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Biomedical subjects

J Cornish

Publications and source records attributed to J Cornish.

At least 37 records · Page 2Linked to original sources
PubMed2001

Effects of calcitonin, amylin, and calcitonin gene-related peptide on osteoclast development.

Amylin and calcitonin gene-related peptide (CGRP) are homologous 37 amino acid peptides that are found in the circulation. Both peptides belong to the calcitonin family. Similar to calcitonin, amylin and CGRP inhibit osteoclast activity, although they are much less potent than calcitonin. Calcitonin is known to act on the latter stages of osteoclast development, inhibiting the fusion of committed preosteoclasts to form mature multinucleated cells; however, whether or not calcitonin acts earlier in the formation of the precursor osteoclasts is controversial. The question of osteoclast development has never been examined with respect to amylin and CGRP. These issues are addressed in the present study. We studied the effects of calcitonin (salmon and rat), amylin (human and rat), and CGRP (human and rat) in mouse bone marrow cultures stimulated to generate osteoclasts using 1alpha,25-dihydroxyvitamin D3. Calcitonin dose-dependently decreased the numbers of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells as well as TRAP-positive mono-/binucleated cells at concentrations >10(-13) mol/L. Amylin and CGRP showed similar effects at concentrations >10(-9) mol/L. In addition, calcitonin substantially reduced the ratio of TRAP-positive multinucleated to mono-binucleated cells, indicating an effect on fusion of osteoclast precursors. The present data establish that this family of peptides not only acts on mature osteoclasts but also inhibits their development in bone marrow cultures. This activity is shared by amylin and CGRP. The much greater potency of calcitonin than amylin and CGRP is consistent with the action of these peptides being mediated by calcitonin receptors.

Amyloid↗
PubMed2001

Lysophosphatidic acid is an osteoblast mitogen whose proliferative actions involve G(i) proteins and protein kinase C, but not P42/44 mitogen-activated protein kinases.

The simple glycerophospholipid lysophosphatidic acid (LPA) acts both as an intermediary in phospholipid metabolism and as an intercellular signaling molecule in its own right. In various cell types, LPA signals through its membrane-bound, G protein-coupled receptors to influence cellular processes such as proliferation, survival, and cytoskeletal function. Its actions in bone cells have not been studied. Here we show that the LPA receptor, LP(A1)/edg-2/vzg-1, is expressed in primary rat osteoblasts and the UMR 106-01 osteoblastic cell line. LPA potently induces DNA synthesis and an increase in cell number in cultures of osteoblastic cells. LPA rapidly (within 10 min) stimulates phosphorylation of p42/44 mitogen-activated protein (MAP) kinases in osteoblastic cells, an effect that is sensitive to inhibition of G(i) proteins, inhibition of influx of extracellular calcium, and inhibition of protein kinase C. LPA-induced DNA synthesis is partially inhibited by either pertussis toxin or calphostin C, but is insensitive to specific inhibitors of MEK, the kinase upstream of p42/44 MAP kinases, or of phosphatidylinositol-3 kinases. These data demonstrate that LPA is an osteoblast mitogen whose signaling effects in osteoblastic cells include activation of p42/44 MAP kinases. However, the LPA mitogenic signal in osteoblastic cells, while requiring G(i) proteins and protein kinase C, is independent of the activity of p42/44 MAP kinases.

Animals↗
PubMed2001

A potential role for adrenomedullin as a local regulator of bone growth.

Bone remodeling is a complex process of coordinated resorption and formation of bone, which is regulated by systemic hormones and by local factors. We have previously shown that the peptide hormone adrenomedullin is mitogenic to osteoblastic cells in vitro and that it promotes bone growth in vivo. The aim of the present study was to characterize the expression of molecules that may mediate adrenomedullin signaling in osteoblasts and to investigate the expression of adrenomedullin itself in these cells. The first adrenomedullin receptor that was cloned is the seven-transmembrane G protein-coupled receptor, L1. Two additional receptors for adrenomedullin, which arise from interactions between calcitonin receptor-like receptor and receptor activity modifying proteins 2 or 3, have now been described. In the current study, we used RT-PCR and Northern blot analysis to demonstrate that messenger RNA for the three adrenomedullin receptors, as well as for adrenomedullin itself, is expressed in primary rat osteoblasts. Treating primary osteoblasts with transforming growth factor-beta and insulin-like growth factor-I moderately reduced adrenomedullin RNA levels, whereas PTH had no effect. We have shown by immunocytochemistry that adrenomedullin peptide is present in osteoblasts, and by competitive binding assays that (125)I-adrenomedullin binds with high affinity to intact osteoblasts and to osteoblast cell membranes. Coexpression of adrenomedullin and adrenomedullin receptors in osteoblasts, taken together with our previous finding that adrenomedullin is mitogenic to these cells, raises the possibility that this peptide is a local regulator of bone growth.

Adrenomedullin↗
PubMed2001

Systemic administration of adrenomedullin(27-52) increases bone volume and strength in male mice.

Adrenomedullin is a 52-amino acid peptide first described in a human phaeochromocytoma but since been found to be present in many tissues, including the vascular system and bone. Because of its structural similarity to amylin and calcitonin gene-related peptide, both of which have actions on bone cells, we have previously assessed the effects of adrenomedullin on the skeleton, and found that it increases osteoblast proliferation in vitro and bone formation following local injection in vivo. The present study carries this work forward by assessing the effects on bone of the systemic administration of a fragment of this peptide lacking the structural requirements for vasodilator activity. Two groups of 20 adult male mice received 20 injections of human adrenomedullin(27-52) 8.1 microg or vehicle over a 4-week period and bone histomorphometry and strength were assessed. In the tibia, adrenomedullin(27-52) produced increases in the indices of osteoblast activity, osteoid perimeter and osteoblast perimeter (P<0.05 for both using Student's t-test). Osteoclast perimeter was not affected. There was a 21% increase in cortical width and a 45% increase in trabecular bone volume in animals treated with adrenomedullin(27-52) (P<0.002 for both). Assessment of bone strength by three-point bending of the humerus showed both the maximal force and the displacement to the point of failure were increased in the animals treated with adrenomedullin(27-52) (P<0.03 for both). There was also a significant increase in the thickness of the epiphyseal growth plate. No adverse effects of the treatment were noted. It is concluded that adrenomedullin(27-52) acts as an anabolic agent on bone. These findings may be relevant to the normal regulation of bone mass and to the design of agents for the treatment of osteoporosis.

Adrenomedullin↗
PubMed2001

Effects of amylin and adrenomedullin on the skeleton.

Amylin and adrenomedullin are related peptides with some homology to both calcitonin and calcitonin gene-related peptide (CGRP). All these peptides have in common a 6-amino acid ring structure at the amino-terminus created by a disulfide bond. In addition, the carboxy-termini are amidated. Both amylin and adrenomedullin have recently been found to stimulate the proliferation of osteoblasts in vitro, and to increase indices of bone formation in vivo when administered either locally or systemically. Both amylin and adrenomedullin have also been found to act on chondrocytes (Cornish et al., submitted for publication), stimulating their proliferation in culture and increasing tibial growth plate thickness when administered systemically to adult mice. Studies of structure-activity relationships have demonstrated that osteotropic effects of amylin and adrenomedullin can be retained in peptide fragments of the molecules. The full-length peptide of amylin has known effects on fuel metabolism, and systemic administration of amylin is also associated with increased fat mass. However, the octapeptide fragment of the molecule, amylin-(1-8), is osteotropic and yet has no activity on fuel metabolism. Similar fragments of adrenomedullin have also been defined, which retain activity on bone but lack the parent peptide's vasodilator properties. Both amylin-(1-8) and adrenomedullin-(27-52) act as anabolic agents on bone, increasing bone strength when administered systemically. Thus, these small peptides, or analogues of it, are potential candidates as anabolic therapies for osteoporosis. Both amylin and adrenomedullin may have effects on bone metabolism. Amylin is secreted following eating and may direct calcium and protein absorbed from the meal into new bone synthesis. Amylin circulates in high concentrations in obese individuals, and might contribute to the association between bone mass and fat mass. Our recent findings demonstrating the co-expression of adrenomedullin and adrenomedullin receptors in osteoblasts, along with the findings that the peptide and its receptor are easily detectable during rodent embryogenesis, suggest that this peptide is a local regulator of bone growth. Thus, the findings reviewed in this paper illustrate that amylin and adrenomedullin may be relevant to the normal regulation of bone mass and to the design of agents for the treatment of osteoporosis.

Journal Article↗
PubMed2000

Pediatric marrow transplantation for acute leukemia using unrelated donors and T-replete or -depleted grafts: a case-matched analysis.

A retrospective, case-matched analysis of the short-term toxicity, risk of GVHD and relapse as well as outcome in pediatric unrelated marrow transplantation was conducted by comparing recipients of T-replete and -depleted grafts in a two-center setting. Both groups contained 30 patients with acute leukemia matched by age at transplant, gender, primary diagnosis and disease status. Acute (90% vs 53%) and chronic (48% vs 0%) GVHD were more common among recipients of T-replete grafts. No significant differences in graft rejection/failure or viral infections were encountered between the two groups. Relapses were more prevalent (37% vs 15%) among recipients of T-depleted grafts. Outcome (EFS) was similar in the two groups. Consequently, in the analysis of transplant outcome, the higher risk of procedure-related, toxic complications among pediatric recipients of T-replete marrow grafts appears to be balanced by an increased risk of relapse among the recipients of T-depleted grafts.

Acute Disease↗
PubMed2000

Statement of current majority practices in graft-versus-host disease prophylaxis and treatment in children.

Great variations exist in the prophylaxis and treatment of GVHD in children undergoing allogeneic stem cell transplantation (SCT). The EBMT Working Party Paediatric Diseases (EBMT-WP PD) and the International BFM Study Group--Subcommittee Bone Marrow Transplantation (IBFM-SG), aimed at evaluating current local standards in the prevention and treatment of GVHD and steps which can be taken to achieve a uniform policy for the individual methods. Several conferences with their members assessed practices which are mainly applied or under investigation in children and identified where additional information is needed. For prevention of GVHD, the majority of the paediatric centres prefer CsA +/- MTX. Addition of folinic acid to MTX was considered for reduction of side-effects. During treatment of acute GVHD most centres administer prednisolone and whole blood level-adjusted CsA as medications of first choice. In cases of poor or no response to this therapy, additional immunosuppressive agents such as ATG, mycophenolate-mofetile and tacrolimus are being increasingly used. The treatment of chronic GVHD usually consists of various combinations of prednisolone and CsA. In severe cases, extracorporeal photopheresis, psoralene-UVA (PUVA) and thalidomide are administered.

Adolescent↗
PubMed2000

Systemic administration of a novel octapeptide, amylin-(1---8), increases bone volume in male mice.

Amylin increases bone mass when administered systemically to mice. However, because of its size, the full peptide is not an ideal candidate for the therapy of osteoporosis. The fragment, amylin-(1---8), stimulates osteoblast proliferation in vitro, although it is without effect on carbohydrate metabolism. The present study assessed the effects of daily administration of this peptide on sexually mature male mice for 4 wk. Amylin-(1---8) almost doubled histomorphometric indices of osteoblast activity but did not change measures of bone resorption. Trabecular bone volume increased by 36% as a result of increases in both trabecular number and trabecular thickness, and tibial cortical width increased by 8%. On three-point bending tests of bone strength, displacement to fracture was increased by amylin-(1---8), from 0.302 +/- 0.013 to 0.351 +/- 0. 017 mm (P = 0.02). In a separate experiment using dynamic histomorphometry with bone-seeking fluorochrome labels, amylin-(1---8) was administered by local injection over the calvariae of female mice. Amylin-(1---8) (40 nM) increased the double-labeled surface threefold. The effect was dose dependent from 0.4 to 40 nM and was greater than that of an equimolar dose of human parathyroid hormone-(1---34) [hPTH-(1---34)]. Mineral apposition rate was increased by 40 nM amylin-(1---8) but not by hPTH-(1---34). Amylin-(1---8) thus has significant anabolic effects in vivo, suggesting that this peptide or analogs of it should be further evaluated as potential therapies for osteoporosis.

Amyloid↗
PubMed2000

Enhanced RANK ligand expression and responsivity of bone marrow cells in Paget's disease of bone.

Paget's disease is characterized by highly localized areas of increased osteoclast (OCL) activity. This suggests that the microenvironment in pagetic lesions is highly osteoclastogenic, or that OCL precursors in these lesions are hyperresponsive to osteoclastogenic factors (or both). To examine these possibilities, we compared RANK ligand (RANKL) mRNA expression in a marrow stromal cell line developed from a pagetic lesion (PSV10) with that in a normal stromal cell line (Saka), and expression in marrow samples from affected bones of Paget's patients with that in normal marrow. RANKL mRNA was increased in PSV10 cells and pagetic marrow compared with Saka cells and normal marrow, and was also increased in marrow from affected bones compared with uninvolved bones from Paget's patients. Furthermore, pagetic marrow cells formed OCLs at much lower RANKL concentrations than did normal marrow. Anti-IL-6 decreased the RANKL responsivity of pagetic marrow to normal levels, whereas addition of IL-6 to normal marrow enhanced RANKL responsivity. Thus, RANKL expression and responsivity is increased in pagetic lesions, in part mediated by IL-6. These data suggest that the combination of enhanced expression of RANKL in affected bones and increased RANKL sensitivity of pagetic OCL precursors may contribute to the elevated numbers of OCLs in Paget's disease.

Antibodies↗
PubMed2000

Amantadine in the treatment of cocaine-dependent patients with severe withdrawal symptoms.

OBJECTIVE: The study examined the effectiveness of amantadine in reducing cocaine withdrawal symptoms and improving treatment outcome among cocaine-dependent patients in outpatient treatment. METHOD: Sixty-one cocaine-dependent subjects participated in a double-blind, placebo-controlled trial of amantadine. RESULTS: Among subjects with severe cocaine withdrawal symptoms at the start of treatment, those who received amantadine used significantly less cocaine during the trial than did subjects who received placebo. Compared to subjects who received placebo, subjects who received amantadine submitted significantly more benzoylecgonine-negative urine samples and used cocaine on significantly fewer days during the trial. CONCLUSIONS: Amantadine may be an effective treatment for cocaine-dependent patients with severe cocaine withdrawal symptoms.

Amantadine↗
PubMed2000

1,25-Dihydroxyvitamin D3 hypersensitivity of osteoclast precursors from patients with Paget's disease.

Our previous studies suggested that increased osteoclast formation and activity in Paget's disease may be related in part to increased responsiveness of highly purified osteoclast precursors to 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. However, the basis for this enhanced sensitivity to 1,25-(OH)2D3 is unclear. To address this question, we examined 24-hydroxylase and 1,25-(OH)2D3 receptor (VDR) messenger RNA (mRNA) expression during human osteoclast differentiation from normal subjects and patients with Paget's disease in response to 1,25-(OH)2D3 as well as VDR content and affinity. Reverse-transcription polymerase chain reaction (RT-PCR) analysis of granulocyte-macrophage colony-forming unit (GM-CFU), the earliest identifiable osteoclast precursor, derived from patients with Paget's disease demonstrated 24-hydroxylase mRNA expression in response to 1,25-(OH)2D3 was induced at concentrations of 1,25-(OH)2D3 that were at least one log less than that required for normal GM-CFU. VDR mRNA and VDR protein were detected in both immature and more differentiated osteoclast precursors, as well as in osteoclast-like multinucleated cells (MNCs). However, VDR expression was lower in MNCs than the mononuclear precursor cells. Osteoclast precursors and MNCs from patients with Paget's disease had levels of VDR expression similar to those of normal subjects but showed increased VDR affinity for 1,25-(OH)2D3. Because the effects of 1,25-(OH)2D3 are in part mediated by induction of expression of RANK ligand on marrow stromal cells, which in turn stimulates osteoclast formation, we examined expression of RANK ligand mRNA by marrow stromal cell lines derived from patients with Paget's disease and normal subjects in response to 1,25-(OH)2D3. RT-PCR analysis showed no difference in sensitivity of marrow stromal cells to 1,25-(OH)2D3 from normal subjects or patients with Paget's disease although the Paget's stromal cells expressed increased basal levels of RANK ligand mRNA. These results show that VDR protein is expressed in early and more differentiated osteoclast precursors, that expression levels of VDR decline with osteoclast differentiation, and that 1,25-(OH)2D3 has direct effects on osteoclast precursors. The enhanced sensitivity to 1,25-(OH)2D3 is an intrinsic property of osteoclast precursors from patients with Paget's disease that distinguishes them from normal osteoclast precursors. Furthermore, our results suggest that an increased affinity of VDR for 1,25-(OH)2D3 may be responsible for the enhanced 1,25-(OH)2D3 sensitivity of osteoclast precursors in patients with Paget's disease compared with normal subjects.

Adult↗
PubMed2000

Evidence for a major gene for bone mineral density in idiopathic osteoporotic families.

Although there have been a number of studies indicating a heritable component for osteoporosis in middle to late adulthood, the etiology of osteoporosis in young people is uncertain. The present study aims to evaluate the extent to which genetic factors influence familial resemblance for bone mineral density (BMD) in families ascertained on the basis of young osteoporotic probands. The sample comprises eight families (74 total individuals) that were identified through a proband under the age of 35 years with a history of two or more fractures and a spinal bone density of at least 2.5 SDs below the mean for age and sex (Z score). Secondary causes of osteoporosis were excluded in the probands. In total, 27% (18/66) of the probands' relatives had osteoporosis and an additional 30% (20/66) had osteopenia. Classical segregation analysis was performed to evaluate the extent to which a genetic etiology could account for familial resemblance in these families. The results indicate a major gene of codominant inheritance for spinal BMD. Model-fitting comparisons revealed no support for environmental effects or for polygenic inheritance.

Adolescent↗
PubMed1999

Attenuation of the euphoric effects of cocaine by the dopamine D1/D5 antagonist ecopipam (SCH 39166)

BACKGROUND: The subjective and reinforcing effects of cocaine in humans are associated with the enhancement of endogenous dopamine function in the mesolimbic system. This study examined the role of dopamine D1-like receptors in the behavioral and mood effects of cocaine by evaluating the effects of the selective D1/D5 antagonist ecopipam (SCH 39166) on subjective responses to intravenous cocaine in 11 subjects with cocaine dependence as defined by DSM-IV. METHODS: Subjects were pretreated in a randomized double-blind fashion with either placebo or 10 mg, 25 mg, or 100 mg of ecopipam orally on 4 separate occasions. Two hours later a single intravenous injection of 30 mg of cocaine was administered. Subjective and cardiovascular responses were measured and blood samples for pharmacokinetic evaluation were obtained prior to cocaine dosing and at various times after dosing. RESULTS: The euphoric (P = .004) and stimulating (P = .03) effects of cocaine were attenuated in a dose-dependent manner by ecopipam, while ratings of desire to take cocaine were diminished (P = .02). Ecopipam in combination with cocaine was safe and well tolerated. CONCLUSION: These data indicate a potentially important role for D1-like receptors in the acute mood-altering and rewarding effects of cocaine in humans.

Adult↗
PubMed1999

Role of surgical biopsies in the management of bone marrow transplant patients.

BACKGROUND: Bone marrow transplantation (BMT) patients frequently develop life-threatening problems that have similar clinical presentations but differing aetiologies. Despite intensive investigation by haematological, biochemical, and microbiological means, accurate diagnosis is not always possible. Histological and microbiological examination of biopsies from the affected organ may be indicated to enable an accurate diagnosis to be made in these patients. Here we assess the indications, findings, and outcomes in patients who have required surgical biopsy after BMT. PROCEDURE: We retrospectively reviewed all BMT patients who had surgical biopsies between February 1994 and January 1997. Twenty-six patients (1-46 years, median age 10 years) underwent 40 biopsies from the upper and lower GI tract, lung, or liver. Indications for BMT were: relapsed leukaemia = 18; other types of leukaemia = 3; aplastic anaemia=3; other diseases = 2. Type of BMT: matched related donor = 3, unrelated T-cell depleted donor = 23. RESULTS: Eleven (42%) cases had a change in management; 4 (16%) patients avoided further aggressive therapy because of poor prognosis. Unexpected diagnoses were found in 7 biopsies: 1 acute colitis, 1 duodenal ulcer, 1 liver aspergilloma, 2 transfusion siderosis, 1 radiation fibrosis of the lung, and 1 cytomegalovirus infection of the lung. Three patients were noted to have complications after their procedure. CONCLUSIONS: Surgical biopsies for undiagnosed problems can be of benefit in the management of very sick patients who have received bone marrow transplantations. Despite the fact that these patients are so unwell, there is a low rate of complications related to surgery and anaesthesia.

Adolescent↗
PubMed1999

Measles virus nucleocapsid transcript expression is not restricted to the osteoclast lineage in patients with Paget's disease of bone.

Abundant evidence supports a viral etiology for Paget's disease of bone (PD), however, an infectious virus has not been isolated from PD patients. Thus, it is unclear how the virus is maintained for the many years that the disease persists in patients. We considered if a primitive multipotential hematopoietic stem cell (HSC), which is self-renewing, passes the virus to its differentiated progeny and serves as a reservoir for the pathogen. If a primitive stem cell harbored measles virus (MV), then other hematopoietic lineages derived from this stem cell in PD patients should also express MV transcripts. Therefore, because the human hematopoietic stem cell has not been clearly identified or isolated in large numbers, we isolated RNA from highly purified erythroid and multipotential hematopoietic progenitors that are the precursors for erythroid, granulocyte, megakaryocyte and macrophages (CFU-GEMM), and used RT-PCR to determine if MV nucleocapsid transcripts were present. MV transcripts were detected in PD patients in early erythroid (BFU-E) and more primitive multipotential myeloid progenitors (CFU-GEMM). Nonhematopoietic stromal cells from PD patients did not express MV transcripts. The expression of MV transcripts in erythroid progenitors was further confirmed by in situ hybridization using antisense riboprobes to MV nucleocapsid transcripts. Thus, our findings suggest that the pluripotent HSCs may be a potential reservoir for the virus. We propose that when HSCs, which contain MV, divide they produce a second HSC that serves as a reservoir for the virus and also transmit the virus to their more differentiated progeny in the erythroid and myeloid lineages. This mechanism would permit a defective virus to persist in HSCs of PD patients for many years, since HSCs are usually in G0 phase, and then be transmitted to more differentiated cells. This model further suggests that a mature complete virus that affects cell function could only act pathogenetically in the osteoclast lineage, which offers a permissive milieu.

Antigens, CD34↗
PubMed1999

Trifluoroacetate, a contaminant in purified proteins, inhibits proliferation of osteoblasts and chondrocytes.

Peptides purified by HPLC are often in the form of a trifluoroacetate (TFA) salt, because trifluoroacetic acid is used as a solvent in reversed-phase HPLC separation. However, the potential effects of this contaminant in culture systems have not been addressed previously. TFA (10(-8) to 10(-7) M) reduced cell numbers and thymidine incorporation into fetal rat osteoblast cultures after 24 h. Similar effects were found in cultures of articular chondrocytes and neonatal mouse calvariae, indicating that the effect is not specific to one cell type or to one species of origin. When the activities of the TFA and hydrochloride salts of amylin, amylin-(1-8), and calcitonin were compared in osteoblasts, cell proliferation was consistently less with the TFA salts of these peptides, resulting in failure to detect a proliferative effect or wrongly attributing an antiproliferative effect. This finding is likely to be relevant to all studies of purified peptides in concentrations above 10(-9) M in whatever cell or tissue type. Such peptides should be converted to a hydrochloride or biologically equivalent salt before assessment of their biological effects is undertaken.

Amyloid↗