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Biomedical subjects

E A Lucas

Publications and source records attributed to E A Lucas.

At least 19 recordsLinked to original sources
PubMed2006

Dried plum prevents bone loss in a male osteoporosis model via IGF-I and the RANK pathway.

Previously, dietary supplementation with dried plums, a rich source of polyphenolic compounds with antioxidant and anti-inflammatory properties, has been shown to improve bone density, microstructure and biomechanics in female animal models of osteopenia. We designed this study to determine the extent to which dried plum prevents skeletal deterioration in gonadal hormone deficient male animals and to begin to understand its mechanism of action. Sixty 6-month-old male Sprague-Dawley rats were either sham-operated (Sham = 1 group) or orchidectomized (ORX = 4 groups) and randomly assigned to dietary treatments: standard semi-purified diet (Control) with either LD = 5%, MD = 15%, or HD = 25% (w/w) dried plum for 90 days. At the end of the treatment period, both the MD and HD dried plum completely prevented the ORX-induced decrease in whole body, femur, and lumbar vertebra bone mineral density (BMD). Biomechanical testing indicated that the MD and HD of dried plum prevented the ORX-induced decrease in ultimate load of the cortical bone as well as the compressive force and stiffness of trabecular bone within the vertebrae. Analyses of trabecular microarchitecture of the distal femur metaphysis and vertebral body revealed that HD dried plum protected against the decrease in trabecular bone volume (BV/TV) induced by ORX. In the distal femur, all doses of dried plum improved trabecular number (TbN) and separation (TbSp) compared to the ORX-control group, while MD and HD dried plum prevented the ORX-induced changes in vertebral TbN and TbSp. At the end of the 90-day treatment, no remarkable changes in serum osteocalcin or alkaline phosphatase in any of the treatment groups were observed, while serum insulin-like growth factor (IGF)-I was increased by dried plum. The ORX-induced increase in urinary deoxypyridinoline (DPD) excretion was completely prevented by all doses of dried plum coinciding with down-regulation of gene expression for receptor activator of NFkappa-B ligand (RANKL) and osteoprotegerin (OPG) in the bone. We conclude that dried plum prevents osteopenia in androgen deficient male rats, and these beneficial effects may be attributed in part to a decrease in osteoclastogenesis via down-regulation of RANKL and stimulation of bone formation mediated by IGF-I.

Animals↗
PubMed2006

Soy affects trabecular microarchitecture and favorably alters select bone-specific gene expressions in a male rat model of osteoporosis.

We have recently reported that soy isoflavones particularly when provided in the context of soy protein are capable of preventing loss of bone mineral density due to orchidectomy in F344 rats. We hypothesize, that soy isoflavones also exert beneficial effects on bone microstructural properties, in part, by enhancing bone formation. Therefore, in the present study, we examined the dose-dependent effects of soy isoflavones on femoral bone microarchitectural properties and select bone-specific gene expressions in the same rat model. Seventy-two, 13-month old rats were either orchidectomized (ORX; 5 groups) or sham-operated (Sham; 1 group) and immediately placed on dietary treatments for 180 days. Four of the ORX groups were fed either casein- or soy protein-based diets each with one of two doses of isoflavones either 600 or 1200 mg/kg diet. Rats in the remaining ORX control and Sham groups were fed a control casein-based diet. Soy protein at the high isoflavone dose, and to a lesser extent with the lower dose, reduced the magnitude of the ORX-induced decreases in trabecular bone volume (BV/TV) and trabecular number (Th.N) and increase in trabecular separation (Tb.Sp) at the femoral neck site. These modulations of trabecular microstructural properties by isoflavones may be due to increased mRNA levels of alkaline phosphatase (ALP), collagen type I (COL), and osteocalcin (OC), which are associated with enhanced bone formation. These findings confirm our earlier observations that the modest bone protective effects of soy isoflavones are due to increased rate of bone formation.

Alkaline Phosphatase↗
PubMed2005

Systemic bone loss and induction of coronary vessel disease in a rat model of chronic inflammation.

Clinically, osteopenia or low bone mass has been observed in a variety of chronic inflammatory diseases, and elevated proinflammatory mediators have implicated this process. The purpose of this study was to develop an in vivo model of bone loss induced by chronic systemic inflammation. Time-release pellets designed to deliver one of three doses of LPS: Low (3.3 microg/day), High (33.3 microg/day), or Placebo over 90 days, were implanted subcutaneously in 3-month-old male Sprague-Dawley rats (n = 8/group). Neutrophil counts, indicative of ongoing inflammation, were elevated (P < 0.05) in both LPS groups at 30 days post-implant and remained significantly elevated in the High dose throughout the 90-day study period. At the end of the study, bone loss occurred in the femur as indicated by decreased bone mineral density (BMD) in both LPS-treated groups, but vertebral BMD was reduced in the High dose animals only. Microcomputed tomography revealed that trabecular bone volume (BV/TV) of the proximal tibial metaphysis tended to be reduced in the High dose LPS group. Deleterious effects on trabecular number (TbN) and trabecular separation (TbSp) were observed in both LPS-treated groups, but only the High dose group reached statistical significance. These alterations in trabecular microarchitecture resulted in compromised biomechanical properties. No changes in cortical thickness, porosity, or area of the tibia midshaft were evident at either dose of LPS. Up-regulation of the proinflammatory mediators, cyclooxygenase (COX)-2, interleukin (IL)-1, and tumor necrosis factor (TNF)-alpha was demonstrated in the metaphyseal region where the deleterious effects of LPS were observed. In addition to these alterations in bone, trichrome staining indicated changes in the coronary arterioles, consistent with vascular disease. Utilization of a LPS time-release pellet appears to provide an in vivo model of chronic inflammation-induced bone loss and a potentially novel system to study concurrent development of osteopenia and vascular disease.

Absorptiometry, Photon↗
PubMed2004

Soy isoflavones may protect against orchidectomy-induced bone loss in aged male rats.

Evidence from several studies suggests that soy protein and/or its isoflavones may have beneficial effects on bone in postmenopausal women and animal models who have osteoporosis. The present study examined the dose-dependent effects of soy isoflavones in the context of soy protein or casein on the male skeleton. Thirteen-month-old male Fisher 344 rats were orchidectomized (ORX; 5 groups) or sham-operated (Sham; 1 group) and immediately placed on dietary treatments for 180 days. Diets were semi-purified and the protein source was either casein (Sham and ORX; controls), casein with two added doses of isoflavones (Iso1; 600 mg/kg diet and Iso2; 1200 mg/kg diet), soy protein with normal isoflavones content (Soy; 600 mg/kg diet), or soy protein with added isoflavones (Soy+; 1200 mg/kg diet). A 7% loss of whole body bone mineral density (BMD) was observed due to orchidectomy; however, the ORX induced BMD loss was significantly reduced to 4.3 and 4.7 % with the Soy and Soy+, respectively. Both doses of isoflavones in conjunction with casein also reduced the loss of whole body BMD, albeit not significantly different from ORX control animals. Trabecular bone histomorphometric analysis of the proximal tibia further supported the bone-sparing role of soy isoflavones as indicated by higher percent bone volume and trabecular number, and lower trabecular separation. We conclude that isoflavones exert modest beneficial effects on the male skeleton whether provided with casein or a soy protein.

Aging↗
PubMed2004

Vitamin E provides protection for bone in mature hindlimb unloaded male rats.

The deleterious effects of skeletal unloading on bone mass and strength may, in part, result from increased production of oxygen-derived free radicals and proinflammatory cytokines. This study was designed to evaluate the ability of vitamin E (alpha-tocopherol), a free-radical scavenger with antiinflammatory properties, to protect against bone loss caused by skeletal unloading in mature male Sprague-Dawley rats. A 2 x 3 factorial design was used with either hindlimb unloading (HU) or normal loading (ambulatory; AMB), and low-dose (LD; 15 IU/kg diet), adequate-dose (AD; 75 IU/kg diet), or high-dose (HD; 500 IU/kg diet) vitamin E (DL-alpha-tocopherol acetate). To optimize the effects of vitamin E on bone, dietary treatments were initiated 9 weeks prior to unloading and continued during the 4-week unloading period, at which time animals were euthanized and blood and tissue samples were collected. Serum vitamin E was dose-dependently increased, confirming the vitamin E status of animals. The HD treatment improved oxidation parameters, as indicated by elevated serum ferric-reducing ability and a trend toward reducing tissue lipid peroxidation. Histomorphometric analysis of the distal femur revealed significant reductions in trabecular thickness (TbTh), double-labeled surface (dLS/BS), and rate of bone formation to bone volume (BFR/BV) due by HU. AMB animals on the HD diet and HU animals on the LD diet had reduced bone surface normalized to tissue volume (BS/TV) and trabecular number (TbN); however, the HD vitamin E protected against these changes in the HU animals. Our findings suggest that vitamin E supplementation provides modest bone protective effects during skeletal unloading.

Animals↗
PubMed2004

Soy protein may alleviate osteoarthritis symptoms.

Alternative and complementary therapeutic approaches, such as the use of a wide array of herbal, nutritional, and physical manipulations, are becoming popular for relieving symptoms of osteoarthritis (OA). The present study evaluated the efficacy of soy protein (SP) supplementation in relieving the pain and discomfort associated with OA. One hundred and thirty-five free-living individuals (64 men and 71 women) with diagnosed OA or with self-reported chronic knee joint pain not attributed to injury or rheumatoid arthritis were recruited for this double-blind, placebo-controlled, parallel design study. Study participants were assigned randomly to consume 40 g of either supplemental SP or milk-based protein (MP) daily for 3 months. Pain, knee range of motion, and overall physical activity were evaluated prior to the start of treatment and monthly thereafter. Serum levels of glycoprotein 39 (YKL-40), a marker of cartilage degradation, and insulin-like growth factor-I (IGF-I), a growth factor associated with cartilage synthesis, were assessed at baseline and at the end of the study. Overall, SP improved OA-associated symptoms such as range of motion and several factors associated with pain and quality of life in comparison to MP. However, these beneficial effects were mainly due to the effect of SP in men rather than women. Biochemical markers of cartilage metabolism further support the efficacy of SP in men as indicated by a significant increase in serum level of IGF-I and a significant decrease in serum level of YKL-40 compared to MP. This study is the first to provide evidence of possible beneficial effects of SP in the management of OA. Examining and verifying the long-term effects of SP on improving symptoms of OA, particularly in men, is warranted.

Adult↗
PubMed2004

Soy isoflavones prevent the ovarian hormone deficiency-associated rise in leukocytes in rats.

Recent reports indicate that ovariectomy (ovx) increases lymphopoiesis. Ipriflavone, a synthetic isoflavone, has been reported to reduce lymphocytes in postmenopausal women. The aim of this study was to investigate whether naturally occurring isoflavones also affect lymphopoiesis in ovarian hormone deficiency. The present study was carried out using an ovariectomized (ovx) rat model. To mimic early menopause, forty-eight 12-month-old Sprague-Dawley rats were either sham-operated (sham; 1 group) or ovx (3 groups) and were fed a standard semi-purified diet for 120 days. Thereafter, the ovx groups received one of the three doses of isoflavones: 0 (ovx), 500 (ISO500), or 1000 (ISO1000) mg/kg diet for 100 days. Ovariectomy increased total leukocyte counts significantly (p < 0.05) as a result of increased (p < 0.05) lymphocyte, monocyte, eosinophil, and basophil differential counts. Isoflavones at 500 and 1000 mg/kg diet returned the total leukocyte counts, as well as leukocyte subpopulations, to levels comparable to that of sham-operated rats. No other hematological parameters, e.g., red blood cell counts or red cell indices, were affected by ovariectomy or isoflavones. We conclude that soy isoflavones restore normal leukocyte counts elevated in ovarian hormone deficiency.

Animals↗
PubMed2001

Ethanol-extracted soy protein isolate does not modulate serum cholesterol in golden Syrian hamsters: a model of postmenopausal hypercholesterolemia.

Soy protein consumption has been linked to reduction in hypercholesterolemia, a risk for coronary heart disease. However, to what extent soy protein itself or its non-nutritive components, e.g., isoflavones and saponins, exert this cholesterol-lowering effect requires further investigation. To evaluate the effect of the protein component alone on lipid variables, ethanol-extracted, isoflavone-depleted soy protein isolate (SPe) was studied in ovarian hormone-deficient hamsters. Forty-eight 6-month-old female Golden Syrian hamsters were either sham-operated or ovariectomized and fed casein-based or SPe-based diets for 70 d. Ovariectomy, but not protein source, significantly (P < 0.05) increased serum phospholipids and total, non-high density lipoprotein, free and esterified cholesterol concentrations. Serum HDL cholesterol concentrations were not altered with either treatment. No significant differences were observed in liver total lipids or liver total cholesterol among the groups. Soy protein isolate, however, lowered serum triglyceride concentrations in both sham-operated and ovariectomized hamsters. These findings confirm the ovariectomized hamster as a model of postmenopausal hypercholesterolemia. The results are consistent with earlier observations that isoflavones or other nonprotein components, perhaps in combination with soy protein, play an important role in exerting this hypocholesterolemic effect. Further studies are needed to investigate whether isolated nonprotein components of soy would be able to prevent the ovarian hormone deficiency-associated rise in serum cholesterol regardless of dietary protein source.

Animals↗
PubMed2001

The energetic costs of diving in Aedes aegypti and Aedes albopictus pupae.

Undisturbed mosquito pupae rest at the water surface and respond to passing shadows or vibrations by diving. Pupae do not feed and rely solely on energy stored from the larval stage. The ability of a newly emerged adult mosquito to survive, and therefore to transmit disease, depends on these energy reserves. Earlier studies of diving behavior in Aedes aegypti, Ae. albopictus, and Ae. triseriatus pupae provided evidence that pupae sense their state of buoyancy and modify their diving behavior accordingly. With strong stimulation pupae tend to dive to a depth where they become neutrally or negatively buoyant and commonly rest on the bottom. This behavior, as well as the tendency to rest when not disturbed, may logically be viewed as energy-conserving. The results of these studies also generated the hypothesis that the diving behavior displayed by these container-breeding mosquitoes helps them avoid being washed from their container by overflowing water during rainfall. Rainfall stimulates diving and logically, prolonged, heavy rainfall stimulates excessive diving, a likely drain on energy reserves. Our objectives were to determine, in Ae. aegypti and Ae. albopictus, the energetic costs associated with resting behavior, with frequent diving, and with buoyancy reduction. Using survival rate, mean survival after adult emergence, and measurement of total calories, we found a clear energetic cost associated with frequent diving. In contrast, relative to diving, essentially no energy cost was associated with buoyancy reduction, that is, pupae behave in response to variations in buoyancy in a way that does not impact significantly on energy reserves.

Aedes↗
PubMed2000

Prune suppresses ovariectomy-induced hypercholesterolemia in rats.

Elevated cholesterol among women who have experienced natural or surgical menopause has been linked to ovarian hormone deficiency. The purpose of this study was to investigate the efficacy of prune, a good source of dietary fiber and phytochemicals, on lowering cholesterol in an ovariectomized (ovx) rat model. Forty-eight 90-day-old female Sprague-Dawley rats were randomly assigned to four groups: sham-operated (sham) + control diet, ovx + control diet, ovx + low-dose (LD; 5%) prune, and ovx + high-dose (HD; 25%) prune. After 45 days of treatment, rats were euthanized and tissues were collected for analyses. Ovariectomy elevated serum total cholesterol by 22% compared with sham, and HD prune diet prevented this increase without affecting high density lipoprotein cholesterol concentrations. Animals fed the HD prune diet had 13% lower liver total lipids compared with ovx animals. The findings of this study showed that prune exhibits hypocholesterolemic properties in ovarian hormone deficiency. Dose-response studies should be conducted to establish the effectiveness of prune in prevention of hypercholesterolemia in postmenopausal women who are not on estrogen replacement therapy and seek dietary alternatives. Mechanistic studies also are needed to establish its mode of action.

Journal Article↗
PubMed1999

Buoyancy and diving behavior in mosquito pupae.

Mosquito pupal diving behavior has been studied mostly in Aedes aegypti and in this species pupal buoyancy varies relative to several factors. The research reported herein addresses the 2 following questions. Does diving behavior vary among different mosquito genera and species? How is diving behavior influenced by variation in buoyancy? Depth and duration of dive, and dive pattern, were compared among Ae. aegypti, Culex pipiens, Anopheles stephensi, Aedes albopictus, and Aedes triseriatus. In response to the stimulation associated with transferring pupae between containers, diving behavior varied dramatically among the different genera studied. Culex pipiens and An. stephensi make short-duration, shallow dives and remain positively buoyant. The 3 aedine species studied make longer-duration dives, typically to a depth at which they become neutrally or negatively buoyant. Buoyancy reduction effects were studied in the 3 aedine species. Normally buoyant pupae tend to dive to greater depths and for longer periods of time than reduced-buoyancy pupae. Aedine pupal diving behavior clearly is closely regulated relative to buoyancy variation. To the earlier hypotheses that pupal behavior may help avoid predation and be energy-conserving, we add the suggestion that the diving behavior displayed by the container-breeding aedine pupae we studied represents an adaptation that helps keep them from being washed from their container habitat by overflowing water during rainfall. We also suggest that the diving behavior of all the species studied may help pupae survive heavy, pelting rainfall by enabling them to avoid the mechanical shock of a direct hit by a raindrop, which could cause disruption of the gas in the ventral air space, thereby causing the loss of hydrostatic balance and drowning.

Aedes↗
PubMed1998

A sleep laboratory evaluation of an automatic positive airway pressure system for treatment of obstructive sleep apnea.

STUDY OBJECTIVES: This paper compares the performance of an experimental nasal positive airway pressure device that automatically adjusts the level of applied pressure (APAP) with the performance of a conventional continuous positive airway pressure (CPAP) in a sleep laboratory study. DESIGN: In a randomized sequence, conventional CPAP therapy was applied for 1 night (CPAP night) and APAP therapy the following night (APAP night). SETTING: The study was conducted in an accredited sleep disorders center. PATIENTS OR PARTICIPANTS: Twenty-six men and 5 women between the ages of 35 to 73 (51 +/- 9.6) years with body mass index 35.82 +/- 8.35 (kg/m2) who were diagnosed (using standard nocturnal polysomnography [NPSG] methods) as having OSA syndrome were studied. The subjects were treated with conventional CPAP for approximately 8 (7.79 +/- 3.16) weeks at home prior to their participation in this study. MEASUREMENTS AND RESULTS: All standard polysomnography data and nasal mask pressures were recorded using a computer-based data acquisition system. Sleep and respiratory data were scored by a registered polysomnographer. The mean apnea-hypopnea index (AHI) for subjects for the NPSG night was 55.2 +/- 33.7. It dropped to 4.2 +/- 3.8 for the CPAP night and to 5.4 +/- 5.4 for the APAP night. There was no significant (p = 0.05) difference between mean AHI indices, sleep stages, sleep stage shifts, and snore arousals for CPAP night and APAP night. However, all the measures showed significant (p = 0.05) improvement over NPSG night. The mean of APAP applied pressure (8.4 +/- 3.3 cm H2O) was significantly (p = 0.05) lower than the prescribed pressure (11.5 +/- 3.1 cm H2O), but there was no significant (p = 0.05) difference between the maximum APAP applied pressure (12.8 +/- 4.3 cm H2O) and the prescribed pressure (11.5 +/- 3.1 cm H2O). All mean comparison tests were carried out using two-tailed statistics. CONCLUSIONS: APAP appears to be as effective as CPAP in treating OSA patients. APAP delivers the same level of therapy as CPAP, but it reduces the average airway pressure while providing needed peak pressures.

Adult↗
PubMed1997

Pharyngeal wall vibration detection using an artificial neural network.

An artificial-neural-network-based detector of pharyngeal wall vibration (PWV) is presented. PWV signals the imminent occurrence of obstructive sleep apnoea (OSA) in adults who suffer from OSA syndrome. Automated detection of PWV is very important in enhancing continuous positive airway pressure (CPAP) therapy by allowing automatic adjustment of the applied airway pressure by a procedure called automatic positive airway pressure (APAP) therapy. A network with 15 inputs, one output, and two hidden layers, each with two Adaline-nodes, is used as part of a PWV detection scheme. The network is initially trained using nasal mask pressure data from five positively diagnosed OSA patients. The performance of the ANN-based detector is evaluated using data from five different OSA patients. The results show that on the average it correctly detects the presence of PWV events at a rate of approximately 92% and correctly distinguishes normal breaths approximately 98% of the time. Further, the ANN-based detector accuracy is not affected by the pressure level required for therapy.

Adult↗
PubMed1997

A noninvasive technique for detecting obstructive and central sleep apnea.

A new noninvasive method to detect obstructive and central sleep apnea [(OSA) and (CSA)] events is described. Data were collected from ten volunteer subjects with a previous diagnosis of OSA while they were titrated for continuous positive airway pressure (CPAP) therapy. Apneic events were identify by analyzing of estimated airway impedance determined from pressure and airflow signals delivered from CPAP. To enhance performance of this technique, a single-frequency (5 Hz with 0.5 cmH2O peak-to-peak amplitude) probing signal was superimposed on the applied CPAP pressure. The results indicated that estimated airway impedance during OSA (mean: 17.9, SD: 3.4, N = 50) was significantly higher then during CSA (mean: 4.1, SD: 1.7, N = 50). When the estimated impedance of OSA and CSA events were compared to a fixed threshold, 100% of all events can be correctly categorized. These results indicate that it may be possible to diagnose OSA and CSA noninvasively based upon this technique. The instrument and the algorithm required are relatively simple and can be incorporated in a home-based device. If this method was used for prescreening apnea patients, it could reduce cost, waiting time, and discomfort associated with traditional diagnostic procedures.

Airway Resistance↗
PubMed1995

Automatic control of airway pressure for treatment of obstructive sleep apnea.

Obstructive sleep apnea (OSA) occurs when airflow ceases because of pharyngeal wall collapse in sleep. Repeated apneic events results in the development of a pathological condition called OSA syndrome. We describe the methodology and design of a prosthetic device, named automatic positive airway pressure (APAP), for treatment of this syndrome. APAP applies a stream of air via a nasal mask at an initial pressure selected by the patient. By sensing specific pressure characteristics of air flow immediately preceding pharyngeal wall collapse, the APAP device automatically raises the applied pressure to maintain a patent upper airway and thus prevent apnea. Conversely, when such conditions are absent, pressure is lowered step wise until a preselected minimum pressure is reached. Performance evaluation of the APAP system in five OSA patients and five normal (asymptomatic for sleep apnea) subjects revealed that it effectively treated OSA syndrome. It lowered the apnea-hypopnea index without disturbing sleep and resulted in a lower mean airway pressure compared to the traditional continuous positive airway pressure (CPAP) therapy. The results also show that the pressure needed to prevent OSA varied significantly throughout the night. For OSA syndrome patients, this pressure ranged from 3 to 18 cm H2O. The mean airway pressure for these patients had a sample average of 6.80 cm H2O and a standard deviation of 3.17 cm H2O. In normal subjects, the device did not raise pressure except in response to Pharyngeal Wall Vibration events.

Adult↗
PubMed1994

Determination of enantiomers in ephedrine mixtures by polarimetry.

Enantiomeric purities have been measured with precisions that are equivalent to those obtained from chiral chromatography by a simple ligand substitution reaction into the first coordination sphere of Cu(II)-tartrate complexes. The model systems are binary mixtures of the ephedrines. Ligand exchange reactions are done in bulk aqueous media. The detector is polarimetry. Multivariate regression analyses of optical rotation data measured at five wavelengths are used to prepare calibration and prediction models for binary mixtures of the enantiomers.

Algorithms↗
PubMed1993

Historical comments on chronobiology with emphasis on cell proliferation, the concept of free running, cancer chemotherapy and experimental design.

A brief historical summary is presented regarding the emergence, over the past several decades, of chronobiology as the newest of the integrating discipline of biology. The emphasis is on the circadian system which normally is synchronized to the 24 h environmental light-dark cycle. In the absence of a suitable synchronizer, the system free runs on its own endogenous genetically determined frequency, which usually only approximates 24 h. Since the metabolic system changes rhythmically in time it follows that an organism such as man is biochemically and physiologically a different entity at different circadian stages; therefore it reacts differently to an identical stimulus given at different times. Different stimuli such as anticancer agents are examples considered clearly timed treatment has been shown to significantly improve therapeutic efficacy, data will be presented using the L1210 mouse leukemic model. Moreover data is presented showing that to ignore such rhythmic fluctuation when designing experiments that such can bring about experimental error and false interpretation. The common "same time of day" sampling does not take care of the rhythmic problem!

Adult↗