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Biomedical subjects

S Allan

Publications and source records attributed to S Allan.

At least 19 recordsLinked to original sources
PubMed1998

Myc activates telomerase.

Telomere maintenance has been proposed as an essential prerequisite to human tumor development. The telomerase enzyme is itself a marker for tumor cells, but the genetic alterations that activate the enzyme during neoplastic transformation have remained a mystery. Here, we show that Myc induces telomerase in both normal human mammary epithelial cells (HMECs) and normal human diploid fibroblasts. Myc increases expression of hEST2 (hTRT/TP2), the limiting subunit of telomerase, and both Myc and hEST2 can extend the life span of HMECs. The ability of Myc to activate telomerase may contribute to its ability to promote tumor formation.

Cell Division↗
PubMed1998

The role of defeat and entrapment (arrested flight) in depression: an exploration of an evolutionary view.

BACKGROUND: The social rank theory of psychopathology suggests that with the evolution of social hierarchies various psychobiological mechanisms became attuned to the success or failure in conflict situations. Specifically, subordinates and those who have lost status are at greater risk of pathology than winners and those of higher status. In this theory concepts of defeat and entrapment are seen to be of special relevance to the study of depression. We outline the role of defeat and entrapment within the social rank theory of depression. METHODS: New self-report measures of entrapment and defeat were developed and used to test predictions of the social rank theory of depression. Both a sample of students and depressed patients were assessed with these new scales and other social rank measures (e.g. social comparison and submissive behaviour). RESULTS: The entrapment and defeat measures were found to have good psychometric properties and significantly correlated with depression. They were also strongly associated with other rank variables. Defeat maintained a strong association with depression even after controlling for hopelessness (r = 0.62), whereas the relationship between hopelessness and depression was substantially reduced when controlling for defeat. Entrapment and defeat added substantially to the explained variance of depression after controlling for the other social rank variables. CONCLUSIONS: Defeat and entrapment appear to be promising variables for the study of depression. These variables may also help to develop linkages between human and animal models of psychopathology.

Adult↗
PubMed1997

Submissive behaviour and psychopathology.

OBJECTIVES: A variety of behaviours have been identified as submissive (Buss & Craik, 1986). These are believed to be associated with vulnerability to psychopathology. This paper explores the construct and measurement of submissive behaviours and their association with psychopathology. DESIGN: Two self-report scales were designed to measure the frequencies of (a) typical submissive behaviours (SBS) and (b) passive/withdrawal and affiliative strategies focused on conflict de-escalation (CDS). The association of these scales with psychopathology was explored in a series of questionnaire studies. METHODS: Study 1 assessed the SBS using a student sample (N = 332) and a mixed clinical group (N = 136). Of these, 177 students and 66 patients also completed the SCL-90-R. In Studies 2 and 3, the CDS and its association with depressive symptoms were assessed using a student sample (N = 154) and a depressed patient group (N = 60). RESULTS: The SBS and CDS appeared reliable. There was a positive relationship between the SBS and the SCL-90-R, including interpersonal sensitivity and unexpressed hostility. The passive/withdrawal subscale of the CDS was associated with depressive symptoms. Evidence was obtained for sex differences with the affiliative subscale. CONCLUSIONS: Some forms of submissive behaviour, especially those associated with passive/withdrawal and inhibition, are associated with a wide range of psychological problems.

Adult↗
PubMed1996

A connection between pre-mRNA splicing and the cell cycle in fission yeast: cdc28+ is allelic with prp8+ and encodes an RNA-dependent ATPase/helicase.

The fission-yeast gene cdc28+ was originally identified in a screen for temperature-sensitive mutants that exhibit a cell-division cycle arrest and was found to be required for mitosis. We undertook a study of this gene to understand more fully the general requirements for entry into mitosis. Cells carrying the conditional lethal cdc28-P8 mutation divide once and arrest in G2 after being shifted to the restrictive temperature. We cloned the cdc28+ gene by complementation of the temperature-sensitive growth arrest in cdc28-P8. DNA sequence analysis indicated that cdc28+ encodes a member of the DEAH-box family of putative RNA-dependent ATPases or helicases. The Cdc28 protein is most similar to the Prp2, Prp16, and Prp22 proteins from budding yeast, which are required for the splicing of mRNA precursors. Consistent with this similarity, the cdc28-P8 mutant accumulates unspliced precursors at the restrictive temperature. Independently, we isolated a temperature-sensitive pre-mRNA splicing mutant prp8-1 that exhibits a cell-cycle phenotype identical to that of cdc28-P8. We have shown that cdc28 and prp8 are allelic. These results suggest a connection between pre-mRNA splicing and progression through the cell cycle.

Adenosine Triphosphatases↗
PubMed1996

Overconfidence and personal evaluations of social rank.

Research on confidence judgements suggests that people are often overconfident. However, some studies have found that depressed mood reduces this positive bias. To date this has been explained as a mood phenomenon. In this study we explore an alternative theory which suggests that confidence is related to internal judgements of social rank and status. This theory suggests that the lower one perceives oneself to be in status and rank the less one can afford to be overconfident. Data from a student population suggests that confidence judgements are associated with internal judgements of status.

Adolescent↗
PubMed1996

A short measure of social and separation anxiety.

Separation and social anxiety have often been seen to relate to different social fears. This paper outlines a pilot study on a short separation and social anxiety scale in relationship to depression. Results suggest an acceptable factor structure and reliability. Both separation and social anxiety were found to be associated with depression and submissive behaviour. The association of social anxiety to depression was particularly strong in a depressed group.

Adult↗
PubMed1995

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.

Adult↗
PubMed1994

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.

Adult↗
PubMed1994

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.

Adolescent↗
PubMed1994

[DNA sequencing of circumsporozoite protein genes of Plasmodium vivax from four different countries in west Pacific region: comparative study on the flank sequences].

P. vivax CSP gene of 18 isolates from infected blood of patients living in China, Philippines, Solomon Islands and Papua New Guinea in West Pacific region has been sequenced from both terminal end. The total readable sequence in most isolates was about 725 base pair (bp), including the first two repeat units (70-330 bp) to the N terminus, and the last two repeat units to the C terminus (763-1,228 bp). Comparison and analysis of these obtained sequences with the published sequences of N.K., Thai., Belem, Sal-l. and BZL strains showed that:the N and C terminus sequences flanking the centre repeats in CSP gene were highly conserved in all isolates and identical with the 5 published sequences but a double base pair substitution in each end and a remarkable polymorphism in the postrepeat variable region in C terminus were found, including some diversities with obvious geographic characteristics which have not been reported previously.

Animals↗
PubMed1993

Experimental Lyme disease in dogs produces arthritis and persistent infection.

Lyme disease was reproduced in specific pathogen-free beagle dogs by exposure to Borrelia burgdorferi-infected ticks (Ixodes dammini). Seroconversion and disease frequency were higher after exposure to infected adult ticks than to infected nymphs. Young pups developed clinical disease more readily than older dogs. The incubation period lasted 2-5 months. Acute recurrent lameness with fibrinopurulent arthritis was the dominant clinical sign. Dogs recovered but developed persistent mild polyarthritis. B. burgdorferi persisted in recovered dogs for at least 1 year. Isolation of B. burgdorferi and detection by polymerase chain reaction was most successful from skin biopsies at the site of the tick bite. Antibody to B. burgdorferi antigens was first detected by ELISA and Western blots by 4-6 weeks after exposure. High serum levels persisted during 17 months of observation. In contrast to infection from ticks, inoculation of dogs with cultured B. burgdorferi resulted in seroconversion with a shorter duration of antibody persistence and no clinical disease.

Age Factors↗
PubMed1993

Development and isotype diversity of antibodies to inhalant and dietary antigens in childhood atopic eczema.

This study demonstrated that a major feature of childhood atopic eczema (AE) is the presence of serum IgG and IgE anti-house dust mite (anti-HDM) antibodies in almost all AE individuals. IgG anti-HDM antibodies, usually of the IgG1 isotype, became prevalent in AE children over the age of 4 years with the highest antibody levels in children in their early teens. In contrast, immunological sensitization to dietary antigens, notably milk and eggs, occurred in both AE children and age-matched non-atopic control children, and was often associated with IgG4 antibodies during early childhood. These became less prevalent with increasing age in control children but persisted in AE children, sometimes together with IgE antibodies. The later occurrence of anti-HDM antibodies in AE children could reflect immunological sensitization following inhalation of antigen, whereas sensitization to dietary antigens appears to be a natural event in early childhood.

Adolescent↗
PubMed1993

Magnetic resonance imaging of limbic encephalitis.

The authors describe the imaging appearance of limbic encephalitis. This condition may be the presenting complaint of patients with an occult malignant lesion, as in the case reported here. The contrast-enhanced cerebral computed tomography scans of patients with limbic encephalitis may be normal, yet magnetic resonance imaging may show distinctive features. Because neurologic improvement may follow treatment of the primary tumour, early diagnosis is important.

Carcinoma, Small Cell↗
PubMed1992

Case-control study of factors associated with failure to detect breast cancer by mammography.

BACKGROUND: Although mammography is widely used to detect breast cancer, it is recognized that not all cancers can be seen on mammographic images. PURPOSE: Our purpose was to examine factors associated with failure to detect breast cancer by mammography. METHODS: A case-control study was carried out in which subjects in whom histologically verified breast cancer was not detected by mammography (false negatives) were contrasted with subjects in whom breast cancer had been detected by mammography (true positives). Mammograms from individuals with histologically confirmed breast cancer were classified independently by two radiologists who were unaware of the clinical or other characteristics of the subjects. Histologic slides of all tumors were reviewed by one pathologist. RESULTS: Three variables were found to be independently and significantly associated with failure to detect breast cancer by mammography. Breast cancer was less likely to be detected by mammography in the presence of extensive parenchymal densities (odds ratio [OR] = 9; 95% confidence interval [CI] = 1.8-44.3), a tumor of lobular histology (OR = 7; 95% CI = 2.2-22.1), and tumors of small size (OR = 0.10; 95% CI = 0.0-0.9). CONCLUSION: Our results indicate that biologic factors are associated with failure to detect some breast cancers by mammography and indicate directions for future research in breast imaging.

Adult↗