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Biomedical subjects

S James

Publications and source records attributed to S James.

At least 73 records · Page 4Linked to original sources
PubMed1994

Purification of antimicrobial peptides from an extract of the skin of Xenopus laevis using heparin-affinity HPLC: characterization by ion-spray mass spectrometry.

A simple scheme was developed for the rapid purification of antimicrobial peptides from the skin of Xenopus laevis. An extract of the frog skin was prepared using an acidic medium designed to maximize the solubilization of low-molecular-weight peptides. This extract was subjected to an enrichment procedure using C18 Sep Pak cartridges to yield a salt-free fraction, devoid of high-molecular-weight proteins. This fraction was in turn subjected to heparin affinity high-performance liquid chromatography on a Shodex AF-Pak column. All the antibacterial activity bound to the column and could be eluted using a linear gradient of increasing sodium chloride concentration. Antibacterial activity emerged from the column in fractions corresponding to a sodium chloride concentration of 0.45 M. Reversed-phase high-performance liquid chromatography resolved this material into a series of compounds which could be readily characterized using a combination of amino acid analysis and ion-spray mass spectrometry. Each peptide was found to be antimicrobial and each was positively identified as belonging to a family of amphipathic helix-forming peptides characterized by other investigators. Listed in their order of elution from the reversed-phase column the peptides were magainin 2, magainin 1, peptide-glycine-leucine amide, xenopsin precursor fragment, levitide precursor fragment, and a mixture of fragments derived from the caerulein precursor. These peptides owe their antimicrobial properties to a predeliction to forming amphipathic alpha-helical structures when associated with lipid membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1994

Differentiation of the spoilage yeast Zygosaccharomyces bailii from other Zygosaccharomyces species using 18S rDNA as target for a non-radioactive ligase detection reaction.

A non-radioactive PCR coupled ligase detection reaction was developed to discriminate the food spoilage yeasts Zygosaccharomyces bailii and Z. bisporus from each other and from other members of the genus. A short region of the 18S rRNA gene was amplified from boiled cell lysates and polymerase chain reaction (PCR) products used as target in the template directed ligation of two adjacent oligonucleotides. Ligated products were captured using biotin-streptavidin chemistry and detected using digoxigenin immuno-chemiluminescence. The ligase detection reaction was able to discriminate to the species level, targeting a single base deletion. The specificity of the reaction was assessed using seven species of the genus Zygosaccharomyces. Only strains of Z. bailii and Z. bisporus gave positive results with their respective primer sets. The lower detection limit of the strategy was 10pg (3 x 10(7) targets) of amplified product.

Base Sequence↗
PubMed1994

Effect of recombinant porcine somatotropin and monoclonal antibody directed to ovine somatotrophic hormone on nitrogen retention and immune parameters in pigs.

Single and combined effects of administration and withdrawal of recombinant porcine somatotropin (rpST) and an enhancing murine antiovine growth hormone monoclonal antibody (OA15) on nitrogen retention, and serological and immunological measurements in pigs were examined in a placebo-controlled experiment. Thirty-six barrows were allotted to one of four treatments: control, rpST, OA15, and OA15+rpST. The trial phase was four balance periods: a preperiod, two periods of treatment, and a postperiod. Weight- and nitrogen gain were higher for the rpST group by 13% (P < .01) and 15% (P < .001), for the OA15 group by 8% (P < .05) and 9% (P < .05), and for the OA15+rpST group by 25% (P < .001) and 20% (P < .001), respectively compared with the control group. During the postperiod, weight gain of the OA15- and the OA15+rpST group was 23% (P < .001) and 22% (P < .001) lower than that of the control group. Nitrogen gain during the postperiod was decreased by 19% (P < .01) for the OA15 group compared with the control group. Single or combined administration of rpST or OA15 did not affect (P > .10) cellular constituents in the blood of all groups during the periods of observation. Animals treated solely with rpST mounted a humoral immune response directed to rpST. This anti-rpST antibody response was, however, decreased (P < .01) in barrows treated with rpST and OA15 simultaneously. Also, a slight anti-rpST antibody response was noticed in barrows solely treated with OA15.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Renal and neuromuscular respiratory failure--is this a syndrome associated with cantharidin poisoning?

OBJECTIVE: To describe the clinical and laboratory features of patients with renal and neuromuscular respiratory failure due to suspected cantharidin poisoning. DESIGN: Retrospective record review of cases with neuromuscular respiratory failure. SETTING: Intensive Care Unit (ICU), Hillbrow Hospital, Johannesburg. PATIENTS: Out of a total of 47 patients with neuromuscular respiratory failure admitted to the ICU between January 1983 and December 1990, 10 with suspected cantharidin poisoning were selected and studied further. OUTCOME MEASURES: Description of clinical features, laboratory data, treatment and prognosis. RESULTS: In 10 of the 47 patients, the cause of renal and neuromuscular respiratory failure that which precipitated the need for ICU admission was suspected to be cantharidin poisoning. This was based on the history and clinical and laboratory features. In 4 cases trace amounts of cantharidin were detected in blood and/or urine, strengthening the diagnosis. There were 8 males and 2 females. All had evidence of renal injury and 9 had gastro-intestinal symptoms. All presented with fixed dilated pupils, varying cranial nerve palsies and muscle weakness, usually ascending and progressive, necessitating admission to the ICU. All but 1 of the patients were mechanically ventilated, 5 required significant inotropic support of the blood pressure, and 6 dialysed. Four patients died soon after admission and the remainder survived with relatively complete return of neurological function. CONCLUSION: This study highlights the possibility that cantharidin poisoning may be a cause of a 'Guillain-Barrè-like' syndrome.

Adult↗
PubMed1993

Care management and mental health.

The community care reforms will produce a new kind of key worker who will organise and budget for packages of care: the care manager. Care management goes live in April 1993 but is still poorly rehearsed and its performance may yet disappoint. This overview sets out the origins of case management, its transformation into care management, and the principles guiding its practice. To spell out how the concept works, plans for care management in Southwark's mental health services are described.

Budgets↗
PubMed1993

Abnormal pedal thermoregulation in interstitial cystitis.

Isolated cold stress tests were used to evaluate the thermoregulatory capacity in the feet of 19 patients with interstitial cystitis (IC) and of 11 healthy volunteer control subjects. Mean pedal skin temperature fell more rapidly in the IC group as compared with controls; significant differences were found at 10-min (P = 0.002) and 20-min (P = 0.0008) cooling. Mean skin temperature remained lower in the IC group throughout the study. Sixteen feet (42%) in the IC group and five (22%) of the control feet failed to return to within 2 degrees C of baseline temperature during the 20-min recovery period. These findings may reflect abnormal vasomotor control in the IC group and, if so, may be indicative of increased spinal sympathetic activity in interstitial cystitis.

Adult↗
PubMed1993

The subcellular distribution of [3H]-CGS 21680 binding sites in the rat striatum: copurification with cholinergic nerve terminals.

The subcellular distribution of the adenosine A2a receptor in rat striatum has been investigated using specific binding of the A2a-selective ligand [3H]-CGS 21680. After subcellular fractionation, the distribution of [3H]-CGS 21680 binding was similar to that of the cholinergic nerve terminal marker acetylcholinesterase rather than the more general membrane marker 5'-nucleotidase, with 42% of binding associated with the synaptosomal sub-fraction and 19% with a light membrane fraction. Binding of [3H]-CGS 21680 was also found to co-purify with the cholinergic nerve terminal marker choline acetyltransferase during immunoaffinity purification of striatal cholinergic nerve terminals. These results demonstrate that some adenosine A2a receptors are present on cholinergic nerve terminals in rat striatum.

Adenosine↗
PubMed1993

Some effects of ivermectin on the yellow dung fly, Scatophaga stercoraria.

Ivermectin was added to fresh cattle dung at a range of concentrations based on those found in faeces of livestock treated by injection. Newly hatched larvae of Scatophaga stercoraria were then reared in the dung as a bioassay. The EC50 values for 24 h and 48 h larval mortalities were 0.051 ppm and 0.036 ppm (wet wt.) respectively. When the dung concentration was 0.015 ppm, 50% of the insects failed to pupariate and a level of 0.001 ppm prevented adult emergence in 50% of the insects. When batches of larvae were reared in dung containing as little as 0.0005 ppm, the emerging adults showed developmental abnormalities in wing morphology. In addition to the significantly higher level of fluctuating asymmetry, 23% of the treated insects developed new veins and new cells in the wings. The observations are discussed in relation to previous work and attention is drawn to the practice of failing to observe the full impact of sublethal effects, which can be as serious as those of acute toxicity.

Animals↗
PubMed1993

Production of adenosine from extracellular ATP at the striatal cholinergic synapse.

The components of the ectonucleotidase pathway at the immunoaffinity-purified striatal cholinergic synapse have been studied. The ecto-ATPase (EC 3.6.1.15) had a Km of 131 microM, whereas the ecto-ADPase (EC 3.6.1.6) had a Km of 58 microM, was Ca(2+)-dependent, and was inhibited by the ATP analogue 5'-adenylylimidodiphosphate (AMPPNP). The ecto-5'-nucleotidase (EC 3.1.3.5) had a Km of 21 microM, was inhibited by AMPPNP and alpha,beta-methylene ADP, and by a specific antiserum. The Vmax values of the ATPase, ADPase, and 5'-nucleotidase enzymes present at this synapse were in a ratio of 30:14:1. Very little ecto-adenylate kinase activity was detected on these purified synapses. The intraterminal 5'-nucleotidase enzyme, which amounted to 40% of the total 5'-nucleotidase activity, was inhibited by AMPPNP, alpha,beta-methylene ADP, and the antiserum, and also had the same kinetic properties as the ectoenzyme. The time course of ATP degradation to adenosine outside the nerve terminals showed a delay, followed by a period of sustained adenosine production. The delay in adenosine production was proportional to the initial ATP concentration, was a consequence of feedforward inhibition of the ADPase and 5'-nucleotidase, and was inversely proportional to the ecto-5'-nucleotidase activity. The function and characteristics of this pathway and the central role of 5'-nucleotidase in the regulation of extraterminal adenosine concentrations are discussed.

5'-Nucleotidase↗
PubMed1993

Immunocytochemical localisation of insulin receptors on rat superior cervical ganglion neurons in dissociated cell culture.

Cells in dissociated culture preparations of the superior cervical ganglion of the adult rat were examined for the presence of insulin receptors. This was assessed immunocytochemically by the demonstration of binding by a mouse monoclonal anti-insulin receptor antibody. A large subpopulation (> or = 90%) of neuronal cell bodies and associated neurites exhibited positive immunostaining. The apparent absence of staining over nuclear regions suggested that the majority of neuronal receptors had an intracytoplasmic localisation. In contrast, a subpopulation of fibroblasts showed punctate immunostaining, which appeared to be confined to the cell surface. Glial (satellite) cells did not appear to be immunostained. The possible effects of insulin on neurons in the peripheral nervous system are discussed.

Animals↗
PubMed1992

Quick, quick, slow.

Explore the source record for details and available documents.

Health Promotion↗
PubMed1992

Clinical issues in social network therapy for clients with schizophrenia.

Social networks are viable foci for therapeutic interventions. A social network therapy program for clients with schizophrenia was developed by a community-based mental health agency. This paper presents four of the most common clinical issues encountered and illustrates each with a case example.

Adult↗
PubMed1992

Reversed-phase liquid chromatographic purification and isolation of a radio-iodinated selective probe for mu opioid receptors in the brain.

A Guard-PAK precolumn system was used for the reversed-phase liquid chromatography purification of a small, synthetic radiolabeled opioid peptide, FK 33-824 (D-Ala2, methyl-phe4, Met (O)ol5 enkephalin) (FK). This procedure involves trace enrichment of iodinated peptide onto the precolumn while iodination reagents are not retained. Radioactive contamination of high-performance liquid chromatography columns and injectors is thus avoided. Precolumn chromatography has sufficient resolving power to separate not only labeled from unlabeled peptide but also mono- from di-iodinated peptide. Purified 125I-labeled FK (estimated specific activity 85.9-153.7 Ci/mmol) showed high specific binding to mouse corpus striatum, neocortex, cingulate cortex, nucleus accumbens septi, diagonal band of Broca, nucleus medialis septi, area preopticus magnocellularis, and the nucleus of the caudate/putamen. Radioligand binding was inhibited by both antagonists (naloxone and naltrexone); and agonists D-Ala2, N-methyl-phe4, gly-ol5-enkephalin [DAGO]; FK; and beta-endorphin at all concentrations tested (1 x 10(-8) to 1 x 10(-4) M). Adrenocorticotropin hormone (ACTH) did not block ligand binding at any concentration tested. Distribution of mu opioid receptors was analyzed by light microscopic autoradiography. Sections incubated with 125I-labeled FK in the presence of agonists and antagonists demonstrated decreasing ligand binding with increasing doses of competitor. ACTH did not block ligand binding at any concentration tested. HPLC analyses of ligand which had been iodinated 1.5 half lives before the date of the experiment demonstrated a single peak similar to that of freshly iodinated ligand. Similar binding kinetics and autoradiographic labeling patterns were observed as compared to those obtained with freshly iodinated peptide.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Adenosine receptors in post-mortem human brain.

1. Adenosine A2-like binding sites were characterized in post-mortem human brain membranes by examining several compounds for their ability to displace [3H]-CGS 21680 (2[p-(2 carboxyethyl)-phenethylamino]-5'-N-ethylcarboxamido adenosine) binding. 2. Two A2-like binding sites were identified in the striatum. 3. The more abundant striatal site was similar to the A2a receptor previously described in rat striatum, both in its pharmacological profile and striatal localization. 4. The less abundant striatal site had a pharmacological profile similar to that of the binding site characterized in the other brain regions examined. This was intermediate in character between A1 and A2 and may represent another adenosine receptor subtype. 5. The co-purification of [3H]-CGS 21680 binding during immunoisolation of human striatal cholinergic membranes was used to assess the possible cholinergic localization of A2-like binding sites in the human striatum. Only the more abundant striatal site co-purified with cholinergic membranes. This suggests that this A2a-like site is present on cholinergic neurones in the human striatum.

Adenosine↗
PubMed1991

Comparison of Th1- and Th2-associated immune reactivities stimulated by single versus multiple vaccination of mice with irradiated Schistosoma mansoni cercariae.

Mice immunized against Schistosoma mansoni by a single percutaneous exposure to radiation-attenuated parasite larvae demonstrate partial resistance to challenge infection that has been shown to correlate with development of cell-mediated immunity, whereas mice hyperimmunized by multiple exposure to attenuated larvae produce antibodies capable of transferring partial protection to naive recipients. Measurement of Ag-specific lymphokine responses in these animals suggested that the difference in resistance mechanisms may be due to the differential induction of Th subset response by the two immunization protocols. Thus, upon Ag stimulation, singly immunized mice predominantly demonstrated responses associated with Th1 reactivity, including IL-2 and IFN-gamma production, whereas multiply immunized animals showed increased IL-5, IL-4, and IgG1 antibody production associated with enhanced Th2 response. These responses demonstrated some degree of organ compartmentalization, with splenocytes demonstrating higher Th1-related lymphokine production and cells from draining lymph nodes showing stronger proliferation and Th2 type reactivity. However, hyperimmunized mice also continued to demonstrate substantial Th1-associated immune reactivity. Moreover, in vivo Ag challenge elicited activated larvacidal macrophages in hyperimmunized animals. These observations indicate that protective cell-mediated mechanisms associated with induction of CD4+ Th1 cell reactivity predominate in singly vaccinated mice. Further vaccination stimulates Th2 responses, such as enhanced IgG1 production, that may also contribute to protective immunity.

Animals↗
PubMed1991

Approximate multinormal probabilities applied to correlated multiple endpoints in clinical trials.

Clinical trials with multiple endpoints incur increased familywise type I errors. The Bonferroni correction is a common method used to modify the p-values to account for multiple significance testing. For independent endpoints the Bonferroni method is slightly conservative whereas with high correlation the conservatism is extreme, as demonstrated by Pocock et al. This paper presents a procedure which allows for the correlation present, whilst adjusting the multiple p-values. The method is based on an approximation derived for multinormal probabilities.

Analysis of Variance↗