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Biomedical subjects

E Ingham

Publications and source records attributed to E Ingham.

At least 127 records · Page 7Linked to original sources
PubMed1990

The effects of tetracyclines and erythromycin on complement activation in vitro.

The effects of tetracycline, minocycline and erythromycin on complement activation in vitro were studied. At concentrations of 100 mg/l or less, these antibiotics did not inhibit the capacity of Propionibacterium acnes to cleave C3 in normal human serum or in serum chelated of Ca2+ allowing complement activation by the alternative pathway alone. The antibiotics had no effect (at 100 mg/l) on total haemolytic activity of complement in normal human serum. This study did not provide evidence to support the hypothesis that the efficacy of these antibiotics in the therapy of inflammatory acne vulgaris can be explained by inhibition of complement activation.

Acne Vulgaris↗
PubMed1988

The microbial content and complement C3 cleaving capacity of comedones in acne vulgaris.

Complement C3 deposition around lesions is an early event in the inflammation of acne vulgaris. The aims of this study were to determine the relationship between the capacity of individual comedones to cleave complement C3 and their microbial flora. The contents of 48 open comedones were expressed from the upper back of acne vulgaris patients and each comedo was homogenized individually and assayed for microbial content and capacity to induce cleavage of complement C3 in an in vitro assay system. An association between Propionibacterium population size and extent of C3 cleavage was found, but Staphylococcus and Pityrosporum population sizes did not appear to have an appreciable influence. A strong association between the weight of expressed material and C3 cleavage was apparent, irrespective of microbial population size. This observation suggests that comedones contain non-microbial material having the capacity to induce complement cleavage and hence initiate inflammation.

Acne Vulgaris↗
PubMed1987

Antibodies to P. acnes and P. acnes exocellular enzymes in the normal population at various ages and in patients with acne vulgaris.

Total serum IgM and IgG agglutinins to P. acnes and neutralizing antibodies to P. acnes lipase, hyaluronate lyase and acid phosphatase were measured in normal individuals of different age groups. Agglutinins to P. acnes were detected in infants at 4 months of age and were present at a high level throughout life. A switch from predominantly IgM agglutinins in children, to IgG agglutinins in adults, occurred during adolescence. Anti-P. acnes lipase antibodies were present in 20% of teenagers and 17-42% of adults. Anti-P. acnes hyaluronate lyase antibodies were found in adults only (4-17%). Antibodies to acid phosphatase were not detected. Agglutinins to P. acnes were measured in individuals with mild, moderate and severe acne, and in normal controls. Only patients with severe acne had significantly higher titres than the controls. IgM and IgG agglutinins were determined in 13-14-year-olds with mild, moderate and severe acne, and in normal controls. Thirty-three per cent, 60% and 100% of the acne patients, respectively, but none of the normal controls, had predominantly IgG agglutinins. No difference in the prevalence or titre of antibodies to P. acnes exocellular enzymes was observed when patients with severe acne were compared with normal controls. There was no evidence to suggest a role for antibodies to P. acnes exocellular enzymes in the initiation of inflammatory acne.

Acne Vulgaris↗
PubMed1986

IgG subclasses in acne vulgaris.

IgG subclasses were measured in male patients with very low grade or severe acne. No IgG subclass deficiencies were found. Patients with severe acne had a significant increase in total IgG attributable to their exposure to antigens which stimulate the production of antibodies in the IgG2 and IgG3 subclasses.

Acne Vulgaris↗
PubMed1985

Effects of tampon materials on the in-vitro physiology of a toxic shock syndrome strain of Staphylococcus aureus.

Seven materials used in the manufacture of tampons-four rayon, one modified rayon, one cotton and one carboxy-methyl cellulose (a modified cotton)-were compared for their effects in vitro on the physiology of a strain of Staphylococcus aureus isolated from a patient with Toxic Shock Syndrome. Experiments were performed in broth culture and, with the exception of two rayon samples, all of the materials tested reduced growth rate and cell yield compared with control values. Exocellular acid phosphatase, lipase, proteinase, hyaluronate lyase and haemolysin in culture filtrates were measured and the lethality of filtrates was determined in mice. The tampon materials had different effects on the levels of exocellular products. Cotton and carboxy-methyl cellulose cotton materials reduced the levels of all of the activities tested. The activities of the other enzymes were reduced or increased, depending on which material was present. All materials reduced both haemolytic activity and lethality of the culture filtrates. The in-vitro data suggest an extremely complex interaction between tampon materials and S. aureus.

Acid Phosphatase↗
PubMed1985

Toxic shock syndrome: the effect of solid phase materials on the physiology of Staphylococcus aureus.

Rayon and chemically modified cotton were compared for their effects in vitro on the physiology of a strain of Staphylococcus aureus isolated from a patient with toxic shock syndrome. Two types of experiment were carried out. The materials were used to pretreat the medium before culturing in the absence of the materials. Chemically modified cotton was either added or removed from three hour cultures and incubation continued. The rayon treated medium had little effect on growth or exoenzyme/toxin production by S. aureus. The chemically modified cotton greatly reduced growth of S. aureus and decreased exoenzyme/toxin production when added to three hour cultures. However, pretreated medium and cultures grown for three hours with the material present followed by incubation in its absence increased the exoenzyme/toxin production by S. aureus. The in vitro data suggests large effects of chemically modified cotton on the physiology of S. aureus by in some way, at present unknown, altering the growth medium.

Bacterial Toxins↗
PubMed1984

A comparison of the in-vitro antibacterial and complement activating effect of 'OpSite' and 'Tegaderm' dressings.

Two readily available semipermeable polyurethane dressings, 'OpSite' and 'Tegaderm', were tested for their in vitro ability to kill potential bacterial pathogens and activate complement C3. In bacterial killing tests, 'OpSite' was superior to 'Tegaderm' and in addition only 'OpSite' activated C3. It is concluded that in the practical situation, 'OpSite' could well confer a greater margin of safety.

Bacteria↗
PubMed1984

Correlations between human skin bacteria and skin lipids.

Correlation matrices were constructed for various human skin variables (propionibacteria, micrococcaceae, sebum excretion rate, percentage of free fatty acids and free fatty acid production rate). Two independent populations were studied (n = 87 and n = 103), and a subpopulation (n = 30) was investigated on three occasions at intervals of I month. In this way consistently high correlations could be differentiated from 'fortuitous' correlations. Propionibacteria versus micrococcaceae showed the highest correlation coefficient and propionibacteria versus percentage free fatty acids was also highly correlated. A scatter diagram indicated a relationship between the lower threshold of microbial density and sebum excretion rate. An explanation based on relative duct and gland size is presented.

Adolescent↗
PubMed1984

Difficulties in producing antibodies to purified Propionibacterium acnes exocellular enzymes.

Attempts were made to produce antisera to purified preparations of Propionibacterium acnes lipase, hyaluronate lyase and acid phosphatase in rabbits. Antiserum to lipase (neutralizing titre I:32) was produced using conventional methods. Lipase (30 micrograms) in Freund's complete adjuvant (FCA) was injected into multiple sites thrice at weekly intervals. Antibody levels were boosted by i.v. injections of 30 micrograms in saline at 2-weekly intervals for 2 months. Such regimes failed to raise antibodies to hyaluronate lyase and acid phosphatase. In order to produce antiserum to hyaluronate lyase, rabbit mononuclear cells were incubated with 45 micrograms of hyaluronate lyase in vitro (I h at 37 degrees C) prior to injection subcutaneously above the rabbit ankle joint. Simultaneous injections of hyaluronate lyase in FCA (45 micrograms) were administered into the footpad and thigh. Three treatments at weekly intervals produced an antiserum with a neutralizing titre of I:256. A similar regime failed to raise antibodies to acid phosphatase. Antibodies to P. acnes lipase and hyaluronate lyase also neutralize the enzymes produced by P. granulosum. The neutralization curves suggest that the enzymes produced by both species are related antigenically but not identical.

Acid Phosphatase↗
PubMed1981

Partial purification and characterization of lipase (EC 3.1.1.3) from Propionibacterium acnes.

Lipase from Propionibacterium acnes has been purified 4800-fold from crude culture supernatant. The purified enzyme preparation had no assayable protease, hyaluronate lyase or acid phosphatase activities. The molecular weight of the lipase was 46,770 as determined by gel filtration. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed a major protein component (mol. wt 41,190) together with two minor protein components (mol. wt 67,000 and 125,900). The lipase had a pH optimum of 6.8, was most stable in the pH range 5.0 to 6.0 and was completely inactivated after 30 min at 60 degrees C. The lipase hydrolysed trilaurin, triolein, trimyristin and tripalmitin at decreasing rates and did not exhibit phospholipase activity. Analysis of the reaction products from the hydrolysis of triolein by P. acnes lipase did not demonstrate an accumulation of 2-monoolein which suggested that the enzyme did not exhibit a positional specificity for the 1-position of the triacylglycerol. Crude lipase preparations contained an aggregated high molecular weight form of the enzyme which was eluted with the void volume from Sephadex G-200. This aggregated form was dissociated to produce the lower molecular weight lipase species by subsequent dialysis and elution from Sephadex G-200 using buffer with a higher ionic strength.

Acid Phosphatase↗
PubMed1980

Purification and partial characterization of an acid phosphatase (EC 3.1.3.2) produced by Propionibacterium acnes.

A strain of Propionibacterium acnes (type I; Marples & McGinley, 1974), isolated from a blackhead acne lesion, produced an acid phosphatase which was present in the culture supernatant in the late-exponential and early-stationary phases of growth. This acid phosphatase was purified more than 45 000-fold (4.5% yeild). The purified enzyme gave two protein bands on sodium dodecyl sulphate-polyacrylamide gel electrophoresis corresponding to molecular weights of 155 000 and 87 100. The enzyme had a single peak of activity on Sephadex G-100, with a molecular weight corresponding to 93 000. The highly purified acid phosphatase had an optimum activity at pH 5.8, was stable from pH 4.0 to 5.5 and was totally inactivated after 30 min at 55 degrees C. The enzyme did not show an absolute requirement for metal ions, but was stimulated by Mg2+, Ca2+, Zn2+ and K+ at concentrations between 0.1 and 1 mM. The acid phosphatase was active against a number of monophosphate esters.

Acid Phosphatase↗
PubMed1979

Purification and partial characterization of hyaluronate lyase (EC 4.2.2.1) from Propionibacterium acnes.

Hyaluronidase from Propionibacterium acnes has been purified 13,000-fold from the culture supernatant to homogeneity (as determined by polyacrylamide disc gel electrophoresis). The molecular weight of the purified enzyme was 85,110 as determined by gel filtration. The purified enzyme had a pH optimum at 6.4, was stable between pH 5 and 5.8 and was completely inactivated after 15 min at 50 degrees C. Preliminary studies suggested that the enzyme is active against chondroitin 4- and 6-sulphates, but not against dermatan sulphate. Analysis by paper chromatography of the reaction products from the degradation of hyaluronic acid by bacterial, testicular and P. acnes enzymes suggested that the P. acnes enzyme is similar in its mode of action to other bacterial hyaluronate lyases. The enzyme from P. acnes may thus be tentatively classified as a hyaluronate lyase.

Buffers↗
PubMedDate not supplied

Long-term wear of HIPed alumina on alumina bearings for THR under microseparation conditions.

The long term wear and wear debris generated in HIPed alumina on alumina bearings for hip prostheses with microseparation in vitro is compared to standard simulator conditions and ex vivo specimens. Microseparation studies were completed to five million cycles at two severity levels in attempts to rigorously evaluate the long-term tribological performance of the bearings. During the first million cycles (bedding-in) of the microseparation tests characteristic stripe wear was observed on all of the femoral heads with a matching area on the rim of the acetabular inserts. Under mild microseparation conditions an average wear rate of 0.55 mm3/million cycles was observed during the initial million cycles which reduced to a steady state level of 0.1 mm3/million cycles. Under more severe conditions an average wear rate of 4.0 mm3/million cycles was observed during bedding-in which reduced to a steady state level of 1.3 mm3/million cycles. These compare to a bedding-in wear rate of 0.11 mm3/million cycles and steady-state wear rate of 0.05 mm3/million cycles for the same material under normal simulation with no microseparation. Furthermore, under microseparation the wear mechanisms and wear debris were similar to those observed in previous alumina retrieval studies with debris ranging from 10 nm to 1 microm in size.

Journal Article↗
PubMedDate not supplied

Comparison of wear in a total knee replacement under different kinematic conditions.

A six station ProSim (Manchester, UK) knee simulator was used to assess the wear of six PFC (DePuy) fixed bearing total knee replacements under two different kinematic conditions defined as low and high kinematic inputs. The high kinematics displacement and rotation inputs were based on the kinematics of the natural knee with ISO standards used for the axial load and flexion. Low kinematics were defined as approximately half the magnitude. The six specimens were run for three million cycles under low kinematics and three million cycles under high kinematics. The mean wear rate found during the low kinematics phase was 7.7 +/- 2 mm3 per million cycles. This then increased significantly to an average wear rate of 41 +/- 14 mm3 during the high kinematics input phase. The wear areas were characterized by a predominant damage mode of burnishing with some abrasive wear occurring during the high kinematics phase. This study supports the findings that introduction of cross-shearing of the polyethylene by introducing both rotational and anterior/posterior displacement increases the wear rate. This has implications for younger patients with higher levels of activity that need knee replacements.

Journal Article↗