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Biomedical subjects

J K Williams

Publications and source records attributed to J K Williams.

At least 55 records · Page 3Linked to original sources
PubMed1998

Coadministration of nomegestrol acetate does not diminish the beneficial effects of estradiol on coronary artery dilator responses in nonhuman primates (Macaca fascicularis).

OBJECTIVE: Our purpose was to examine the effect of coadministered nomegestrol acetate on estradiol-induced dilator responses of coronary arteries. STUDY DESIGN: In this prospective randomized trial, ovariectomized monkeys were fed a moderately atherogenic diet for 3 months while being treated with (1) no hormone replacement (control, n = 12), (2) estradiol (1.5 mg/d equivalent) added to the diet (n = 12), or (3) estradiol (1.5 mg/d equivalent) plus nomegestrol acetate (3.75 mg/d equivalent) (n = 12) added to the diet. Effects of treatment were measured with analysis of variance. Post hoc analyses were done by multiple comparison tests with Bonferroni corrections. RESULTS: Constrictor responses of epicardial coronary arteries (measured with quantitative angiography) and decreased coronary blood velocity (measured with Doppler ultrasonography) to acetylcholine (10(-6) mol/L) were less in the estradiol-treated monkeys (with or without cotreatment with nomegestrol acetate) than in the untreated monkeys (P <.05). Typical estrogenic responses were induced by estradiol in the endometrium (ie, increased proliferation [Ki-67 expression] [P <.04] and increased hormone receptor expression). These effects were antagonized by nomegestrol acetate. CONCLUSIONS: Although nomegestrol acetate has typical progestin-like effects on the uterus, it does not diminish the beneficial effects of estrogen on acetylcholine-induced dilator responses of coronary arteries.

Acetylcholine↗
PubMed1998

Conjugated equine estrogens inhibit progression of atherosclerosis but have no effect on intimal hyperplasia or arterial remodeling induced by balloon catheter injury in monkeys.

OBJECTIVES: This study sought to determine the effects of estrogen treatment on atherosclerosis progression and the proliferative and structural responses of the atherosclerotic arteries to injury. BACKGROUND: Estrogen treatment suppresses the intimal response to arterial injury in nonatherosclerotic rodents and rabbits and inhibits the in vitro proliferation of smooth muscle cells. However, the effect of estrogen on the response of atherosclerotic arteries to transmural injury, as occurs in balloon catheter angioplasty in humans, is unknown. METHODS: Forty-six ovariectomized cynomolgus monkeys were fed an atherogenic diet for 30 months; 25 received 175 microg/day of conjugated equine estrogens, and 21 served as untreated control animals. All animals underwent balloon catheter injury of the left iliac artery. Subsets of animals underwent a necropsy study at 4, 7, 14 and 28 days after injury; injured and contralateral (uninjured) arteries were pressure-fixed and evaluated morphometrically. RESULTS: Estrogen treatment resulted in a 37% decrease (p < 0.05) in atherosclerosis (plaque area) in the uninjured artery. In response to injury, arterial cell proliferation increased at days 4 and 7, and intimal area was increased two- to threefold at day 28 (p < 0.05). Although estrogen treatment resulted in a trend toward decreased arterial cell proliferation at day 4, there was evidence of increased cell proliferation in both media and intima at day 7 (p < 0.05). However, there was no effect of estrogen treatment on intimal area or indexes of arterial remodeling in the injured artery at day 28 (p > 0.4). CONCLUSIONS. In contrast to previous studies of nonatherosclerotic animals, the results indicate that in the circumstance of transmural injury to arteries of primates with preexisting atherosclerosis, estrogen does not suppress arterial neointimal or structural responses to injury.

Animals↗
PubMed1998

Wound healing: a paradigm for lumen narrowing after arterial reconstruction.

PURPOSE: The intimal hyperplasia hypothesis that equates lumen narrowing after arterial injury with intimal mass has recently been challenged. Evidence has emerged to suggest that lumen narrowing is caused in large part by changes in artery wall geometry rather than intimal mass per se. We have begun to explore this hypothesis in a unique nonhuman primate model of atherosclerosis. METHODS: Monkeys who were fed an atherogenic diet for 3 to 5 years underwent experimental angioplasty of the left iliac artery. The contralateral iliac artery served as an intraanimal control. Arteries were removed 2, 4, 7, 14, 28, or 112 days later for analysis (6 or 13 per time point). Angioplasty dilated arteries by fracturing atheroma and stretching or tearing the media. Cross-sections of injured arteries were analyzed for expression of extracellular matrix components and cell surface integrins that are important in wound healing. Antibodies, riboprobes, or histochemical stains specific for fibrin, hyaluronan, versican (chondroitin sulfate-containing proteoglycan), procollagen-I, elastin, and the alpha 2 beta 1 and alpha V beta 3 integrins were used. RESULTS: A thin mural thrombus was seen at sites of denudation and plaque fracture (days 2 to 7). This provisional matrix was invaded by leukocytes (days 2 to 4) and alpha-actin-positive smooth muscle cells (SMCs; days 4 to 7). Thrombus was replaced by SMCs expressing hyaluronan and the associated versican proteoglycans (day 14). Versican was expressed throughout the neointima as it enlarged (day 28), but expression later subsided (day 112). Procollagen-I expression initially increased in the adventitia (day 4) and then in the forming neointima (day 14). Procollagen-I expression was found to persist within the adventitia and in the neointima in SMCs nearest the lumen (days 28 to 112). Elastin staining was prominent within the mature neointima (day 112) but not at earlier time points. Integrin expression also increased within the injured artery wall. alpha v beta 3 staining (fibrin[ogen] receptor) increased in the injured media (days 2 to 7) and was then seen throughout the early neointima (day 7). Low level expression of alpha V beta 3 subsequently persisted within the forming neointima (day 28). alpha 2 beta 1 (collagen receptor) expression increased in the neointima in SMCs nearest the lumen (day 28). CONCLUSIONS: Lumen narrowing after angioplasty in this model of atherosclerosis is caused largely by decreased artery wall diameter. The pattern of matrix and integrin expression within the injured artery wall is in many ways analogous to that of healing wounds. These observations suggest that tissue contraction may play a role in lumen narrowing at sites of arterial reconstruction. Strategies to inhibit wound contraction may prove effective in preventing restenosis.

Angioplasty, Balloon↗
PubMed1998

Estrogens, progestins, and coronary artery reactivity in atherosclerotic monkeys.

It has been known for many years that sex hormones modulate vasodilator responses of arteries supplying the uterus with blood. Recently, it has been shown that sex hormones such as estrogen modulate vasomotor responses of other arteries, including coronary arteries. It is thought that modulation of vasodilator and constrictor responses of coronary arteries may be one mechanism by which estrogen affects the risk of coronary heart disease. Although several studies have examined the effects (and potential mechanisms) of estrogen on vasodilator responses of nonatherosclerotic arteries, few have focused on estrogen's effects on atherosclerotic coronary arteries. In studies of ovariectomized atherosclerotic female cynomolgus monkeys, both long-term (2 years) and short-term (20 min) estradiol treatment augments dilator responses to acetylcholine, but not nitroglycerin. Presumably, this indicates an effect of estradiol on endothelium-mediated dilator responses of coronary arteries. Addition of the progestin medroxyprogesterone acetate diminishes the beneficial effect of conjugated equine estrogens on these dilator responses. This is significant because a progestin is usually added to estrogen replacement to reduce the risk of endometrial and breast cancer associated with unopposed estrogen therapy. However, it would seem that not all progestins act similarly on vascular reactivity. Studies in monkeys indicate that addition of progesterone or the progestin medroxyprogesterone acetate does not diminish the beneficial effects of estrogen on coronary dilator responses. Thus it would appear that different estrogen/progestin combinations may affect vascular reactivity in different manners, There is also an effort being made to examine the potential of different kinds of estrogens on cardiovascular risk. Studies in monkeys indicate that one of the estrogens found in conjugated equine estrogens (17 alpha-dihydroequilenin) has estrogen effects on vascular reactivity without having detrimental effects on uterine pathology. The isoflavones "plant estrogens" found in soy protein also have estrogenic effects on vascular reactivity and inhibition.

Acetylcholine↗
PubMed1998

Effects of soy isoflavones on atherosclerosis: potential mechanisms.

It has long been recognized that coronary heart disease rates are lower in Japan, where soy consumption is common, than in Western countries. In experimental studies, atherosclerosis was reduced in animals fed diets containing soy protein compared with those fed diets with animal protein. Recently, several lines of evidence have suggested that the components of soy protein that lower lipid concentrations are extractable by alcohol (eg, the isoflavones genistein and daidzein). We recently evaluated the relative effect of the soy protein versus the alcohol-extractable components of soy on cardiovascular disease and its risk factors. Young male and female cynomolgus monkeys were fed diets that contained either 1) casein-lactalbumin as the source of protein (casein), 2) soy protein isolate from which the isoflavones were alcohol extracted (SPI-), or 3) isoflavone-intact soy protein (SPI+). The SPI+ group had significant improvements in LDL cholesterol and HDL cholesterol. Only HDL cholesterol was significantly improved in the SPI- group males compared with the casein group. The casein group had the most atherosclerosis, the SPI+ group had the least, and the SPI- group was intermediate but did not differ significantly from the casein group. Potential mechanisms by which soy isoflavones might prevent atherosclerosis include a beneficial effect on plasma lipid concentrations, antioxidant effects, antiproliferative and antimigratory effects on smooth muscle cells, effects on thrombus formation, and maintenance of normal vascular reactivity.

Animals↗
PubMed1998

Controlled multiplanar distraction of the mandible: device development and clinical application.

Distraction osteogenesis has been shown to be an effective method of lengthening and augmenting endochondral bone. It has also been applied effectively in the reconstruction of the membranous bones of the craniofacial skeleton. With the accumulation of clinical experience in mandibular distraction, the differences between endochondral and membranous bone distraction have become apparent, especially in the limitations of uniplanar distraction for the three-dimensional reconstruction of the deficient mandible. Distraction of the mandible in a single plane cannot satisfy fully the functional and structural requirements of the patient with malocclusion as well as deficiency of the skeletal and soft tissue. This study reports the development and clinical use of a multiplanar mandibular distraction device with the ability to achieve linear distraction (Z-plane or sagittal), angular distraction (Y-plane or vertical), and transverse distraction (X-plane or coronal). The device contains two independent gear arrangements attached to two arms that extend from the central unit. Therefore, the trajectory of the regenerated bone may be changed during the distraction process. The device also allows manipulation of the various planes of movement independent of each other. Furthermore, the rotational points for the multiplanar distraction devices are located at a single point; therefore only a single osteotomy and two pin sites are required. The multiplanar distraction device allows the surgeon to customize and contour the dimensions of the distraction process by controlling the trajectory of the translation of the regenerated bone.

Child, Preschool↗
PubMed1998

The combination of endoscopy and distraction osteogenesis in the development of a canine midface advancement model.

The requirements for reconstruction in patients with midface hypoplasia can be formidable: a bicoronal scalp incision, Le Fort III or monobloc skeletal advancement, harvesting and insertion of bone grafts, application of rigid (and occasionally intermaxillary) fixation, blood transfusions, and prolonged operative time and hospitalization. The introduction of the endoscope offers the possibility of minimally invasive surgery with improved visualization of the osteotomy sites. The development of distraction osteogenesis as a surgical technique allows controlled and gradual advancement of the osteotomized skeletal segment and associated soft tissue. The purpose of this study was to develop a canine model of an endoscopically assisted Le Fort III osteotomy with attendant midface distraction. Four mongrels (20 kg in weight) were study subjects. Three 2-cm skin incisions were made (two perpendicular to the zygomaticomaxillary suture and one perpendicular to the nasofrontal suture). The soft tissue and periosteum were evaluated bluntly. Retractors specially designed for the project created a space for endoscopic visualization. Bilateral zygomatic, nasofrontal, and medial orbital wall osteotomies, corticotomies, or both were performed under endoscopic visualization using a reciprocating saw; the medial orbital wall sectioning was specifically not completed (i.e., corticotomy) to avoid laceration of the mucosa and attendant bleeding. The pterygomaxillary osteotomy was completed with an osteotome and mallet. Finally, the nasal septum was only partially divided with an osteotome to avoid excessive blood loss. Four distraction devices were placed across the above-noted osteotomies (two across the nasofrontal osteotomy and one across each lateral osteotomy). The animals were distracted 1 mm per day for 16 to 40 days after surgery (16-40 mm of linear distraction). Cephalograms and computed tomography scans were obtained before and after distraction. The animals were killed after remaining in fixation for 4 to 6 weeks after distraction. All soft tissue was removed and the skull was examined. Photos were obtained throughout the experiment for documentation. The study demonstrated that Le Fort III osteotomies can be performed successfully via small incisions with endoscopic assistance in canine subjects with excellent visualization and minimal bleeding. The advancement of the midface segment can be achieved by activation of an external distraction device.

Animals↗
PubMed1998

Controlled multiplanar distraction of the mandible, Part II: Laboratory studies of sagittal (anteroposterior) and vertical (superoinferior) movements.

The application of distraction osteogenesis in craniofacial surgery has significantly altered the treatment of congenital mandibular deficiencies. However, evaluation of results in both animal studies and clinical cases has revealed deficiencies, particularly in two areas. First, distraction using a uniplanar device in an anteroposterior direction can result in a persistent anterior open bite. Second, the lateralization of the distracted hemimandible was often limited, with insufficient incremental gain in the bigonial distance. To overcome these shortcomings, a multiplanar distraction device was developed and tested in the canine model. This report details canine studies addressing the first problem: combined anteroposterior or sagittal (z-axis) and superoinferior or vertical (y-axis) movements. Six dogs underwent bilateral mandibular distraction with an external (extraoral), multiplanar device and completed sagittal plus vertical distraction. Evaluation included clinical examination (facial form, jaw position, and occlusion), photography, cephalograms (posteroanterior, basilar, and lateral), three-dimensional computed tomography reconstructions, and examination of dry skulls. The dogs averaged 18.5 mm (range, 15-20 mm) of sagittal distraction and 41.0 degrees (range, 21-50 degrees) of vertical distraction. Marked anterior open bites were produced after vertical distraction secondary to premature contact of the maxillary and mandibular molars. Distraction in the vertical direction also had the additive effect of increasing the sagittal gains by approximately 5% to 10%. In conclusion, a multiplanar distraction device (with the potential for distraction in three planes) was effective in increasing mandibular anteroposterior thrust (sagittal distraction) and also in creating an anterior open bite (vertical or superoinferior distraction). Vertical distraction probably requires bilateral osteotomies to obtain optimal results. The preliminary gains in sagittal length are modified (reduced or increased) after distraction in a second plane (vertical and horizontal). Specifically, vertical distraction in the inferior direction (creating an open bite) also leads to isolated increases in the anteroposterior plane. Conversely, vertical distraction in the superior direction (closing an open bite), as seen in a human malocclusion, may lead to isolated decreases in the anteroposterior plane, but this question remains to be investigated in the laboratory.

Animals↗
PubMed1998

Genetics and community health nursing.

Genetic discoveries affect the practice of community health nurses. These nurses identify groups at risk for genetic diseases and participate in newborn screening, carrier detection testing, and presymptomatic genetic testing programs. Community health nurses also provide direct nursing care to individuals with genetic disorders. Protecting clients from harmful use of genetic information, planning and implementing genetic screening programs, and identifying genetic resources are essential components of the community health nurse's role.

Adult↗
PubMed1998

Role of tensor fasciae latae in abdominal wall reconstruction.

The role of the tensor fasciae latae as autogenous tissue in reconstruction of abdominal wall defects is well established. The use of various forms of the tensor fasciae latae (free graft versus pedicled flap versus free flap) is determined by the characteristics of the defect. A review of abdominal wall reconstructions using tensor fasciae latae was completed to determine efficacy and establish guidelines for its use. Abdominal wall reconstructions from 1991 to 1994 using tensor fasciae latae were reviewed. Demographics, wound characteristics, and complications were evaluated. Twenty-seven patients with a mean follow-up of 23.6 months underwent abdominal wall reconstruction with the tensor fasciae latae: free grafts, 12; pedicled flaps, 9; and free flaps, 6. An average defect size of 14.4 x 13.1 cm was seen. Fourteen (52 percent) of the reconstructions were completed in contaminated or infected wounds. One recurrent enteric fistula was seen. Twelve (44 percent) of the patients had flap complications of which 50 percent involved partial flap necrosis. Donor site complications were seen in five patients (18 percent) and included a hematoma, seroma, and two cases of skin graft dehiscence along the edge of the wound. Tensor fasciae latae free grafts are an option for repair of abdominal hernias if abdominal soft tissue is adequate. Pedicled flaps may be used for defects of soft tissue and fascia but are limited by the arc of rotation and size of the defect. Tensor fasciae latae free flaps are versatile in orientation and may be used for supraumbilical defects. Tip necrosis is significant in both types of vascularized flaps.

Abdominal Muscles↗
PubMed1998

Dietary soy isoflavones inhibit in-vivo constrictor responses of coronary arteries to collagen-induced platelet activation.

BACKGROUND: Soy isoflavones (particularly genistein) improve impaired acetylcholine-induced dilator responses of atherosclerotic coronary arteries. Genistein reduces platelet accumulation of serotonin, whose constrictor properties are augmented by dyslipoproteinemia and atherosclerosis. Studies were therefore designed to examine the effects of soy protein (with and without the isoflavones) on platelet-induced constrictor responses of coronary arteries of primates. METHODS: Twelve adult female rhesus monkeys were fed for 6 months an atherogenic diet identical in composition, except that isoflavones were either extracted with alcohol [n = 6, Soy(-)] or left intact (n = 6, Soy(+)]. Vasomotor responses were assessed in vivo using quantitative coronary angiography and intravascular Doppler measurements of blood flow velocity. RESULTS: As shown previously, soy isoflavones improve impaired dilator responses to acetylcholine. Furthermore, in response to activation of platelets by intracoronary infusion of collagen, reductions in blood flow through the left circumflex coronary artery, but not large artery constriction, were less in the Soy(+) (10 +/- 5%) than in the Soy (-) monkeys (35 +/- 6%, P = 0.02). In-vitro platelet aggregation to thrombin and serotonin were less in the Soy(+) than in the Soy(-) monkeys (P < 0.05). However, soy diets did not affect vascular reactivity properties of large artery or resistance size arteries to adenosine diphosphate (ADP), nitroglycerin, or serotonin (P > 0.05). CONCLUSIONS: We conclude that components of the soy protein removed by alcohol extraction (probably the isoflavones) promoted endothelium-modulated dilation and inhibited constrictor responses to collagen infusion by inhibiting platelet aggregation or platelet release of vasoconstrictors, or both.

Animals↗
PubMed1998

Oral contraceptives and hormone replacement therapy do not increase the incidence of arterial thrombosis in a nonhuman primate model.

Older oral contraceptive (OC) formulations containing high doses of potent synthetic estrogens and progestins are associated with increased risk of thrombosis. To examine the effects of current low-dose OC and hormone replacement therapy (HRT) regimens on arterial thrombosis, premenopausal and surgically postmenopausal cynomolgus monkeys were divided into four treatment groups. Premenopausal monkeys were given either no OCs or ethinyl estradiol and levonorgestrel as an OC at a dose equivalent to that currently given to women. Postmenopausal monkeys were given either no HRT or conjugated equine estrogens and medroxyprogesterone as an HRT at a dose equivalent to that currently given to women. The monkeys were fed an atherogenic diet containing these treatments for 27 to 30 months. At the end of this time, arterial thrombosis was evaluated with a standardized stenosis/injury procedure in the left carotid artery. Blood flow velocity was monitored for cyclic or permanent occlusive thrombosis. The current OC and HRT regimens did not increase the susceptibility of the artery wall to develop an occlusive thrombus following injury and stenosis. In fact, there was a reduction in the incidence of thrombosis in the OC animals compared with untreated controls. Increased amounts of atherosclerosis were associated with an increased incidence of occlusive arterial thrombosis. Several selected coagulation parameters [von Willebrand factor, protein C, lipoprotein(a), and platelet aggregation] did not appear to be associated with either the amount of atherosclerosis or incidence of arterial thrombosis.

Animals↗
PubMed1998

Effects of beta3-integrin blockade (c7E3) on the response to angioplasty and intra-arterial stenting in atherosclerotic nonhuman primates.

Because the beta3-antagonist abciximab (c7E3 Fab) has significantly improved late outcomes after coronary angioplasty, the beta3 integrins have been implicated in the arterial response to injury. However, the mechanisms underlying this benefit are unknown. The observation that c7E3 binds beta3 integrins on vascular cells (alphavbeta3) with affinity equal to that for the platelet glycoprotein IIb/IIIa integrin has led to the hypothesis that c7E3 may act directly on the artery wall to prevent restenosis after angioplasty. To test this hypothesis, we studied the effects of c7E3 on structural changes within the artery wall after angioplasty or stent angioplasty in 23 male cynomolgus monkeys with established atherosclerosis. Animals were randomly assigned to receive either a bolus of c7E3 (0.4 mg/kg IV, n=11) followed by a 48-hour infusion (0. 2 microg. kg-1. min-1) or an equal volume of vehicle (n=12). Animals received weight-adjusted aspirin and heparin and then underwent unilateral iliac artery experimental angioplasty and subclavian artery stent angioplasty (Palmaz). Iliac artery lumen diameter (LD) was determined by angiography at baseline (LDPre), after angioplasty (LDPost), and 35 days later (LDDay35). Arteries were then fixed by perfusion and removed for analysis. Lumen, intima, media, and external elastic lamina (EEL) areas were measured in iliac artery cross sections. Values from each injured iliac artery were normalized to the contralateral uninjured iliac artery to control for interanimal variability in baseline artery size and atherosclerosis extent. Intimal area was also measured in subclavian stent cross sections. c7E3 blocked platelet aggregation and prolonged the bleeding time from 2.8+/-1.1 to 19.8+/-2.5 minutes, P<0.001. Experimental angioplasty increased LDPost an average of 28%, and the initial gain was similar in both groups (P=NS). Despite an anti-platelet effect, c7E3 did not inhibit iliac lumen narrowing (LDDay35-LDPost: c7E3, -0.69+/-0.17 versus vehicle, -0.99+/-.17 mm, P=0.35); intimal hyperplasia (neointima area: c7E3, 1.12+/-.28 versus vehicle, 1.22+/-.20 mm2, P=0.77); or decrease in artery wall size (EEL area [percent of uninjured control]: c7E3, 101+/-7% versus vehicle, 121+/-7%). Stent intimal hyperplasia was also unaltered by c7E3 treatment (neointimal area: c7E3, 1.09+/-0.16 versus vehicle, 1. 28+/-0.11 mm2, P=0.36). These results suggest that the benefits of c7E3 treatment in coronary angioplasty were not from inhibition of intimal hyperplasia or improved artery wall remodeling. Alternative mechanisms should be explored to explain improved late outcomes after angioplasty in patients treated with c7E3.

Abciximab↗
PubMed1998

Insulin sensitivity and cardiovascular risk factors in ovariectomized monkeys with estradiol alone or combined with nomegestrol acetate.

We have previously shown that medroxyprogesterone acetate (MPA), either alone or combined with conjugated equine estrogens (CEE), significantly decreased insulin sensitivity (SI), compared with both untreated controls and those treated with CEE alone. The purpose of this study was to determine the effects of estradiol (E2), with and without nomegestrol acetate (NA; a potent progestin that lacks androgenic activity), on SI and arterial antioxidant activity, as determined by F2-isoprostanes. Thirty-six adult female cynomolgus monkeys (Macaca fascicularis) were ovariectomized and fed a moderately atherogenic diet, with one of the following three treatments added to the diet, for 12 weeks: 1) no treatment (control); 2) E2; or 3) continuous combined E2 + NA (E2+NA). SI and glucose effectiveness were assessed by the frequently sampled i.v. glucose tolerance test using a third-phase insulin infusion after 10 weeks of treatment. Cholesterol content and F2-isoprostanes were measured in the thoracic aorta after 12 weeks of treatment. E2 treatment resulted in a significantly greater SI, compared with control or E2+NA-treated monkeys (10.03 +/- 0.91 vs. 6.35 and 6.49 x 10(-4) min(-1) microU(-1) mL; P < 0.05). In contrast to our studies of CEE and MPA, E2+NA treatment, though reducing the SI below that of the E2 group, did not reduce the SI below that of control monkeys. As expected, the short period of treatment resulted in no significant differences in aortic cholesterol content. There was no treatment effect on total F2-isoprostanes (representing F2-isoprostane formation caused primarily by autooxidation), suggesting minimal antioxidant activity. However, there was a treatment difference in the prostaglandin F2alpha (PGF2alpha) isomer (a prostaglandin (PG) isomer formed by both autooxidation of arachidonate and cyclooxygenase activity). PGF2alpha concentrations were 32% lower with E2 treatment, compared with controls, and 36% lower, compared with E2+NA treatment (0.48 +/- 0.08 vs. 0.71 +/- 0.12 and 0.75 +/- 0.06; P < 0.05), suggesting differences in PG synthesis between hormone treatments. In conclusion, NA, a progestin without androgenic activity, may still affect some cardiovascular risk factors differently than estrogen-only therapy. However, it seems to be less detrimental than MPA.

Administration, Oral↗
PubMed1998

The potential of soybean phytoestrogens for postmenopausal hormone replacement therapy.

Hormone replacement therapy for postmenopausal women greatly reduces their risk of coronary heart disease. However, current pharmaceutical regimens have a low acceptance rate among postmenopausal women. We have sought to identify an alternative treatment that would retain the beneficial health effects of current standard therapy without its negative aspects. We have concentrated our research on naturally occurring estrogens (called phytoestrogens) found in soybeans, in the belief that delivery of phytoestrogens via the diet would be more acceptable than pharmaceutical regimens. Using a well-established nonhuman primate model of postmenopausal women, we have investigated the effects of soy phytoestrogens on cardiovascular risk factors and the reproductive system. In this review, we summarize the results of our ongoing research.

Animals↗
PubMed1997

Contrasting effects of conjugated estrogens and tamoxifen on dilator responses of atherosclerotic epicardial coronary arteries in nonhuman primates.

BACKGROUND: Estrogens have been shown to improve dilator responses of atherosclerotic coronary arteries. Tamoxifen is a mixed estrogen agonist/antagonist with as yet unexplored effects on vascular function. Therefore, the goal of this study was to compare the effects of conjugated equine estrogens (CEEs) with those of tamoxifen on epicardial coronary artery dilator responses in atherosclerotic, ovariectomized monkeys. METHODS AND RESULTS: Fifty ovariectomized cynomolgus monkeys were fed an atherogenic diet for 34 months. During this time, monkeys were assigned to one of three treatment groups: (1) control, no hormone replacement (n=15); (2) CEEs mixed in the diet at a dose of 0.043 mg x kg(-1) x d(-1) (n=14); or (3) tamoxifen mixed in the diet at a dose of 1.3 mg x kg(-1) x d(-1) (n=21). Quantitative angiography was used to measure coronary artery dilator responses to intracoronary infusions of acetylcholine (10(-8), 10(-7), and 10(-6) mol/L) and nitroglycerin (15 microg/min). Coronary arteries of the tamoxifen-treated group constricted in response to high-dose acetylcholine (-5.4+/-2.3%, P<.05 versus control), whereas those of the CEE group did not (P>.05 versus control). Conversely, arteries from the CEE group dilated in response to nitroglycerin (9.1+/-2.1%, P<.05 versus control), whereas those from the tamoxifen group did not (P>.05 versus control). Statistical adjustments for variations in plaque extent (determined subsequently after necropsy) and plasma lipoproteins did not alter the results. CONCLUSIONS: Tamoxifen has primarily estrogen-antagonistic effects on epicardial coronary artery dilator responses in atherosclerotic monkeys. Results implicate the estrogen receptor as a modulator of coronary artery dilator responses in ovariectomized, atherosclerotic monkeys.

Acetylcholine↗