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Biomedical subjects

N J Russell

Publications and source records attributed to N J Russell.

At least 55 records · Page 3Linked to original sources
PubMed1990

Cold adaptation of microorganisms.

Psychrophilic and psychrotrophic microorganisms are important in global ecology as a large proportion of our planet is cold (below 5 degrees C); they are responsible for the spoilage of chilled food and they also have potential uses in low-temperature biotechnological processes. Psychrophiles and psychrotrophs are both capable of growing at or close to zero, but the optimum and upper temperature limits for growth are lower for psychrophiles compared with psychrotrophs. Psychrophiles are more often isolated from permanently cold habitats, whereas psychrotrophs tend to dominate those environments that undergo thermal fluctuations. The molecular basis of psychrophily is reviewed in terms of biochemical mechanisms. The lower growth temperature limit is fixed by the freezing properties of dilute aqueous solutions inside and outside the cell. In contrast, the ability of psychrophiles and psychrotrophs to grow at low, but not moderate, temperatures depends on adaptive changes in cellular proteins and lipids. Changes in proteins are genotypic, and are related to the properties of enzymes and translation systems, whereas changes in lipids are genotypic or phenotypic and are important in regulating membrane fluidity and permeability. The ability to adapt their solute uptake systems through membrane lipid modulation may distinguish psychrophiles from psychrotrophs. The upper growth temperature limit can result from the inactivation of a single enzyme type or system, including protein synthesis or energy generation.

Adaptation, Physiological↗
PubMed1990

Immunization with calcitonin gene-related peptide reduces the inflammatory response to adjuvant arthritis in the rat.

The influence of circulating antibodies to calcitonin gene-related peptide on the inflammatory response was examined in rats with adjuvant-induced arthritis. Rats were immunized with alpha calcitonin gene-related peptide conjugated to thyroglobulin, and circulating antibodies were identified by their capacity to bind radiolabelled rat alpha or human calcitonin gene-related peptide. In unimmunized rats and rats immunized with thyroglobulin alone, the secondary lesions (characterized as paw swelling, nodules on ears and tail, and inflamed nose) produced after adjuvant-induced arthritis were similar. However, at 21 days, when these lesions were maximal, the animals immunized with calcitonin gene-related peptide showed decreased numbers of lesions. An additional marker of disease activity, namely alpha 1 glycoprotein levels in plasma, was also measured. Again, plasma alpha 1 glycoprotein levels were similar in rats that were unimmunized or received thyroglobulin alone, but at 21 days were significantly reduced in animals immunized with calcitonin gene-related peptide. In contrast, the initial foot swelling seen in the first few days after injection of adjuvant was not significantly different in the various groups. The results suggest that antibodies to calcitonin gene-related peptide are able to reduce the severity of the adjuvant arthritis syndrome, and that this peptide contributes to the inflammatory response seen in the later stages of the disease model.

Animals↗
PubMed1990

Die-away kinetic analysis of the capacity of epilithic and planktonic bacteria from clean and polluted river water to biodegrade sodium dodecyl sulfate.

The capacities of epilithic and planktonic river bacterial populations to degrade sodium dodecyl sulfate (SDS) in samples taken at two times during 1987 from one clean and four polluted sites in a South Wales river were estimated in die-away tests under simulated environmental conditions. There was a relatively slow disappearance of SDS in die-away tests for both planktonic and epilithic populations taken from the clean source site, as compared with those taken from the downstream polluted sites, for which the rate of biodegradation was accelerated, sometimes after an apparent initial lag period. The kinetic components contributing to the die-away curves were quantified by nonlinear regression analysis in which the experimental data were fitted to a variety of possible kinetic models. All samples except for one from the polluted sites best fitted a model which describes the biodegradation of SDS at concentrations well below its K(m) by bacteria whose growth is exponential and unaffected by the addition of a test substrate. Each sample from the clean source site fitted a different model, but there was generally little or no growth on endogenous carbon. A consideration of the numerical values of constants derived from the modeling of epilithic and planktonic populations from polluted sites indicated clearly that the biodegradative capacity of epilithic bacterial populations towards SDS is more stable than that of planktonic bacterial populations.

Journal Article↗
PubMed1989

Antibodies to calcitonin-gene related peptide reduce inflammation induced by topical mustard oil but not that due to carrageenin in the rat.

The influence of prior immunization to calcitonin gene-related peptide (CGRP) was examined on responses in two models of inflammation plasma: protein extravasation following topical application of mustard oil to the hind paw, and changes in paw volume following subplantar injection of carrageenin. In rats with antibodies to CGRP, there was an approximately 50% decrease compared to the control animals in extravasation, measured by the Evans blue method after topical mustard oil. In contrast, there was no difference in the inflammatory response to carrageenin in control and immunized rats. The results indicate that CGRP, which is probably released from the peripheral endings of cutaneous primary afferents, plays a role in the inflammatory response to mustard oil, but not carrageenin.

Administration, Topical↗
PubMed1989

Dextromethorphan attenuates post-ischemic hypoperfusion following incomplete global ischemia in the anesthetized rat.

The effects of dextromethorphan (DM) were tested in an in vivo model of incomplete global cerebral ischemia. Anesthetized rats were divided into 4 groups: Group 1 (saline); Group 2 (DM pre-treatment, 20 mg/kg i.v. bolus followed by 10 mg/kg/h DM infusion); Group 3 (DM post-treatment, 2 mg/kg i.v. bolus followed by 10 mg/kg/h DM infusion at the onset of post-ischemic hypoperfusion); and Group 4 (sham-operated, drug-treated). Groups 1-3 underwent 15 min of 4-vessel occlusion followed by 3 h of reperfusion. Administration of DM in sham-operated animals (Group 4) had no effect on cerebral blood flow or electroencephalographic (EEG) activity. In contrast, when compared to the Group 1 saline controls, significant attenuation of post-ischemic hypoperfusion and EEG dysfunction was demonstrated in ischemic rats treated with DM (both pre- and post-treatment), suggesting an ability of DM to improve cerebral blood flow (CBF) and brain function in cerebral ischemia.

Animals↗
PubMed1989

Adaptive modifications in membranes of halotolerant and halophilic microorganisms.

Halotolerant and halophilic microorganisms can grow in (hyper)saline environments, but only halophiles specifically require salt. Genotypic and phenotypic adaptations are displayed by halophiles; the halotolerants adapt phenotypically, but it is not established whether they show genotypic adaptation. This paper reviews the various strategies of haloadaptation of membrane proteins and lipids by halotolerant and halophilic microorganisms. Moderate halophiles and halotolerants adapt their membrane lipid composition by increasing the proportion of anionic lipids, often phosphatidylglycerol and/or glycolipids, which in the moderately halophilic bacterium Vibrio costicola appears to be part of an osmoregulatory response to minimize membrane stress at high salinities. Extreme halophiles possess typical archaebacterial ether lipids, which are genotypically adapted by having additional substitutions with negatively-charged residues such as sulfate. In contrast to the lipids, it is less clear whether membrane proteins are haloadapted, although they may be more acidic; very few depend on salt for their activity.

Bacteria↗
PubMed1989

Distribution of planktonic bacteria capable of degrading sodium dodecyl sulphate (SDS) in a polluted South Wales river.

The temporal and geographical distributions of planktonic bacteria, and their ability to degrade sodium dodecyl sulphate (SDS) (AS(+) phenotype), in a polluted South Wales river, is reported for five sites source to estuary sampled during a one-year period. The annual mean prevalence of AS(+) isolates at all sites was 8.1-16.0% of the total number of isolates, and these values were not altered by including SDS in culture media. Although the proportion of AS(+) isolates in clean water at the source was not significantly different to that of polluted sites, the AS(+) cell density was lower at the source because of its lower overall numbers. The percentage of AS(+) isolates in estuarine water was higher than at the three polluted mid-river sites, but when cell numbers were taken into account, the AS(+) cell density was the same at all polluted sites including the estuary. There was no correlation between percentage of AS(+) and either BOD or oxygen concentration, but AS(+) isolates were significantly more prevalent at the end of summer. Of the AS(+) isolates, more than half contained constitute alkysulphate enzymes, the remainder being induced or repressed by SDS; the relative proportions of enzyme regulatory type did not vary significant between sites or at different sampling times.

Journal Article↗
PubMed1989

The role of substance P and calcitonin gene-related peptide in neurogenic plasma extravasation and vasodilatation in the rat.

Immunohistochemistry combined with retrograde tracing has been used to show that of the afferent neurons supplying the dorsomedial surface of the hind paw, approximately 30% contain substance P and 50% calcitonin gene-related peptide immunoreactivity. Stimulation of the saphenous nerve causes plasma extravasation and antidromic vasodilatation in this area of skin. The roles of calcitonin gene-related peptide and substance P released from peripheral afferent endings in mediating these effects were examined using immunoneutralization. In pilot experiments, the binding of radiolabelled peptide to the immunoglobulin fraction of calcitonin gene-related peptide and substance P antisera was characterized in quasi-physiological conditions. Systemic administration of either substance P or calcitonin gene-related peptide antibodies caused a significant decrease (P less than 0.05) in plasma extravasation measured by the Evans Blue method in response to topical application of mustard oil (0.5%) to the skin, or of capsaicin (5 microM) to the saphenous nerve. Topical application of mustard oil also produced a 52.9 +/- 5.1% increase in skin red cell flux. This increase was significantly decreased by both substance P and calcitonin gene-related peptide antibodies. The results suggest that both peptides are involved in mediating neurogenic inflammatory responses.

Animals↗
PubMed1989

The lipid composition and permeability to the triazole antifungal antibiotic ICI 153066 of serum-grown mycelial cultures of Candida albicans.

The total lipid content of Candida albicans (serotype A: NCPF 3153) exponential-phase mycelial cultures grown in tissue-culture medium 199 (containing 10%, v/v, foetal calf serum) was 29.8 +/- 8 mg (g dry weight)-1 (mean +/- SD). The weight ratios of phospholipid to neutral lipid and phospholipid to non-esterified sterol were 2.6 +/- 0.4 and 24.9 +/- 0.5, respectively. The major phospholipid was phosphatidylcholine with smaller amounts of phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidylglycerol and diphosphatidylglycerol; the most abundant fatty acids were palmitic, palmitoleic, oleic and linoleic acids. The major neutral lipids comprised esterified sterol, triacylglycerol and non-esterified fatty acid with a smaller amount of non-esterified sterol. The fatty acid compositions of the three fatty-acid-containing neutral lipids were distinct from each other and the phospholipids. Comparison with previous data on yeast cultures of C. albicans A grown in glucose broth shows that mycelial cultures have a larger lipid content, lower phospholipid to neutral lipid ratio and higher phospholipid to non-esterified sterol ratio. We now show that mycelial cultures were more permeable to a [14C]triazole antifungal antibiotic compared with exponentially growing yeast cultures of several azole-sensitive strains. Taken together these data are consistent with there being a relationship between the phospholipid/non-esterified sterol ratio of a culture and its ability to accumulate a triazole.

Antifungal Agents↗
PubMed1989

Isolation of mucoid strains of Pseudomonas aeruginosa from non-cystic-fibrosis patients and characterisation of the structure of their secreted alginate.

When the incubation period of primary isolation plates was extended to 48 h, mucoid strains of Pseudomonas aeruginosa were found in specimens from various infected sites in patients who did not have cystic fibrosis. The 17 mucoid isolates were characterised in terms of mucoid type, pyocin type, and their sensitivity or resistance to seven beta-lactam and two aminoglycoside antibiotics. The carbohydrate, uronic acid (alginate) and protein content of the water-soluble extracellular material of 15 strains was determined. This material was fractionated by ion-exchange chromatography, and the presence of alginate confirmed by the chemical assay of uronic acids and their quantitation by gas-liquid chromatography. Uronic acids were absent from a non-mucoid revertant of one strain. The strains produced alginate with a high content of mannuronic acid and substituted with O-acetyl groups. By proton nuclear magnetic resonance (1H-nmr) analysis the alginate from three strains was shown to lack polyguluronate blocks in its structure. These properties are also found in the alginate of mucoid P. aeruginosa strains from patients with cystic fibrosis.

Alginates↗
PubMed1989

An audit of doctor's management of patients with chest pain in the accident and emergency department.

In a series of 604 patients attending an accident and emergency department with chest pain, the decisions made by casualty officers about admission to the coronary care unit were compared with the retrospective opinions of experienced clinical assessors who knew the results of any subsequent investigations. Of the 119 patients whom the assessors judged should have been admitted to the coronary care unit, 14 (11.8 per cent) were judged to have been discharged in error. Of the 485 patients whom the assessors judged should not have been admitted to the coronary care unit, 32 (16 per cent) were judged to have been advised admission unnecessarily. Misinterpretation of the electrocardiographic results was apparently the reason for five of the 14 false negative errors and four of the 32 false positive errors. The median time that patients who were eventually admitted to the coronary care unit spent in the accident and emergency department was 78 min.

Chest Pain↗