Characteristics of magnetic resonance sequences used for imaging silicone gel, saline, and gel-saline implants at low field strengths

RATIONALE AND OBJECTIVES

Low-field magnetic resonance imaging (MRI) evaluation of breast implants is described, with emphasis on the capabilities provided by different imaging sequences.

METHODS

Open architecture MR images using a .064-T permanent magnet and three-dimensional Fourier transform and inversion recovery sequences were obtained. A breast coil was designed and built for this project. Symptomatic and asymptomatic patients with silicone, saline-silicone and saline implants, and phantoms were part of this study. Phase images were used to differentiate protons in silicone, water, and fat.

RESULTS AND CONCLUSIONS

Low-field MRI permitted differentiation of silicone, water, and fat. Implant anatomy and surrounding pathology could be imaged and identified.

Prevention of suicide: aspirations and evidence

The Health of the Nation white paper set a target for 15% reduction in overall suicide rates by the year 2000. If the targets are to be achieved interventions must be identified which are of proved effectiveness. This paper examines the evidence on the available interventions and points of access to the population at risk. No single intervention has been shown in a well conducted randomised controlled trial to reduce suicide. The greatest potential seems to arise from limiting the availability of methods. In particular it is likely that the introduction of the catalytic convertor will lead to reduced lethality of care exhausts and reductions in suicide using this method. General practitioner education programmes, the effectiveness of lithium and maintenance antidepressants, and limits on the quantity of medicines available over the counter or on prescription should all be evaluated. Particular high risk groups include people recently discharged from psychiatric hospitals and those with a history of parasuicide. Many social processes affect suicide rates and these rather than specific interventions may help or hinder the ability to realise the Health of the Nation targets. Well conducted trials are essential to distinguish complex social processes from the effects of specific interventions for suicide prevention. This review of the available evidence offers little support for the aspiration that the posited targets can be achieved on the basis of current knowledge and current policy.

Identification of a divergent actin-related protein in Drosophila

The actin-related proteins (ARPs) have primary sequence homology to actin, have no homology to other proteins and, unlike the conventional actins, are clearly divergent. We have identified an ARP in Drosophila that has approximately 30% amino acid identity to most actins, making it the most divergent yet reported. It is also quite divergent from all other ARP sequences. When the Drosophila ARP is aligned with actin it contains sequence insertions, as is the case with all other ARPs. The unique location of the insertions, as well as its overall divergence, indicates it may represent a new isotype. Only one gene was detected by hybridization to both genomic DNA and polytene chromosomes; the location of the gene is 13E on the X chromosome. A transcript of 1350 bases was detected at all stages of development. This transcript was relatively abundant during early embryogenesis, decreasing during the later stages of embryogenesis and increasing again in larvae and adults.

Differences in dendritic cells in congenital and acquired cholesteatomas

Cholesteatomas are histologically benign, though biologically invasive lesions that arise from the migration of squamous epithelium of the ear. Acquired cholesteatomas usually arise in an antigenically active environment, i.e., a chronically and/or recurrently inflamed middle ear. In contrast, congenital cholesteatomas occur in an uninflamed environment. The potential role of dendritic cells (DCs) in the evolution of this lesion has not been thoroughly studied. By staining for S-100 protein, the authors evaluated the presence and distribution of DCs in cholesteatomas. Sixteen cases of cholesteatomas diagnosed from 1987 to 1989 were selected for this study. The formalin-fixed, paraffin-embedded sections were processed by a standard avidin-biotin peroxidase-antiperoxidase method for S-100 protein and for leukocyte common antigen (LCA). The presence and distribution of S-100 protein-positive DCs was evaluated and compared to canal wall skin. DCs were present in all cases. Nine acquired cholesteatomas had 5 to 16 epithelial DCs per high-power field (HPF). Seven congenital cholesteatomas were examined. Four with isolated congenital pearl-like cholesteatomas had 1 to 3/HPF epithelial DCs. In contrast, the three inflamed congenital cholesteatomas had 6 to 12/HPF DCs. The control uninflamed canal wall skin had only 1 to 3/HPF DCs. All DCs were LCA negative, as expected.

The limits of lifestyle: re-assessing 'fatalism' in the popular culture of illness prevention

This paper is concerned with the development of preventive medicine in the field of Coronary Heart Disease. It is based on an in-depth, ethnographic investigation into the popular culture of prophylactic behaviour carried out in South Wales (U.K.) during 1988 and 1989. The focus of the data and analysis presented here is the operation of cultural norms and practices related to the understanding and explanation of the cause and distribution of illness and death from heart ailments. The paper illustrates how the everyday cultural practice of 'lay epidemiology' is involved in accounting for illness misfortune and in assessing the potential benefits of prophylactic behaviour change. A central issue dealt with here is the relationship of lifestyle to environment in the popular understanding of chronic disease. Lay notions of luck, fate, destiny, randomness and chaos in the distribution of heart disease are explored. In conclusion, some implications for health education in this field are put forward.

Lay epidemiology and the rationality of responses to health education

Health education has long been seen as an important component of primary care, and under the new contract has become routine. It is important to consider the likely impact of general practitioners' endeavours in the light of the experience of health education to date. Despite decades of efforts directed towards reducing the population's adherence to practices deemed harmful to health, it must be acknowledged that the impact of such activity has been disappointing. This paper considers some cultural origins of public scepticism to health education messages, and argues for a more balanced presentation of current knowledge concerning the causes of disease and the probability that individuals will benefit by changing their behaviour.

Potential availability of cadaver organs for transplantation

OBJECTIVE

To determine the potential number of cadaver kidney donors by applying defined donor criteria to people dying in hospital.

DESIGN

Prospective study of all deaths occurring in 21 hospitals from 1 September 1988 to 31 August 1989. Questionnaires were administered to medical and nursing staff and families of potential donors aged 1-69.

SETTING

Acute care hospitals in Gwent, South Glamorgan, Mid Glamorgan, West Glamorgan, Pembrokeshire, and East Dyfed health authorities, serving a population of 2.2 million.

MAIN OUTCOME MEASURES

Cause of death, age, ventilation at time of death, diagnosis of brain death, and consideration of consent.

RESULTS

Adequate data were available for 9840 of 10,095 hospital deaths (97.5% coverage). 188 patients aged 0-69 were identified as potential organ donors (widest definition), and of these 108 died without being ventilated at the time of death. Tests of brain stem death were formally completed in 57 cases, and organ donation was considered by the families of 47 of these potential donors. 26 patients became organ donors. Patients aged 50-69 with stroke were less likely to be ventilated than those aged less than or equal to 49 (21/96 v 24/34). Families of potential donors aged 20-39 were least likely to give permission.

CONCLUSIONS

The supply of donor organs (specifically kidneys) could be increased by altering the management of patients aged 50-69 dying of severe cerebrovascular disease in general medical wards, in particular by increasing the proportion ventilated. The ethics of elective ventilation for the purposes of organ donation require discussion.

The use of sarkosyl in generating soluble protein after bacterial expression

Actin, like many other proteins, is highly insoluble after expression in Escherichia coli. In order to understand the origin of insoluble aggregates, we asked whether morphological inclusions were always correlated with insolubility. The strain expressing actin was compared to one that expresses part of the myosin tail; the latter strain yields soluble protein after various cell lysis or disruption procedures. Morphological inclusions were observed in both strains, indicating there is no obligate relationship between solubility and inclusions. Studies presented here suggest that extreme insolubility results from coaggregation of the actin with bacterial outer membrane components upon bacterial lysis. The properties of the outer membrane have been exploited in the development of nondenaturing procedures that yield soluble actin. One procedure involves the disruption of coaggregates with sarkosyl detergent (N-laurylsarcosine); another prevents the formation of coaggregates by lysing in the presence of sarkosyl. These methods may be useful for other proteins that become insoluble after bacterial expression.

A xanthogranulomatous histiocytosis in a child presenting with short stature

We evaluated a 7-year-old boy presenting with a neck mass that was diagnosed as juvenile xanthogranuloma on excisional biopsy. Despite this diagnosis, an exhaustive evaluation was undertaken because of marked short stature. Examination revealed growth hormone deficiency and diabetes insipidus, as well as widespread lesions in the head, mediastinum, retroperitoneum, skeleton, and elsewhere. Biopsies of the lesions in the mediastinum and right tibia suggested a diagnosis of xanthoma disseminatum with bony involvement, suggesting the Erdheim-Chester variant of xanthogranulomatous histiocytosis, previously reported only in adults. The diagnosis is contrasted to the more common clinical entities of juvenile xanthogranuloma and the Langerhans' cell histiocytoses. This case illustrates the gravity with which otherwise unexplained short stature should be considered.

Expression of actin in Escherichia coli. Aggregation, solubilization, and functional analysis

Wild type Dictyostelium discoideum actin (42 kDa) and a truncated form of actin were expressed in Escherichia coli. Amino-terminal sequencing indicated that the truncated species was composed of two peptides, which were the result of internal translation initiation at Met-119 and Met-123. After sonication or French press lysis, all of the actin was present in highly insoluble aggregates. When bacteria were lysed directly into Sarkosyl detergent, most of the actin was soluble, and greater than 50% remained soluble after Sarkosyl was removed. Full-length wild type actin was purified using DNase I affinity chromatography and gel filtration. This species was able both to polymerize and to bind myosin in an ATP-sensitive manner, indicating it was native. Affinity chromatography demonstrated that the truncated form of actin bound DNase I to the same extent as actin synthesized in eukaryotes, indicating the applicability of this approach to mutant forms of actin. Thus, lysis procedures utilizing Sarkosyl may prove useful in isolating some of the other proteins which are normally soluble but become insoluble after bacterial expression.

Assessing the need for hospice beds

This paper considers means for determining the level of hospice provision that might be appropriate for particular populations. An analysis of the need for hospice beds is described, and the findings are assessed in relation to the subsequent experience of hospice utilisation. Finally, the implications for hospice provision are discussed.

Non-admission or non-invitation? A case-control study of failed admissions

OBJECTIVE

To examine the causes of non-admission to hospital.

DESIGN

Validation of published rates of non-admission by examination of medical records, followed by a case-control study of non-attenders (cases) and attenders (controls).

SETTING

General hospital.

SUBJECTS

246 Patients (cases in the case-control study) booked for admissions in four specialties (general surgery, gynaecology, otorhinolaryngology, and trauma and orthopaedics) during April, May, and June 1987 who were not admitted for reasons that seemed to be attributable to the patients. Controls comprised 167 patients admitted to the same specialty on the same day.

RESULTS

The validation of administrative records indicated that it is unusual for patients to fail to present for admission without advising the hospital beforehand; this occurred in only 1-3% of all bookings. Information on the circumstances of non-admission and clinical and personal details were collected by means of a six page questionnaire completed by the patients. The case-control study showed that those not admitted were younger and had been on the waiting list longer. Otherwise only small differences were found in the social and clinical characteristics.

CONCLUSIONS

Despite a common tendency to blame patients for non-admission, factors due to patients are fairly unimportant.

Non-attendance or non-invitation? A case-control study of failed outpatient appointments

OBJECTIVE

To determine the causes of non-attendance at new outpatient appointments.

DESIGN

Case-control study of non-attenders and attenders.

SETTING

Outpatient department of a general hospital.

SUBJECTS

All non-attenders (n = 277) for first outpatient appointments in six specialties during a three month period were included. Controls (n = 135) were the attenders who followed every second non-attender; thus they attended the same consultant on the same day that the non-attenders were expected.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Information on the clinical problem, difficulties in attending the hospital, and reasons for non-attendance from the questionnaire were coded and classified. Non-attenders had received shorter notice of their appointment than attenders (14% v 1% had received three days' notice or less). There were small differences in the seriousness of patients' clinical condition.

CONCLUSIONS

Client factors are less important than aspects of the service in explaining non-attendance at outpatient appointments.