alpha on renal and systemic hemodynamics in pregnant rats, we infused TNF-alpha for 5 days at a rate of 50 ng/d during days 14 to 19 of gestation in pregnant rats. Serum levels were 7+/-2 pg/mL in the control pregnant rats and 14+/-2 pg/mL in the TNF-alpha-treated pregnant rats. Mean arterial pressure was higher in the TNF-alpha-treated pregnant rats (123+/-3 mm Hg) compared with pregnant controls (96+/-3 mm Hg) at day 19 of gestation. TNF-alpha increased renal vascular resistance in pregnant rats by 182%. Renal plasma flow was 5.4+/-1.2 mL/min in the TNF-alpha-treated group and 9.2+/-1.6 mL/min in the control group. Glomerular filtration rate was 1.7+/-0.4 mL/min in the TNF-alpha-treated group and 2.6+/-0.4 mL/min in the control group. In summary, these data suggest that TNF-alpha may play an important role in mediating the increased arterial pressure in response to chronic RUPPs in pregnant rats.
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http://dx.doi.org/10.1161/01.HYP.0000175476.26719.36DOI Listing
October 2005

Suppression of glial activation is involved in the protection of IL-10 on maternal E. coli induced neonatal white matter injury.

Brain Res Dev Brain Res 2005 Jun;157(2):141-9

Department of Pediatrics, University of Mississippi Med. Ctr., Jackson, MS 39216-4505, USA.

White matter damage (WMD) is an important cause of disability including cerebral palsy in preterm, low birth-weight infants. Maternal infection is now recognized as one of the risk factors for WMD. Previously we reported that intrauterine inoculation of Escherichia coli to pregnant rats resulted in WMD in offspring and interleukin-10 (IL-10) was protective against this damage. The objective of this study was to elucidate the mechanism involved in the protective effect of IL-10 against neonatal WMD. We found that E. coli treatment in dams resulted in significant apoptosis in periventricular white matter of rat pups on postnatal day 0 (P0). On P8, a remarkable increase in ED-1 immunostaining (indicating either microglial activation or macrophage infiltration) was detected in brains of pups in the E. coli-treated group. Astrogliosis was also noticed in brain white matter of pups in the E. coli-treated group. In addition to the strong activation of microglia and astrocytes, oligodendrocytes (OLs) were significantly reduced in periventricular areas in the brains of pups from the E. coli-treated group. Later, on P15, hypomyelination was also noticed in rat brains from the E. coli-treated group, using myelin basic protein (MBP) immunostaining. Treatment with IL-10 after E. coli inoculation significantly reduced TUNEL staining and caspase-3 activation, and partially restored the impaired immunostaining markers for immature and mature OLs, such as CNPase, O4, adenomatous polyposis coli (APC) and MBP. These results indicate that the protective effect of IL-10 against brain WMD is linked with suppression of microglial activation/macrophage infiltration, as shown by significantly reduced ED-1+ cells in the white matter.
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http://dx.doi.org/10.1016/j.devbrainres.2005.03.015DOI Listing
June 2005

Maternal infection-induced white matter injury is reduced by treatment with interleukin-10.

Am J Obstet Gynecol 2004 Oct;191(4):1387-92

Department of Obstetrics and Gynecology, University of Mississippi Medical Center, Jackson, MS, USA.

Objective: The purpose of this study was to test the hypothesis that interleukin-10 can prevent white matter injury in neonatal rats that are born to infected dams.

Study Design: Timed pregnant rats (day 17) were assigned to the following treatment groups: (1) saline control (n = 5 rats), (2) Escherichia coli- infected (n = 10 rats), and (3) E coli + interleukin-10 (n = 5 rats). E coli was administered at a titer of 1 x 10(7) colony-forming units by intrauterine inoculation just above the cervix at the bifurcation of the uterine horns. Rat interleukin-10 was administered intravenously at a dose of 1 microg/kg of body weight. After delivery, the pups were maintained with dams until day 8, at which time they were placed under general anesthesia and perfused with saline solution followed by 10% paraformaldehyde. The brains were removed, placed in 30% sucrose solution, and then frozen at -20 degrees C until the preparation of the frozen sections. Standard hematoxylin/eosin staining was performed, and the brains were evaluated for matter necrosis, apoptotic cells, and ventricular swelling.

Results: In pups that were born to infected dams, 11 of 38 pups (29%) displayed symmetric lesions around the lateral ventricles. These lesions were characterized by marked looseness/edema of the neuropil, foamy-appearing histiocytes, and granular neuropil breakdown. None of the pups (n = 17) that were born to interleukin-10-treated infected dams displayed this pattern of severe white matter injury.

Conclusion: These results suggest that maternal interleukin-10 therapy could provide neuroprotection for infants who are born to mothers with intrauterine infection.
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http://dx.doi.org/10.1016/j.ajog.2004.06.093DOI Listing
October 2004

Evaluation of a rat model of preeclampsia for HELLP syndrome characteristics.

J Soc Gynecol Investig 2003 Apr;10(3):151-3

Department of Obstetrics and Gynecology, East Carolina University Brody School of Medicine, Greenville, North Carolina, USA.

Objective: To determine whether a rat model of preeclampsia includes features consistent with HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome.

Methods: Preeclampsia was induced experimentally in timed-pregnant Sprague-Dawley rats using the reduced uterine perfusion pressure (RUPP) model. On day 14 of gestation, silver clips were placed around the aorta below the renal arteries and on the left and right uterine arcade at the ovarian artery. All animals were chronically instrumented to determine conscious blood pressure and to obtain blood samples for analysis of complete blood count, platelet count, liver function tests, uric acid, creatinine, and albumin. Blood samples were collected and animals sacrificed on day 19 of gestation, at which time placental and pup weight were obtained. A control group was analyzed similarly. Statistical analysis was performed with the Student t test.

Results: The RUPP model animals (n = 8), when compared with the normotensive controls (n = 9), did not show a statistically significant difference in hemoglobin, platelets, liver function tests, uric acid, creatinine, or albumin, although the mean arterial pressure was higher (mean +/- SD 131.9 +/- 17.1 mmHg versus 104.0 +/- 14.0 mmHg, respectively; P = .003) and pup number was lower (RUPP 6.6 +/- 2.4 versus control 13.8 +/- 2.3, P < .001).

Conclusion: Although decreased uteroplacental perfusion induces changes similar to symptoms of preeclampsia, the RUPP rat model does not appear to express features of HELLP syndrome.
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http://dx.doi.org/10.1016/s1071-5576(03)00009-1DOI Listing
April 2003

Pathophysiology of preeclampsia: linking placental ischemia/hypoxia with microvascular dysfunction.

Microcirculation 2002 Jul;9(3):147-60

Center for Excellence in Cardiovascular-Renal Research, University of Mississippi Medical Center, Jackson, MS, USA.

Studies during the past decade have provided a better understanding of the potential mechanisms responsible for the pathogenesis of preeclampsia. The initiating event in preeclampsia has been postulated to be reduced uteroplacental perfusion as a result of abnormal cytotrophoblast invasion of spiral arterioles. Placental ischemia/hypoxia is thought to lead to widespread activation/dysfunction of the maternal vascular endothelium which results in enhanced formation of endothelin, thromboxane, and superoxide, increased vascular sensitivity to angiotensin II, and decreased formation of vasodilators such as nitric oxide and prostacyclin. These endothelial abnormalities, in turn, cause hypertension by impairing renal function and increasing total peripheral resistance. While recent studies support a role for cytokines and other factors such as lipid peroxides and reactive oxygen intermediates as potential mediators of endothelial dysfunction, finding the link between placental ischemia/hypoxia and maternal endothelial and vascular abnormalities remains an important area of investigation. The quantitative importance of the various endothelial and humoral factors in mediating the vasoconstriction and elevation in arterial pressure during preeclampsia has also not been completely elucidated.
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http://dx.doi.org/10.1038/sj.mn.7800137DOI Listing
July 2002

Tumor necrosis factor-alpha-induced hypertension in pregnant rats results in decreased renal neuronal nitric oxide synthase expression.

Am J Hypertens 2002 Feb;15(2 Pt 1):170-5

Department of Physiology, Center for Excellence in Cardiovascular-Renal Research Center, University of Mississippi Medical Center, Jackson 39216-4505, USA.

Background: Preeclampsia is associated with increases in plasma levels of tumor necrosis factor-alpha (TNF-alpha), a cytokine known to contribute to endothelial dysfunction. We recently reported that a twofold elevation in plasma TNF-alpha produces significant reductions in renal function and hypertension in pregnant rats. The purpose of this study was to determine the role of the nitric oxide (NO) system in TNF-alpha-induced hypertension in pregnant rats.

Methods: Tumor necrosis factor-alpha (50 ng/day) was chronically infused starting at day 14 of gestation. Mean arterial pressure, 24-h urinary nitrite/nitrate excretion, and renal nitric oxide synthase (NOS) protein expression by Western blot analysis was measured at day 19 of gestation.

Results: A twofold increase in plasma TNF-alpha levels in pregnant rats resulted in a significant increase in arterial pressure (97 +/- 3.6 v 116 +/- 2.1 mm Hg, pregnant versus TNF-alpha pregnant, respectively, P < .05), but no significant change in urinary nitrite/nitrate excretion (22.0 +/- 1.9 v 20.8 +/- 2.5 micromol/24 h, pregnant versus TNF-alpha pregnant, respectively), a measure of whole body NO production. As abnormalities in renal production of NO would not be reflected in the measure of whole body NO production, changes in renal NOS protein levels were determined. The protein expression of both neuronal (nNOS) and inducible (iNOS) nitric oxide synthase were significantly decreased in the medulla of TNF-alpha pregnant rats (nNOS: 10.6 +/- 0.7 v 8.2 +/- 0.8 densitometric units, P < .05; and iNOS: 19.2 +/- 0.9 v 15.4 +/- 0.8 densitometric units, P < .05, pregnant versus TNF-alpha pregnant, respectively).

Conclusion: The hypertension associated with a chronic twofold increase in TNF-alpha in pregnant rats is associated with significant decreases in renal nNOS and iNOS protein production.
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http://dx.doi.org/10.1016/s0895-7061(01)02255-5DOI Listing
February 2002
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