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Biomedical subjects

M Fletcher

Publications and source records attributed to M Fletcher.

At least 37 records · Page 2Linked to original sources
PubMed1987

Adhesion of bacteria from mixed cell suspension to solid surfaces.

The attachment of four species of bacteria to solid surfaces was investigated to determine whether the attachment of one species of bacterium could be influenced by the presence of other attaching or attached species. Three types of experiment were done: attachment of bacteria from suspensions containing two species (termed "simultaneous attachment") was compared to attachment of each species in pure culture, the attachment of one species of bacterium to surfaces already colonized by a second species (termed "sequential attachment") was compared to attachment of the bacteria to clean, uncolonized surfaces, and bacteria were allowed to attach to a surface already colonized by a second strain, and their effect on the stabilization of adhesion of the initial colonizing strain was determined. The bacteria were Acinetobacter calcoaceticus, a Staphylococcus sp., a coryneform (isolates from a canning factory), and Staphylococcus aureus. The surfaces were tin plate, glass, and nylon. The attachment of each species was either increased, decreased or not affected by the simultaneous or sequential attachment of another species. The results depended upon the species combination, the surface composition, and the sequence of attachment. The detachment of a primary colonizing species was either increased, decreased or not affected by the subsequent attachment of a second species, depending on the species combination and surface. The results demonstrate that bacterial attachment to a surface can be influenced by the composition of the attaching population and can differ considerably from the attachment of the component species in pure culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Acinetobacter↗
PubMed1987

Renal involvement in essential mixed cryoglobulinemia.

Essential mixed cryoglobulinemia (EMC) is infrequently recognized in this country. We report studies performed in six patients with EMC evaluated by us over the last 6 years. Purpura was present in three patients and glomerulonephritis in all. Two patients had chronic hepatitis B infection. Positive cryoglobulins and C1q binding, hypocomplementemia (especially low C4), positive rheumatoid factor titer, and negative anti-DNA antibodies were characteristic laboratory findings. The cryoprecipitate had strongly positive rheumatoid factor activity and contained a monoclonal IgM, kappa type in one of the two patients evaluated. The predominant lesion by renal biopsy was mesangiocapillary glomerulonephritis type I; electron microscopy revealed typical fibrillar structures in four cases. The above-mentioned features help distinguish EMC from other forms of glomerulonephritis.

Adult↗
PubMed1987

Recent advances in the understanding of the biochemistry and clinical pharmacology of interleukin-2.

This review covers significant developments in the understanding of the biochemistry and clinical pharmacology of Interleukin-2 (IL-2) that were achieved from 1984 through September 1986. These include developments in the molecular biology of IL-2 and its receptors. Human IL-2 was cloned and sequenced by Taniguchi et al. in 1983. The gene for human IL-2 is located on the long arm of chromosome 4. The secondary structure of the gene is predominantly alpha helix. The mature gene product is a 133 amino acid glycoprotein with a molecular weight of 15,420 Daltons. The IL-2 receptor was revealed to be a glycoprotein of 272 amino acids. The mature receptor has a molecular weight of 55,000 Daltons. A more precise understanding of the mechanism of action IL-2, in particular its role in the induction of the IL-2 receptor, and aspects of the control of IL-2 production was also achieved. Metabolic and morphologic studies have revealed that activation of the T-cell antigen receptor renders the cells responsive to IL-2, but does not move them through the cell cycle. Rather, it appears that IL-2 stimulates G1 progression to S phase ie. blastic transformation. During this progression the cellular proto-oncogene c-myb is induced transiently to 6 to 7 times basal levels. The role of IL-2 as a growth factor for several subsets of T cells has been confirmed, and a new role as a growth factor for B cells was defined. Most importantly, IL-2 was shown to be directly mitogenic for and to expand subpopulations of peripheral blood cells, termed lymphokine-activated killer (LAK) cells and tumor-infiltrating lymphocytes (TIL). A number of pathologies of IL-2 production or activity have been defined, including Hodgkin's disease, graft versus host disease, systemic lupus erythematosus, lepromatous leprosy, acquired immune deficiency syndrome, and adult T cell leukemia. Murine and human in vivo studies reviewed here have revealed significant parameters of the therapeutic potential as well as the toxicity of this growth factor. Finally, the modulation of IL-2 receptors on human PBL's by thymosin fraction 5 and thymosin alpha 1 suggests that it might be possible to up-regulate IL-2 receptor expression in certain disease states and thus increase the efficacy of IL-2.

Animals↗
PubMed1987

C4 binding protein deficiency in a patient with atypical Behçet's disease.

Primary deficiency of the C4 binding protein (C4bp) was present in a patient with disease clinically resembling Behçet's disease. Her father and her sister were also deficient. This protein, as a cofactor for factor I, interferes with the assembly of, and accelerates the decay of, the classical C3 convertase. Thus, the deficiency favours C3 conversion by classical pathway activation. In addition to genital and oral ulceration, cutaneous vasculitis and synovitis, our patient had relapses complicated by angioedema, atypical for Behçet's disease. It is not clear whether her total disease, or only the complicating angioedema, was a consequence of the C4bp deficiency.

Adult↗
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

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↗
PubMed1976

Impact of the new generation coronary care unit.

A 30-bed coronary care unit with facilities for fluoroscopy, haemodynamic monitoring, mechanical heart assistance, and long-term electrocardiographic monitoring operated at a reasonable cost over five years. Much of the work was entrusted to trained nurses, and there was close consultation with cardiac surgeons over those patients who needed catheterisation or surgery. New procedures greatly reduced the numbers of early deaths from cardiac arrest and cardiac failure but had less influence on late mortality. Hospital mortality for all 3353 patients was 6-8%, and for patients under 65 with definite infarction, who were admitted direct it was 5-7%.

Aged↗
PubMed1976

The effects of proteins on bacterial attachment to polystyrene.

Bovine serum albumin, gelatin, fibrinogen and pepsin impaired the attachment of a marine pseudomonad to polystyrene Petri dishes, apparently through adsorption on the dish surface. Serum albumin also appeared to affect the bacterial surface. The basic proteins protamine and histone did not markedly inhibit attachment. These findings are discussed in relation to comparative experiments using tissue cells.

Adsorption↗