Biomedical subjects
P Gilbert
Publications and source records attributed to P Gilbert.
A simple in vitro model for growth control of bacterial biofilms.
The perfused biofilm fermenter was found to be unsuitable for the long-term culture and growth rate control of Staphylococcus aureus and Pseudomonas aeruginosa biofilms. In a simplified approach, biofilms of these organisms were grown within Sorbarod filter plugs which were perfused with culture medium. Pseudo-steady states were established which were stable over several days at which the growth rate of the biofilm was reproducible, measurable and significantly slower than in broth culture. Environmental scanning electron microscopy of dissected Sorbarods demonstrated an association of cells with the surfaces of individual cellulose fibres, and growth characteristic of biofilms. Relatively high cell numbers recovered from the Sorbarod model facilitated biochemical investigations of biofilm populations and cells released spontaneously from them. SDS-PAGE demonstrated significant differences between the protein profiles of biofilm and eluted populations, which include, in Staph. aureus, the repression of a 48 kDa protein and increased expression of a 21 kDa protein relative to planktonic controls cultured at equivalent growth rates. The paper demonstrates the suitability of the approach for the culture of biofilm samples which are suitable for biochemical analysis.
Involuntary subordination or dependency as key dimensions of depressive vulnerability?
Dependency associated with depression involves at least two forms of social behavior: (a) needs for nurturance/protection and close attachment, and an inability to function independently and (b) being (de)valued, fear of disapproval, and social status. In many studies, measures of dependency combine these two dimensions. This paper argues that this has led to confusion on the salient dimensions related to depression. It is suggested that behaviors currently regarded as dependent, and linked to depression, are better understood as forms of involuntary subordination that involve judgments of personal inferiority, and submissive-appeasement behavior. This paper presents preliminary evidence that social status, and its associated features of negative self-other comparisons and submissive behavior, may be particularly relevant to depression.
Stereoselective determination of verapamil and norverapamil by capillary electrophoresis.
An analytical method has been developed to determine simultaneously the verapamil and norverapamil enantiomers in human plasma using capillary electrophoresis. Among the cyclodextrins tested as chiral selector, only trimethyl-beta-cyclodextrin was suitable to resolve the four enantiomers. The analysis was achieved in less than 10 min. Selectivity, linearity, precision and accuracy were evaluated before the chiral method was successfully implemented for routine use to simultaneously determine the four enantiomers in several thousands of human plasma samples. The robustness of the capillary electrophoretic method and its suitability were demonstrated by the coefficients of variation which were lower than 11%, even at the limit of quantification (2.5 ng/ml), for the analysis of more than one hundred quality control samples.
Treatment of obsessive-compulsive symptoms in schizophrenia with a neuroleptic-selective serotonin reuptake inhibitor combination: two case reports.
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Iron chelator, exopolysaccharide and protease production in Staphylococcus epidermidis: a comparative study of the effects of specific growth rate in biofilm and planktonic culture.
The growth rate of Staphylococcus epidermidis was controlled for populations growing as a biofilm and perfused with supplemented, simple-salts medium. Production of iron chelators, extracellular protease and exopolysaccharide (EPS) by these populations was assessed as a function of specific growth rate and compared to that by planktonic populations grown in the same medium within a chemostat. Perfused biofilms increased their iron chelator and protease production with increasing growth rate. Chemostat populations decreased their production of iron chelators with increasing growth rate, whilst showing much enhanced production of proteases at intermediate growth rates (mu 0.15-0.25 h-1). Production of iron chelator and protease was generally 2-50 times higher by biofilms than by planktonic populations. EPS production was low and relatively unaffected by growth rate for the chemostat cultures (about 0.2 micrograms per unit cell mass) but high for the attached biofilms, particularly at slow growth rates (about 4 micrograms per unit cell mass). EPS production within the biofilms decreased markedly with increasing growth rate. At growth rates of 0.35 h-1 and above, the levels of EPS for biofilms and planktonic populations were equivalent. The results of this study clearly indicate that growth as a biofilm markedly influences extracellular virulence factor production by S. epidermidis.
Loss of salt-tolerance and transformation efficiency in Escherichia coli associated with sub-lethal injury by centrifugation.
Sub-lethal injury of Escherichia coli has been detected following centrifugation at g-forces between 5 and 30 kg. The extent of injury was measured either as a reduction in colony forming ability when plated onto NaCl-containing plates (2% w/v), or as a reduction in transformation efficiency associated with plasmid pBR322 encoding ampicillin resistance. In both cases, the extent of sub-lethal injury was found to increase with increasing centrifugal force and probably reflects structural damage to the cell envelope.
Assertiveness, submissive behaviour and social comparison.
This paper explores the relationship between a new assertiveness measure (the Scale for Interpersonal Behaviour--SIB), social comparison and submissive behaviour. The paper investigates these measures in relation to the personality traits of neuroticism and introversion. Findings suggest: (a) that social comparison may be an important variable in assertiveness and submissive behaviour and shows a strong relationship to neuroticism and introversion; (b) that submissive behaviour is not the mirror opposite of assertive behaviour; and (c) submissive behaviour seems more strongly associated with introversion and neuroticism than assertive performance.
The phenomenology of shame and guilt: an empirical investigation.
This paper explores the various literatures concerned with shame and guilt. Lewis' (1987) model of shame is outlined. The phenomena she suggested to be part of shame (feelings of helplessness, anger at others, anger at self, self-consciousness and feelings of inferiority) were investigated as to their relationship with shame. Strong support for these phenomena being related to shame, but not guilt, was found. Although located in separate literatures, shame and fear of negative evaluation have considerable overlap and this study set out to explore this relationship. The study further considered the role of submissive behaviour in shame and depression. Evidence was found to support the view that submissive behaviour is involved in both shame and depression.
Adaptive function of depression: psychotherapeutic implications.
Using the frameworks of attachment and social hierarchy theories, strategies seen in depression and in normal life are better understood. A hierarchial encounter elicits the "Involuntary Subordinate Strategy" ("ISS") in the loser, which terminates the "ISS" and brings the encounter to an end. These are psychophysiological mechanisms deeply rooted in our phylogenetic ancestry. Loss of a love object also elicits ineffective anger or rage which may, in turn, trigger the ISS. A prolonged intense ISS manifests in depression. Factors are examined that prevent "acceptance" of losing, thereby contributing to an escalation of the ISS and culminating in depressive illness. Psychotherapeutic implications include cognitive restructuring to enable the patient to explore options that might turn off the ISS such as "acceptance" (without making negative self-evaluations), changing unrealistic ideals and aspirations, leaving the scene, or becoming more self-assertive. Case examples are given to illustrate these interventions.
The social competition hypothesis of depression.
Depressive personality and depressive illness are examined from an evolutionary adaptationist standpoint. It is postulated that the depressive state evolved in relation to social competition, as an unconscious, involuntary losing strategy, enabling the individual to accept defeat in ritual agonistic encounters and to accommodate to what would otherwise be unacceptably low social rank.
[27-year-old patient with nodules in the breast, tongue, subcutis and brain].
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[Digital necrosis of the arm excluding scleroderma. Retrospective study of 45 cases].
UNLABELLED: The causes of digital necrosis are so diverse that it should be considered not as a surgical but as a medical emergency. In women, digital necrosis first suggests connective tissue disease, and especially Progressive Systemic Sclerosis. In men the causes are more diverse. In this retrospective study, we have tried to identify and categorize the cause of digital necrosis in patients without Progressive Systemic Sclerosis. The medical files of all patients admitted from 1/1/89 to 1/1/93 for digital necrosis were retrospectively reviewed. All patients with Progressive Systemic Sclerosis, either diagnosed at that time or know before, were excluded. All 45 patients in the study had an evaluation of coagulation, vascular risk factors, a cardiac examination and nailfold capillary microscopy, as well as tests for antinuclear antibodies, and cryoglobulinaemia. Other tests were done according to the clinical presentation. Upper limb angiography was done 26 times. RESULTS: there were 10 women and 35 men, mean age 53 years (24-85 years). In the women, the following diagnosis were found: atherosclerosis 1, paraneoplastic syndrome 1, one thrombocythemia, and 6 connective tissue diseases (one dermatopolymyositis, 1 essential cryoglobulinaemia, 2 lupus erythematous and two suspected secondary Raynaud's phenomenon. Twelve men had arterial diseases: 6 thromboangiitis obliterans and 6 obliterans atherosclerosis. Seven times, the cause was local: 5 hammer's syndromes, 2 thoracic outlet syndrome. In the other patients, the causes were extremely diverse: cardiac embolism (4), primary antiphospholipid syndrome (3), polyarteritis nodosa (1), leprosy seroconversion (1), connective tissue disease (3). In 4 patients (3 of whom were smokers) no cause was found.(ABSTRACT TRUNCATED AT 250 WORDS)
[Bilateral ureteroiliac fistula coincident with radiotherapy and ureteral splint].
Fistulas between the iliac artery and the ureter are uncommon. Overall, fewer than 20 cases have been described in the literature. We report the first bilateral case, in which there was an association with indwelling bilateral ureteral stents and a history of radiation therapy following hysterectomy performed because of malignancy. The patient presented with massive gross haematuria.
Formation and dispersal of bacterial biofilms in vivo and in situ.
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Sensitivity of biofilms to antimicrobial agents.
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Defence and safety: their function in social behaviour and psychopathology.
This paper suggests that our intuitive use and understanding of the concepts defence and safety can be opened up to more systematic study and theory. This may provide a powerful framework for biopsychosocial approaches in clinical psychology. Defence and safety can be seen as two fundamental, evolutionary adaptive, information-organizing systems. The operation of these two systems has major effects on biological patterns, social behaviour, relationships and the maturation of self-constructs. It is suggested that many forms of psychopathology represent the activation of evolved, defensive strategies. This paper explores the organization and operation of these two systems and attempts to integrate data from neuropsychological work with ideas from evolutionary theory and social psychology on the effects of threat sensitivity and defensiveness, and safety. It is suggested that interpersonal threats are the most common sources of human defensive behaviour and these are often about separation-rejection or power and subordination. In the latter part of the paper discussion will be on the way people try to create safe environments by putting others down, or by submitting to more powerful others.
The Manitoba Project: a re-examination of the link between menopause and depression.
This paper re-examines the association between menopause and depression using data from a study in which 477 women were interviewed 6 times over a 3-year period. Menopause is examined as one of a series of factors which may increase the risk of depression for women in middle age, such as children leaving home, the death and illness of family members, the stresses of daily living, health and the onset of chronic disease. Rather than hormonal changes, it seems to be her health coupled with the shifts and stresses of family life in a woman's menopausal years which may trigger her depression.