Biomedical subjects

Paul Morley

Publications and source records attributed to Paul Morley.

At least 19 recordsLinked to original sources

PubMed2006

Competing approaches to excitotoxic neuroprotection by inert and catalytic antioxidant porphyrins.

The goal of this study was to determine if novel porphyrins protect cultured cortical neurons from excitotoxic NMDA exposure or oxygen-glucose deprivation (OGD), which model key aspects of cerebral ischemia. Porphyrins were chosen based on conventional and unconventional criteria. Metalloporphyrin catalytic antioxidants possessing a redox-sensitive metal core can exhibit potent and wide-ranging catalytic antioxidant abilities, which are conventionally believed to underlie neuroprotection. We report here that a recent-generation potent peroxynitrite decomposition catalyst, FP-15, protected a majority of neurons against OGD and NMDA toxicity, without suppressing NMDA-mediated intracellular Ca2+ (Cai2+) elevations or whole-cell currents. We have previously shown that neuroprotection against OGD and NMDA toxicity correlated with an ability to suppress neurotoxic Cai2+ elevations and not antioxidant ability. We now evaluate if this unconventional mechanism extends to inert metal-free porphyrins. Neuron cultures were completely protected against OGD and NMDA toxicity by H2-meso-tetrakis(3-benzoic acid)porphyrin (H2-TBAP(3)) or H2-meso-tetrakis(4-sulfonatophenyl)porphyrin (H2-TPPS(4)), although only H2-TPPS(4) suppressed (completely) NMDA-induced Cai2+ rises. H2-meso-tetrakis(3,3'-benzoic acid)porphyrin (H2-TBAP(3,3')) or H2-meso-tetrakis(N-methylpyridynium-4-yl)porphyrin (H2-TM-PyP(4)) provided at least partial protection against OGD and NMDA toxicity and partially suppressed NMDA-induced Cai2+ elevations. Despite the complexity of Ca2+-independent and -dependent based mechanisms, the inventory of porphyrins demonstrating neuroprotection in ischemia-relevant insults is now expanded to include FP-15 and inert metal-free compounds, although with no apparent advantage gained by using FP-15.

Animals↗

PubMed2006

Unconventional neuroprotection against Ca2+ -dependent insults by metalloporphyrin catalytic antioxidants.

We evaluated whether both inert and catalytically active metalloporphyrin antioxidants, meso-substituted with either phenyl-based or N-alkylpyridinium-based groups, suppress Ca(2+)-dependent neurotoxicity in cell culture models of relevance to cerebral ischemia. Representatives from both metalloporphyrin classes, regardless of antioxidant strength, protected cultured cortical neurons or PC-12 cultures against the Ca(2+) ionophores ionomycin or A23187, by suppressing neurotoxic Ca(2+) influx. Some metalloporphyrins suppressed excitotoxic Ca(2+) influx indirectly induced by the Ca(2+) ionophores in cortical neurons. Metalloporphyrins did not quench intracellular fluorescence, suggesting localization to the plasma membrane interface and/or interference with Ca(2+) ionophores. Metalloporphyrins suppressed ionomycin-induced Mn(2+) influx, but did not protect cortical neurons against pyrithione, a Zn(2+) ionophore. In other Ca(2+)-dependent paradigms, Ca(2+) influx via plasma membrane depolarization, but not through reversal of plasmalemmal Na(+)/Ca(2+) exchangers, was modestly suppressed by Mn(III)meso-tetrakis(4-benzoic acid)porphyrin (Mn(III)TBAP) or by an inert analog, Zn(II)TBAP. Mn(III)TBAP and Zn(II)TBAP potently protected cortical neurons against long-duration oxygen-glucose deprivation (OGD), performed in the presence of antagonists of NMDA, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate and L-type voltage-gated Ca(2+) channels, raising the possibility of an unconventional mode of blockade of transient receptor protein melastatin 7 channels by a metalloTBAP family of metalloporphyrins. The present study extends the range of Ca(2+)-dependent insults for which metalloporphyrins demonstrate unconventional neuroprotection. MetalloTBAPs appear capable of targeting an OGD temporal continuum.

Animals↗

PubMed2005

Cobra cardiotoxin-induced cell death in fetal rat cardiomyocytes and cortical neurons: different pathway but similar cell surface target.

Cobra cardiotoxins (CTXs) are basic polypeptides with diverse pharmacological functions that are cytotoxic to many different cell types through both necrotic and apoptotic cell death pathways. In this comparative study of the action of CTX A3 from the Taiwan cobra (Naja atra) on fetal rat cardiomyocytes and cortical neurons, it was shown that CTX A3 induced different patterns of elevation of intracellular Ca2+ concentration ([Ca2+]i), CTX internalization, caspase-3 activity and viability. Application of an anti-sulfatide monoclonal antibody, O4 specific for 3-sulfo-galactose lipid, but not in the control experiments using anti-GM3 monoclonal antibody, reduces CTX-induced [Ca2+]i elevation, CTX internalization and toxicity. Therefore, CTX may target similar sulfo-containing cell surface receptors in both fetal rat cardiomyocytes and cortical neurons, but induce cell death through different pathways specific to each cell type.

Animals↗

PubMed2005

An alternative Ca2+-dependent mechanism of neuroprotection by the metalloporphyrin class of superoxide dismutase mimetics.

This study challenges the conventional view that metalloporphyrins protect cultured cortical neurons in models of cerebral ischemia by acting as intracellular catalytic antioxidants [superoxide dismutase (SOD) mimetics]. High SOD-active Mn(III)porphyrins meso-substituted with N,N'-dimethylimidazolium or N-alkylpyridinium groups did not protect neurons against oxygen-glucose deprivation (OGD), although lower SOD-active and -inactive para isomers protected against N-methyl-D-aspartate (NMDA) exposure. Mn(III)meso-tetrakis(4-benzoic acid)porphyrin (Mn(III)TBAP), as well as SOD-inactive metalloTBAPs and other phenyl ring- or beta-substituted metalloporphyrins that contained redox-insensitive metals, protected cultures against OGD and NMDA neurotoxicity. Crucially, neuroprotective metalloporphyrins suppressed OGD- or NMDA-induced rises in intracellular Ca2+ concentration in the same general rank order as observed for neuroprotection. Results from paraquat toxicity, intracellular fluorescence quenching, electrophysiology, mitochondrial Ca2+, and spontaneous synaptic activity experiments suggest a model in which metalloporphyrins, acting at the plasma membrane, protect neurons against OGD by suppressing postsynaptic NMDA receptor-mediated Ca2+ rises, thereby indirectly preventing accumulation of neurotoxic mitochondrial Ca2+ levels. Though neuroprotective in a manner not originally intended, SOD-inactive metalloporphyrins may represent promising therapeutic agents in diseases such as cerebral ischemia, in which Ca2+ toxicity is implicated. Conventional syntheses aimed at improving the catalytic antioxidant capability and/or intracellular access of metalloporphyrins may not yield improved efficacy in some disease models.

Animals↗

PubMed2005

Modified bacterial mutation test procedures for evaluation of peptides and amino acid-containing material.

Biological materials can release amino acids during the course of bacterial mutation testing. Low levels of released amino acids from soluble materials can cause moderate increases in the number of revertant colonies on the plate, whereas higher levels lead to overgrowth of the background lawn, making counting of revertant colonies impossible. For poorly soluble material, the released amino acids can be present at high levels in localized spots on the plate, leading to the growth of 'pseudorevertant' colonies. The 'treat and wash' modified preincubation method employed here is an adaptation of the treat and plate method (used for evaluation of antibiotics) and involves washing the bacteria free of test compound after a 90 min exposure prior to plating out on minimal plates. The MC overlay method is a modified version of the standard plate incorporation assay, in which a top overlay containing 4% high viscosity methylcellulose is used in place of agar to stabilize the test compound in solution, preventing precipitation and subsequent localized amino acid release. Both modified methods produce the expected results for negative and positive controls. Peptides [synthetic curtailed analogs of human parathyroid hormone, PTH(1-34) and Ostabolin-C] that produced false positive results or could not be evaluated owing to overgrowth of the background lawn using standard methods, showed no artifacts and no evidence of genotoxicity using the modified methods. It is concluded that the treat and wash and MC overlay methods are valid versions of the bacterial mutation test for avoiding complications associated with released amino acids.

Amino Acids↗

PubMed2005

The dual role of prostaglandin E(2) in excitotoxicity and preconditioning-induced neuroprotection.

Cyclooxygenase-2 is harmful in models of cerebral ischemia yet plays a protective role in preconditioning-induced ischemic tolerance in the heart. This study examined the mechanisms underlying cyclooxygenase-2-mediated neurotoxicity and preconditioning-induced neuroprotection in an in vitro model of cerebral ischemia. Inhibition of cyclooxygenase-2 protects cortical neuronal cultures from death induced by oxygen-glucose deprivation and reduces oxygen-glucose deprivation-induced increases in intracellular Ca(2+) ([Ca(2+)](i)). In the present study, we determined if prostaglandin E(2) (PGE(2)) is responsible for this cyclooxygenase-2-mediated effect. Rat cortical cultures expressed mRNA for the prostanoid EP(1)-EP(4) receptors. PGE(2) reversed the attenuation in [Ca(2+)](i) and the protection offered by cyclooxygenase-2 inhibition during oxygen-glucose deprivation. These effects likely occur via activation of the prostanoid EP(1) receptor since blocking this receptor during oxygen-glucose deprivation reduced [Ca(2+)](i) and neurotoxicity. Next, we considered if the moderate activation of this pathway, by preconditioning cultures with sub-lethal oxygen-glucose deprivation, influenced the development of tolerance to an otherwise lethal oxygen-glucose deprivation insult, 48 h later. Inhibition of cyclooxygenase-2 during oxygen-glucose deprivation-preconditioning abolished preconditioning-induced protection. Furthermore, cultures were rendered tolerant to oxygen-glucose deprivation by the transient exposure to exogenous PGE(2) 24 h prior to the insult, indicating that this product of the cyclooxygenase-2 pathway is sufficient to induce ischemic tolerance. This study shows that cyclooxygenase-2 and PGE(2) are involved in both oxygen-glucose deprivation-induced neurotoxicity and preconditioning-induced neuroprotection. While neurotoxic in the context of lethal oxygen-glucose deprivation, the moderate activation of this signalling pathway confers ischemic tolerance.

Animals↗

PubMed2005

The gas7 protein potentiates NGF-mediated differentiation of PC12 cells.

The growth-arrest-specific protein gas7 is required for morphological differentiation of cultured mouse cerebellar neurons and PC12 cells. Moreover, its overexpression in various cell types induces neurite-like outgrowth. The role of gas7 in neuronal differentiation was further characterized by adenovirus-mediated overexpression in PC12 cells and quantification of the expression of various neuronal markers, in the absence and presence of different concentrations of nerve growth factor (NGF). The potential neuroprotective activity of gas7 against various neurotoxic insults was also assessed. In addition to promoting the formation of neurite-like extensions, overexpression of gas7 potentiated NGF-mediated neuronal differentiation of PC12 cells, as shown by the enhanced expression of the neuronal proteins betaIII-tubulin, synaptotagmin, alpha7 subunit of the acetylcholine receptor, and dihydropyrimidinase related protein-3. This effect was exerted independently of cell cycle progression, as gas7 did not affect proliferation of PC12 cells. While some differentiation enhancers protect PC12 cells against lethal insults, gas7 overexpression in PC12 cells did not protect against oxygen-glucose deprivation, the calcium ionophore A23187, or the nitric oxide donor sodium nitroprusside, suggesting that gas7 is not neuroprotective. The ability of gas7 to potentiate neuronal differentiation makes it a potential therapeutic target to promote re-establishment of neuronal connections in the injured or diseased brain, such as following stroke.

Animals↗

PubMed2005

Delivery of parathyroid hormone for the treatment of osteoporosis.

Parathyroid hormone (PTH), along with its fragments and analogues, potently restores bone mass and biomechanical strength in animal models of osteoporosis, and reduces fractures by up to 65% in clinical trials in osteoporotic patients. Despite this demonstrated efficacy, patient acceptance and compliance with PTH is limited by the need for daily subcutaneous injections. The development of an equally efficacious, noninjectable form of PTH would significantly expand the present market. A challenge to the development of an alternative delivery system is the requirement for low-dose, daily, intermittent pulses of PTH to induce the anabolic actions on bone. In this review, recent basic and clinical efforts to deliver PTH by oral, buccal, sublingual, transdermal, nasal and pulmonary approaches will be addressed.

Animals↗

PubMed2004

Opposing effects of cyclooxygenase-2 selective inhibitors on oxygen-glucose deprivation-induced neurotoxicity.

Cyclooxygenase-2 inhibitors protect against excitotoxicity in vitro yet provide conflicting results in in vivo models of ischemia. To bridge the gap in understanding the discrepancies among these studies, the effects of different cyclooxygenase-2 inhibitors were studied in an in vitro model of ischemia. Oxygen-glucose deprivation (OGD) induced cyclooxygenase-2 protein expression in neuronal cortical cultures. Cyclooxygenase-2 inhibitors exhibited opposing effects on neuronal death induced by OGD. The acidic sulfonamides, N-(2-cyclohexyloxy-4-nitrophenyl) methanesulfonamide (NS-398) and N-(4-nitro-2-phenoxyphenyl)-methanesulfonamide (nimesulide), aggravated neuronal death by enhancing OGD-induced increases in extracellular glutamate and intracellular Ca2+ levels. In contrast, 1-[(4-methylsulfonyl)phenyl]-3-tri-fluoromethyl-5-(4-fluorophenyl)pyrazole (SC-58125) dose-dependently protected cultures against OGD by suppressing increases in extracellular glutamate and intracellular Ca2+ levels. The NS-398-induced aggravation of neuronal death was lost if the inhibitor was added only following the OGD. The timing of inhibitor application also determined its effects on N-methyl-D-aspartate (NMDA)-induced excitoxicity. NS-398 was protective when added both during and post-NMDA exposure, but not if NS-398 was also applied for 60 min prior to the insult. In contrast, SC-58125 afforded protection against NMDA in the presence or absence of a pre-incubation period. This study demonstrates that certain cyclooxygenase-2 inhibitors have opposing effects on neuronal survival depending on the timing of application and the nature of the insult. These results may account for the discrepancies among previous studies which used different inhibitors and different models of neurotoxicity.

Animals↗

PubMed2004

Systemic bone formation with weekly PTH administration in ovariectomized rats.

PURPOSE: Weekly subcutaneous administration of 0 (vehicle), 10 and 80 microg/kg doses of human parathyroid hormone (1-34) [PTH (1-34)] were compared based on their capacity to induce systemic formation of bone in 9 month-old ovariectomized (OVX) Sprague-Dawley rats. METHODS: Changes elicited at bone tissue after 4 weeks of treatment were assessed using dual x-ray absorptiometry, micro-computed tomography (microCT), and ashing. RESULTS: The 10 microg/kg dose led to a significant increase (p<0.025) in femoral bone mineral density (BMD) over vehicle- and 80 microg/kg-treated groups. Similarly, structural analysis of the femoral neck trabecular bone by microCT revealed increases in bone volume fraction and trabecular thickness over the pre-treatment baseline, and vehicle- and 80 microg/kg-treated groups. CONCLUSIONS: The data suggest that the weekly administration of 10 microg/kg of PTH (1-34) was sufficient to significantly promote the bone mineral density systemically. The weekly administration of 10 microg/kg over a 4-week treatment period is, to our knowledge, one of the lowest reported total dose of PTH (1-34) shown to induce a net anabolic effect on skeletal tissue in OVX rats.

Animals↗

PubMed2004

Constrained analogs of osteogenic peptides.

Osteogenic peptides are, or have potential to be, therapies for the treatment of osteoporosis, fracture repair, and repair of loosened bone implants. Human parathyroid hormone has been approved for the treatment of post-menopausal osteoporosis. Constrained analogs of PTH and the parathyroid-hormone related peptide (PTHrP) have aided the understanding of how PTH and PTHrP bind to their common receptor and some of these analogs have improved properties that make them possible candidates for clinical trial. Cyclization by lactam formation has shown that a core region of human PTH (hPTH) from residues 16-26 binds as an alpha-helix to the receptor and that the biological effects are remarkably sensitive to ring size. Appropriate cyclization in this region of the molecule not only has yielded analogs with improved receptor activation but also ones less susceptible to protease degradation and thus more active in vivo. Cyclization has been less successful in the N-terminus region, residues 1-12, of hPTH(1-34) with only a cyclization between residues 6 and 10 showing some promise. The growing understanding of how this region binds to the receptor will lead to other productive constraints. This review also covers the potential of a different class of molecule, the osteogenic growth peptide (OPG), as an anabolic bone agent. These molecules have much weaker anabolic effects than PTH and cyclization does not result in improved activity. However, the information gained from these studies may yield analogs with better pharmacological profiles.

Amino Acid Sequence↗

PubMed2003

The effects of parathyroid hormone fragments on bone formation and their lack of effects on the initiation of colon carcinogenesis in rats as indicated by preneoplastic aberrant crypt formation.

The parathyroid hormone (PTH) and some of its fragments and analogs stimulate bone growth in various animal models and humans and one of them (hPTH-(1-34)) has been approved by the USFDA for treating osteoporosis. However, there are reports that PTH can stimulate the PI-3 kinase/mitogen-activated protein kinases-mediated proliferation of rat enterocytes and that primary hyperparathyroidism in humans is associated with an increased incidence of colon cancer. Here we have investigated the ability of two PTH fragments, hPTH-(1-34)NH(2) and [Leu(27)]cyclo(Glu(22)-Lys(26))hPTH-(1-31)NH(2) to initiate colon carcinogenesis or increase the initiatory activity of the widely used colon carcinogen azoxymethane (AOM). The initiation of colon carcinogenesis by AOM was indicated by the very early appearance of aberrant crypt foci. While both PTH peptides strongly stimulated femoral bone formation, they did not cause the appearance of ACFs or affect the number or the distribution along the colon of AOM-induced ACFs. Nor did AOM affect the PTHs' ability to stimulate bone formation. Thus, a relatively short PTH treatment that is long enough to strongly stimulate bone formation does not initiate colon carcinogenesis in rats.

Animals↗

PubMed2003

Preconditioning of cortical neurons by oxygen-glucose deprivation: tolerance induction through abbreviated neurotoxic signaling.

Transient exposure of rat cortical cultures to nonlethal oxygen-glucose deprivation (OGD preconditioning) induces tolerance to otherwise lethal oxygen-glucose deprivation (OGD) or N-methyl-D-aspartate 24 h later. This study evaluates the role of cytosolic and mitochondrial Ca2+-dependent cellular signaling. Mechanistic findings are placed in context with other models of ischemic preconditioning or known neurotoxic pathways within cortical neurons. Tolerance to otherwise lethal OGD is suppressed by performing OGD preconditioning in the presence of the broad-scope catalytic antioxidants Mn(III)tetra(4-carboxyphenyl)porphyrin (MnTBAP) or Zn(II)tetra(4-carboxyphenyl)porphyrin [Zn(II)TBAP], but not by a less active analog, Mn(III)tetra(4-sulfonatophenyl)porphyrin, or a potent superoxide scavenger, Mn(III)tetra(N-ethyl-2-pyridyl)porphyrin chloride. Inhibitors of adenosine A1 receptors, nitric oxide synthase, mitogen-activated protein kinase, and poly(ADP-ribose) polymerase fail to suppress OGD preconditioning despite possible links with reactive oxygen species in other models of ischemic preconditioning. Preconditioning is suppressed by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), which has been ascribed elsewhere to inhibition of superoxide transport to the cytosol through mitochondrial anion channels. However, although it induces mitochondrial Ca2+ uptake, neuronal preconditioning is largely insensitive to mitochondrial uncoupling with carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone or 2,4-dinitrophenol. Un-couplers will prevent production of mitochondrial reactive oxygen species, implying nonmitochondrial targets by MnTBAP, Zn(II)TBAP, and DIDS. Emphasizing the importance of an increase in cytosolic Ca2+ during preconditioning, a Ca2+/calmodulin-dependent protein kinase II inhibitor, KN-62, suppresses development of subsequent tolerance. Summarizing, only those cellular transduction pathways that have the potential to be neurotoxic may be activated by preconditioning in cortical neurons. Finally, a marked decrease in extracellular glutamate is observed during otherwise lethal OGD in preconditioned cultures, suggesting that this end effector may represent a point of convergence across different preconditioning models.

2,4-Dinitrophenol↗

PubMed2003

Protection of cortical neurons against oxygen-glucose deprivation and N-methyl-D-aspartate by DIDS and SITS.

The Cl(-) channel blockers, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) or 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid (SITS) dose-dependently protected against oxygen-glucose deprivation in cultured rat cortical neurons. DIDS or SITS attenuated oxygen-glucose deprivation-induced increases in extracellular glutamate concentrations and intracellular Ca(2+). DIDS or SITS provided moderate protection against N-methyl-D-aspartate (NMDA) toxicity and decreased NMDA receptor-mediated increases in intracellular Ca(2+). Whole-cell NMDA receptor currents were attenuated 39+/-2% and 21+/-3% by 1 mM DIDS and SITS, respectively. Other Cl(-) channel blockers as equipotent as DIDS and SITS did not decrease oxygen-glucose deprivation- or NMDA-mediated neuronal Ca(2+) influx or toxicity. Neurotoxicity by exogenous glutamate was not prevented by SITS and was exacerbated by DIDS. Reductions in oxygen-glucose deprivation-induced increases in intracellular Ca(2+) levels underlie neuroprotection by DIDS and SITS. This was a reflection of lower extracellular [glutamate], direct inhibition of Ca(2+) influx through postsynaptic NMDA receptors, and possibly through other protective properties associated with DIDS and SITS.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed2002

Bone growth stimulators. New tools for treating bone loss and mending fractures.

In the new millennium, humans will be traveling to Mars and eventually beyond with skeletons that respond to microgravity by self-destructing. Meanwhile in Earth's aging populations growing numbers of men and many more women are suffering from crippling bone loss. During the first decade after menopause all women suffer an accelerating loss of bone, which in some of them is severe enough to result in "spontaneous" crushing of vertebrae and fracturing of hips by ordinary body movements. This is osteoporosis, which all too often requires prolonged and expensive care, the physical and mental stress of which may even kill the patient. Osteoporosis in postmenopausal women is caused by the loss of estrogen. The slower development of osteoporosis in aging men is also due at least in part to a loss of the estrogen made in ever smaller amounts in bone cells from the declining level of circulating testosterone and is needed for bone maintenance as it is in women. The loss of estrogen increases the generation, longevity, and activity of bone-resorbing osteoclasts. The destructive osteoclast surge can be blocked by estrogens and selective estrogen receptor modulators (SERMs) as well as antiosteoclast agents such as bisphosphonates and calcitonin. But these agents stimulate only a limited amount of bone growth as the unaffected osteoblasts fill in the holes that were dug by the now suppressed osteoclasts. They do not stimulate osteoblasts to make bone--they are antiresorptives not bone anabolic agents. (However, certain estrogen analogs and bisphosphates may stimulate bone growth to some extent by lengthening osteoblast working lives.) To grow new bone and restore bone strength lost in space and on Earth we must know what controls bone growth and destruction. Here we discuss the newest bone controllers and how they might operate. These include leptin from adipocytes and osteoblasts and the statins that are widely used to reduce blood cholesterol and cardiovascular damage. But the main focus of this article is necessarily the currently most promising of the anabolic agents, the potent parathyroid hormone (PTH) and certain of its 31- to 38-aminoacid fragments, which are either in or about to be in clinical trial or in the case of Lilly's Forteo [hPTH-(1-34)] tentatively approved by the Food and Drug Administration for treating osteoporosis and mending fractures.

Animals↗

PubMed2002

Identification of two phylogenetically related organisms from feces by PCR for detection of Salmonella spp.

Two previously reported PCR methods were evaluated to determine whether they are as sensitive and specific as conventional culture methods in detecting Salmonella spp. from feces. Bovine and equine feces were enriched overnight in brain heart infusion broth and assayed using PCR methods and primer sets described by other investigators. A total of 774 fecal specimens were tested using a primer set (invE-A primer set) that amplifies a region spanning the invasin E and A genes of Salmonella enterica serovar Typhimurium. A subset of these fecal specimens (306 of the 774 total) were tested using primers (hisJ primer set) that amplify a portion of the histidine transport J gene. The PCR required 24 h to obtain results, whereas it took 5 to 7 days to identify Salmonella spp. by culture. PCR detection of Salmonella spp. using the hisJ primers and the invE-A primers had a sensitivity of 93.3 and 80%, respectively, and a specificity of 85.6 and 98.6%, respectively, compared with bacterial culture. Amplification of 42 culture-negative fecal specimens (of 306 total specimens) generated a DNA fragment that corresponded to the molecular weight of the amplified hisJ gene. The hisJ-generated amplicons from six culture-negative and six culture-positive specimens were sequenced and analyzed using DNA sequence alignment and phylogenetic analysis software. A neighbor-joining dendrogram of the DNA sequences of both sets of hisJ amplicons revealed two distinct groups-one group of amplicons from culture-positive specimens identical to the hisJ gene of S. enterica serovar Typhimurium and a second group of amplicons from culture-negative specimens that were more closely related to hisJ of S. enterica serovar Typhimurium than to other hisJ sequences present in nucleotide databases.

Animals↗

PubMed2002

The control of bone growth by parathyroid hormone, leptin, & statins.

There is a need for anabolic drugs that can stimulate bone growth, improve bone microarchitecture, accelerate fracture healing and thus restore bone strength to oteoporotics. The anabolic agents currently leading the way to the clinic are the parathroid hormone (PTH) and some of its adenylyl cyclase-stimulating fragments. Here we discuss what is known about the genes and their products that are stimulated by PTHR1 receptor signals and in four ways cause a large accumulation of bone-building osteoblasts. We will also discuss the currently controversial anabolic activity of the cholesterol-lowering statins and outline a possible mechanism by which they might stimulate BMP-2 expession and bone growth. Finally, we will present the growing evidence for the body's "fat-o-stat" cytokine-leptin-indirectly restraining bone growth via a hypothalamic factor and at the same serving as a local autocrine/paracrine stimulator of osteoblast activity via IGF-I and an inhibitor of osteoclast generation by stimulating osteoblastic cells' antiosteoclast OPG (osteoprotegerin) expression and reducing their proosteoclast RANKL expression.

Animals↗

PubMed2002

Parathyroid hormone, its fragments and their analogs for the treatment of osteoporosis.

The susceptibility to traumatic fracturing of osteopenic bones, and the spontaneous fracturing of osteoporotic bones by normal body movements caused by the microstructural deterioration and loss of bone, are currently treated with antiresorptive drugs, such as the bisphosphonates, calcitonin, estrogens, and selective estrogen receptor modulators. These antiresorptive agents target osteoclasts and, as their name indicates, reduce or stop bone resorption. They cannot directly stimulate bone formation, increase bone mass above normal values in ovariectomized rat models, or improve microstructure. However, there is a family of agents - the parathyroid hormone (PTH) and some of its fragments and their analogs - which directly stimulate bone growth and improve microstructure independently from impairing osteoclasts. These drugs are about to make their clinical debut in treating patients with osteoporosis and, probably not too far in the future, for accelerating fracture healing. They stimulate osteoblast accumulation and bone formation in three ways via signals from the type 1 PTH/PTH-related protein (PTHR1) receptors on proliferatively inactive preosteoblasts, osteoblasts, osteocytes and bone-lining cells. The receptor signals shut down the proliferative machinery in preosteoblasts and push their maturation to osteoblasts, cause the osteoblastic cells to make and secrete several factors that stimulate the extensive proliferation of osteoprogenitors without PTHRI receptors, stimulate the reversion of bone-lining cells to osteoblasts, and extend osteoblast lifespan and productivity by preventing them from suicidally initiating apoptosis. The first of the PTHs to reach the clinic will be teriparatide [recombinant human (h)PTH-(1-34)], which was recommended for approval in 2001 by the US Food and Drug Administration Endocrinology and Metabolic Drugs Advisory Committee for the treatment of postmenopausal osteoporosis. Teriparatide has been shown to considerably increase cancellous and cortical bone mass, improve bone microstructure, prevent fractures and thus provide benefits that cannot be provided by current antiresorptive drugs, when administered subcutaneously at a daily dose of 20 microg for no longer than 2 years to patients with osteoporosis.

Animals↗