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Biomedical subjects

J Elliott

Publications and source records attributed to J Elliott.

At least 109 records · Page 6Linked to original sources
PubMed1998

Plasma 5-hydroxytryptamine constricts equine digital blood vessels in vitro: implications for pathogenesis of acute laminitis.

Cumulative concentration response curves to 5-hydroxytryptamine (5-HT; 10(-10)-10(-4) mol/l) were constructed using isolated rings of equine digital, facial, tail and coronary arteries (endothelium intact). 5-HT was 17.7 and 41 times more potent as a vasoconstrictor of digital arteries than facial and tail arteries respectively. Removal of the endothelium increased the vasoconstrictor potency of 5-HT in the facial artery by 3.7-fold (P<0.05) but did not alter the sensitivity of digital arteries to 5-HT. Coronary arteries failed to contract to 5-HT. Coronary arteries pre-contracted with U44069 showed concentration dependent relaxation to 5-HT, a response which was partially dependent on the presence of the endothelium. No vasorelaxant effects were found in the digital or facial arteries. The concentration of 5-HT in platelet poor and platelet rich equine plasma was found to be 6.70+/-1.1 x 10(-8) mol/l and 1.77+/-0.36 x 10(-6) mol/l (mean +/-s.e.) respectively by high performance liquid chromatography (HPLC). Plasma which contained no detectable platelets had a 5-HT concentration of 1.12+/-0.48 x 10(-8) mol/l. Isolated digital arteries constricted when exposed to dilutions of platelet poor and platelet depleted equine plasma. These plasma induced contractions were almost completely inhibited by 5-HT receptor antagonists, ketanserin and methiothepin. The change in isometric tension in rings of equine digital artery in vitro was therefore used as a bioassay for plasma 5-HT and the results obtained by this method showed an excellent correlation (r2 = 97.2%, P<0.001) with the concentration estimated by HPLC. Circulating free concentrations of 5-HT in normal horses may be sufficient to constrict digital blood vessels partially in vivo but are well below the threshold for contraction of other peripheral blood vessels examined.

Animals↗
PubMed1998

Streptomyces griseus protease B: secretion correlates with the length of the propeptide.

Streptomyces griseus protease B, a member of the chymotrypsin superfamily, is encoded by a gene that express a pre-pro-mature protein. During secretion the precursor protein is processed into a mature, fully folded protease. In this study, we constructed a family of genes which encode deletions at the amino-terminal end of the propeptide. The secretion of active protease B was seen to decrease in an exponential manner according to the length of the deletion. The results underscore the intimate relationship between folding and secretion in bacterial protease expression. They further suggest that the propeptide segment of the zymogen stabilizes the folding of the mature through many small binding interactions over the entire surface of the peptide rather than through a few specific contacts.

Binding Sites↗
PubMed1998

Structural organization of virulence-associated plasmids of Yersinia pestis.

The complete nucleotide sequence and gene organization of the three virulence plasmids from Yersinia pestis KIM5 were determined. Plasmid pPCP1 (9,610 bp) has a GC content of 45.3% and encodes two previously known virulence factors, an associated protein, and a single copy of IS100. Plasmid pCD1 (70,504 bp) has a GC content of 44.8%. It is known to encode a number of essential virulence determinants, regulatory functions, and a multiprotein secretory system comprising the low-calcium response stimulation that is shared with the other two Yersinia species pathogenic for humans (Y. pseudotuberculosis and Y. enterocolitica). A new pseudogene, which occurs as an intact gene in the Y. enterocolitica and Y. pseudotuberculosis-derived analogues, was found in pCD1. It corresponds to that encoding the lipoprotein YlpA. Several intact and partial insertion sequences and/or transposons were also found in pCD1, as well as six putative structural genes with high homology to proteins of unknown function in other yersiniae. The sequences of the genes involved in the replication of pCD1 are highly homologous to those of the cognate plasmids in Y. pseudotuberculosis and Y. enterocolitica, but their localization within the plasmid differs markedly from those of the latter. Plasmid pMT1 (100,984 bp) has a GC content of 50.2%. It possesses two copies of IS100, which are located 25 kb apart and in opposite orientations. Adjacent to one of these IS100 inserts is a partial copy of IS285. A single copy of an IS200-like element (recently named IS1541) was also located in pMT1. In addition to 5 previously described genes, such as murine toxin, capsule antigen, capsule anchoring protein, etc., 30 homologues to genes of several bacterial species were found in this plasmid, and another 44 open reading frames without homology to any known or hypothetical protein in the databases were predicted.

Base Composition↗
PubMed1998

A combination of osteoclast differentiation factor and macrophage-colony stimulating factor is sufficient for both human and mouse osteoclast formation in vitro.

Both human and murine osteoclasts can be derived in vitro from hematopoietic cells or monocytes that are co-cultured with osteoblasts or marrow-derived stromal cells. The osteoclastogenic stimulus provided by murine osteoblasts and marrow-derived stromal cells is now known to be mediated by osteoclast differentiation factor (ODF), a membrane-bound tumor necrosis factor-related ligand. This study demonstrates that mouse spleen cells and monocytes form osteoclasts when cultured in the presence of macrophage-colony stimulating factor (M-CSF) and a soluble form of murine ODF (sODF). Numerous multinucleated osteoclasts expressing tartrate resistant acid phosphatase (TRAP) and calcitonin receptor (CTR) formed within 7 days of culture and engaged in extensive lacunar bone resorption. Osteoclast number and bone resorption area was dependent on sODF concentration. Long-term cultured human monocytes also formed bone resorbing osteoclasts in response to co-stimulation by sODF and M-CSF, although this required more than 11 days in culture. This human osteoclast differentiation was strongly inhibited by granulocyte-macrophage colony stimulating factor. This study further characterises murine osteoclast differentiation caused by sODF and M-CSF co-stimulation in vitro, and shows that the same co-stimulation causes human osteoclast differentiation to occur. We propose that this methodology can be employed to investigate the direct effects of cytokines and other factors on human osteoclast differentiation.

Acid Phosphatase↗
PubMed1998

Osteotropic agents regulate the expression of osteoclast differentiation factor and osteoprotegerin in osteoblastic stromal cells.

The osteoclastogenic factor of osteoblastic origin has recently been elucidated as a novel Tumor Necrosis Factor (TNF)-ligand family member, termed osteoclast differentiation factor (ODF). Using a semiquantitative RT-PCR approach, we sought to determine the mRNA expression of ODF and its decoy receptor, osteoprotegerin (OPG), in a selection of osteoblastic cell lines and in response to three factors representative of different signal transduction pathways, vitamin D receptor, protein kinase A or gp130. Each osteotropic agent, either 1,25-(OH)2D3, PTH or IL-11, promoted an increase in the ratio of ODF:OPG, with maximal stimulation occurring at 24 h, 4 h, and 8 h, respectively, and furthermore each was shown to act in a dose-dependent manner. This report establishes that osteoblastic cell lines incapable of supporting osteoclast formation have markedly reduced ODF expression and also illustrates the importance of the relative abundance of ODF compared with the levels of OPG for the induction of osteoclastogenesis.

Animals↗
PubMed1998

Comparison of various antibiotic treatments for cows diagnosed with toxic puerperal metritis.

Holstein cows (n = 51) that had been diagnosed with toxic puerperal metritis were used to determine the treatment efficacy of various antibiotics. On the day of diagnosis, cows affected with toxic puerperal metritis were assigned randomly to three treatment groups. Cows in groups 1 and 2 received 22,000 IU/kg of procaine penicillin G i.m. for 5 d. In addition, cows in group 2 received an intrauterine infusion of 6 g of oxytetracycline on d 1, 3, and 5. Cows in group 3 received 2.2 mg/kg of ceftiofur sodium i.m. for 5 d. Dependent variables used to determine antibiotic efficacy included milk yield on d 1 through 12, rectal temperature on d 1 through 5, and serum haptoglobin concentration on d 1, 3, and 5. No difference was observed among groups for milk yield on d 1 and 12 or for temperature on d 1 and 5. Serum haptoglobin was elevated to > 10 mg/dl for cows in all groups; however, no difference was observed among groups on d 1 and 5. Because all groups showed a favorable response, this study suggests that there is no difference in treatment efficacy among antibiotics used to treat cows affected with toxic puerperal metritis.

Animals↗
PubMed1998

The urge to merge.

Explore the source record for details and available documents.

Capital Financing↗
PubMed1998

Countdown to the CPR. Survey of CPR vendors reflects industry growth.

While functions of computer-based patient record (CPR) systems are far from standard among vendors, many companies have done extensive development in the area of CPR systems. Our search for companies that provide some or all components of a CPR system has revealed the following list. Along with information that will help you locate and contact each company, we have provided details on each CPR product including hardware and software requirements and a brief description of the product (where provided by the company). For additional details on each vendor's system, please contact the vendor directly. Note: As much as we attempted to include every company with a CPR system, there may be some inadvertently missed. If your company is a CPR vendor, please make us aware so we can include your product in future resource issues.

Catalogs, Commercial as Topic↗
PubMed1998

Cutaneous vasculitis in a defined population--clinical and epidemiological associations.

OBJECTIVE: To examine the value of the American College of Rheumatology (ACR) 1990 criteria for Henoch-Schönlein purpura (HSP) and hypersensitivity vasculitis (HSV) and the Chapel Hill Consensus Conference (CHCC) definition of cutaneous leukocytoclastic angiitis (CLA) in the classification of cutaneous vasculitis and to estimate the annual incidence of biopsy proven cutaneous vasculitis in a well defined population. METHODS: ACR criteria for HSP and HSV and the CHCC definition for CLA and HSP were applied to an unselected cohort of 84 patients with biopsy proven cutaneous vasculitis attending a single district hospital in the United Kingdom between January 1990 and December 1994. RESULTS: Thirty-seven patients fulfilled ACR criteria for HSV, of whom 27 also fulfilled the ACR criteria for HSP. Thirty-two patients met the CHCC definition for CLA and 7 the CHCC definition for HSP. The overall annual incidence of cutaneous vasculitis was 38.6/million (95% CI 30.6-48.1), and for CLA 15.4/million (95% CI 10.6-21.8). CONCLUSION: The ACR 1990 criteria for HSP and HSV overlap; the CHCC definitions for CLA and HSP provide clearer distinction. Cutaneous vasculitis is as common as systemic vasculitis.

Antibodies, Antinuclear↗
PubMed1997

Tumor necrosis factor-alpha induces leukocyte recruitment by different mechanisms in vivo and in vitro.

It is well established that E-selectin is the endothelial adhesion molecule that is primarily responsible for mediating leukocyte rolling on TNF-alpha-stimulated cultured endothelial cells. Despite this, few studies in in vivo inflammatory models have observed reduced leukocyte accumulation using mAbs against E-selectin. The objective of this study was to compare the function of E-selectin on endothelial cells in vitro with its role in TNF-alpha-induced leukocyte recruitment in vivo using EL246, a mAb that blocks the function of E-selectin on activated feline endothelial cells. In vitro experiments using feline endothelial cells showed that EL246 functionally inhibits E-selectin-dependent leukocyte recruitment induced by TNF-alpha, without affecting the function of other rolling mechanisms. Intravital microscopy of single 25- to 40-microm venules in the feline mesentery was then used to examine leukocyte rolling and adhesion in response to superfusion with TNF-alpha. TNF-alpha treatment significantly increased the number of both rolling and adherent leukocytes and significantly decreased leukocyte rolling velocity. Treatment with EL246 (1 mg/kg), either i.v. at the start of the TNF-alpha protocol or directly into the superior mesenteric artery after 3 h of TNF-alpha treatment, had no effect on leukocyte rolling, adhesion, or rolling velocity. However, treatment with the selectin-binding carbohydrate, fucoidan, reduced leukocyte rolling to below baseline levels. These results suggest that in contrast to its prominent role on cultured endothelial cells, E-selectin does not contribute to leukocyte recruitment in TNF-alpha-stimulated feline mesenteric venules in vivo.

Animals↗
PubMed1997

Interleukin-18 (interferon-gamma-inducing factor) is produced by osteoblasts and acts via granulocyte/macrophage colony-stimulating factor and not via interferon-gamma to inhibit osteoclast formation.

We have established by differential display polymerase chain reaction of mRNA that interleukin (IL)-18 is expressed by osteoblastic stromal cells. The stromal cell populations used for comparison differed in their ability to promote osteoclast-like multinucleated cell (OCL) formation. mRNA for IL-18 was found to be expressed in greater abundance in lines that were unable to support OCL formation than in supportive cells. Recombinant IL-18 was found to inhibit OCL formation in cocultures of osteoblasts and hemopoietic cells of spleen or bone marrow origin. IL-18 inhibited OCL formation in the presence of osteoclastogenic agents including 1alpha,25-dihydroxyvitamin D3, prostaglandin E2, parathyroid hormone, IL-1, and IL-11. The inhibitory effect of IL-18 was limited to the early phase of the cocultures, which coincides with proliferation of hemopoietic precursors. IL-18 has been reported to induce interferon-gamma (IFN-gamma) and granulocyte/macrophage colony-stimulating factor (GM-CSF) production in T cells, and both agents also inhibit OCL formation in vitro. Neutralizing antibodies to GM-CSF were able to rescue IL-18 inhibition of OCL formation, whereas neutralizing antibodies to IFN-gamma did not. In cocultures with osteoblasts and spleen cells from IFN-gamma receptor type II-deficient mice, IL-18 was found to inhibit OCL formation, indicating that IL-18 acted independently of IFN-gamma production: IFN-gamma had no effect in these cocultures. Additionally, in cocultures in which spleen cells were derived from receptor-deficient mice and osteoblasts were from wild-type mice and vice versa, we identified that the target cells for IFN-gamma inhibition of OCL formation were the hemopoietic cells. The work provides evidence that IL-18 is expressed by osteoblasts and inhibits OCL formation via GM-CSF production and not via IFN-gamma production.

Animals↗
PubMed1997

Fetal fibronectin as a predictor of preterm birth in patients with symptoms: a multicenter trial.

OBJECTIVE: Our aim was to determine whether the presence of fetal fibronectin in vaginal secretions of patients with symptoms suggestive of preterm labor predicts preterm delivery. STUDY DESIGN: Patients who were examined at the hospital between 24 weeks' and 34 weeks 6 days' gestation with intact membranes, no prior tocolysis, symptoms suggestive of preterm labor, and cervical dilation < 3 cm were recruited at 10 sites. Swabs of the posterior fornix were assayed for the presence of fetal fibronectin by monoclonal antibody assay, with a positive result defined as > or = 50 ng/ml. Results were not available to the managing physicians. Tocolysis was used when clinically indicated after specimen collection. RESULTS: A total of 763 patients had fetal fibronectin results and pregnancy outcome data available for analysis. Fetal fibronectin was detected in specimens from 150 (20%) patients. Compared with patients who had negative results, patients who had positive results for fetal fibronectin were more likely to be delivered within 7 days (relative risk 25.9 [95% confidence interval 7.8 to 86]), within 14 days (relative risk 20.4 [95% confidence interval 8.0 to 53]), and before 37 completed weeks (relative risk 2.9 [95% confidence interval 2.2 to 3.7]). The negative predictive values for delivery within 7 days, within 14 days, and at < 37 weeks were 99.5%, 99.2%, and 84.5%, respectively. When we used multiple logistic regression analysis to control for potential confounding variables among singleton pregnancies, only the presence of fetal fibronectin (odds ratio 48.8, 95% confidence interval 7.4 to 320), prior preterm birth (odds ratio 8.3, 95% confidence interval 1.5 to 46.6), and tocolysis (odds ratio 4.1, 95% confidence interval 1.0 to 16.0) were associated with birth within 7 days; fetal fibronectin (odds ratio 3.6, 95% confidence interval 2.2 to 5.9), prior preterm birth (odds ratio 2.5, 95% confidence interval 1.4 to 4.4), cervical dilatation > 1 cm (odds ratio 2.9, 95% confidence interval 1.6 to 5.2), and tocolysis (odds ratio 4.5, 95% confidence interval 2.8 to 7.2) were all independently associated with delivery before 37 weeks. CONCLUSION: In a population of patients with symptoms, the presence of fetal fibronectin in vaginal secretions best defines a subgroup at increased risk for delivery within 7 days; the high negative predictive value of fetal fibronectin sampling supports less intervention for patients with this result.

Adult↗
PubMed1997

Tolerance to mu-opioid agonists in human neuroblastoma SH-SY5Y cells as determined by changes in guanosine-5'-O-(3-[35S]-thio)triphosphate binding.

1. The agonist action of morphine on membranes prepared from human neuroblastoma SH-SY5Y cells was measured by an increase in the binding of the GTP analogue [35S]-GTPgammaS. Morphine increased the binding of [35S]-GTPgammaS to SH-SY5Y cell membranes by 30 fmol mg(-1) protein with an EC50 value of 76 +/- 10 nM. 2. Incubation of SH-SY5Y cells with 10 microM morphine for 48 h caused a tolerance to morphine manifested by a 2.5 fold shift to the right in the EC50 value with a 31 +/- 6% decrease in the maximum stimulation of [35S]-GTPgammaS binding. The response caused by the partial agonist pentazocine was reduced to a greater extent. 3. Chronic treatment of the cells with the more efficacious mu-ligand [D-Ala2, MePhe4, Gly-ol5]enkephalin (DAMGO, 10 microM) for 48 h afforded a greater effect than treatment with morphine. The maximal agonist effect of morphine was reduced to 58.9 +/- 6% of that seen in control cells while the maximal effect of DAMGO was reduced to 62.8 +/- 4%. There was a complete loss of agonist activity for pentazocine. 4. The development of tolerance was complete within 24 h and was blocked by naloxone and by the nonselective protein kinase inhibitor H7, but not by the putative beta-adrenoceptor kinase (beta-ARK) inhibitor suramin. 5. The observed tolerance effect was accompanied by a down-regulation of mu-opioid receptors determined by a decrease in the maximal binding capacity for the opioid antagonist [3H]-diprenorphine of 66 +/- 4%, but with no change in binding affinity. Binding of the agonist [3H]-DAMGO was similarly reduced. 6. The modulation of [35S]-GTPgammaS binding in SH-SY5Y cell membranes by opioids provides a simple method for the study of opioid tolerance at a site early in the signal transduction cascade.

Drug Tolerance↗