Effects of mutant rat dynamin on endocytosis.

Dynamin is a 100-kD microtubule-activated GTPase. Recent evidence has revealed a high degree of sequence homology with the product of the Drosophila gene shibire, mutations in which block the recycling of synaptic vesicles and, more generally, the formation of coated and non-coated vesicles at the plasma membrane. We have now transfected cultured mammalian COS-7 cells with both wild-type and mutant dynamin cDNAs. Point mutations in the GTP-binding consensus sequence elements of dynamin equivalent to dominant negative mutations in ras, and an NH2-terminal deletion of the entire GTP-binding domain of dynamin, block transferrin uptake and alter the distribution of clathrin heavy chain and alpha-, but not gamma-, adaptin. COOH-terminal deletions reverse these effects, identifying this portion of dynamin as a site of interaction with other components of the endocytic pathway. Over-expression of neither wild-type nor mutant forms of dynamin affected the distribution of microtubules. These results demonstrate a specific role for dynamin and for GTP in the initial stages of receptor-mediated endocytosis.

Breast cancer awareness among older women.

The aim of this study was to elicit the level of breast cancer awareness in older women. A cross-sectional study-specific questionnaire survey of 712 British women aged 67-73 years (response rate 83.8%), assessing knowledge of symptoms and risk and confidence to detect a change, was conducted. Over 85% of respondents were aware that a lump was a symptom of breast cancer but knowledge of non-lump symptoms was limited. Knowledge of risk was poor; 50% believed that the lifetime risk of developing breast cancer was less than 1 in 100 women and 75% were not aware that age is a risk factor. Thirty-one percent of women reported low levels of confidence to detect a breast change and 19% rarely or never checked their breasts. Those with fewer educational qualifications had poorer knowledge of symptoms, less awareness of lifetime and age-related risks, but were more likely to check their breasts than more highly educated women. This national survey demonstrates a significant lack of the prerequisite knowledge and confidence to detect a breast change. Raising breast cancer awareness and promoting early presentation among older women is important, as they are more at risk of breast cancer and more likely to delay seeking help with breast cancer symptoms than younger women.

Does the method of detection of breast cancer affect subsequent psychiatric morbidity?

The aim of this prospective study was to compare the prevalence of psychiatric morbidity following diagnosis of breast cancer between a group of women presenting with screen-detected cancer and a group presenting with symptomatic disease. Psychiatric symptoms were elicited using the Structured Clinical Interview (SCID) and classified according to DSM-III criteria. 61 (46%) of 132 women interviewed experienced an episode of psychiatric disorder between 1 month before diagnosis and 12 months post-diagnosis. There was no association between detection by screening of breast cancer and psychiatric disorder (Odds Ratio (OR) 0.8, 95% Confidence Interval (CI) 0.4-1.8 P=0.7). The occurrence of an episode of psychiatric disorder was associated with a previous history of treatment for psychological problems (OR 2.4, 95% CI 1.1-5.5, P=0.02). The results suggest there is no increased risk of developing psychiatric morbidity associated with the detection of cancer through the National Breast Screening Programme.

Do adverse life events and mood disorders influence delayed presentation of breast cancer?

OBJECTIVE: The purpose of this study is to examine the influence of adverse life experiences and mood disorders on delayed presentation of breast cancer. METHODS: One hundred fifty-eight patients were interviewed 5 months after diagnosis to assess the prevalence of adverse life events and difficulties using the Bedford College Life Events and Difficulties Schedule, and psychiatric morbidity using the Structured Clinical Interview (SCID) and DSM-III-R diagnostic criteria. RESULTS: There was no association between experiencing a severe life event (p = 0.5) or difficulty, whether severe or nonsevere (p = 0.8), in the year preceding symptom discovery and patient delay. Counterintuitively, women who presented promptly to their GP (<12 weeks) with breast symptoms were more likely than those who delayed >/=12 weeks to report having a nonsevere event in the year before symptom discovery (p < 0.001). This appeared however, to be an artifact, because the women presenting promptly were recalling events that were closer in time to the research interview. Patient delay was not related to prevalence of depression (p = 0.2) or anxiety (p = 0.8) in the year preceding symptom discovery. CONCLUSION: This study suggests that neither adverse life experiences nor mood disorder in the year before symptom discovery increase the risk of patients with symptoms of breast cancer delaying their presentation to a general practitioner.

Promoting early presentation of breast cancer: development of a psycho-educational intervention.

OBJECTIVES: Women who delay presenting with breast cancer have a reduced chance of survival. Older women, who are at greater risk of developing breast cancer, are more likely to delay presenting with the disease. The aim of this developmental work was to design a psycho-educational intervention to promote early help-seeking by older women with breast cancer symptoms. We also aimed to demonstrate the feasibility of implementing the intervention with women attending for their final invited mammogram in the National Health Service (NHS) Breast Screening Programme. METHODS: The intervention was designed to address the factors associated with delayed presentation by women with breast cancer. These risk factors were placed in a theoretical framework to understand patient delay. The intervention incorporated behavioural change techniques that, according to previous research, have been demonstrated to be effective. RESULTS: The intervention was developed in two formats to be delivered by diagnostic radiographers: a booklet alone and a brief interview plus the booklet. The intervention was acceptable to both older women and healthcare professionals in the NHS Breast Screening Programme. DISCUSSION: The intervention will be tested ultimately in a multicentre randomized controlled trial to determine whether it can reduce the proportion of older women who delay their presentation and thereby save lives.

Why do older women delay presentation with breast cancer symptoms?

Women who delay their presentation with breast cancer for three months or longer are more likely to be diagnosed with later stage disease and have poorer survival. Older women, who are at greater risk of developing breast cancer, are also more likely to delay their presentation. Factors associated with delayed presentation were assessed in 69 women (>65 years) with breast cancer. Previous factors identified for women of all ages were confirmed (having a non-lump symptom p=0.003) or strengthened (non-disclosure of symptom discovery to a relative or close friend p=0.001). Additional factors for delay in this older group included reservations about seeing their GP (p=0.02) and fear of the consequences of cancer (p=0.04). These factors should inform the design of interventions to reduce delays.

Who and what influences delayed presentation in breast cancer?

This study aimed to examine the extent and determinants of patient and general practitioner delay in the presentation of breast cancer. One hundred and eighty-five cancer patients attending a breast unit were interviewed 2 months after diagnosis. The main outcome measures were patient delay in presentation to the general practitioner and non-referral by the general practitioner to hospital after the patient's first visit. Nineteen per cent of patients delayed > or = 12 weeks. Patient delay was related to clinical tumour size > or = 4 cm (P = 0.0002) and with a higher incidence of locally advanced and metastatic disease (P = 0.01). A number of factors predicted patient delay: initial breast symptom(s) that did not include a lump (OR 4.5, P = 0.003), not disclosing discovery of the breast symptom immediately to someone else (OR 6.0, P < 0.001), seeking help only after being prompted by others (OR 4.4, P = 0.007) and presenting to the general practitioner with a non-breast problem (OR 3.5, P = 0.03). Eighty-three per cent of patients were referred to hospital directly after their first general practitioner visit. Presenting to the GP with a breast symptom that did not include a lump independently predicted general practitioner delay (OR 3.6, P = 0.002). In view of the increasing evidence that delay adversely affects survival, a large multicentre study is now warranted to confirm these findings that may have implications for public and medical education.

Microtubules and Src homology 3 domains stimulate the dynamin GTPase via its C-terminal domain.

Dynamin is a 100-kDa GTPase that plays a critical role in the initial stages of endocytosis. Dynamin binds to microtubules, which potently stimulate its GTPase activity. Binding to Src homology 3 (SH3) domains of proteins involved in signal transduction has also recently been reported. In the present study, the protein was digested with a variety of proteases to define its functional domains. Limited digestion with papain split the protein into an approximately 7- to 9-kDa microtubule-binding fragment and a 90-kDa nonbinding fragment. Immunoblotting with an antibody to the C-terminal 20 amino acids of rat dynamin showed the small fragment to derive from the C-terminal end of the polypeptide. Microtubule-activated GTPase activity, but not basal GTPase activity, was abolished by papain digestion, identifying the basic, proline-rich C-terminal region of dynamin as an important regulatory site. Bacterially expressed growth factor receptor-bound protein 2 (GRB2) and the SH3 domain of c-Src were also found to stimulate GTPase activity, although to a lesser extent than microtubules. Stimulation of GTPase activity by the recombinant proteins was similarly abolished by papain digestion. These results identify the basic, proline-rich C-terminal region of dynamin as the binding site for both microtubules and SH3 domains and demonstrate an allosteric interaction between this region of the molecule and the N-terminal GTPase domain.

Developmental stage- and tissue-specific expression of shibire, a Drosophila gene involved in endocytosis.

Dynamin, a microtubule-activated GTPase, has recently been identified as the product of the shibire gene in Drosophila. shi(ts) mutants are defective in synaptic vesicle recycling, which leads to rapid and reversible temperature-sensitive paralysis. In the present study, results from RNase protection assays and analysis of cDNA clones define a complex pattern of developmental- and tissue-specific alternative splicing at two sites within the coding region. This analysis is also supported by western blot analysis with two polyclonal antibodies. In situ hybridization data revealed a high concentration of shi transcripts in the central and peripheral nervous system throughout neuronal development. Other than the nervous system, shi transcripts are also expressed at a high level in early embryos, larval imaginal discs, and male and female gonads. These data provide a basis for interpreting the wide range of phenotypic effects of shi mutations in terms of the putative membrane-sorting properties of dynamin and for further functional study of different dynamin isoforms.

Dynamin, a GTPase involved in the initial stages of endocytosis.

Dynamin is a high molecular mass (100 kDa) GTPase which binds to and co-purifies with microtubules. Molecular cloning of rat brain dynamin has revealed the three well-established consensus sequence elements for GTP binding within the N-terminal third of the protein, as well as sequence similarity within this region to the interferon-inducible antiviral Mx proteins, the product of the yeast membrane sorting gene VPS1, and the product of the yeast mitochondrial replication gene MGM1. More extensive sequence similarity between rat dynamin and the product of the Drosophila gene shibire, which is involved in endocytosis, has also been found. In in vitro assays microtubules strongly stimulate the dynamin GTPase. This effect can be reversed by removal of the dynamin C-terminus using papain, which abolishes microtubule binding. Overexpression of mutant forms of dynamin in vivo using Cos-7 cells inhibits transferrin uptake and alters the distribution of clathrin and of alpha-adaptin, but not gamma-adaptin. Deletion of the C-terminus of mutant forms of dynamin abolishes these effects. Together these results suggest a critical role for dynamin in the early stages of endocytosis. It is uncertain whether microtubules interact with dynamin in vivo or whether the in vitro effects of microtubules mimic the effects of other regulatory elements in vivo.

Factors predicting delayed presentation of symptomatic breast cancer: a systematic review.

BACKGROUND: Delayed presentation of symptomatic breast cancer is associated with lower survival. Understanding of the factors that influence delay is important for the development of strategies to shorten delays. We did a systematic review to assess the quality and strength of evidence on risk factors for delays by patients and providers. METHODS: We generated hypotheses about the relation between each putative risk factor and delay, against which we tested studies. We did searches to identify papers containing original data related to risk factors for delays by patients (n=86) and providers (n=28). We critically appraised the papers for inclusion in the review according to predefined criteria. The small number of studies of adequate quality did not allow formal meta-analysis. We therefore assigned strength of evidence according to a combination of the number and size of studies supporting, not supporting, or refuting the hypotheses. FINDINGS: Most studies were deemed to be of poor quality and were excluded. Among 23 studies of adequate quality, however, there was strong evidence for an association between older age and delay by patients, and strong evidence that marital status was unrelated to delays by patients. Younger age and presentation with a breast symptom other than a lump were strong risk factors for delays by providers. Moderate evidence was shown for several other factors. INTERPRETATION: The strength of the current evidence is inadequate to inform the development of specific strategies to shorten delays by patients or providers. Clarification of the findings of this review through a major programme of primary research is urgently required.