Detecting Multiple Damages in UHPFRC Beams through Modal Curvature Analysis

Curvature-based damage detection has been previously applied to identify damage in concrete structures, but little attention has been given to the capacity of this method to identify distributed damage in multiple damage zones. This study aims to apply for the first time an enhanced existing method based on modal curvature analysis combined with wavelet transform curvature (WTC) to identify zones and highlight the damage zones of a beam made of ultra-high-performance fiber-reinforced concrete (UHPFRC), a construction material that is emerging worldwide for its outstanding performance and durability. First, three beams with a 2 m span of UHPFRC material were cast, and damaged zones were created by sawing. A reference beam without cracks was also cast. The free vibration responses were measured by 12 accelerometers and calculated by operational modal analysis. Moreover, for the sake of comparison, a finite element model (FEM) was also applied to two identical beams to generate numerical acceleration without noise. Second, the modal curvature was calculated for different modes for both experimental and FEM-simulated acceleration after applying cubic spline interpolation. Finally, two damage identification methods were considered: (i) the damage index (DI), based on averaging the quadratic difference of the local curvature with respect to the reference beam, and (ii) the WTC method, applied to the quadratic difference of the local curvature with respect the reference beam. The results indicate that the developed coupled modal curvature WTC method can better identify the damaged zones of UHPFRC beams.

Inhibition of both sclerostin and DKK1 results in novel skull findings in the rat and non-human primate that is not observed with inhibition of sclerostin alone

Sclerostin is an extracellular inhibitor of canonical Wnt signaling that inhibits bone formation and stimulates bone resorption. Anti-sclerostin antibodies (Scl-Ab) have been developed as bone-building agents. DKK1, another extracellular inhibitor of the pathway, is upregulated in osteocytes in response to sclerostin inhibition. To further enhance bone-forming effects, a bispecific antibody inhibiting both sclerostin and DKK1 was created (AMG 147). In nonclinical safety studies, AMG 147 resulted in novel skull findings. In the rat, there was increased thickness of skull bones of neural crest origin due to increased subperiosteal compact lamellar and intramembranous woven bone. Externally, subperiosteal fibroblastic/osteoblastic stromal cell proliferation with woven bone and hemorrhage was also observed. Scl-Ab alone resulted in increased skull thickness in the rat, like AMG 147, but without the stromal cell proliferation/woven bone formation. In contrast to embryonic flat bone development, intramembranous bone formed similar to plexiform bone. In the monkey, AMG 147 resulted in macroscopic skull thickening due to a diffuse increase in appositional lamellar bone and increased intramembranous bone on both periosteal surfaces of all skull bones. These data demonstrate that dual inhibition of sclerostin and DDK1 results in unique effects on the skull not observed with sclerostin inhibition alone.

Robust Synchronization of Ambient Vibration Time Histories Based on Phase Angle Compensations and Kernel Density Function

The output-only modal analysis is ubiquitously used for structural health monitoring of civil engineering systems. The measurements for such applications require the use of multiple data acquisition systems (DAS) to avoid complicated meshes of cables in high-rise buildings, avoid traffic constriction on a bridge during measurements, or to avoid having limited channels in a single DAS. Nevertheless, such requirements introduce time synchronization problems which potentially lead to erroneous structural dynamic characterization and hence misleading or inconclusive structural health monitoring results. This research aims at proposing a system-identification-based time synchronization algorithm for output-only modal analysis using multiple DAS. A new procedure based on the compensation of the phase angle shifts is proposed to identify and address the time synchronization issue in ambient vibration data measured through multiple DAS. To increase the robustness of the proposed algorithm to the inherent inconsistencies in these datasets, the kernel density function is applied to rank multiple time-shift estimates that are sometimes detected by the algorithm when inaccuracies exist in the data arising from low signal-to-noise ratio and/or presence of colored noise in the ambient excitations. First, the synchronized ambient vibration dataset of a full-scale bridge is artificially de-synchronized and used to present a proof of concept for the proposed algorithm. Next, the algorithm is applied to ambient vibration data of a 30-story, reinforced concrete building, where the synchronization of the data could not be achieved using two DAS despite best efforts. The application of the proposed time synchronization algorithm is shown to both detect and correct the time synchronization discrepancies in the output-only modal analysis.

Laboratory safety evaluation of bedinvetmab, a canine anti-nerve growth factor monoclonal antibody, in dogs

Nerve growth factor (NGF), a critical mediator of nociception, is a novel analgesic therapeutic target. Bedinvetmab, a canine monoclonal antibody (mAb), binds NGF and inhibits its interaction with tropomyosin receptor kinase A (trkA) and p75 neurotrophin receptor (p75^NTR) receptors. The objective of three integrated laboratory studies was to demonstrate the safety of bedinvetmab in adult laboratory Beagle dogs. Daily health, veterinary, clinical pathology, systemic exposure, and anti-drug antibody evaluations were performed. Study 1 additionally included electrocardiography, neurologic, and ophthalmic assessments, and radiographic monitoring of joints of the appendicular skeleton. Study 2 evaluated T-lymphocyte-dependent immune function. Study 3 evaluated the safety of short-term concurrent administration of carprofen, a nonsteroidal anti-inflammatory drug (NSAID), with bedinvetmab. Studies 1 and 3 included terminal pathology and histopathology evaluations. Study designs and procedures included directed complementary morphologic and functional evaluations of a literature- and in vitro-based list of potential safety issues related to the NGF signaling pathway and characteristics engineered into this mAb. Screening-level general procedures evaluated effects associated with mAbs that target and inhibit soluble agonist cytokines. There were no treatment-related adverse changes in clinical evaluations, clinical neurological and ophthalmic examinations, joints, immune morphology or function, and no effects of short-term concurrent NSAID usage. Treatment-emergent immunogenicity was not observed. Bedinvetmab (1 mg/kg SC monthly; 3× and 10× dose multiples) was well tolerated in normal laboratory Beagle dogs for 6 months and with 2 weeks' concurrent NSAID administration.

Studies on articular and general toxicity of orally administered ozenoxacin in juvenile rats and dogs

AIM

Ozenoxacin is a nonfluorinated quinolone antibacterial approved for topical treatment of impetigo. Because quinolones have known chondrotoxic effects in juvenile animals, the potential toxicity of ozenoxacin was assessed in preclinical studies.

MATERIALS & METHODS

Ozenoxacin or ofloxacin (300 mg/kg/day for 5 days, for each compound) was orally administered to juvenile rats, and oral ozenoxacin (10-100 mg/kg/day for 14 days) was administered to juvenile dogs.

RESULTS

In juvenile rats, ozenoxacin showed no chondrotoxicity, whereas ofloxacin produced typical quinolone-induced lesions in articular cartilage in three of ten rats. Oral ozenoxacin administration to juvenile dogs showed no chondrotoxicity or toxicologically relevant findings in selected target organs.

CONCLUSION

Ozenoxacin was generally well-tolerated in juvenile rats and dogs, with no evidence of quinolone-induced arthropathy.

One year of abaloparatide, a selective peptide activator of the PTH1 receptor, increased bone mass and strength in ovariectomized rats

Abaloparatide is a novel 34 amino acid peptide selected to be a potent and selective activator of the parathyroid hormone receptor 1 (PTHR1) signaling pathway. The effects of 12months of abaloparatide treatment on bone mass, bone strength and bone quality was assessed in osteopenic ovariectomized (OVX) rats. SD rats were subjected to OVX or sham surgery at 6months of age and left untreated for 3months to allow OVX-induced bone loss. Eighteen OVX rats were sacrificed after this bone depletion period, and the remaining OVX rats received daily s.c. injections of vehicle (n=18) or abaloparatide at 1, 5 or 25μg/kg/d (n=18/dose level) for 12months. Sham controls (n=18) received vehicle daily. Bone changes were assessed by DXA and pQCT after 0, 3, 6 or 12months of treatment, and destructive biomechanical testing was conducted at month 12 to assess bone strength and bone quality. Abaloparatide dose-dependently increased bone mass at the lumbar spine and at the proximal and diaphyseal regions of the tibia and femur. pQCT revealed that increased cortical bone volume at the tibia was a result of periosteal expansion and endocortical bone apposition. Abaloparatide dose-dependently increased structural strength of L4-L5 vertebral bodies, the femur diaphysis, and the femur neck. Increments in peak load for lumbar spine and the femur diaphysis of abaloparatide-treated rats persisted even after adjusting for treatment-related increments in BMC, and estimated material properties were maintained or increased at the femur diaphysis with abaloparatide. The abaloparatide groups also exhibited significant and positive correlations between bone mass and bone strength at these sites. These data indicate that gains in cortical and trabecular bone mass with abaloparatide are accompanied by and correlated with improvements in bone strength, resulting in maintenance or improvement in bone quality. Thus, this study demonstrated that long-term daily administration of abaloparatide to osteopenic OVX rats led to dose-dependent improvements in bone mass, geometry and strength.

One Year of Abaloparatide, a Selective Activator of the PTH1 Receptor, Increased Bone Formation and Bone Mass in Osteopenic Ovariectomized Rats Without Increasing Bone Resorption

Abaloparatide is a novel 34-amino acid peptide selected to be a potent and selective activator of the parathyroid hormone receptor (PTH1R) signaling pathway with 41% homology to PTH(1-34) and 76% homology to PTHrP(1-34). A 12-month treatment study was conducted in osteopenic ovariectomized (OVX) rats to characterize the mechanisms by which abaloparatide increases bone mass. Sprague-Dawley (SD) rats were subjected to OVX or sham surgery at age 6 months and left untreated for 3 months to allow OVX-induced bone loss. Ten OVX rats were euthanized after this bone depletion period, and the remaining OVX rats received daily subcutaneous injections of vehicle (n = 18) or abaloparatide at 1, 5, or 25 μg/kg/d (n = 18/dose level) for 12 months. Sham controls (n = 18) received vehicle daily. Bone densitometry and biochemical markers of bone formation and resorption were assessed longitudinally, and L₃ vertebra and tibia were collected at necropsy for histomorphometry. Abaloparatide increased biochemical bone formation markers without increasing bone resorption markers or causing hypercalcemia. Abaloparatide increased histomorphometric indices of bone formation on trabecular, endocortical, and periosteal surfaces without increasing osteoclasts or eroded surfaces. Abaloparatide induced substantial increases in trabecular bone volume and density and improvements in trabecular microarchitecture. Abaloparatide stimulated periosteal expansion and endocortical bone apposition at the tibial diaphysis, leading to marked increases in cortical bone volume and density. Whole-body bone mineral density (BMD) remained stable in OVX-Vehicle controls while increasing 25% after 12 months of abaloparatide (25 μg/kg). Histomorphometry and biomarker data suggest that gains in cortical and trabecular bone mass were attributable to selective anabolic effects of abaloparatide, without evidence for stimulated bone resorption. © 2016 American Society for Bone and Mineral Research.

Carcinogenicity risk assessment of romosozumab: A review of scientific weight-of-evidence and findings in a rat lifetime pharmacology study

Romosozumab is a humanized immunoglobulin G₂ monoclonal antibody that binds and blocks the action of sclerostin, a protein secreted by the osteocyte and an extracellular inhibitor of canonical Wnt signaling. Blockade of sclerostin binding to low-density lipoprotein receptor-related proteins 5 and 6 (LRP5 and LRP6) allows Wnt ligands to activate canonical Wnt signaling in bone, increasing bone formation and decreasing bone resorption, making sclerostin an attractive target for osteoporosis therapy. Because romosozumab is a bone-forming agent and an activator of canonical Wnt signaling, questions have arisen regarding a potential carcinogenic risk. Weight-of-evidence factors used in the assessment of human carcinogenic risk of romosozumab included features of canonical Wnt signaling, expression pattern of sclerostin, phenotype of loss-of-function mutations in humans and mice, mode and mechanism of action of romosozumab, and findings from romosozumab chronic toxicity studies in rats and monkeys. Although the weight-of-evidence factors supported that romosozumab would pose a low carcinogenic risk to humans, the carcinogenic potential of romosozumab was assessed in a rat lifetime study. There were no romosozumab-related effects on tumor incidence in rats. The findings of the lifetime study and the weight-of-evidence factors collectively indicate that romosozumab administration would not pose a carcinogenic risk to humans.

Effects of pioglitazone and fenofibrate co-administration on bone biomechanics and histomorphometry in ovariectomized rats

Pioglitazone, the peroxisome proliferator-activated receptor-gamma (PPAR-γ) agonist is an effective therapy for type 2 diabetes, but has been associated with increased risk for bone fracture. Preclinical studies suggest that PPAR-α agonists (e.g., fenofibrate) increase bone mineral density/content, although clinical data on bone effects of fibrates are lacking. We investigated the effects of pioglitazone (10 mg/kg/day) and fenofibrate (25 mg/kg/day) on bone strength and bone histomorphometric parameters in osteopenic ovariectomized (OVX) rats. An additional group of rats received a combination of pioglitazone + fenofibrate to mimic the effects of a dual PPAR-α/γ agonist. The study consisted of a 13-week treatment phase followed by a 6-week treatment-free recovery period. Pioglitazone significantly reduced biomechanical strength at the lumbar spine and femoral neck compared with rats administered fenofibrate. Co-treatment with pioglitazone + fenofibrate had no significant effect on bone strength in comparison with OVX vehicle controls. Histomorphometric analysis of the proximal tibia revealed that pioglitazone suppressed bone formation and increased bone resorption at both cancellous and cortical bone sites relative to OVX vehicle controls. In contrast, fenofibrate did not affect bone resorption and only slightly suppressed bone formation. Discontinuation of pioglitazone treatment, both in the monotherapy and in the combination therapy arms, resulted in restoration of bone formation and resorption rates, demonstrating reversibility of effects. The above data support the concept that dual activation of PPAR-γ and PPAR-α attenuates the negative effects of PPAR-γ agonism on bone strength.

The effects of bazedoxifene in the ovariectomized aged cynomolgus monkey

Bazedoxifene (BZA) is a novel selective estrogen receptor modulator in clinical development for the prevention and treatment of postmenopausal osteoporosis. This preclinical study evaluated the efficacy and safety of BZA in preventing ovariectomy (OVX)-induced bone loss in aged cynomolgus monkeys. Animals (18 per group) underwent OVX and were administered BZA (0.2, 0.5, 1, 5, or 25 mg/kg/day) or vehicle, or were sham-operated and administered vehicle, by daily oral gavage for 18 months. Biochemical markers of bone turnover were assessed at 6, 12, and 18 months, along with bone densitometry using dual energy X-ray absorptiometry and peripheral quantitative computed tomography. Animals were killed after 18 months. Uterine and pituitary weights were determined, and histomorphometric and biomechanical measurements were performed. OVX vehicle controls showed increases in bone turnover associated with cancellous and cortical bone osteopenia (in vivo), and slight decreases (not statistically significant) in biomechanical strength parameters at the lumbar spine and femoral neck. BZA partially preserved cortical and cancellous bone mass by preventing the OVX-induced increases in bone turnover. Although the response was often similar among BZA-treated groups, the strongest efficacy was generally seen at 25 mg/kg/day. Treatment with BZA did not adversely affect measures of bone strength and was well tolerated; there was no evidence of uterotrophic activity, mammary tissue was unaffected, and there were no adverse effects on plasma lipids. Treatment of ovariectomized animals with BZA partially prevented changes in bone remodeling that correlated with increases in bone mineral density, while maintaining bone strength and a favorable safety profile.

Infant cynomolgus monkeys exposed to denosumab in utero exhibit an osteoclast-poor osteopetrotic-like skeletal phenotype at birth and in the early postnatal period

RANKL is a key regulator of bone resorption and osteoclastogenesis. Denosumab is a fully human IgG2 monoclonal antibody that inhibits bone resorption by binding and inhibiting the activity of RANKL. To determine the effects of denosumab on pre- and postnatal skeletal growth and development, subcutaneous injections of 0 (control) or 50 mg/kg/month denosumab were given to pregnant cynomolgus monkeys from approximately gestation day (GD) 20 until parturition (up to 6 doses). For up to 6 months postpartum (birth day [BD] 180/181), evaluation of the infants included skeletal radiographs, bone biomarkers, and oral examinations for assessment of tooth eruption. Infant bones were collected at necropsy for densitometry, biomechanical testing, and histopathologic evaluation from control and denosumab-exposed infants on BD1 (or within 2 weeks of birth) and BD181, and from infants that died or were euthanized moribund from BD5 to BD69. In all denosumab-exposed infants, biomarkers of bone resorption and formation were markedly decreased at BD1 and BD14 and slightly greater at BD91 vs. control, then similar to control values by BD181. Spontaneous long bone fractures were detected clinically or radiographically in 4 denosumab-exposed infants at BD28 and BD60, with evidence of radiographic healing at ≥BD60. In BD1 infants exposed to denosumab in utero, radiographic evaluations of the skeleton revealed decreased long bone length; a generalized increased radio-opacity of the axial and appendicular skeleton and bones at the base of the skull with decreased or absent marrow cavities, widened growth plates, flared/club-shaped metaphysis, altered jaw/skull shape, and reduced jaw length; and delayed development of secondary ossification centers. Densitometric evaluations in these infants demonstrated a marked increase in bone mineral density at trabecular sites, but cortical bone mineral density was decreased. Histologically, long bone cortices were attenuated and there was an absence of osteoclasts. Bones with active endochondral ossification consisted largely of a dense network of retained primary spongiosa with reduced marrow space consistent with an osteopetrotic phenotype. A minimal increase in growth plate thickness largely due to the expansion of the hypertrophic zone was present. Retained woven bone was observed in bones formed by intramembranous ossification, consistent with absence of bone remodeling. These changes in bone tissue composition and geometry were reflected in reduced biomechanical strength and material properties of bones from denosumab-exposed infants. Material property changes were characterized by increased tissue brittleness reflected in reductions in calculated material toughness at the femur diaphysis and lack of correlation between energy and bone mass at the vertebra; these changes were likely the basis for the increased skeletal fragility (fractures). Although tooth eruption was not impaired in denosumab-exposed infants, the reduced growth and increased bone density of the mandible resulted in dental abnormalities consisting of tooth malalignment and dental dysplasia. Radiographic changes at BD1 persisted at BD28, with evidence of resumption of bone resorption and remodeling observed in most infants at BD60 and/or BD90. In 2 infants euthanized on BD60 and BD69, there was histologic and radiographic evidence of subphyseal/metaphyseal bone resorption accompanied by multiple foci of ossification in growth plates that were markedly increased in thickness. In infants necropsied at BD181, where systemic exposure to denosumab had been below limits of quantitation for approximately 3months, there was largely full recovery from all bone-related changes observed earlier postpartum, including tissue brittleness. Persistent changes included dental dysplasia, decreased bone length, reduced cortical thickness, and decreased peak load and ultimate strength at the femur diaphysis. In conclusion, the skeletal and secondary dental effects observed in infant monkeys exposed in utero to denosumab are consistent with the anticipated pharmacological activity of denosumab as a monoclonal antibody against RANKL and inhibitor of osteoclastogenesis. The resulting inhibition of resorption impaired both bone modeling and remodeling during skeletal development and growth. The skeletal phenotype of these infant monkeys resembles human infants with osteoclast-poor osteopetrosis due to inactivating mutations of RANK or RANKL.

Lasting alterations of the sodium current by short-term hyperlipidemia as a mechanism for initiation of cardiac remodeling

Clinical and animal studies indicate that increased fatty acid delivery to lean tissues induces cardiac electrical remodeling and alterations of cellular calcium homeostasis. Since this may represent a mechanism initiating cardiac dysfunction during establishment of insulin resistance and diabetes or anaerobic cardiac metabolism (ischemia), we sought to determine if short-term exposure to high plasma concentration of fatty acid in vivo was sufficient to alter the cardiac sodium current ( INa) in dog ventricular myocytes. Our results show that delivery of triglycerides and nonesterified fatty acids by infusion of Intralipid + heparin (IH) for 8 h increased the amplitude of INa by 43% and shifted its activation threshold by −5 mV, closer to the resting membrane potential. Steady-state inactivation (availability) of the channels was reduced by IH with no changes in recovery from inactivation. As a consequence, INa “window” current, a strong determinant of intracellular Na+ and Ca2+ concentrations, was significantly increased. The results indicate that increased circulating fatty acids alter INa gating in manners consistent with an increased cardiac excitability and augmentation of intracellular calcium. Moreover, these changes could still be measured after the dogs were left to recover for 12 h after IH perfusion, suggesting lasting changes in INa. Our results indicate that fatty acids rapidly induce cardiac remodeling and suggest that this process may be involved in the development of cardiac dysfunctions associated to insulin resistance and diabetes.

Eldecalcitol, a vitamin D analog, reduces bone turnover and increases trabecular and cortical bone mass, density, and strength in ovariectomized cynomolgus monkeys

Vitamin D insufficiency is common in elderly people worldwide, and intake of supplementary calcium and vitamin D is recommended to those with a high risk of fracture. Several clinical studies and meta-analyses have shown that calcium and vitamin D supplementation reduces osteoporotic fractures, and a strong correlation exists between vitamin D status and fracture risk. Vitamin D supplementations improve calcium balance in the body; however, it remains unclear whether vitamin D directly affects bone metabolism. Recently, eldecalcitol (ELD), an active form of vitamin D analog, has been approved for the treatment of osteoporosis in Japan. A 3-year clinical trial showed ELD treatment increased lumbar spine bone mineral density (BMD) and reduced fracture risk in patients with osteoporosis. To evaluate the mechanism of ELD action in bone remodeling, ovariectomized cynomolgus monkeys were treated with 0.1 or 0.3μg/day of ELD for 6months. This treatment increased lumbar BMD by 4.4% and 10.2%, respectively, and suppressed ovariectomy-induced increases in bone turnover markers compared to OVX-vehicle control. Histomorphometric analysis of bone revealed that both bone formation parameters and bone resorption parameters in the trabecular bone of the lumbar vertebrae were suppressed by ELD treatment. ELD treatment also improved biomechanical properties of the lumbar vertebrae and the femoral neck in the ovariectomized cynomolgus monkeys. These results indicate that, in a bone-remodeling animal model, ELD increases BMD and improves bone biomechanical properties by normalizing bone turnover. Therefore, ELD has a direct and potentially beneficial effect on bone metabolism.

Proliferative and nonproliferative lesions of the rat and mouse mammary, Zymbal's, preputial, and clitoral glands

The mammary gland of laboratory rodents is an important organ for the evaluation of effects of xenobiotics, especially those that perturb hormonal homeostasis or are potentially carcinogenic. Mammary gland cancer is a leading cause of human mortality and morbidity worldwide and is a subject of major research efforts utilizing rodent models. Zymbal's, preputial, and clitoral glands are standard tissues that are evaluated in animal models that enable human risk assessment of xenobiotics. A widely accepted and utilized international harmonization of nomenclature for mammary, Zymbal's, preputial, and clitoral gland lesions in laboratory animals will improve diagnostic alignment among regulatory and scientific research organizations and enrich international exchanges of information among toxicologists and pathologists.

Proliferative and non-proliferative lesions of the rat and mouse soft tissue, skeletal muscle and mesothelium

The INHAND Project (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP), and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying lesions observed in the soft tissues including skeletal muscle as well as the mesothelium of rats and mice. The standardized nomenclature of lesions presented in this document is also available electronically on the Internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous developmental and aging lesions as well as those induced by exposure to test materials. A widely accepted and utilized international harmonization of nomenclature for lesions in soft tissues, skeletal muscle and mesothelium in laboratory animals will decrease confusion among regulatory and scientific research organizations in different countries and provide a common language to increase and enrich international exchanges of information among toxicologists and pathologists. (DOI: 10.1293/tox.26.1S; J Toxicol Pathol 2013; 26: 1S-26S).

Rat-specific decreases in platelet count caused by a humanized monoclonal antibody against sclerostin

LY2541546 is a humanized monoclonal antibody (IgG(4)) that has been optimized for neutralizing activity against sclerostin. In 5-week and 6-month nonclinical safety studies in rats, LY2541546 caused dose-dependent reversible decreases in platelet counts accompanied by accelerated platelet production, increased megakaryocytes, and altered megakaryocyte morphology. These treatment-related effects resulted in altered primary hemostasis as manifested by prolonged bleeding after phlebotomy or incidental toenail break. In some cases, the defects in hemostasis were sufficient to result in death of the affected rats. There was no evidence in rats of general bone marrow suppression or processes (e.g., disseminated intravascular coagulopathy) that may result in thrombocytopenia. Cynomolgus monkeys given LY2541546 for 5 weeks or 9 months had no changes in platelet count or megakaryocytes. In vitro cross-reactivity studies in rats, cynomolgus monkeys, and humans revealed LY2541546-bound rat but not cynomolgus monkey or human platelets and megakaryocytes. These data taken together demonstrated that the platelet and megakaryocyte effects in rats had a species-specific pathogenesis which likely involved LY2541546 binding of a rat-specific antigen on the surface of platelets and megakaryocytes resulting in the increased clearance of platelets and megakaryocyte hyperplasia. The species-specific nature of these reversible toxicological findings combined with the ease of clinical monitoring using standard hematology enabled the safe initiation of clinical studies in human volunteers.

Skeletal effects of bazedoxifene paired with conjugated estrogens in ovariectomized rats

A novel approach to menopausal therapy is the tissue selective estrogen complex (TSEC) that partners bazedoxifene (BZA) with conjugated estrogens (CE). We examined the effects of daily treatment with BZA 0.3mg/kg, CE 2.5mg/kg, or combined BZA/CE (BZA 0.1, 0.3, or 1.0mg/kg with CE 2.5mg/kg) over 12months on bone mass, bone architecture and strength, and biochemical markers of bone turnover in ovariectomized (OVX) female Sprague-Dawley rats vs OVX control rats. Total cholesterol and uterine weights were also evaluated. All BZA/CE dose combinations prevented ovariectomy-induced increases in bone turnover and significantly increased bone mineral density (BMD) at the lumbar spine, proximal femur, and tibia compared with OVX controls. All BZA/CE doses evaluated also prevented many of the ovariectomy-induced changes of the static and dynamic parameters of the cortical compartment of the tibia and the cancellous compartment of the L1 and L2 vertebrae. All BZA/CE doses increased biomechanical strength at the lumbar spine (L4) compared with OVX animals. The co-administration of BZA 0.3 and 1.0mg/kg/day with CE 2.5mg/kg/day showed a dose-dependent reduction in uterine wet weight compared with administration of CE alone. All BZA/CE doses significantly lowered total cholesterol levels compared with OVX controls. In conclusion, 12months of treatment with BZA/CE in OVX rats effectively maintained BMD, bone microstructure, and bone quality; and the pairing of BZA with CE prevented CE-induced uterine stimulation.

Potential of Skin Fibroblasts for Application to Anterior Cruciate Ligament Tissue Engineering

Fibroblasts isolated from skin and from anterior cruciate ligament (ACL) secrete type I and type III collagens in vivo and in vitro. However, it is much easier and practical to obtain a small skin biopsy than an ACL sample to isolate fibroblasts for tissue engineering applications. Various tissue engineering strategies have been proposed for torn ACL replacement. We report here the results of the implantation of bioengineered ACLs (bACLs), reconstructed in vitro using a type I collagen scaffold, anchored with two porous bone plugs to allow bone–ligament–bone surgical engraftment. The bACLs were seeded with autologous living dermal fibroblasts, and grafted for 6 months in goat knee joints. Histological and ultrastructural observations ex vivo demonstrated a highly organized ligamentous structure, rich in type I collagen fibers and cells. Grafts' vascularization and innervation were observed in all bACLs that were entirely reconstructed in vitro. Organized Sharpey's fibers and fibrocartilage, including chondrocytes, were present at the osseous insertion sites of the grafts. They showed remodeling and matrix synthesis postimplantation. Our tissue engineering approach may eventually provide a new solution to replace torn ACL in humans.

Instilled or injected purified natural capsaicin has no adverse effects on rat hindlimb sensory-motor behavior or osteotomy repair

BACKGROUND

A novel formulation of > or = 98% pure capsaicin (4975) is currently undergoing clinical investigation using novel routes of delivery to provide selective analgesia lasting weeks to months with a single dose. We conducted this study to assess the safety and effects of instilled and injected 4975 in rat models of wound healing osteotomy repair and sensory-motor nerve function.

METHODS

Adult male and female Sprague-Dawley rats were used. To assess the effects of 4975 on nerve or muscle, 0.0083 or 0.025 mg 4975 or vehicle (25% polyethylene glycol-300) was applied to exposed sciatic nerve, or 0.1 mg 4975 or vehicle was injected into the surrounding muscle (Group 1). To assess the effect of 4975 on bone healing, an osteotomy was made in one femur and 0.5 mg of 4975 or vehicle was instilled into the site (Group 2). Behavioral testing was performed on both groups of rats and histological evaluation of the sciatic nerve, and surrounding soft tissue and bone was done at days 3, 14, and 28 after surgery. Femurs from osteotomy rats were assessed using peripheral quantitative computed tomography and biomechanical testing. Standard statistical tests were used to compare groups.

RESULTS

Rats with direct application of 4975 to the sciatic nerve and surrounding muscle were no different from the controls in nociceptive sensory responses (F = 0.910, P = 0.454), grip strength (F = 0.550, P = 0.654), or histology of the muscle or sciatic nerve. In osteotomy rats, there were no statistical differences between 4975 and vehicle-treated rats for bone area (H = 2.858, P = 0.414), bone mineral content (F = 0.945, P = 0.425), or bone mineral density (F = 0.87, P = 0.462) and no difference in soft tissue healing. There were neither differences in bone stiffness (F = 1.369, P = 0.268) nor were there noticeable differences in the macro- or microscopic appearance of the right femur osteotomy healing site and surrounding soft tissues between the control group and the 4975-treated animals.

CONCLUSION

A single, clinically relevant application of instilled or injected 4975 has no observable adverse effect on wound and bone healing after osteotomy or on the structural integrity of exposed muscle and nerve.

Neurotoxic Effects of Zoniporide: A Selective Inhibitor of the Na+/H+ Exchanger Isoform 1

Zoniporide, an inhibitor of the Na+-H+ exchanger-1, was administered by continuous intravenous infusion to rats and dogs for up to 1 month. In 1-month studies, histological and functional changes were observed in select portions of the peripheral nervous system; however, these findings were not detected in 2-week studies at similar or higher doses. In the 1-month rat study, there was dose-dependent, minimal, focal, or multifocal nerve fiber (axonal) degeneration in the spinal cord and/or sciatic nerve. In a follow-up rat study, findings included slowing of caudal nerve conduction velocity and axonal degeneration in the spinal cord (dorsal funiculus), dorsal roots, dorsal root ganglia (DRG), radial, sciatic, and tibial nerves. In the 1-month dog study, there was impairment of the patellar reflex and associated postural reaction changes, minimal to marked proximal nerve fiber degeneration in the DRG, and minimal nerve fiber degeneration in the dorsal roots and funiculi of the spinal cord. Minimal nerve fiber degeneration of equivocal significance was noted in various peripheral nerves. Taken together, these findings were consistent with a specific effect on peripheral sensory nerve fibers. These studies demonstrated that zoniporide produces clinical, electrophysiologic, and microscopic evidence of peripheral sensory axonopathy and establishes the importance of careful preclinical evaluation of neurological function.

The utility of measuring C-terminal telopeptides of collagen type II (CTX-II) in serum and synovial fluid samples for estimation of articular cartilage status in experimental models of destructive joint diseases

OBJECTIVE

To characterize and validate a novel, enzyme-linked immunoassay for measuring cross-linked dimer forms of C-terminal telopeptides of type II collagen (CTX-II) in serum and synovial fluid of rodents, and investigate whether CTX-II measurements can reflect joint status in two established animal models of destructive joint diseases.

METHODS

Firstly, the specificity, in vivo validity, antigen recovery, and reproducibility of the assay were investigated. Secondly, we induced arthritis in rats using either bovine collagen type II or mono-iodoacetate. CTX-II levels were measured in the serum and synovial fluid of the affected femoro-tibial joint and correlated with microscopic severity of joint lesions as determined by validated scoring systems.

RESULTS

The F4601 monoclonal antibody (mAb) is highly specific for the EKGPDP sequence at the CTX-II. Strong CTX-II signals were detected during enzymatic degradation of articular cartilage explants by matrix metalloproteinase (MMP)-9 or MMP-13. The assay presented a good degree of precision and reproducibility (inter- and intra-assay CVs< 8.0%). In the collagen-induced arthritis (CIA) model, the assay indicated markedly increased levels of CTX-II in both the synovial fluid and the serum. Furthermore, CTX-II levels in both the synovial fluid (r = 0.76; P < 0.0001) and the serum (r = 0.85; P < 0.0001) showed strong correlations with the microscopic severity scores of joint lesions at Day 22. In the mono-iodoacetate-induced arthritis (MIA) model, CTX-II concentration in the synovial fluid (r = 0.53; P < 0.0001), but not in the serum, correlated with the microscopic severity score.

CONCLUSIONS

The Preclinical CTX-II assay could provide a useful supplement to currently available methods for the non-invasive assessment of cartilage status. The utility of serum CTX-II to reflect joint status appeared to be limited to systemic forms of destructive joint diseases.

Early elevation in circulating levels of C-telopeptides of type II collagen predicts structural damage in articular cartilage in the rodent model of collagen-induced arthritis

OBJECTIVE

To investigate changes in the circulating levels of the C-telopeptide of type II collagen (CTX-II) with relation to disease onset and structural damage of cartilage in a rodent model of collagen-induced arthritis (CIA), and to investigate immunolocalization of the CTX-II epitope in the articular cartilage of affected joints.

METHODS

Seven-week-old female Lewis rats were immunized with type II collagen and monitored using blood sampling at weekly intervals. At study termination (day 23), the animals were killed, synovial fluid was collected, and the affected joints were scored macroscopically for disease severity and underwent immunohistochemical evaluation.

RESULTS

At the time of disease onset (day 15), which was characterized by redness and swelling of the affected joints (mean +/- SD macroscopic severity score 9.1 +/- 1.6), there was a 355% increase in serum CTX-II levels. The early change in serum CTX-II from day 0 to day 15 showed a significant association with the severity of cartilage damage (r = 0.61, P < 0.01). Immunostaining revealed extensive presence of the CTX-II epitope in the damaged, uncalcified cartilage tissue.

CONCLUSION

The elevation in serum CTX-II concomitant with the onset of disease and proportional to cartilage damage demonstrates that CTX-II is a sensitive diagnostic tool for monitoring joint disease in the rodent model of CIA. Furthermore, the immunohistochemical findings are consistent with the concept that the major source of serum CTX-II is the damaged articular cartilage.

NFATc3 deficiency may contribute to the development of mammary gland adenocarcinoma in aging female mice

The nuclear transcription factor of activated T cells (NFAT) suggested to be a tumor suppressor. Here we report that two out of three NFATc3-/- and two in four NFATc3 +/- female mice developed aggressive mammary adenocarcinoma by 12.5 and 16 mo of age, respectively, with no occurrences in age-matched wild-type littermates (N-14). Thus, our data suggest that NFATc3 can suppress the development of mammary gland tumors in female mice.

Effect of oral glucosamine on cartilage degradation in a rabbit model of osteoarthritis

OBJECTIVE

To determine whether oral glucosamine alleviates cartilage degradation in an animal model of osteoarthritis (OA).

METHODS

The effect of 8 weeks of daily oral glucosamine hydrochloride on degeneration of articular cartilage was evaluated in rabbits in which anterior cruciate ligament transection (ACLT) was performed to induce OA. Animals were treated with glucosamine (n = 16) or a placebo (n = 16) and necropsied at 11 weeks. Seven unoperated rabbits served as controls. The articular cartilage was evaluated macroscopically and histologically and analyzed for total type II collagen and glycosaminoglycan (GAG) content.

RESULTS

Histologic analysis revealed that loss of proteoglycan, based on Safranin O-fast green staining, was significantly reduced in the lateral tibial plateau cartilage of ACL-transected limbs in the glucosamine group compared with ACL-transected limbs in the placebo group, with a similar, but not significant, trend for the lateral femoral condylar cartilage. Likewise, macroscopic analysis of cartilage showed that the lateral tibial plateau alone had a significantly lower rate of disease in the glucosamine group, which was consistent with the results of the independent histologic assessment. However, no significant treatment effect was detected when composite histologic scores were analyzed. A significant reduction in GAG content was observed in the femoral condyles of placebo-treated ACL-transected joints, but not in the same region of glucosamine-treated ACL-transected joints, compared with their respective contralateral unoperated joints.

CONCLUSION

Oral administration of glucosamine had a detectable, site-specific, partial disease-modifying effect in this model of OA. From a clinical perspective, the administration of glucosamine did not prevent fibrillation and/or erosions of the articular cartilage in all of the treated animals, and no effects were detected in the medial joint compartments.

Prevention and treatment of experimental osteomyelitis in dogs with ciprofloxacin-loaded crosslinked high amylose starch implants

Crosslinked high amylose starch (CLHAS) matrix was used as a biodegradable drug delivery implant for the prevention and treatment of osteomyelitis. Thirty-two dogs underwent the femoral insertion of a screw inoculated with Staphylococcus aureus and were then randomly assigned to four groups: (A) prevention with ciprofloxacin-CLHAS implants, (B) surgical debridement (positive control), (C) surgical debridement and oral ciprofloxacin treatment and (D) surgical debridement and treatment with ciprofloxacin-CLHAS implants. At week 4 the osteomyelitis was confirmed, the infected site debrided and respective treatments initiated for groups B, C and D. Radiographs, macroscopic evaluations, bacterial cultures and histopathological examinations were used to evaluate the femora at week 10. Femora from preventive group A were almost normal. Dogs of both ciprofloxacin treatment groups C and D showed better bone healing, less periosteal reaction and less screw mobility than dogs from group B. Eradication of infection was observed at proximal/distal sites in B: 25%/12%, C: 37%/62% and D: 62%/75%. Both ciprofloxacin treated groups improved radiographically from week 4 to week 10. Periosteal and marrow neutrophilic and lymphoplasmocytic infiltrations were less severe in groups C and D versus group B. These data suggest that biodegradable ciprofloxacin-CLHAS implants are a safe and efficient modality for the prevention and treatment of osteomyelitis.

Characterization of the inflammatory infiltrate in canine chronic hepatitis

Canine chronic hepatitis (CCH) is a progressive inflammatory disease of unknown etiology. To characterize the inflammatory infiltrate, 16 dogs with CCH were selected and classified into three groups based on the stage of fibrosis, as evaluated with Masson's trichrome stain. The inflammatory infiltrate in each liver section was immunohistochemically characterized and evaluated using CD3, lysozyme, lamba and kappa light chain, and alpha-smooth muscle actin antibodies. Numerous breeds were affected, and middle-aged females predominated in this select group. Necroinflammatory activity progressively increased and then waned as the hepatitis progressed to cirrhosis. CD3+ lymphocytes were the most numerous lymphoid cells in dogs with CCH. Degenerate hepatocytes were occasionally surrounded by CD3+ lymphocytes. Necrosis was positively correlated with the number of CD3+ lymphocytes. The lamba and kappa light chain-positive cell infiltrate was variable but generally mild. A positive correlation between the lambda and kappa light chain-positive cells and the portal alpha-smooth muscle actin was found. The number of alpha-smooth muscle actin-positive cells (myofibroblasts) in portal triads and fibrous septa was positively correlated with the stage of fibrosis. In contrast, no correlation was found between the number of lysozyme-positive cells (Kupffer cells) and the stage of fibrosis. These results further support the idea of an immune-mediated process in CCH and suggest that periductular myofibroblasts play an important role in canine liver fibrogenesis.

Occurrence and effect of PACAP in the human fetal adrenal gland

In the study reported in this paper, we characterized PACAP in the human fetal adrenal gland and we investigated the effect of PACAP on steroid secretion from cultured fetal adrenal cells. The adrenal gland from 20-week-old fetuses contained substantial concentrations of PACAP-immunoreactive material (88.6 ng/g wet tissue). HPLC analysis of adrenal extracts revealed the presence of both PACAP27 and PACAP38, the latter being the predominant form. Incubation of cultured fetal adrenal cells with PACAP38 (10(-7) M) significantly increased cortisol and DHEAS secretion. Administration of the beta-adrenoreceptor agonist isoproterenol mimicked the stimulatory effect of PACAP on both steroid secretion whereas preincubation of fetal cells with the beta-adrenoreceptor antagonist propranolol suppressed the steroidogenic effect of PACAP. These data, together with the observation that PACAP receptors are exclusively located on chromaffin cells, suggest that, in the fetal human adrenal gland, the effect of PACAP on steroid secretion is mediated via the local release of catecholamines.

Etiology, forms, and prognosis of gastrointestinal dysfunction resembling vagal indigestion occurring after surgical correction of right abomasal displacement

The objectives of this study were to determine the etiology and types of vagal indigestion (VI) occurring after right displacement of the abomasum or abomasal volvulus (RDA/AV), and the prognosis for each type. Data of cows presented for RDA/AV from a retrospective (n = 288) and a prospective (n = 132) study were used. Vagal indigestion occurred in 39 and 22 cows in each study, respectively. A necropsy was performed in 29 cases. Gastric compartment dilation compatible with VI type III or IV occurred in 23 cases. An abnormal gastric wall was detected in 22 cases. Peritonitis was present in 18 cows. Vagal nerve lesions were present in 5 out of 13 cases studied. Clinical, hematological, and necropsy results suggested a classification of VI with respect to presence or absence of peritonitis. Gastric wall damage, peritonitis and vagal nerve lesions appear important in the etiology. Considering peritonitis occurrence, antimicrobial therapy appears necessary in the treatment of RDA/AV.

Characterization of an ACTH-induced chloride current in rat adrenal zona glomerulosa cells

Adrenocorticotropic hormone (ACTH) is one of the principal activator of aldosterone secretion in rat zona glomerulosa cells, but its action on chloride currents is not well established. Here, we demonstrate that the hormone provoked a transient increase in a chloride current with a small unitary conductance estimated at 3.35 pS. Amplitude, as well as time-dependent increase of the ACTH-induced chloride current was independent of the intracellular cAMP concentration. In contrary, its decrease was sensitive to alkaline phosphatase and PKA-inhibitor H-89, indicating that protein phosphorylation, at least in part via PKA, is involved in the decline of the current.

Vasopressin regulates adrenal functions by acting through different vasopressin receptor subtypes

In mammals, vasopressin is known to be synthesized in the hypothalamus and released in the blood stream at the pituitary level. This neuropeptide is also synthesized and secreted by the adrenal medulla in many species including human. Moreover, agents like acetylcholine and corticotropin releasing factor stimulates its basal secretion. V1a vasopressin receptors are present in the adrenal cortex and are involved in steroids secretion (aldosterone in the zona glomerulosa and glucocorticoids in the zona fasciculata of some species). These receptors are coupled to phospholipase C beta and to dihydropyridine-sensitive calcium channels via heterotrimeric G proteins differing by their sensitivities to pertussis toxin. The adrenal medulla, from many species, exhibits V1a vasopressin receptors. In rat adrenal medulla, functional V1b vasopressin receptors could also be characterized. These receptors stimulate catecholamines secretion via activation of phospholipase C beta and subsequent mobilization of intracellular calcium. The adrenal medulla secretes AVP and exhibits functional vasopressin receptors. The adrenal cortex also possesses functional vasopressin receptors and is in contact with adrenal medulla via "medullary rays". We may thus reasonably conclude that AVP physiologically regulates adrenal gland functions via autocrine/paracrine mechanisms.

Isolation of Actinobacillus suis from a cat's lung

Actinobacillus suis has been isolated from the lungs of 9-month-old cat. The bacterium was characterized biochemically as well as genetically, and its sensitivity profile to different antimicrobial agents was established. The role of this isolate in the cat's condition is discussed.

Use of polymerase chain reaction and immunohistochemistry for detection of canine adenovirus type 1 in formalin-fixed, paraffin-embedded liver of dogs with chronic hepatitis or cirrhosis

To assess the possible involvement of canine adenovirus type 1 (CAV-1) in naturally occurring cases of canine chronic liver disease, a polymerase chain reaction (PCR)-based assay was developed to detect a conserved region of the major core protein gene (pVII) of CAV-1 in formalin-fixed, paraffin-embedded liver sections. Results were compared with a standard avidin-biotin immunoperoxidase complex technique that detected CAV-1 antigens using a commercial monoclonal anti-adenovirus antibody. Seventeen cases of cirrhosis and 28 cases of chronic hepatitis with piecemeal necrosis and progressive fibrosis were selected for the study. Formalin-fixed, paraffin-embedded liver sections of 2 cases of infectious canine hepatitis (ICH) and crude DNA extract from CAV-1 (ATCC VR 293 Utrecht strain) served as positive controls. A 411-base-pair viral region was amplified and sequenced as CAV-1 pVII in both cases of infectious canine hepatitis and in the CAV-1 crude DNA extract. The 2 ICH cases were positive for CAV-1 antigens by the immunoperoxidase method. CAV-1 DNA or antigens were not detected by either technique in any of the 45 cases of chronic liver disease selected for the study. These results indicate that both PCR and immunohistochemistry are reliable and rapid techniques for detecting CAV-1 in formalin-fixed, paraffin-embedded liver sections of dogs with ICH. Several possibilities may explain the negative results obtained with both techniques in this study, including the noninvolvement of CAV-1 in canine chronic hepatitis and cirrhosis and the possibility that the virus causes initial damage, provokes a self-perpetuating chronic liver disease, and disappears.

Involvement of tyrosine phosphorylation and MAPK activation in the mechanism of action of ACTH, angiotensin II and vasopressin

ACTH, Angiotensin II (Ang II) and Vasopressin (AVP) are among the well known regulators of aldosterone secretion and also have a trophic action on the adrenal gland. According to classic studies, Ang II and AVP activate phospholipase C (PLC), diacylglycerol (DAG) and inositol phosphate (InsPs) production whereas ACTH activates cAMP production. However, our data indicate that the three peptides are able to induce a time-dependent increase in the level of Tyr-phosphorylation of several proteins. Western Blot analysis indicates a biphasic activation of Tyr-phosphorylation by AVP, with a peak at 30 s and a second one at 15 min incubation. Ang II induced a rapid (2 min) and sustained activation of Tyr-phosphorylation, while ACTH induced a progressive time course with a plateau reached at 15 min. Ang II and AVP also increased phosphorylation of p42mapk and p44mapk, while ACTH did not affect MAPK activity. Moreover, pre-incubation of the cells with genistein (Tyr-kinase inhibitor) and PD 098059 (a MAPK inhibitor) did not affect InsPs production or aldosterone secretion induced by Ang II or AVP. These results suggest that the MAPK pathway is involved in the control of cell growth rather than aldosterone secretion.

Vasopressin : a potent autocrine/paracrine regulator of mammal adrenal functions

The control of adrenal functions by locally secreted neuropeptides or neurotransmitters is of great physiological importance. Vasopressin (VP) is one of these autocrine/paracrine regulators. We demonstrated by RT-PCR and perifusion experiments that rat and human adrenal medulla expressed and released vasopressin under basal conditions and under stimulation by acetylcholine. Intra-adrenal concentrations of VP may be sufficient to activate adrenal VP receptors. In the cortex, only the V1a receptor subtype has been detected. It triggered both steroid secretion and cortical growth. In the medulla, both V1a and V1b receptor subtypes were expressed. V1b receptors were mainly present on chromaffin cells and stimulated catecholamine secretion. The role of the V1a receptor remains unclear. Pathophysiological studies also revealed that human pheochromocytoma did not overexpress vasopressin receptors but might oversecrete vasopressin causing high plasma VP concentrations and elevated blood pressure.

Role of Ca2+ in the action of adrenocorticotropin in cultured human adrenal glomerulosa cells

The present report details the role of Ca2+ in the early events of ACTH action in human adrenal glomerulosa cells. Threshold stimulations of both aldosterone and cAMP production were obtained with a concentration of 10 pM ACTH, an ED50 of 0.1 nM, and maximal aldosterone stimulation (5.5-fold increase over control) at 10 nM ACTH. ACTH also induced a sustained increase of intracellular calcium ([Ca2+]i) with maximal stimulation of 1.6 +/- 0.1-fold over control values. This increase does not involve mobilization of calcium from intracellular pools since no response was observed in Ca2+-free medium or in the presence of nifedipine, suggesting the involvement of Ca2+ influx by L-type Ca2+ channels. This was confirmed by patch clamp studies that demonstrated that ACTH stimulates L-type Ca2+ channels. Moreover, the Ca2+ ion is not required for ACTH binding to its receptor, but is essential for sustained cAMP production and aldosterone secretion after ACTH stimulation. These results indicate that, in human adrenal glomerulosa cells, a positive feedback loop between adenylyl cyclase-protein kinase A-Ca2+ channels ensures a slow but sustained [Ca2+]i increase that is responsible for sustained cAMP production and aldosterone secretion.

Dual effects of fluoroaluminate on activation of calcium influx and inhibition of agonist-induced calcium mobilization in rat glomerulosa cells

Results presented in this study demonstrate that, in rat glomerulosa cells, fluoroaluminate (AlF4-) alone stimulates both cAMP accumulation (maximal stimulation 10-fold, ED50, 24 mM) and total inositol phosphate accumulation (maximal stimulation 12-fold, ED50 14 mM). Despite a transient accumulation of Ins(1,4,5)P3 after AlF4- stimulation, no rapid and transient intracellular calcium mobilization was observed. In contrast to angiotensin II (Ang II) or vasopressin (AVP), AlF4- induces only a slow and sustained increase in intracellular Ca2+. We demonstrate that this increase results from a Ca2+ influx mediated by cAMP-protein kinase A (PKA) pathway since preincubation with H-89, a potent PKA inhibitor, inhibits this influx. Moreover, a short preincubation (15 min at 37 degrees C) of cells with AlF4- or ACTH prevents the initial release of Ca2+ from intracellular stores induced by Ang II, but does not affect the amount of InsPs accumulated under Ang II stimulation. This rapid inhibition of Ang II action is mediated by ACTH- or AlF4(-)-stimulated cAMP production since pretreatment with H-89 leads to a complete reversal. cAMP most likely acts at the level of Ins(1,4,5)P3 receptors since an increase in intracellular cAMP blunts the calcium response induced by addition of exogenous Ins(1,4,5)P3 to permeabilized cells. These results point out that, in rat glomerulosa cells, activation of the cAMP pathway can induce a rapid desensitization of the phospholipase C pathway by acting downstream of inositol phosphate accumulation.

Vasopressin stimulates steroid secretion in human adrenal glands: comparison with angiotensin-II effect

Autoradiographic experiments using iodinated vasopressin analog revealed the presence of specific vasopressin-binding sites in the human adrenal cortex (zona glomerulosa and zona fasciculata). These receptors exhibited a good affinity for arginine vasopressin (3.3 nM), with classical V1a pharmacology and densities of 65 and 135 fmol/mg protein-enriched membranes from zona glomerulosa and fasciculata, respectively. Vasopressin receptors present in both glomerulosa and fasciculata cell-enriched primary cultures were coupled to phospholipase C (ED50, 0.9 and 1.8 nM; maximal stimulation, 4.3- and 5.8-fold, respectively). Vasopressin also stimulated an increase in intracellular calcium through at least two distinct mechanisms: the mobilization of intracellular pools via vasopressin-stimulated inositol phosphate accumulation and the activation of calcium influx. In glomerulosa cell-enriched primary cultures, vasopressin increased aldosterone secretion (ED50, 0.4 nM; maximal stimulation, 2.5-fold) and was found to be as potent as angiotensin-II in stimulating aldosterone secretion, phosphoinositide turnover, and calcium mobilization. In fasciculata cells, vasopressin and angiotensin-II were also able to stimulate cortisol secretion and inositol phosphate accumulation. Moreover, perifusion experiments demonstrated that vasopressin was released from the adrenal medulla. Together, these results indicate that vasopressin can be considered a potent paracrine modulator of adrenal steroid secretion in man.

A model for studying regulation of aldosterone secretion: freshly isolated cells or cultured cells?

Practically all studies relating to zona glomerulosa function have been performed either with freshly isolated cells or with cells used after 2 or 3 days in culture. This study compares the step-by-step response (binding, second messenger production and aldosterone response) of isolated glomerulosa cells vs cells maintained in primary culture to the main stimuli of aldosterone secretion. One day in culture induces a decrease of 77 and 65% in the basal level of corticosterone and aldosterone secretions, compared to that observed in freshly isolated cells. In these conditions, the cells become more sensitive to most of their stimuli, but not all: e.g. important differences are noted in the dose-response of aldosterone secretion to adrenocorticotropin (ACTH), which is often shifted to a lower concentration sensitivity in cultured cells. For example, 0.1 nM ACTH stimulates steroid secretion by three-fold in isolated cells while 1 pM ACTH already induces a 25 and nine-fold increase, respectively, in corticosterone and aldosterone output in cultured cells. Moreover, some stimuli such as isoproterenol do not have any effect in isolated cells but do stimulate steroid secretion in cultured cells. In contrast, other stimuli, such as serotonin or DA (via DA2 receptors) act preferentially in freshly isolated cells. The main observation derived from this study is that glomerulosa cells, under appropriate conditions, are able to respond to their main secretagogues even after 4 days in culture. At this time, glomerulosa cells maintain their ultrastructural characteristics and functional properties and, aside from a few exceptions, demonstrate higher sensitivity to their known stimuli.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms involved in the interaction of dopamine with angiotensin II on aldosterone secretion in isolated and cultured rat adrenal glomerulosa cells

In a previous study, we have shown that freshly isolated glomerulosa cells possess dopamine (DA) receptors from both DA-1 and DA-2 subclasses, whereas in cultured conditions, cells exhibit dopamine receptors from the DA-1 subclass only. In the present work, we have studied the effect of DA on angiotensin-stimulated glomerulosa cells in these two experimental conditions. Our results demonstrate that in isolated cells, angiotensin II (AT) stimulates inositol phosphate accumulation, calcium influx and steroid secretion. Treatment with pertussis toxin completely blocks AT-stimulated steroid secretion and calcium influx and partially reduces inositol phosphate accumulation. DA alone has no effect on cAMP accumulation. However, in the presence of a specific DA-1 antagonist (SCH 23390), DA reduces intracellular cAMP content. Similarly, DA-like pertussis toxin produces the same inhibitory effects on AT-stimulated cells. The combined influence of DA and pertussis toxin is not additive suggesting that a 'Gi' GTP-binding protein is involved in the DA action. Specific DA antagonists indicate that these inhibitory processes are mediated through the DA-2 receptor subtype. DA may act by decreasing the intracellular calcium concentration since it reduces AT-stimulated Ca2+ influx and that both phospholipase C (PLC) and steroid accumulation are calcium dependent. Yet a direct inhibitory coupling between the DA-2 receptor and PLC may represent a second alternative since DA inhibitory effects are always present when calcium influx is artificially increased or decreased. In cultured cells, we observe an additive effect of DA and AT on aldosterone secretion, which is the result of additive interactions of the second messengers involved, namely cAMP for dopamine and inositol phosphates for angiotensin II. From these studies, we conclude that DA may exert a more versatile effect on aldosterone secretion than previously suspected.

Involvement of protein kinase C in the coupling between the V1 vasopressin receptor and phospholipase C in rat glomerulosa cells: effects on aldosterone secretion

We have previously shown that arginine vasopressin (AVP) possesses specific binding sites on rat adrenal glomerulosa cells and stimulates phosphoinositide breakdown and accumulation of inositol phosphates (IP) and diacylglycerol. Kinetic experiments also revealed that the production of IP declines rapidly under hormonal stimulation, even in the presence of Ca2+ in the external medium. In the present investigation, we studied the effects of a protein kinase C (PKC) activator phorbol ester (PDBu) on AVP-sensitive accumulation of IP. Experiments were conducted on glomerulosa cells cultured for 3 days. Results show that short term preincubation (5-10 min) with PDBu inhibits AVP-stimulated IP accumulation by 50% (ED50 = 2.6 +/- 0.9 nM). PKC most likely acts on the coupling between AVP receptor and the G-protein since PDBu reduces AVP-sensitive phospholipase C but does not alter either NaF-sensitive phospholipase C, AVP binding, or inositol lipid pools. However, after a 1- or 2-h preincubation with AVP or PDBu, a decrease in both IP accumulation and AVP binding capacity is observed. With regard to aldosterone secretion, PDBu alone stimulates hormone output, but when added simultaneously with AVP, it inhibits AVP-stimulated aldosterone secretion by 70%. If cells are allowed a resting period of 14 h after AVP or PDBu treatment, the AVP response (IP accumulation, AVP binding, and aldosterone output) is recovered and even enhanced. All these effects are specific since the inactive phorbol ester 4 alpha PDD is inactive, and staurosporine (a PKC inhibitor) reverses the PDBu effect. AVP stimulates transiently the translocation of PKC from the cytosol to the membrane, suggesting that the effect observed with PDBu reflects the effect of endogenous PKC stimulated by AVP. These results outline the complexities involved during hormonal stimulation and, at the same time, homologous desensitization phenomena. On one hand, acute treatment with PDBu--which induces PKC activation--is able to stimulate aldosterone secretion but at the same time initiate desensitization, since phorbol ester uncouples the AVP receptor from the coupling G protein. This suggests that PKC may participate in the first step of homologous desensitization. On the other hand, a 2-h incubation with PDBu induces a loss of AVP binding sites. This may represent the second step of homologous desensitization. Finally, a long term treatment with PDBu completely inactivates PKC, hence enabling AVP to further stimulate aldosterone secretion.

Dual effects of dopamine in rat adrenal glomerulosa cells

The effects of dopamine (DA) on cAMP production and aldosterone secretion were compared in freshly isolated cells and in primary cultures of rat adrenal glomerulosa cells. Under isolated conditions, glomerulosa cells exhibited dopamine receptors from DA-1 and DA-2 subclass, whereas in cultured conditions, where cells are very sensitive to their known stimuli, cells only exhibited dopamine receptors from the DA-1 subclass. Moreover, unlike freshly isolated cells, dopamine stimulated both cAMP production and aldosterone secretion in 3-day cultured preparations. These effects were receptor specific since they were completely suppressed by Scherring 23390 (a specific DA-1 antagonist) and were unaffected by a beta-adrenergic antagonist. As in vivo rat adrenal cortex contains DA, we discuss a possible involvement of this neurotransmitter in the regulation of aldosterone secretion.

Involvement of distinct G-proteins in the action of vasopressin on rat glomerulosa cells

We have previously shown that vasopressin (VP) induces breakdown of membrane phosphoinositides in adrenal glomerulosa cells. In the present study we demonstrate that the accumulation of inositol phosphates (IP) measured in the presence of arginine vasopressin (AVP) is reduced if the cells are incubated in a calcium-free medium. This effect cannot be accounted for by modification of VP binding, reduction of inositol lipid labeling, or stimulation of inositol, 1,4,5,-triphosphate 5-monophosphatase. It mainly affects phospholipase-C activity, since this enzyme is highly sensitive to calcium. Ionomycine and nifedipine, which, respectively, increase and decrease the intracellular calcium concentration, also, respectively, stimulate and inhibit IP accumulation. In membranes prepared from pertussis toxin (IAP)-treated cells, AVP stimulates inositol monophosphate accumulation to the same extent as in membranes derived from untreated cells. However, in intact cells, IAP decreases the inositol monophosphate accumulation. This decrease probably involves calcium influx, since we show that AVP stimulates a unidirectional calcium influx, which is completely blocked by IAP treatment. In rat adrenal glomerulosa cells, the AVP-stimulated secretion of aldosterone is mainly under the control of calcium, since a full inhibition of its secretion is observed under conditions in which the calcium influxes are completely suppressed despite a sustained accumulation of IP (calcium depletion or IAP treatment). Together, these results signify that VP acts on rat glomerulosa cells by two distinct mechanisms: calcium influx, which is IAP sensitive, and phosphoinositide turnover, which is IAP insensitive.

Structural identification, subcellular localization and secretion of bovine adrenomedullary neuromedin C [GRP-(18-27)]

Bombesin-like immunoreactivity (BLI) was purified from acid (HCl) extracts of bovine adrenal medulla. High performance liquid chromatography (HPLC) on a mu-Bondapak C18 column revealed the presence of five molecular forms of BLI, one coeluting with synthetic gastrin releasing peptide (GRP), the mammalian counterpart of amphibian bombesin, one coeluting with neuromedin C, one coeluting with neuromedin B and the two other ones coeluting with the oxidized forms of neuromedins B and C. The material corresponding to neuromedin C was purified to homogeneity and its amino acid composition and sequence corresponded to those expected for neuromedin C. HPLC analysis on an analytical SP-5PW column of subcellular extracts of bovine adrenal medulla indicated that neuromedin C is almost exclusively localized in secretory granules. The neuropeptide function of neuromedin C and/or other BLI peptides at this level was supported by the stimulatory effect of carbamylcholine (500 microM) on the release of BLI (4.5-fold increase over the basal release of 19 fmol/5 min) from perfused bovine adrenal glands.

Effects of Cold Hardening on the Regulation of Polyamine Levels in Wheat (Triticum aestivum L.) and Alfalfa (Medicago sativa L.)

When leaves of wheat (Triticum aestivum L.) are exposed to a cold hardening temperature, a major accumulation of putrescine (6-9 times) takes place. Spermidine accumulates to a lesser extent and, conversely, spermine decreases slightly. These variations are completely reversible when plants are returned to initial growing conditions. A similar response is obtained with crowns. During cold hardening, arginine decarboxylase activity remains near its initial level while a considerable loss of activity is observed in control plants. Ornithine decarboxylase and diamine oxidase activity levels are not substantially modified by the treatment. Alfalfa (Medicago sativa L.) also accumulates putrescine under low temperature stress, indicating that this phenomenon is not typical of cereals. The physiological significance of this accumulation of putrescine is still unexplained but the results obtained suggest the involvement of polyamines in the biochemical processes of cold hardening.

Bombesin-like immunoreactivity in bovine adrenal medulla

The presence of immunoreactive (ir)-bombesin in bovine adrenal medulla, isolated adrenal chromaffin cells and subcellular fractions of the adrenal medulla was demonstrated using a specific antibody to the synthetic peptide. High levels of ir-bombesin were detected in acid (HCl) extracts of the adrenal tissue (27 pmol/g) and isolated cells (0.35 pmol per 10(6) cells). Subpopulations of adrenal chromaffin cells were also obtained by centrifugation of the original cell preparation through a stepwise bovine serum albumin gradient (cell layers I, II and III). The highest concentration of ir-bombesin (0.77 pmol/10(6) cells) was found in a cell population (cell layer I) enriched in noradrenaline (adrenaline/noradrenaline ratio of 0.6). At the subcellular level, ir-bombesin was mainly concentrated in the secretory granules (0.61 pmol/mg protein) along with catecholamines (1097 nmol/mg protein), but a relatively high concentration of ir-bombesin (0.26 pmol/mg protein) was also found in the microsomal fraction. Isolation and high performance liquid chromatography (HPLC) analysis of adrenomedullary ir-bombesin revealed the presence of four molecular forms, one of them corresponding to gastrin releasing peptide (GRP), another one (major peak) eluting closely to synthetic neuromedin B and another one coeluting with GRP-(18-27). HPLC analysis of the molecular forms of ir-bombesin in the microsomes and secretory granules indicated that GRP- and neuromedin B-like materials can be generated between the two fractions.

Dynorphin and enkephalins in adrenal paraneurones. Opiates in the adrenal medulla

Immunoreactive dynorphin (ir-Dyn), immunoreactive leucine-enkephalin (ir-Leu-Enk) and various other neuropeptides were measured in acid extracts of bovine adrenal medulla and isolated adrenal chromaffin cells. Their respective levels ranged as follows: Leu-Enk greater than Dyn greater than bombesin greater than vasoactive intestinal peptide (VIP) greater than neurotensin greater than substance P. Comparisons of the total catecholamine levels with the levels of Leu-Enk in both extracts gave ratios in the same order of magnitude (2600, tissue extract and 5000, cell extract). However, the catecholamine/Dyn ratio in the tissue extract (138 000) was much higher than that found in the cell extract (20 180), suggesting a possible selective degradation of Dyn in tissue extract as compared with cell extract or an induction of Dyn biosynthesis in cells which have been isolated from their natural microenvironment. Immunofluorescence staining of isolated chromaffin cell sections revealed the presence of ir-Dyn in 5 to 10% of the total cell population. To localize ir-Dyn in regard to Leu-Enk and catecholamines, adrenal chromaffin cells were separated into three populations (I, II, and III) on a stepwise bovine serum albumin (BSA) gradient. Relative high levels of ir-Dyn were measured in cell layer I (4 pmol/10(6) cells), a cell population enriched in noradrenaline. However, ir-Leu-Enk was more concentrated in cell layers II and III (5.3 and 8.3 pmol/10(6) cells), two populations enriched in adrenaline. Isolation and high pressure liquid chromatography (HPLC) analysis of adrenomedullary Dyn indicated the presence of at least five molecular forms corresponding to Dyn-(1-11), Dyn-(1-12), Dyn-(1-13), Ala-containing-Dyn-(1-13) and a nonidentified molecule eluting closely to Dyn-(1-13). These data indicate that adrenal ir-Dyn and ir-Leu-Enk have distinct cellular distributions. In addition, the identification of Dyn fragments in bovine adrenal medulla indicates that these short peptides may be considered as natural active forms of Dyn.