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Biomedical subjects

M Fletcher

Publications and source records attributed to M Fletcher.

At least 109 records · Page 6Linked to original sources
PubMed1986

Evidence of inadequate humidification of inspired gas during artificial ventilation of newborn babies in the British Isles.

Data on routine humidifier settings used in respiratory support for newborn babies were obtained from 242 neonatal units in the British Isles. For each of the most commonly used humidifiers inspired gas humidity was measured under routine clinical conditions with an electronic hygrometer. Most endotracheally intubated babies breathe inspired gas of well below physiological humidity (44 mg H2O/l) and many below the minimum recommended for adults by the British Standards Institution (33 mg H2O/l). Inadequate humidification could contribute to several complications of artificial ventilation in newborn babies by inhibiting mucociliary clearance.

Aged↗
PubMed1986

Survey of bereaved parents.

A retrospective study in Vancouver was designed to evaluate parents' perceptions of support received after the death of a child up to 5 years old. The families were contacted with the help of health care professionals and the news media. A standardized questionnaire was used in a personal interview or occasionally by mail. The contact with health care professionals after the child's death was frequently considered by the 61 families not to have been helpful: 80% of the families judged the information or counselling they had received to be inadequate, and over 50% had received none; many listed comments and behaviour that they considered harmful. The families desired both full medical information and grief support; what forms such support could take are suggested.

Adult↗
PubMed1986

The reorganization of the Golgi complex in anoxic pancreatic acinar cells.

An extensive reorganization of the Golgi complex (GC) was found in the acinar cells of pancreatic lobules incubated in vitro under conditions which inhibited ATP synthesis and thereby blocked the intracellular transport of secretory proteins. After 15-min incubation under N2 or in the presence of 1 mM dinitrophenol (DNP), transitional elements of the endoplasmic reticulum (ER) lost their protrusions, small peripheral Golgi vesicles decreased drastically in number, and fibrillar aggregates approximately 0.2 to 0.5 micron in diameter appeared on the cis side of the stacks of Golgi cisternae. These aggregates often contained vesicle-free, small (approximately 40 nm), globular cages and, occasionally, vesicle-free, clathrin-like cages. Fibrillar aggregates were also observed on the trans side of Golgi stacks. Other changes included the proliferation of GERL-elements ("rigid lamellae") and a striking increase in the population of coated vesicles trans to the Golgi complex and throughout the apical region of the anoxic acinar cells. All changes were found to be reversible provided the cells were incubated for less than 1 h under N2. These observations suggest that the fibrillar elements and the associated cages described in this study may play a role in the vesicular transport of newly synthesized proteins from the ER to the Golgi complex. Further work is needed to explore this possibility.

Animals↗
PubMed1986

Influence of substratum hydration and adsorbed macromolecules on bacterial attachment to surfaces.

The attachment of Pseudomonas fluorescens and an Acinetobacter sp. to hydrogel and polystyrene surfaces was investigated to evaluate the influence of adsorbed water and macromolecules on adhesion. With both organisms, there was a decrease in attachment numbers with increasing water content of the hydrogels. There was also a decrease in attachment with a decrease in water contact angle on untreated, tissue culture and sulfonated polystyrene surfaces; however, the attachment numbers were higher than would be expected on the basis of the hydrogel data. With P. fluorescens, attachment to untreated and tissue culture polystyrene was inhibited by bovine serum albumin, Escherichia coli lipopolysaccharide, and the supernatant from spent medium, both when the conditioning substances were added to the suspension of attaching cells and when they were preadsorbed onto the surfaces. Dextran inhibited attachment only when added to the bacterial suspension. Supernatants from centrifuged natural freshwater samples had no effect. Thus, hydration of a surface and the adsorption of macromolecules can reduce bacterial attachment; however, additional factors relating to the chemical composition of the substratum and polymeric stabilization of suspended cells can affect the adhesion interaction and resultant numbers of attached cells.

Acinetobacter↗
PubMed1986

Variability of the influence of physicochemical factors affecting bacterial adhesion to polystyrene substrata.

The role of electrostatic and hydrophobic interactions and solid and liquid surface tensions in the adhesion of four bacterial species (Pseudomonas fluorescens, Enterobacter cloacae, Chromobacterium sp., and Flexibacter sp.) to hydrophobic polystyrene petri dishes and to more hydrophilic polystyrene tissue culture dishes was investigated. The effect of electrostatic interactions was investigated by determining the effects of different electrolyte solutions on attachment to and of different electrolyte and pH solutions on detachment from the polystyrene substrate. The significance of solid and liquid surface tensions and hydrophobic interactions was investigated by measuring the effects of different surfactants (including a concentration series of dimethyl sulfoxide) on adhesion and detachment. Adhesion varied with bacterial species, substratum, and electrolyte type and concentration, with no apparent correlation between adhesion and electrolyte valence or concentration. The influence of different pH and detergent solutions on bacterial detachment also varied with species, substratum, pH, and detergent type; however, the greatest degree of detachment of all strains from the surfaces was produced by detergent treatment. The results suggest that adhesion cannot be attributed to any one type of adhesive interaction. There was some evidence for both electrostatic and hydrophobic interactions, but neither interaction could wholly account for the data.

Journal Article↗
PubMed1986

Measurement of Glucose Utilization by Pseudomonas fluorescens That Are Free-Living and That Are Attached to Surfaces.

The assimilation and respiration of glucose by attached and free-living Pseudomonas fluorescens were compared. The attachment surfaces were polyvinylidene fluoride, polyethylene, and glass. Specific uptake of [C]glucose was determined after bacterial biomass was measured by (i) microscopic counts or (ii) prelabeling of cells by providing [H]leucine as substrate, followed by dual-labeling scintillation counting. The glucose concentration was 1.4, 3.5, 5.5, 7.6, or 9.7 muM. Glucose assimilation by cells which became detached from the surfaces during incubation with glucose was also measured after the detached cells were collected by filtration. The composition of the substratum had no effect on the amount of glucose assimilated by attached cells. Glucose assimilation by attached cells exceeded that by free-living cells by a factor of between 2 and 5 or more, and respiration of glucose by surface-associated cells was greater than that by free-living bacteria. Glucose assimilation by detached cells was greater than that by attached bacteria. Measurements of biomass by microscopic counts gave more consistent results that those obtained with dual-labeling, but in general, results obtained by both methods were corroborative.

Journal Article↗
PubMed1986

Laboratory evaluation of Gambusia affinis fish as predators of the schistosome-bearing snails Bulinus truncatus.

In this laboratory-based study involving numerous experiments, it was demonstrated that the mosquito fish Gambusia affinis preys effectively upon the schistosome-bearing snail Bulinus truncatus, even in the presence of an alternative source of food. Egg masses and juvenile snails less than or equal to 2 mm in size are preferred. Individual eggs are nibbled, and the tiny snails with fragile shells are swallowed and digested. In the absence of other foods, the fish consume the flesh of snails 3 to 6 mm in size, leaving their empty shells intact. The larger snails are unharmed, but their offspring could be eradicated by the fish under favourable conditions.

Animals↗
PubMed1985

Internal biliary drainage and local radiotherapy with iridium-192 wire in treatment of hilar cholangiocarcinoma.

Curative surgery is not possible in the vast majority of patients who present with hilar cholangiocarcinoma. Palliative therapy to relieve jaundice, either at laparotomy or percutaneously, is therefore necessary. The mean survival of these patients is of the order of 8.5 months (Wheeler et al., 1981). We report a significant increase in mean survival to 16.8 months in patients treated with internal biliary drainage when combined with local irradiation to the tumour with iridium-192.

Adenoma, Bile Duct↗
PubMed1983

Influence of substratum wettability on attachment of freshwater bacteria to solid surfaces.

We studied the attachment of a number of freshwater bacteria from River Sowe, Coventry, England, to test substrata. The attachment of each organism to hydrophobic and hydrophilic surfaces was evaluated, and further studies evaluated the attachment of selected isolates to a number of substrata with a range of water wettabilities. The wettability of each substratum was determined by contact angle measurements and was expressed as the work of adhesion (W(A)). No generic pattern of attachment to the test surfaces was found, although the majority of the organisms isolated showed a preference for the hydrophobic surface. A more detailed study of selected isolates showed a relationship between W(A) and number of attached cells. Each bacterium attached in maximum numbers to a surface that was characteristic of that organism and that had a W(A) between 75 and 105 mJ m.

Journal Article↗
PubMed1983

Amino Acid assimilation and electron transport system activity in attached and free-living marine bacteria.

Amino acid assimilation and electron transport system activity of a marine Pseudomonas sp. was evaluated to determine whether the activity of bacteria attached to solid surfaces differed from that of free-living bacteria or bacteria which had been attached but subsequently desorbed from the substratum (detached bacteria). Bacteria were allowed to attach to glass and to a range of plastic surfaces (Thermanox, polyvinylidene fluoride, polyethylene, polytetrafluoroethylene). Microautoradiography and staining with a tetrazolium salt to demonstrate electron transport system activity were used to compare the activity of these organisms with that of free-living or detached cells. The water-wettability of the surfaces was evaluated by measuring the advancing contact angle (theta(A)) of water on each surface, to determine whether there was a relationship between activity and substratum hydrophilicity. There was an increase in the proportion of leucine-assimilating attached bacteria and in the proportion of attached cells demonstrating electron transport system activity with an increase in substratum theta(A), but the relationship between activity of attached and free-living cells depended on the substratum. Activity appeared to promote firm attachment, and detached bacteria assimilated fewer amino acids than did attached cells. There was no general effect of surfaces on attached bacterial activity, and attached cells may be more, or less, active than free-living cells, depending on the amino acid, its concentration, and substratum properties.

Journal Article↗
PubMed1982

Low-molecular-weight heparin and prevention of postoperative deep vein thrombosis.

The efficacy of low-molecular-weight heparin as a prophylactic agent was assessed in 150 consecutive patients over the age of 40 undergoing major abdominal surgery. Fifty of these patients received 1250 activated partial thromboplastin time (APTT) units of low-molecular-weight heparin every 12 hours: three developed isotopic deep vein thrombosis, which was confirmed by phlebography in two cases. The other 100 patients received a single injection of 1850 APTT units of low-molecular-weight heparin. Three of them developed isotopic deep vein thrombosis; phlebography failed to confirm the presence of thrombi in each case. None of the 150 patients studied died from fatal or contributory pulmonary emboli. Low-molecular-weight heparin was not associated with any increase in preoperative or postoperative bleeding. The effect of equal amounts of postoperative bleeding. The effect of equal amounts of low-molecular-weight heparin and unfractionated heparin on the coagulation mechanism during surgery was investigated in another 30 patients. The clotting assays and results of in-vivo platelet function tests indicated that both preparations produced similar effect. Intragroup comparisons, however, showed significant differences in the anti-factor Xa activity, lipoprotein lipase release, and plasma prekallikrein concentrations. A single injection of low-molecular-weight heparin daily is a convenient way of preventing deep vein thrombosis in high-risk patients undergoing major abdominal surgery.

Adult↗
PubMed1982

Bubble contact angle method for evaluating substratum interfacial characteristics and its relevance to bacterial attachment.

A bubble contact angle method was used to determine interfacial free-energy characteristics of polystyrene substrata in the presence and absence of potential surface-conditioning proteins (bovine glycoprotein, bovine serum albumin, fatty acid-free bovine serum albumin), a bacterial culture supernatant, and a bacterial exopolymer. Clean petri dish substrata gave a contact angle of 90 degrees , but tissue culture dish substrata were more hydrophilic, giving an angle of 29 degrees or less. Bubble contact angles at the surfaces exposed to the macromolecular solutions varied with the composition and concentration of the solution. Modification by pronase enzymes of the conditioning effect of proteins depended on the nature of both the substratum and the protein, as well as the time of addition of the enzyme relative to the conditioning of the substratum. The effects of dissolved and substratum-adsorbed proteins on the attachment of Pseudomonas sp. strain NCMB 2021 to petri dishes and tissue culture dishes were consistent with changes in bubble contact angles (except when proteins were adsorbed to tissue culture dishes before attachment) as were alterations in protein-induced inhibition of bacterial attachment to petri dishes by treatment with pronase. Differences between the attachment of pseudomonads to petri dishes and tissue culture dishes suggested that different mechanisms of adhesion are involved at the surfaces of these two substrata.

Journal Article↗
PubMed1980

A low dose regime of 1 alpha hydroxyvitamin D3 in the management of senile osteoporosis: a pilot study.

A comparison has been made between themetabolic consequences of daily administration for 6 weeks of 1.0 micrograms and 0.5 micrograms 1 alpha hydroxyvitamine D3 (1 alpha(OH)D3) in twenty patients with senile osteoporosis. There was no significant difference in the increase of calcium absorption which occurred in the two treatment groups between the beginning and end of the trial period. Serum and urinary calcium rose significantly in those receiving 1.0 micrograms 1 alpha(OH)D3 but not in the lower dosage group. Serum parathyroid hormone levels were suppressed in the higher dosage group only. There was a significantly greater rise of serum inorganic phosphate, and fall of serum magnesium, on the higher dosage, but no significant change in serum creatinine occurred in either group. It is, therefore, suggested that in long term therapy regimes for osteoporosis incorporating 1 alpha(OH)D3, 0.5 micrograms may be a more suitable daily dose than 1.0 micrograms 1 alpha(OH)D3.

Aged↗