Search PubMed⌕ Search

Biomedical subjects

H J Harris

Publications and source records attributed to H J Harris.

16 recordsLinked to original sources
PubMed2002

Validation of an indirect enzyme-linked immunosorbent assay for the detection of antibody against Brucella abortus in cattle sera using an automated ELISA workstation.

An automated indirect enzyme-linked immunosorbent assay (I-ELISA) for the serological diagnosis of bovine brucellosis was developed and validated in-house. A total of 4,803 cattle sera from South Africa (n = 3,643), Canada (n = 652), Germany (n = 240), France (n = 73) and the USA (n = 195) was used. The South African panel of sera represented 834 sera known to be positive by the Rose Bengal test (RBT), serum agglutination test (SAT) and complement fixation test (CFT), 2709 sera that were negative by CFT, and 100 sera from animals vaccinated with a standard dose of Brucella abortus strain 19. Overseas sera were obtained from reference non-vaccinated brucella-free cattle (n = 834), naturally infected (n = 72), experimentally infected (n = 71), and vaccinated animals (n = 83). Also 100 sera collected from cattle in Canada and known to be positive by competitive ELISA (C-ELISA) were used. The intermediate ranges ("borderline" range for the interpretation of test results) were derived from two-graph receiver operating characteristics analysis. The lowest values of the misclassification cost-term analysis obtained from testing overseas panels, covered lower I-ELISA cut-off PP values (0.02-3.0) than those from local panels (1.5-5.0). The relatively low cut-off PP values selected for I-ELISA were due to the fact that the positive control used represents a very strong standard compared to other reference positive sera. The greater overlap found between negative and positive cattle sera from South Africa than that between reference overseas panels was probably due to the different criteria used in classifying these panels as negative (sera from true non-diseased/non-infected animals) or positive (sera from true diseased/infected animals). The diagnostic sensitivity of the I-ELISA (at the optimum cut-off value) was 100% and of the CFT 83.3%. The diagnostic specificity of I-ELISA was 99.8% and of the CFT 100%. Estimate of Youden's index was higher for the I-ELISA (0.998) than that for the CFT (0.833). Analysis of distribution of PP values in sera from vaccinated and naturally infected cattle shows that in vaccinated animals all readings were below 31 PP where in infected ones these values represented 43%. Therefore, it appears that I-ELISA could be of use in identifying some naturally infected animals (with values > 31 PP), but more sera from reference vaccinated and infected animals need to be tested to further substantiate this statistically. Of 834 sera positive by RBT, SAT and CFT, 825 (98.9%) were positive in the I-ELISA. Compared to C-ELISA the relative diagnostic sensitivity of the I-ELISA was 94% and of the CFT 88% when testing 100 Canadian cattle sera. Of 258 South African cattle sera, of which 183 (70.9 %) were positive by the I-ELISA and 148 (57.4 %) by the CFT, 197 (76.4%) were positive by C-ELISA when re-tested in Canada. One has to stress, however, that Canadian C-ELISA has not been optimised locally. Thus, the C-ELISA was probably not used at the best diagnostic threshold for testing South African cattle sera. This study shows that the I-ELISA performed on an automated ELISA workstation provides a rapid, simple, highly sensitive and specific diagnostic system for large-scale detection of antibodies against B. abortus. Based on the diagnostic accuracy of this assay reported here, the authors suggest that it could replace not only the currently used confirmatory CFT test, but also the two in-use screening tests, namely the RBT and SAT.

Agglutination Tests↗
PubMed2001

Intracellular regeneration of glucocorticoids by 11beta-hydroxysteroid dehydrogenase (11beta-HSD)-1 plays a key role in regulation of the hypothalamic-pituitary-adrenal axis: analysis of 11beta-HSD-1-deficient mice.

11beta-Hydroxysteroid dehydrogenases (11beta-HSDs) catalyze interconversion of active corticosterone and inert 11-dehydrocorticosterone, thus regulating glucocorticoid access to intracellular receptors in vivo. 11beta-HSD type 1 is a reductase, locally regenerating active glucocorticoids. To explore the role of this isozyme in the brain, we examined hypothalamic-pituitary-adrenal axis (HPA) regulation in mice homozygous for a targeted disruption of the 11beta-HSD-1 gene. 11beta-HSD-1-deficient mice showed elevated plasma corticosterone and ACTH levels at the diurnal nadir, with a prolonged corticosterone peak, suggesting abnormal HPA control and enhanced circadian HPA drive. Despite elevated corticosterone levels, several hippocampal and hypothalamic glucocorticoid-sensitive messenger RNAs were normally expressed in 11beta-HSD-1-deficient mice, implying reduced effective glucocorticoid activity within neurons. 11beta-HSD-1-deficient mice showed exaggerated ACTH and corticosterone responses to restraint stress, with a delayed fall after stress, suggesting diminished glucocorticoid feedback. Indeed, 11beta-HSD-1-deficient mice were less sensitive to exogenous cortisol suppression of HPA activation. Thus 11beta-HSD-1 amplifies glucocorticoid feedback on the HPA axis and is an important regulator of neuronal glucocorticoid exposure under both basal and stress conditions in vivo.

11-beta-Hydroxysteroid Dehydrogenase Type 1↗
PubMed1999

The annexin protein lipocortin 1 regulates the MAPK/ERK pathway.

Lipocortin 1 (annexin 1) is a calcium- and phospholipid-binding protein that modulates anti-inflammatory responses including those induced by lipopolysaccharide. To investigate the precise role of lipocortin 1 in regulating the lipopolysaccharide-induced signal transduction pathways, we generated stable RAW 264.7 macrophage cell lines expressing decreased and increased lipocortin 1 protein. Several RAW 264.7 clones with increased lipocortin 1 protein levels showed constitutive activation of the mitogen-activated protein kinase extracellular signal-regulated kinase, which was down-regulated following lipopolysaccharide treatment. Conversely, clones with decreased lipocortin 1 protein expression showed prolonged extracellular signal-regulated kinase activity, following lipopolysaccharide activation. Lipocortin 1 specifically regulates the components of the extracellular signal-regulated kinase pathway, since changes in lipocortin 1 protein expression had no affect on the related mitogen-activated protein kinases p38 and c-Jun N-terminal kinase. Lipocortin 1 modulated upstream components of the extracellular signal-regulated kinase pathway and associated with the adaptor protein growth factor binding protein. The downstream consequences of altered extracellular signal-regulated kinase activity were independent of the proinflammatory transcription factor nuclear factor kappa B. These data indicate that lipocortin 1 specifically regulates proximal signaling components of the extracellular signal-regulated kinase signal transduction pathway, resulting in the modulation of biochemical functions in RAW macrophages.

Adaptor Proteins, Signal Transducing↗
PubMed1999

The glucocorticoid receptor is essential for maintaining basal and dexamethasone-induced repression of the murine corticosteroid-binding globulin gene.

We have investigated hepatic expression and glucocorticoid regulation of the corticosteroid-binding globulin (CBG) gene in mice lacking a functional glucocorticoid receptor (GR). GR-/- mice show impaired negative feedback in the hypothalamic-pituitary-adrenal axis, resulting in elevated circulating levels of ACTH and corticosterone. This is seen in the neonatal period and continues into adulthood where ACTH and corticosterone levels are increased up to 4-5 fold. Despite high elevation of corticosterone we find no change in mean arterial blood pressure in GR-/- mice and no change in the renal activity of the glucocorticoid-metabolising enzymes 11beta-hydroxysteroid dehydrogenase type-1 (HSD1) and type-2 (HSD2). We do find markedly increased hepatic expression of CBG with a 50% increase in plasma CBG levels. Increased expression of CBG was detected in adult GR-/- mice and also at birth with a greater than 10-fold increase in CBG hepatic mRNA in day-18.5 embryonic GR-/- mice. Adult GR-/- mice were also resistant to dexamethasone-induced repression of CBG expression in the liver. These results indicate that in mice, GR is essential for maintaining the basal level of CBG gene expression in the liver, and is also required for dexamethasone-induced repression of the CBG gene in the adult.

Adrenocorticotropic Hormone↗
PubMed1996

Acute inflammatory response in the mouse: exacerbation by immunoneutralization of lipocortin 1.

1. An immuno-neutralization strategy was employed to investigate the role of endogenous lipocortin 1 (LC1) in acute inflammation in the mouse. 2. Mice were treated subcutaneously with phosphate-buffered solution (PBS), non-immune sheep serum (NSS) or with one of two sheep antisera raised against LC1 (LCS3), or its N-terminal peptide (LCPS1), three times over a period of seven days. Twenty four hours after the last injection several parameters of acute inflammation were measured including zymosan-induced inflammation in 6-day-old air-pouches, zymosan-activated serum (ZAS)-induced oedema in the skin, platelet-activating factor (PAF)-induced neutrophilia and interleukin-1 beta (IL-1 beta)-induced corticosterone (CCS) release. 3. At the 4 h time-point of the zymosan inflamed air-pouch model, treatment with LCS3 did not modify the number of polymorphonuclear leucocytes (PMN) recruited: 7.84 +/- 1.01 and 7.00 +/- 0.77 x 10(6) PMN per mouse for NSS- and LCS3 group, n = 7. However, several other parameters of cell activation including myeloperoxidase (MPO) and elastase activities were increased (2.2 fold, P < 0.05, and 6.5 fold, P < 0.05, respectively) in the lavage fluids of these mice. Similarly, a significant increase in the amount of immunoreactive prostaglandin E2 (PGE2; 1.81 fold, P < 0.05) and IL-1 alpha (2.75 fold, P < 0.05), but not tumour necrosis factor-alpha (TNF-alpha), was also observed in LCS3-treated mice. 4. The recruitment of PMN into the zymosan inflamed air-pouches by 24 h had declined substantially (4.13 +/- 0.61 x 10(6) PMN per mouse, n = 12) in the NSS-treated mice, whereas high values were still measured in those treated with LCS3 (9.35 +/- 1.20 x 10(6) PMN per mouse, n = 12, P < 0.05). A similar effect was also found following sub-chronic treatment of mice with LCPS1: 6.48 +/- 0.10 x 10(6) PMN per mouse, vs. 2.77 +/- 1.20 and 2.64 +/- 0.49 x 10(6) PMN per mouse for PBS- and NSS-treated groups (n = 7, P < 0.05). Most markers of inflammation were also increased in the lavage fluids of LCS3-treated mice: MPO and elastase showed a 2.47 fold and 17 fold increase, respectively (P < 0.05 in both cases); TNF-alpha showed a 11.1 fold increase (P < 0.05) whereas the IL-1 alpha levels were not significantly modified. PGE2 was still detectable in most (5 out of 7) of the mice treated with LCS3 but only in 2 out of 7 of the NSS-treated mice. 5. Intradermal injection of 50% ZAS caused a significant increase in the 2 hoedema formation in the skin of LCS3-treated mice in comparison to PBS- and NSS-treated animals: 16.7 +/- 1.5 microliters vs. 10.8 +/- 1.2 microliters and 10.2 +/- 1.0 microliters, respectively (n = 14 mice per group, P < 0.05). ZAS-induced oedema had subsided by 24 h in control animals but a residual significant amount of extravasation was still detectable in LCS3-treated mice: 4.4 +/- 0.8 microliters (P < 0.05). 6. A recently described model driven by endogenous glucocorticoids is the blood neutrophilia observed following administration of PAF. In our experimental conditions, a single bolus of PAF (100 ng, i.v.) provoked a marked neutrophilia at 2 h (2.43 and 2.01 fold) in NSS- and PBS-treated mice (n = 11), respectively, which was significantly attenuated in the animals treated with LCS3: 1.26 fold increase in circulating PMN (n = 11, P < 0.01 vs. NSS- and PBS-groups). 7. Intraperitoneal injection of IL-1 beta (5 micrograms kg-1) caused a marked increase in circulating plasma CCS by 2 h, to a similar extent in all experimental groups. In contrast, measurement of CCS levels in the plasma of mice bearing air-pouches inflamed with zymosan revealed significant differences between LCS3 and NSS-treated mice at the 4 h time-point: 198 +/- 26 ng ml-1 vs. 110 +/- 31 ng ml-1 (n = 8, P < 0.05). 8. In conclusion, we found a remarkable exacerbation of the inflammatory process with respect to both humoral and cellular components in mice passively immunised agains

Animals↗
PubMed1995

Effect of rolipram in a murine model of acute inflammation: comparison with the corticoid dexamethasone.

Treatment of mice with rolipram, a phosphodiesterase type 4 inhibitor, selectively modified the acute inflammatory reaction elicited by zymosan administration in 6-day-old mouse air-pouches. Rolipram (1-10 mg kg-1, i.p.) prevented the rise of endogenous tumor necrosis factor-alpha (TNF-alpha) in the lavage fluids (approximately 60% inhibition) induced by zymosan, with no effect upon interleukin-1 alpha levels. This action was not accompanied by changes in neutrophil accumulation, but the amount of elastase released in the lavage fluids was significantly reduced (approximately 50%). Dexamethasone (1.5 mg kg-1, i.v.), used for comparative purposes, significantly reduced the release of TNF-alpha (> 50%), interleukin-1 alpha (> 70%) and cellular infiltration (approximately 50%), but had only a marginal effect on the release of elastase activity. In conclusion, in this murine model of acute inflammation induced by zymosan, rolipram inhibited the endogenous TNF-alpha production at a local site of inflammation, such as the subcutaneous air-pouch, and prevented the full activation of migrated cells.

Acute Disease↗
PubMed1990

Endothelial cells metabolize NG-monomethyl-L-arginine to L-citrulline and subsequently to L-arginine.

NG-monomethyl-L-arginine (MeArg) inhibits the release of endothelium-derived relaxing factor (EDRF) from endothelial cells (EC) and the formation of nitric oxide (NO) from L-arginine (Arg) in EC and activated macrophages. We have compared the inhibitory potency of MeArg to that of N omega-nitro-L-arginine (NO2Arg), a more potent inhibitor of EDRF synthesis in vitro. NO2Arg (100 microM) was significantly more potent than MeArg in inhibiting the endothelium-dependent relaxation of rabbit aorta induced by acetylcholine. MeArg and NO2Arg (10 and 30 microM) also inhibited the release of EDRF from bovine aortic cultured EC. In the anaesthetized rat in vivo, the pressor effect of NO2Arg (3 and 10 mg kg-1) was significantly larger and longer lasting than that of MeArg. These differences in potency could be due to the extensive metabolism of MeArg but not NO2Arg to L-citrulline (Cit) and subsequently to Arg by EC. The enzyme responsible for the conversion of MeArg to Cit had the characteristics of a novel deiminase, NG,NG-dimethylarginine dimethylaminohydrolase, recently isolated from rat kidney.

Acetylcholine↗
PubMed1990

The metabolism of L-arginine and its significance for the biosynthesis of endothelium-derived relaxing factor: cultured endothelial cells recycle L-citrulline to L-arginine.

We have investigated the mechanism by which cultured endothelial cells generate L-arginine (L-Arg), the substrate for the biosynthesis of endothelium-derived relaxing factor. When Arg-depleted endothelial cells were incubated in Krebs' solution for 60 min, L-Arg levels were significantly (9.7-fold) elevated. The generation of L-Arg coincided with a substantial decrease (90%) in intracellular L-glutamine (L-Gln), whereas all other amino acids were virtually unaffected. Changes in calcium, pH, or oxygen tension had no effect on L-Arg generation, which was, however, prevented when the cells were incubated in culture medium containing L-Gln. L-Arg generated by endothelial cells labeled with L-[14C]Arg was derived from an unlabeled intracellular source, for the specific activity of the intracellular L-Arg pool decreased substantially (8.8-fold) over 60 min. Arg-depleted endothelial cells did not form urea or metabolize L-ornithine but converted L-citrulline (L-Cit) to L-Arg possibly via formation of L-argininosuccinic acid. Nondepleted cells stimulated with the calcium ionophore A23187 showed only a transient accumulation of L-Cit, indicating that L-Cit is recycled to L-Arg during the biosynthesis of endothelium-derived relaxing factor. The generation of L-Arg by Arg-depleted endothelial cells was partially (45%) blocked by protease inhibitors, and various Arg-containing dipeptides were rapidly cleaved to yield L-Arg. Thus, cultured endothelial cells recycle L-Cit to L-Arg and possibly liberate peptidyl L-Arg. The Arg-Cit cycle appears to be the equivalent in the endothelial cell to the formation of urea by the liver. The biosynthesis of endothelium-derived relaxing factor may, therefore, not only produce a powerful vasodilator but also relieve the endothelial cell of excess nitrogen.

Animals↗
PubMed1989

Microcontaminants and reproductive impairment of the Forster's tern on Green Bay, Lake Michigan--1983.

For the 1983 nesting season, Forster's tern (Sterna forsteri) reproductive success was significantly impaired on organochlorine contaminated Green Bay, Lake Michigan compared to a relatively uncontaminated inland location at Lake Poygan, Wisconsin. Compared with tern eggs from Lake Poygan, eggs from Green Bay had significantly higher median concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), other polychlorinated dibenzo-p-dioxins (PCDDs), total polychlorinated biphenyls (PCBs), total (three congeners) non-ortho, ortho' PCBs, five individual PCB congeners known to induce aryl hydrocarbon hydroxylase (AHH) and several other organochlorine contaminants. Conversions of analytical concentrations of TCDD and PCB congeners based on relative AHH induction potencies allowed for estimation of total 2,3,7,8-TCDD equivalents. Two PCB congeners, 2,3,3',4,4'- and 3,3',4,4',5-pentachlorobiphenyl (PeCB) accounted for more than 90% of the median estimated TCDD equivalents at both Green Bay and Lake Poygan. The median estimated TCDD equivalents were almost 11-fold higher in tern eggs from Green Bay than in eggs from Lake Poygan (2175 and 201 pg/g). The hatching success of Green Bay sibling eggs from nests where eggs were collected for contaminant analyses was 75% lower at Green Bay than at Lake Poygan. Hatchability of eggs taken from other nests and artificially incubated was about 50% lower for Green Bay than for Lake Poygan. Among hatchlings from laboratory incubation, those from Green Bay weighed approximately 20% less and had a mean liver weight to body weight ratio 26% greater than those from Lake Poygan. In both field and laboratory, mean minimum incubation periods were significantly longer for eggs from Green Bay compared to Lake Poygan (8.25 and 4.58 days, respectively). Mean minimum incubation time for Green Bay eggs in the field was 4.37 days longer than in the laboratory. Hatchability was greatly improved when Green Bay eggs were incubated by Lake Poygan adults in an egg-exchange experiment, but was sharply decreased in Lake Poygan eggs incubated in Green Bay nests. Nest abandonment and egg disappearance were substantial at Green Bay but nil at Lake Poygan. Thus, not only factors intrinsic to the egg, but also extrinsic factors (parental attentiveness), impaired reproductive outcome at Green Bay. The epidemiological evidence from this study strongly suggested that contaminants were a causal factor. AHH-active PCB congeners (intrinsic effects) and PCBs in general (extrinsic effects) appeared to be the only contaminants at the concentrations measured in eggs, capable of producing the effects that were observed at Green Bay.

Animals↗
PubMed1975

Lepromatous leprosy presenting with polyarthritis, myositis, and immune-complex glomerulonephritis.

A Pakistani man aged 19 years was admitted to a rheumatological unit in the United Kingdom with acute widespread polyarthritis accompanied by night sweats and fever. Preliminary examination suggested Reiter's disease, but further investigation showed acute glomerulonephritis with uraemia. The possibility of periarteritis nodosa, and the prominence of muscle tenderness in the legs, led to biopsies of striated muscle and skin, in both of which were changes typical of lepromatous leprosy, with many Mycobacterium leprae on Ziehl-Neelsen staining. Serum showed IgG-IgM cryoglobulinaemia without antiglobulin activity, and in the recovery phase renal biopsy showed a resolving proliferative glomerulonephritis with linear IgG and IgM immunofluorescence and granular deposits of C3. Clinical signs subsided rapidly under steroid treatment and subsequent progress on anti-leprosy drugs was uneventful. The term erythema nodosum leprosum is inadequate and misleading as a title for a common and important immune-complex reaction of lepromatous leprosy, in which numerous body systems may be involved.

Adult↗
PubMed1973

Brucella antigen.

Explore the source record for details and available documents.

Antigens, Bacterial↗