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Biomedical subjects

E Jackson

Publications and source records attributed to E Jackson.

At least 19 recordsLinked to original sources
PubMed1995

Primary structure of the variable regions encoding antibody to NG2, a tumour-specific antigen on the rat chondrosarcoma HSN. Correlation of idiotypic specificities with amino acid sequences.

Eight syngeneic rat monoclonal antibodies that recognize structurally overlapping epitopes on the chondroitin proteoglycan NG2, a tumour-specific antigen on the chemically induced rat chondrosarcoma HSN, have been analysed for the sequence of their immunoglobulin heavy (H) and light (L) chain variable (V) regions. This analysis defined five groups of antibodies which are very similar for both the H and L chains and revealed that a wide range of different V regions are capable of binding to the same antigenic determinant. However, three mAbs, 11/160, ALN/12/17 and ALN/9/94, which recognize a sequential epitope, were found to use almost identical heavy (V-D-J) and light (V-J) chains in regions demonstrating an exclusivity in specific protein-protein interaction for this particular epitope. Two other mAbs, ALN/11/53 and AL/3/12, used similar V and J segments but totally different D regions. With the exception of the pair ALN/11/53 and AL/3/12, this grouping of antibodies matches that derived from the idiotypic specificity study we have reported previously. The reactivity pattern of Ab1 11/160, ALN/12/17 and ALN/9/94 with six anti-idiotopic mAbs raised against 11/160 demonstrated that the idiotope recognized by Ab2 HIM/3/41 was defined by a single amino acid, Asn, at position 52 within the CDR2 loop of the VH region; whereas the D region of Ab1 ALN/11/53 was implicated as the structural correlate of idiotypy. The substitution of AsnH52 influenced the Id recognition but Ag binding was not affected suggesting that Ab2 HIM/3/41 did not mimic the NG2 Ag.

Amino Acid Sequence↗
PubMed1992

Prevalence of anthelmintic-resistant nematodes in fibre-producing goats in Scotland.

Six cashmere goat herds in Scotland were surveyed to assess the prevalence of anthelmintic resistance and the species of nematode involved. Resistance was determined in vivo by a faecal egg count reduction test and in vitro using an egg hatch assay and specific faecal egg identification techniques. Benzimidazole resistance was present in five of the herds, insufficient eggs were obtained from the other herd to draw firm conclusions. Teladorsagia (Ostertagia) species predominated in four of the five herds in which resistance was detected and Haemonchus contorus was the dominant species in the other.

Animals↗
PubMed1992

Interactions between Teladorsagia circumcincta and Trichostrongylus vitrinus infections in young lambs.

Groups containing six lambs that previously had been infected five times each week for four, eight or 12 weeks, either with 1000 Trichostrongylus vitrinus third stage larvae (L3) or 1000 T vitrinus L3 and 2500 L3 Teladorsagia (previously Ostertagia) circumcincta were challenged, along with six worm-free control lambs, with 3000 75Se-labelled T vitrinus L3. The lambs were killed 10 days after challenge. Those given a dual infection for four and eight weeks had significantly lower total T vitrinus numbers than monospecifically infected lambs. Significantly fewer radiolabelled larvae were recovered from the dual infected group killed after four weeks exposure to infection than from lambs infected monospecifically. The negative interaction between these two nematode species appears to be physiologically mediated and may be an important factor in accounting for differences in their seasonal prevalence.

Abomasum↗
PubMed1992

Evidence of multiple anthelmintic resistance in a strain of Teladorsagia circumcincta (Ostertagia circumcincta) isolated from goats in Scotland.

The efficacy of ivermectin, fenbendazole and levamisole was determined in lambs individually infected with 5000 third stage larvae of Teladorsagia (Ostertagia) species isolated from a herd of goats with a history of benzimidazole resistance and where the efficacy of ivermectin had also suffered an apparent decline. Efficacies, calculated using geometric means, for groups where treatments were directed against adult worms were 90.3 per cent (ivermectin), 43.4 per cent (fenbendazole) and 100 per cent (levamisole). The efficacy of ivermectin against immature stages was 83.2 per cent. Ivermectin was highly effective (99.9 per cent) against a known susceptible ovine strain of Teladorsagia.

Animals↗
PubMed1991

1,25-dihydroxyvitamin D reduces parathyroid hormone receptor number in ROS 17/2.8 cells and prevents the glucocorticoid-induced increase in these receptors: relationship to adenylate cyclase activation.

We have previously shown that 1,25-dihydroxyvitamin D [1,25-(OH)2D3] and glucocorticoid modulate adenylate cyclase activation by PTH in osteoblast-like cells. Here we examine whether steroid effects on PTH receptor density explain the modulation of PTH action. Receptor assays were performed on late logarithmicphase monolayers of ROS 17/2.8 cells using human PTH-like peptide (hPLP) as radioligand. Kd and receptor density were computed from competition of tracer amounts of [125I-Tyr36] hPLP-(1-36) with unlabeled hPLP-(1-36) (0.1-30 nM). Steroid treatment had little or no effect on affinity for ligand. Pretreating cells with 10 nM 1,25-(OH)2D3 for 48 h decreased PTH receptor number to 17% of control values. Treating cells with 10 nM of the glucocorticoid triamcinolone acetonide (TRM) increased receptor number 10-fold, but simultaneous treatment with 1,25-(OH)2D3 (10 nM) completely prevented this receptor increase. Steroid effects required 13-18 h of treatment. Dose-response relationships for steroid modulation, determined from binding at 0.17 nM radioligand, indicated an EC50 of 0.3 nM for glucocorticoid augmentation of PTH receptor number and 0.02 nM for 1,25-(OH)2D3 reduction of receptor number in the presence of absence of the maximum TRM effect. The initial rate of cAMP production by receptor-saturating concentrations of PTH was 11,500 molecules per receptor per minute in untreated cells, comparable to reported turnover numbers for mammalian adenylate cyclase. Control experiments were validated measuring cAMP in intact cells as an indicator of adenylate cyclase activity. Cyclic AMP production was reduced 63% by 1,25-(OH)2D3 (10 nM) treatment. Glucocorticoid (10 nM) enhanced cAMP production twofold but reduced cAMP generation per receptor by 80%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗
PubMed1991

Relative contribution of cattle to contamination of pasture with Nematodirus battus under an alternate grazing system of husbandry.

Calves, aged six months grazing on pasture on which lambs infected with Nematodirus battus had grazed the previous season, became infected and passed eggs of N battus. Transfer of these calves onto 'clean' pasture showed that their faecal contamination was sufficient to cause moderate infections of N battus in lambs grazing this area the following season. It was also shown that significant N battus contamination could survive on pasture for at least 18 to 24 months in the absence of further grazing by sheep. Under husbandry systems involving alternate grazing there is likely to be a combination of contamination by young susceptible calves, and a two year carry-over of infectivity.

Animal Husbandry↗
PubMed1991

Effect of parasitism with Nematodirus battus on the pharmacokinetics of levamisole, ivermectin and netobimin.

The pharmacokinetics of levamisole, ivermectin and netobimin administered orally and by subcutaneous injection were compared in lambs exposed to a moderate challenge with Nematodirus battus and in parasite naive lambs. There were no significant differences (P greater than 0.05) in the bioavailability of any of the anthelmintics tested between parasitized and non-parasitized animals. Levamisole reduced nematode faecal egg output by more than 99% when administered by either route. Ivermectin was also highly effective (greater than 99%). Orally administered netobimin reduced egg output by more than 98% seven days after administration. However egg output was only reduced by 89% 21 days after administration, suggesting poor activity against the early parasitic stages of N. battus. Netobimin was not effective against N. battus when administered by the subcutaneous route and this was probably because very low plasma concentrations of its active albendazole metabolites were achieved.

Administration, Oral↗
PubMed1991

Adolescent pregnancy: effects of nutrients on hematocrit and birth weight in Orangeburg County.

Effect of nutrients on hematocrit and birth weight during teenage pregnancy was studied for both Blacks and non-Blacks in Orangeburg County. The results of this study indicated that both Blacks and non-Blacks were considered to be at risk for nutritional anemia, based on hematocrit values. It further showed that Blacks and non-Blacks consumed an inadequate diet, particularly in iron and folic acid.

Adolescent↗
PubMed1990

Preparation and properties of recombinant DNA derived tobacco mosaic virus coat protein.

Recombinant DNA derived tobacco mosaic virus (vulgare strain) coat protein (r-TMVP) was obtained by cloning and expression in Escherichia coli and was purified by column chromatography, self-assembly polymerization, and precipitation. SDS-PAGE, amino terminal sequencing, and immunoblotting with polyclonal antibodies raised against TMVP confirmed the identify and purity of the recombinant protein. Isoelectric focusing in 8 M urea and fast atom bombardment mass spectrometry demonstrated that the r-TMVP is not acetylated at the amino terminus, unlike the wild-type protein isolated from the tobacco plant derived virus. The characterization of r-TMVP with regard to its self-assembly properties revealed reversible endothermic polymerization as studied by analytical ultracentrifugation, circular dichroism, and electron microscopy. However, the details of the assembly process differed from those of the wild-type protein. At neutral pH, low ionic strength, and 20 degrees C, TMVP forms a 20S two-turn helical rod that acts as a nucleus for further assembly with RNA and additional TMVP to form TMV. Under more acidic conditions, this 20S structure also acts as a nucleus for protein self-assembly to form viruslike RNA-free rods. The r-TMVP that is not acetylated carries an extra positive charge at the amino terminus and does not appear to form the 20S nucleus. Instead, it forms a 28S four-layer structure, which resembles in size and structure the dimer of the bilayer disk formed by the wild-type protein at pH 8.0, high ionic strength, and 20 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylation↗
PubMed1990

Teladorsagia circumcincta egg output at the onset of natural and induced lactation in ewes.

Nineteen ewes maintained under 'worm-free' conditions received anthelmintic and 1 week later were dosed on 5 days each week with 500 Teladorsagia circumcincta larvae for between 10 and 12.5 weeks. Faecal egg counts were determined twice weekly. There were three groups: pregnant (P) ewes (n = 6) which each reared twin lambs, hormone-treated (H) ewes (n = 7) which were not pregnant and were given exogenous hormones (dexamethasone, oestradiol-17 beta, progesterone) for 37 days to induce udder development and milk production, and untreated barren (B) ewes (n = 6). The plasma concentrations of oestradiol-17 beta, prolactin and progesterone were measured. Starting 10-15 days before birth in Group P, there was a biphasic periparturient rise in egg count and the onset of the first peak in egg count preceded the parturient peak in plasma prolactin concentration by several days. Most Group H (5/7) and all Group B ewes remained highly resistant to Teladorsagia infection throughout, despite an induced rise in prolactin concentrations in Group H ewes. It was concluded that factors other than prolactin initiate the periparturient rise but that prolactin is one factor which maintains the response once lactation commences.

Animals↗
PubMed1990

Autoantibody to complement neoantigens in membranoproliferative glomerulonephritis.

With the exception of C3 nephritic factor, autoantibody formation has not been commonly associated with membranoproliferative nephritis (MPGN). We measured autoantibodies (nephritic factors) to the C3 convertases C3bBb (NFa) and C3bBbP (NFt), which result in fast and slow C3 activation, respectively, and to a neoantigen on C1q fixed to a solid phase (spC1q) in sera from 29 patients with MPGN type I, 26 with type II, and 28 with type III. Autoantibody formation was common in all MPGN types. An autoantibody to a C3 convertase neoantigen was identified in more than 75% of the hypocomplementemic MPGN sera tested. Anti-C3bBb (NFa) was present in 81% of patients with MPGN type II but was rarely found in either type I or type III. Anti-C3bBbP (NFt) was common in both MPGN I and III. Anti-spC1q was present in 74% of patients with type I and in 38% and 48% of types II and III MPGN, respectively. Patients with MPGN types I, II, and III had one and two serum autoantibodies detected significantly more frequently than did a group of healthy subjects. The presence of any one autoantibody was not specifically associated with the presence of any other autoantibody. The results indicate that multiple autoantibody formation is common in all MPGN types. MPGN II, and possibly MPGN I, tend to form more specific autoantibodies.

Antigen-Antibody Complex↗
PubMed1990

Maternal-infant clinical nurse specialist performance assessment: development of an evaluation tool.

The Maternal-Infant Clinical Nurse Specialist Performance Evaluation Tool was developed to assist students to enact certain role behaviors of the clinical nurse specialist (CNS) in maternal-infant nursing and to provide faculty with a measurement of such behaviors for the purpose of student clinical evaluation. Items for the behaviorally-anchored, criterion-referenced tool were derived from current standards of CNS practice, expected competencies of the CNS as reported in the literature, and program and course objectives. Initial use of the tool with graduate students in the maternal-infant specialty indicated a valid and reliable rationale for continued use. Since the categories of the tool represent common CNS roles, it should be applicable to other specialties.

Clinical Competence↗
PubMed1990

Rhesus monkey model of familial hypercholesterolemia: relation between plasma Lp[a] levels, apo[a] isoforms, and LDL-receptor function.

We previously described a family of rhesus monkeys in which three out of six members had a spontaneous hypercholesterolemia related to a decrease in number of low density lipoprotein receptors (LDL-R) (Scanu et al. 1988. J. Lipid Res. 29: 1671-1681). During the current work an additional female normocholesterolemic offspring was generated from the mating of the original dam and sire. Moreover, from the breeding of one of the affected male offspring with six unrelated normocholesterolemic female monkeys, eight offspring were generated of which three were hypercholesterolemic on a cholesterol-free diet and exhibited the same degree of LDL-R deficiency as shown by studies in skin fibroblast cultures. All of the animals studied had levels of plasma lipoprotein[a] protein ranging between 1.0 mg/dl and 57.5 mg/dl that were only weakly correlated with total plasma cholesterol, LDL cholesterol, and apoB. LDL-R deficiency correlated with plasma LDL but not Lp[a]. A 7 week fat challenge (16.5% lard, 0.64% cholesterol) that raised the plasma LDL levels markedly had no effect on plasma Lp[a]. Animals with the single band apo[a] phenotype moving on SDS-PAGE faster than apoB-100 exhibited a tendency for high plasma Lp[a] levels which, however, varied widely. Wide variations in Lp[a] levels were also noted with the other apo[a] phenotypes. Taken together our results demonstrate a successful transmission to second generation animals of the LDL-R deficiency phenotype and provide evidence that this phenotype correlates well with plasma LDL levels but not Lp[a]. Our data also suggest that the apo[a] gene is only partially involved in the regulation of the plasma Lp[a] levels.

Animals↗
PubMed1989

Failure to label baboon milk intrinsically with iron.

The widely held belief that 50% of the iron in human milk is absorbed is based on studies that have used an extrinsic radioactive iron tag. To determine the validity of an extrinsic tag, it is necessary to label the milk intrinsically with one isotope and to compare absorption of this isotope with absorption of another isotope added as the extrinsic tag. We chose the baboon as a model and infused 59Fe intravenously. In each of three attempts we failed to label the milk intrinsically.

Absorption↗