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Biomedical subjects

G Reid

Publications and source records attributed to G Reid.

At least 109 records · Page 6Linked to original sources
PubMed1997

Effect on uropathogens of prophylaxis for urinary tract infection in spinal cord injured patients: preliminary study.

Spinal cord injured patients are highly prone to urinary tract infections. The high frequency of recurrences, the problems with drug resistance and the difficulties associated with diagnosis complicate the management. In a preliminary retrospective study of 30 patient files, we discovered that prophylactic antimicrobial therapy with trimethoprim-sulfamethoxazole, significantly reduced the incidence of symptomatic urinary tract infections. The prevention of infection resulted in cheaper healthcare expenses than treatment. ONe problematic outcome was that antibiotic therapy resulted in a dramatic change in the population of uropathogens infecting the host, from a predominantly Gram negative type to one dominated by Enterococcus faecalis.

Adolescent↗
PubMed1996

Uropathogenic Escherichia coli adhere to urinary catheters without using fimbriae.

Five well-characterized urinary and fecal isolates of Escherichia coli were found to be hydrophilic irrespective of their serotypes and their ability to express fimbriae. All the strains were able to adhere to silicone latex urinary catheters, although strain 917, which expressed type P fimbriae as its only adhesin, adhered poorly. Although specific adhesins, particularly fimbriae, have been shown to mediate adhesion of E. coli to uroepithelial cells, they do not mediate specific adhesion onto urinary catheter material. The overall surfaces of the strains, tested using microelectrophoresis as a function of pH and X-ray photoelectron spectroscopy, were not significantly different, thus suggesting more non-specific adhesion mechanisms to urinary catheters.

Bacterial Adhesion↗
PubMed1996

Most lactotrophs from lactating rats are able to respond to both thyrotropin-releasing hormone and dopamine.

Intracellular free calcium concentration ([Ca2+]i) was measured with video imaging in lactotrophs from lactating rats. The median resting [Ca2+]i was 24 nM (85 cells). The great majority of cells responded to thyrotropin-releasing hormone (TRH) with an increase in [Ca2+]i, (median peak [Ca2+]i after TRH = 298 nM; n = 73). In 77% of these cells this [Ca2+]i increase was biphasic, with [Ca2+]i remaining high after the initial peak (median [Ca2+]i 90 s after TRH application = 104 nM; n = 56); the second phase depended on calcium influx. Most cells also responded to dopamine (DA), after TRH had been applied. DA reduced or abolished TRH-induced calcium influx and also reduced resting [Ca2+]i if this was above its initial value. A few lactotrophs responded to TRH only after DA application and withdrawal. We conclude that the population of lactotrophs in lactating rats is heterogeneous, but is not composed of two distinct sub-groups defined by their responsiveness to TRH or DA.

Animals↗
PubMed1996

Immunogenicity of a peptide from a major neutralising determinant of the feline immunodeficiency virus surface glycoprotein.

The third variable region (V3) of the feline immunodeficiency virus (FIV) surface glycoprotein is predicted to have similar physical properties to that of HIV and has been shown to contain immunodominant and neutralizing epitopes. Immunological characteristics of this region were investigated further using a peptide corresponding to the middle of the putative FIV V3 loop. The peptide was recognized in ELISA by sera from the majority of naturally FIV-infected cats, and absorbed a significant fraction of the virus neutralizing activity from a pool of sera of cats naturally infected with FIV, confirming the immunogenic nature of this region. A sheep immunized with an octameric form of the peptide (multiple antigenic peptide; MAP) in Freund's complete adjuvant generated neutralizing antibody to a higher titre than infected cats. However, immunization of cats with the same MAP in an acceptable adjuvant formulation (Quil A) induced antibody and cytotoxic T-cell responses to the immunizing peptides but only minimal neutralizing activity. These responses did not significantly alter the kinetics of infection or the proviral load after challenge with a homologous strain of FIV, compared with naive controls. While the potential efficacy of peptide vaccines to lentiviruses remains to be determined, this study shows that the immune response evoked may be highly dependent on the delivery and adjuvant regime used.

Amino Acid Sequence↗
PubMed1996

Identification and plasmid profiles of Lactobacillus species from the vagina of 100 healthy women.

It was hypothesized that Lactobacillus acidophilus might not be the dominant aerobic or microaerophilic Lactobacillus species in the human vagina, and that the dominant isolates are likely to express a variety of properties associated with colonization. To examine the question, vaginal swabs were collected from 100 healthy premenopausal women and cultured to detect the dominant aerobic or microaerophilic isolates of Lactobacillus. Only eight species were detected, with Lactobacillus jensenii being the dominant colonizers in the highest number (35) of women. Twelve different plasmid profiles were found amongst the isolates, but there was no association between plasmids and vaginal colonization or hydrogen peroxide production. Of the strains tested, few were resistant to the spermicidal agent nonoxynol-9. The data identify species within which strains may possess properties associated with maintenance of a healthy vaginal ecology.

Drug Resistance, Microbial↗
PubMed1996

Inhibition of initial adhesion of uropathogenic Enterococcus faecalis by biosurfactants from Lactobacillus isolates.

In this study, 15 Lactobacillus isolates were found to produce biosurfactants in the mid-exponential and stationary growth phases. The stationary-phase biosurfactants from lactobacillus casei subsp. rhamnosus 36 and ATCC 7469, Lactobacillus fermentum B54, and Lactobacillus acidophilus RC14 were investigated further to determine their capacity to inhibit the initial adhesion of uropathogenic Enterococcus faecalis 1131 to glass in a parallel-plate flow chamber. The initial deposition rate of E. faecalis to glass with an adsorbed biosurfactant layer from L. acidophilus RC14 or L. fermentum B54 was significantly decreased by approximately 70%, while the number of adhering enterococci after 4 h of adhesion was reduced by an average of 77%. The surface activity of the biosurfactants and their activity inhibiting the initial adhesion of E. faecalis 1131 were retained after dialysis (molecular weight cutoff, 6,000 to 8,000) and freeze-drying. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy revealed that the freeze-dried biosurfactants from L. acidophilus RC14 and L. fermentum B54 were richest in protein, while those from L. casei subsp. rhamnosus 36 and ATCC 7469 had relatively high polysaccharide and phosphate contents.

Bacterial Adhesion↗
PubMed1995

An unusual sequela to an inferior dental block injection.

This report describes an unusual case of blanching of the facial and palatal soft tissues following the administration of an inferior dental block injection. Possible anatomical explanations for the clinical observations are discussed.

Face↗
PubMed1995

Action potentials and membrane currents in the human node of Ranvier.

Action potentials and membrane currents were recorded in single human myelinated nerve fibres under current- and voltage-clamp conditions at room temperature. Nerve material was obtained from patients undergoing nerve graft operations. Successful recordings were made in 11 nerve fibres. In Ringer's solution, large transient Na currents were recorded, which could be blocked completely with tetrodotoxin. Partial block of these currents with 3 nM tetrodotoxin was used to reduce the voltage-clamp error due to series resistance. Outward K currents were very small in intact nerve fibres, but had a large amplitude in fibres showing signs of paranodal demyelination. In isotonic KCl, the K current could be separated into three components: two fast components (Kf1 and Kf2) and one slow component (Ks). Time constants and steady-state activation and inactivation of Na permeability and of fast and slow K conductance were measured within the potential range of -145 mV to +115 mV. From these parameters, the corresponding rate constants were calculated and a mathematical model based on the Frankenhaeuser-Huxley equations was derived. Calculated action potentials closely matched those recorded. Single calculated action potentials were little affected by removing the fast or slow K conductance, but the slow K conductance was required to limit the repetitive response of the model to prolonged stimulating currents.

Action Potentials↗
PubMed1995

Influence of lactobacilli on the adhesion of Staphylococcus aureus and Candida albicans to fibers and epithelial cells.

The ability of organisms to adhere to and form biofilms on fibrous materials is believed to be an important initiating step in the induction of several diseases, such as toxic shock syndrome. Using an in vitro assay, a moderately hydrophobic strain of Staphylococcus aureus (water contact angle 35 degrees) and a hydrophilic Candida albicans (shown by a hexadecane test) were highly adherent to commercial diaper fibers. The lumen side of the diaper was porous and the fibers were very hydrophobic (> 140 degrees), but the internal section was very hydrophilic (0 degrees), presumably for lus strains was present. Surfaces precoated with lactobacilli inhibited staphylococcal adhesion by 26-97%, and candida by 0-67%. When the lactobacilli were used to challenge adherent pathogens, there was 99% displacement of the S. aureus and up to 91% displacement of C. albicans. Hydrophobic L. acidophilus 76 (54 degrees) and T-13 (80 degrees) were the most effective of five Lactobacillus isolates tested at interference by precoating. The moderately hydrophilic L. casei var rhamnosus GR-1 (33 degrees) was the most effective at displacing the yeast. Experiments with uroepithelial cells also showed that the lactobacilli could significantly interfere with the adhesion of both pathogens to the cells. The results demonstrate the rapidity with which two pathogens adhered to fibers and epithelial cells, and raised the possibility that members of the normal female urogenital flora might interfere with infections caused by these organisms.

Adult↗
PubMed1995

The effects of vasoactive intestinal polypeptide and substance P on methacholine-induced sweating and vascular flare in diabetic neuropathy.

Vasoactive intestinal polypeptide (VIP) and substance P (SP) immunoreactivity are reduced in the cutaneous nerves of diabetic patients with peripheral neuropathy. The functional significance of this finding was studied by measuring the forearm sweat response to intradermal methacholine and the effect of coadministration of VIP and SP in six normal subjects, and in six diabetic patients with neuropathy and eight without. Flare responses to the two peptides were also measured. Methacholine-induced sweat output was significantly greater in neuropathic patients compared with the other groups (p < 0.05), suggesting upper limb denervation supersensitivity. VIP and SP alone did not evoke sweating in any subject. Injection of VIP or SP reduced methacholine-induced sweating to a similar degree in all groups, except that the reduction was smaller in the non-neuropathic group than in the others (p = 0.028 versus normal subjects, p = 0.014 versus neuropathic diabetic patients). Flare responses to the peptides were markedly reduced in the neuropathic patients compared with the other groups (p < 0.01). In neuropathic patients, increased sweat responses and decreased flare coexist with diminished neurophysiological measurements; cutaneous sweating and flare responses provide valuable additional information to conventional methods of neurological assessment in diabetic neuropathy.

Adult↗
PubMed1995

Bacterial adhesion to dental amalgam and three resin composites.

OBJECTIVES: The ability of three oral bacteria to adhere to hydrophobic amalgam (water contact angle 60 degrees) and hydrophobic resin composites (Prisma-AP.H 56 degrees. Herculite XRV 82 degrees and Z100 89 degrees) was compared using an in vitro assay. METHODS AND RESULTS: Following preincubation of the materials with human saliva, X-ray photoelectron spectroscopy showed the surfaces to adsorb carbon and nitrogen-containing compounds in a conditioning film that appeared to block the detection of Na and others in 2100 resin. Hg and Ag in amalgam, Si and Zn in Prisma AP.H resin and Ag and Na in Herculite resin. The precoating of the substrata by a proteinaceous conditioning film led to decreased binding of viable cells of Streptococcus sanguis CH3, Streptococcus salivarius HB and Actinomyces viscosus WG as compared with the adhesion to bare composites. With and without salivary coating, there was a correlation between increased bacterial hydrophobicity and increased retention on the substrata. However, there was no statistical difference in binding to the amalgam compared with the resin composites. In vitro studies showed that the bacteria autoaggregated in the presence of saliva. CONCLUSION: The results indicate the potential ability of normal oral flora to colonize resin composite.

Actinomyces viscosus↗
PubMed1995

Axonal ion channel dysfunction in amyotrophic lateral sclerosis.

In amyotrophic lateral sclerosis (ALS) it is not known how or why the motor neurons die, but a clue is provided by observations that the dying cells discharge spontaneously, producing muscle fasciculations. The fasciculations can arise either proximally or distally in the motor unit, suggesting a widespread disturbance of membrane excitability. To test for this, we applied the technique of threshold electrotonus to ulnar motor axons at the wrist, comparing the responses to 100 ms polarizing currents in 11 ALS patients with those from 15 normal controls, six patients with benign fasciculations, 19 with lower motor neuron disorders and six with upper motor neuron disorders. We found that the motor axons of ALS patients, unlike those in the neurological control groups, responded abnormally to subthreshold depolarizing currents, becoming either more (seven cases) or much less excitable (four cases) than normal. Both types of abnormality could be reproduced in rat nerves in vitro, and in a computer model of human motor axons, by reducing voltage dependent potassium conductances. When sufficient potassium channels were blocked, the model axon became unstable and depolarized regeneratively, resulting in an abrupt fall in excitability. We conclude that the fasciculations in ALS are caused by an imbalance between functional sodium and potassium channels, and we propose that this ion channel dysfunction could also be responsible for the motor neuron degeneration in this disease.

Adult↗
PubMed1995

Induction of feline immunodeficiency virus-specific cell-mediated and humoral immune responses following immunization with a multiple antigenic peptide from the envelope V3 domain.

Cytotoxic T-cell determinants should be an important component of a vaccine against feline immunodeficiency virus (FIV). Epitope mapping studies have revealed an immunodominant neutralization epitope within the third variable (V3) domain of the viral envelope glycoprotein comprizing 17 amino acids (residues 390-406: RAISSWKQRNRWEWRPD). We have investigated the induction of FIV-specific cytotoxicity and anti-peptide antibody in cats immunized with a multiple antigenic peptide (MAP) containing this epitope. Virus-specific lymphocytotoxicity was determined using autologous or allogeneic skin fibroblasts as target cells labelled with chromium-51 and pulsed with overlapping 10 amino acid peptides. Cytotoxic effector cells derived from fresh peripheral blood were detected in five out of 10 immunized cats. The cell-mediated immune response appeared to be directed to envelope peptide 1 (RAISSWKQRN) and peptide 2 (SWKQRNRWEW), with recognition of peptide 3 (QRNRWEWRPD) in only one cat. An antibody response to the 17 amino acid peptide immunogen was detected in seven immunized cats, which was directed to envelope peptides 2 and 3. These results suggest that different epitopes may be recognized by the cell-mediated and humoral immune responses. None of the cats was protected from challenge with the Glasgow8 isolate of FIV (FIV/GL-8). This study has implications for vaccine strategies using synthetic peptides to induce virus-specific cell-mediated immune responses.

Amino Acid Sequence↗
PubMed1995

Effects of ciprofloxacin and vancomycin on physicochemical surface properties of Staphylococcus epidermidis, Escherichia coli, Lactobacillus casei and Lactobacillus acidophilus.

Under clinical conditions, during antibiotic treatment, micro-organisms often grow at sub-inhibitory concentrations. This may lead to altered adhesive cell surface properties and to a disruption of the indigenous microflora, in addition to the creation of a more pathogenic biofilm. The effects of growing Staphylococcus epidermidis, Escherichia coli and lactobacilli in the presence of sub-inhibitory concentrations of ciprofloxacin and vancomycin were determined. Growing the cells under antibiotic burden sometimes led to altered cell surface hydrophobicity (by adhesion to hexadecane), changes in the pH-dependence of zeta potentials, and elemental surface compositions or in different SDS-PAGE protein profiles. For several isolates only one of the surface properties was altered by the presence of an antibiotic in the growth medium and no systematic effects were observed for all isolates representing a certain species or even strain. The important conclusion to be drawn from the results of this study is that the effects of growing cells under antibiotic burden on their adhesive cell surface properties can only be established when using a variety of techniques.

Alkanes↗