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Biomedical subjects

J Merry

Publications and source records attributed to J Merry.

At least 19 recordsLinked to original sources
PubMed2006

The mechanical properties of calcium phospate ceramics modified by collagen coating and populated by osteoblasts.

Bioceramics containing hydroxyapatite (HA), tricalcium phosphate (TCP) or composites which combine the best properties of both materials are among the principal candidates for bone replacement grafts. In this study we have investigated the mechanical strength of HA, TCP and composites of the two in the ratios 75;25 (H75), 50:50 (H50) and 25:75 (H25). The strength of each material was investigated in the presence and absence of collagen coating, and the influence of osteoblast culture for up to 28 days on strength was determined. TCP, H25 and H75 were significantly weakened by collagen coating, the strengths of the other materials were either not affected (HA) or increased (H50). Culture with osteoblasts significantly increased the strength of uncoated HA and H50, but this effect was not observed when the materials were coated with collagen. Our results indicate that ceramic composition affects the interactions between collagen coating, culture with osteoblasts and mechanical strength of the material. Although collagen coating has been found to increase the proliferation of osteoblasts into these ceramic materials, it may be necessary to stabilise and optimise the coating process to minimise effects on mechanical strength.

Animals↗
PubMed2005

Osteoblast interactions with calcium phosphate ceramics modified by coating with type I collagen.

Complications associated with the use of autogenous bone in the repair or replacement of tissue lost through injury or disease have driven the search for alternative sources of graft material. Bioceramics containing hydroxyapatite (HA), tricalcium phosphate (TCP), or composites that combine the best properties of both of these materials are among the principal candidates. In this study, we have investigated the in vitro proliferation, morphology, and viability of an immortalized rat osteoblast cell line cultured on HA, TCP, and composites of the two in the ratios 75:25 (H75), 50:50 (H50), and 25:75 (H25) for 28 days. The biocompatibility of each material was examined in the presence and absence of a collagen coating. With the exception of H50, cell proliferation, quantified by carboxyfluorescein fluorescence, was enhanced by collagen coating of all materials for the first 14 days, although at later time points cell numbers were unaffected. It is notable that the collagen coating was least stable on H50, the only material not to show enhancement of cell growth on coating. Confocal laser scanning microscopy confirmed that cell growth was more extensive on coated materials over the first 7-14 days in culture, and the development of cell extensions and bridges across the pores in the materials was observed. Results indicate that collagen coating of calcium phosphate ceramics may also increase their compatibility and osseointegration in vivo.

Animals↗
PubMed1997

New genetic techniques for group B streptococci: high-efficiency transformation, maintenance of temperature-sensitive pWV01 plasmids, and mutagenesis with Tn917.

Three techniques were developed to improve the genetic manipulation of group B streptococci (GBS). We first optimized a protocol for transformation of GBS by electroporation, which provided transformation efficiencies of 10(5) CFU/microgram. Variables that influenced the transformation efficiency were the glycine content of the competent cell growth media, the electric field strength during electroporation, the electroporation buffer composition, the host origin of the transforming plasmid, and the concentration of selective antibiotic at the final plating. Our transformation protocol provides an efficiency sufficient for cloning from ligation reactions directly into GBS, obviating an intermediate host such as Escherichia coli. Second, temperature-sensitive plasmids of the pWV01 lineage were shown to transform GBS, and their temperature-sensitive replication was confirmed. Lastly, the temperature-sensitive pWV01 plasmid pTV1OK, which contains Tn917, was used as a transposon delivery vector for the construction of genomic Tn917 mutant libraries. We have shown, for the first time, that Tn917 transposes to the GBS chromosome and at a frequency of 10(-3)/CFU. Furthermore, representative clones from a Tn917 library contained single transposon insertions that were randomly located throughout the chromosome. These techniques should provide useful methods for cloning, mutagenesis, and characterization of genes from GBS.

DNA Replication↗
PubMed1996

Time-limited group psychotherapy for patients with personality disorders: outcomes and dropouts.

This study reports on the time-limited (18-month long) group therapy of 49 outpatients, most of whom were diagnosed with DSM-III-R, Axis II personality disorders (American Psychiatric Association, 1987). Although many patients did not complete the full course of treatment, those who did experienced many areas of change. Completers reported substantial changes in self-esteem, symptomatology, and diagnosability on Axis II. This type of group treatment appears to be a promising mode of intervention for those with personality disorders.

Adult↗
PubMed1993

Diagnostic agreement between the Personality Disorder Examination and the MCMI-II.

In an attempt to compare different methods for assessing personality disorder, this study compared the Millon Clinical Multiaxial Inventory-II (MCMI-II; Millon, 1987), a self-report questionnaire, and the Personality Disorder Examination (PDE; Loranger, 1988), a semistructured clinical interview. Subjects (N = 97) were mental health outpatients of a health maintenance organization in New England. The instruments were compared in terms of the presence of personality disorder, the number of diagnoses assigned to a patient, and agreement in specific diagnoses and in cluster assignment. Agreement between the two instruments was low; the two instruments exhibited greater agreement in predicting the absence of diagnoses than their presence. Agreement was best for the borderline and avoidant diagnoses. Correlations between scales exhibited somewhat better agreement than was evident for diagnoses. Analyses at the cluster level resulted in moderate correlations between the instruments. Very high intracluster correlations were found for the MCMI-II, but not for the PDE.

Adult↗
PubMed1986

The adherence of Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli on cotton, polyester and their blends.

The adherent behaviour of the Gram-positive Staphylococcus aureus and Staphylococcus epidermidis and the Gram-negative Escherichia coli on cotton, polyester and their blends through contact in aqueous suspensions was studied. Staphylococcus epidermidis was found to adhere to fabrics much more so than Staph. aureus. The adherence of both Staph. epidermidis and Staph. aureus to fabrics increased as the content of polyester fibres in the fabrics increased. The attachment of E. coli to all fabrics was very low and was not affected by the fibre contents. Total numbers of adherent bacteria on cotton and polyester fabrics were related directly to the concentrations of the bacterial suspensions. The extents of adherence, expressed by the percentage of adherent bacteria from the suspension, however, were independent of the concentration. The length of contact with bacteria was also found to affect the adherence of bacteria on fabrics studied.

Absorption↗
PubMed1984

Dexamethasone suppression test in alcoholism.

The hypothalamic-pituitary-adrenal function was investigated in alcoholic patients using the dexamethasone suppression test (DST). Seventy-two patients were studied when they had been abstinent from alcohol for 3 to 6 weeks. Eight patients undergoing detoxification and 79 control subjects were investigated for comparison. Alcoholic patients after a 3- to 6-week abstinence period showed significantly higher prevalence of abnormal DST results (28%) than control subjects (11%). Patients undergoing detoxification showed even a higher prevalence of abnormal DST results (62%). Abnormal DST status was not associated with the presence of depression in these patients but was associated with abnormal liver function. It is supposed that abnormal DST responses in alcoholic patients are not diagnostic of depression but appear to be related to effects of alcohol either on liver metabolism or on the hypothalamic-pituitary-adrenal function or both.

Adult↗
PubMed1976

Prophylactic treatment of alcoholism by lithium carbonate. A controlled study.

Lithium therapy has been shown to have a therapeutic influence in reducing the drinking and incapacity by alcohol in depressive alcoholics in a prospective double-blind placebo-controlled trial conducted over one year, but it had no significant effect on non-depressed patients. Patients in the trial treated by placebo had significantly greater alcoholic morbidity if they were depressive than if they were non-depressive.

Adult↗
PubMed1975

Pituitary function in chronic alcoholism.

Elevated basal LH levels and an exaggerated response to LHRH were found in a high proportion of male chronic alcoholics. This was not associated with reduced plasma testosterone values. In addition, previous reports of an absent cortisol response to hypoglycaemia in a proportion of chronic alcoholics are confirmed.

Adult↗