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Biomedical subjects

H R Miller

Publications and source records attributed to H R Miller.

At least 109 records · Page 6Linked to original sources
PubMed1988

Immune exclusion of Haemonchus contortus larvae in sheep: dose dependency, steroid sensitivity and persistence of the response.

Naive and immune sheep, treated with anthelmintic, challenged directly into the abomasum and killed 48 hours later were used to examine the steroid sensitivity, persistence and dose dependency of immune mechanisms which result in the failure of incoming Haemonchus contortus larvae to establish (immune exclusion). Immune exclusion was almost totally abolished by corticosteroid treatment, the mean percentage of larvae establishing in the mucosa of immune sheep was 1.4 per cent of the challenge infection whereas in those treated with dexamethasone it was 24.4 per cent and in naive sheep 27.3 per cent. Immune animals challenged after seven and 42 days without antigenic experience excluded more than 90 per cent of the challenge larvae from their mucosae, whereas those challenged after 84 days without antigenic experience were as susceptible as naive animals. Immune exclusion was dose dependent, animals challenged with 10(6) and 10(5) larvae excluded 93 per cent and 82.5 per cent of the challenge dose whereas those challenged with 10(4) larvae failed to exclude larvae.

Adrenal Cortex Hormones↗
PubMed1988

Intestinal hypersensitivity reactions in the rat. I. Uptake of intact protein, permeability to sugars and their correlation with mucosal mast-cell activation.

We have confirmed previous observations that intestinal anaphylaxis induced in rats previously sensitized to ovalbumin (OVA) is associated with an increased uptake of an unrelated 'bystander' protein, bovine serum albumin (BSA) fed 1 hr previously. In this study, this enhanced protein uptake was associated with an increased lactulose/rhamnose excretion ratio after administration of these sugars, although there was no correlation between the two measurements. One hour after antigen challenge the serum levels of rat mast-cell protease II (RMCPII), a specific marker for mucosal mast-cell secretion, were significantly higher than both the pre-challenge levels and those of sham-challenged controls (P less than 0.002). There was a significant positive correlation between the serum levels of RMCPII and the lactulose/rhamnose excretion ratios (P less than 0.05), but no such correlation existed between RMCPII and BSA levels in the challenged rats. In other studies the urinary lactulose/rhamnose ratios of rats with cetrimide-induced gut damage were found to be significantly increased, although BSA uptake into the serum remained unaltered. We conclude that there is no simple correlation between gut permeation of low-molecular weight sugars and and the uptake of macromolecular proteins.

Animals↗
PubMed1987

Studies on ovine efferent lymph following infection with Toxoplasma gondii.

Cell output was monitored in efferent popliteal lymphatics of sheep following subcutaneous injection into the lateral tarsus of either 100 T. gondii tissue cysts or control inoculum. Sheep undergoing a primary infection developed a substantially increased lymphoblast output which reached a peak of more than 50 per cent of all cells. The majority of lymphoblasts did not contain Ig and may have been T cells. IgG antibody against T. gondii was detected in lymph by day 9. Animals with naturally acquired antibody to T. gondii developed a more rapid lymphoblast response to the parasite which, at its peak, accounted for 27.5 per cent of all cells. Many of these lymphoblasts contained Ig, presumably specific antibody, which, by increasing phagocytosis and intracellular killing of the T. gondii, would prevent multiplication and dissemination of the parasite.

Animals↗
PubMed1987

Resistance of nematode secretory products to cleavage by mast cell proteinases.

Mast cell proteinases are known to be released in response to helminth infection, and are, in particular, characteristic of the immune rejection of intestinal nematode parasites. In intestinal mucosal tissue the relevant enzyme is rat mast cell proteinase II (RMCP II) and that of other tissues, including the lung, is rat mast cell proteinase I (RMCP I). The function of these enzymes is unknown, and we have examined the possibility that they directly attack the parasites. This was done by examining the cleavage patterns produced by both proteinases on 125I-labelled excretory/secretory (ES) products of two intestinal nematodes (the infective larva of Ascaris suum, and adult Nippostrongylus brasiliensis) and one which has a pulmonary migration route (the third/fourth stage larva of A. suum). It was first established that all the labelled molecules were proteinaceous, by their susceptibility to broad spectrum proteinases, and that none were host components carried over into culture, by their antigenicity to infected hosts. All the nematode ES products were found to be remarkably resistant to RMCP I and II, only one major component of the infective larva of A. suum being cleaved by both enzymes. This was not found to reflect a resistance to serine proteinases in general, since selected ES components were cleaved by chymotrypsin and trypsin. This would, therefore, argue that, if the enzymes play any direct role in the immune expulsion of nematodes, it is unlikely to be successfully directed at their secretions.

Animals↗
PubMed1987

Systemic release of a mast cell proteinase following nematode infections in sheep.

An enzyme-linked immunosorbent assay (ELISA) for sheep mast cell proteinase (SMCP) has been developed. Concentrations of SMCP in homogenates of abomasal tissue from parasite-immune sheep (341 micrograms SMCP/g tissues) were raised when compared to those in normal (non-infected) abomasa (0.145 micrograms SMCP/g tissue). SMCP was not detected in sera from normal animals challenged with Haemonchus contortus but was present (less than 1.0 ng SMCP/ml) in sera from 8/11 immune sheep 2 h after intra-abomasal challenge with 1 x 10(6) exsheathed Haemonchus larvae. In two further experiments, the SMCP response in gastric lymph was monitored after homologous larval challenge in sheep immune to Ostertagia circumcincta and in normal controls. SMCP (less than 1.4 ng SMCP/ml) was detected in lymph from 2/3 and 4/5 immune animals between 1 and 4 days post-challenge with 50,000 larvae, but not from normal animals. SMCP was not detected in lymph from immune animals following challenge with 1000 Ostertagia larvae. The relatively low concentrations of SMCP in blood and lymph reflect the presence of proteinase inhibitor(s) which interfered with the ELISA.

Abomasum↗
PubMed1987

Phenotypic expression of mast cell granule proteinases. Distribution of mast cell proteinases I and II in the rat digestive system.

The distribution of mast cell granule proteinases in the rat digestive system was determined immunohistochemically. The population of toluidine blue-staining mast cells was accounted for by cells containing either rat mast cell proteinase I (RMCPI) or rat mast cell proteinase II (RMCPII). Granules in greater than 90% of RMCPI-containing cells stained red after the Alcian blue/safranin sequence, whereas all RMCPII-containing mast cells stained blue. The red/RMCPI phenotype was typical of the connective tissue mast cells (CTMC) that populate the proximal, non-mucosal, regions of the digestive system, and was also abundant in the serosa and in rectal and gastric muscularis. The blue/RMCPII phenotype, absent from non-mucosal sites except for rare cells in intestinal submucosa and muscularis, predominated in all mucosal tissues and resembled mucosal mast cells (MMC). A third, minor population of cells containing RMCPI but staining blue in the Alcian blue/safranin sequence was detected in both non-mucosal and mucosal tissues. Blue/RMCPI mast cells were rare in the small intestine but more frequent in the mucosa of the stomach and large intestine and in the connective tissues. It is suggested that granule proteinase phenotyping may provide an alternative technique in the analysis of mast cell heterogeneity.

Animals↗
PubMed1987

Characterization and mast cell origin of a chymotrypsin-like proteinase isolated from intestines of mice infected with Trichinella spiralis.

A proteinase was purified by cation exchange and affinity chromatography from the small intestines of mice infected with Trichinella spiralis. The enzyme was highly soluble and was chymotrypsin-like in its substrate specificities and susceptibility to inhibitors. It had a MW of 26,000, as determined by SDS-PAGE electrophoresis. Antibodies raised against the proteinase were affinity purified and their specificity confirmed by Western blot analysis. When used to localize the enzyme immunohistochemically, they reacted with granules of mast cells in the epithelium and lamina propria of the parasitized small intestine. The antibodies also bound to mast cell granules in a number of other sites, including tracheal epithelium, gastric mucosa, skin and tongue. Affinity-purified antibodies raised against rat mast cell proteinase II (RMCPII) cross-reacted with the mouse mast cell proteinase on Western blots.

Animals↗
PubMed1987

Roles of mucosal mast cells in intestinal cell-mediated immunity.

Mucosal mast cells in rats with GvHR have been studied by cell counts, tissue levels of the specific protease RMCPII, and, as an index of MMC activation, serum RMCPII. In semi-allogeneic GvHR without host irradiation, GvHR produced modest increases in these three indices. In contrast, irradiation profoundly depleted MMC even though enteropathy was more severe than in non-irradiated hosts. We suggest that enteropathy is not dependent on the presence of MMC. In rats given cyclosporin A, lesions of GvHR were mild and numbers of MMC were low.

Animals↗
PubMed1987

Phenotypic analysis of mast cell granule proteinases in normal rat bone marrow cultures.

Mast cells with morphological and some biochemical properties of mucosal mast cells (MMC) proliferate and mature in rat bone marrow cultures stimulated with factors from antigen- or mitogen-activated T lymphocytes. There has been much controversy over the criteria used to distinguish the different mast cell subsets, and because histochemistry of granule glycosaminoglycans does not adequately define mast cell subsets morphologically, the proteinase phenotypes of cultured mast cells were analysed. Affinity-purified cross-absorbed monospecific F(ab')2 antibodies raised against rat mast cell protease I (RMCPI) from connective tissue mast cells (CTMC) and against rat mast cell protease II (RMCPII) isolated from mucosal mast cells were used to stain granule proteinase by an immunohistochemical technique. Mast cells grown in culture from normal rat bone marrow stained exclusively with anti-RMCPII antibodies, thus providing further confirmation of their similarity to, and identity with, MMC.

Animals↗
PubMed1986

Enteral and systemic release of leukotrienes during anaphylaxis of Nippostrongylus brasiliensis-primed rats.

Rats with acquired immunity to the intestinal nematode Nippostrongylus brasiliensis develop anaphylaxis after i.v. challenge with an extract of worm antigen, with the small intestine being the primary shock organ. In the present study we have shown that these events were associated with significant elevations in intestinal and plasma concentrations of leukotrienes LTB4 and LTC4. The changes were observed in immune rats over 10-, 30-, and 60-min intervals after antigen challenge but were absent in control animals. These lipid mediators were identified both in the perfusate of the gut lumen, which contained large quantities of mucus, and in homogenates of intestinal tissue. In addition, significant elevations in the concentrations of plasma LTB4 and LTC4 were detected in immune challenged rats but not in controls. Leukotrienes were identified by radioimmunoassay and validated by reverse-phase high-performance liquid chromatography (RP-HPLC). RP-HPLC analysis of SRS-A leukotrienes in immune challenged rats indicated that LTC4 was the predominant sulfidopeptide leukotriene at 10 min, with almost complete biodegradation to LTD4 and LTE4 within 30 min. Infected rats also had significant increases in the numbers of intestinal mucosal mast cells (MMC) and eosinophils. Evidence of MMC activation during anaphylaxis was obtained by showing significant elevations of intestinal and systemic concentrations of their exclusive serine enzyme, rat mast cell proteinase II (RMCPII). Thus, the release of substantial amounts of leukotrienes in the gut and plasma of N. brasiliensis-primed rats after interaction with worm antigens suggests that these potent mediators may play an important role in allergic-type hypersensitivity known to occur during immune reactions against parasitic helminths.

Anaphylaxis↗
PubMed1986

Performance of psychiatric inpatients and intellectually deficient individuals on a task that assesses the validity of memory complaints.

A brief psychological screening test, devised by Rey (1964), was developed to assess the validity of memory complaints. Although Rey hypothesized that malingerers would be mislead to perform poorly while even individuals with severe concentration problems could succeed, a review of the literature did not reveal any empirical reports that examined the actual performance of nonmalingering though disturbed patients. Therefore, Rey's test was administered to samples of acutely disturbed psychiatric patients (N = 50) and intellectually deficient individuals (N = 16). The results confirmed the criterion proposed by Lezak (1983) and suggested that malingering should be considered among individuals who deny remembering at least 9 of the 15 times of the Rey test.

Adolescent↗
PubMed1986

Gut mucosal mast cells in Nippostrongylus-primed rats are the major source of secreted rat mast cell protease II following systemic anaphylaxis.

The distribution of the predominant chymotrypsin-like enzyme of mucosal mast cells (rat mast cell protease II: RMCP II) was examined in naive and Nippostrongylus-primed rats both before and after the induction of systemic anaphylaxis. Anaphylactic secretion of RMCP II following i.v. challenge of primed rats with worm antigen was accompanied by significant depletion of this enzyme from the jejunal and gastric mucosae; the concentrations were not altered in the ileum and colon. Despite significant increases in the levels of RMCP II in lung and mesenteric lymph node following infection with N. brasiliensis there was no anaphylactic depletion of this enzyme from these sites. No RMCP II was detected in liver, spleen, kidney or bone marrow either before or after systemic anaphylaxis. Mucosal mast cells were depleted from the jejunal, gastric and colonic mucosae following antigen challenge of primed rats. These data provide further evidence that gastrointestinal mucosal mast cells are the major source of secreted RMCP II following systemic anaphylaxis in the rat.

Anaphylaxis↗
PubMed1986

The isolation and purification of a proteinase with chymotrypsin-like properties from ovine mucosal mast cells.

A mast cell granule proteinase was purified from isolated ovine mucosal mast cells by cation exchange chromatography, which defined the conditions for enzyme purification from sheep gastric mucosae. Antibodies raised against the proteinase were used in subsequent purification procedures which yielded 78 micrograms of enzyme per 5 g wet wt of abomasal tissue. Immuno-histochemistry confirmed that mucosal mast cells were the source of the enzyme. The proteinase had chymotrypsin-like esterase activity, with a molecular weight between 19,000 and 25,000.

Abomasum↗