Computation of Expected Deaths for Prediction and for Long-Term Follow-up Studies

In this paper we discuss an uncomplicated procedure for computing the expected number of deaths in a heterogeneous study sample without requiring any information about the number or distribution of observed deaths. This procedure can thus be used to compare grouped mortality data to a large reference population and also to make predictions about the number of deaths to be expected in the not too distant future based on current population rates. The estimation procedure is introduced in a simple context and later extended to allow for multiple hazard rates, for right censoring, and for competing causes of death.

Development and validation of the Surgical Outcome Risk Tool (SORT)

Background

Existing risk stratification tools have limitations and clinical experience suggests they are not used routinely. The aim of this study was to develop and validate a preoperative risk stratification tool to predict 30-day mortality after non-cardiac surgery in adults by analysis of data from the observational National Confidential Enquiry into Patient Outcome and Death (NCEPOD) Knowing the Risk study.

Methods

The data set was split into derivation and validation cohorts. Logistic regression was used to construct a model in the derivation cohort to create the Surgical Outcome Risk Tool (SORT), which was tested in the validation cohort.

Results

Prospective data for 19 097 cases in 326 hospitals were obtained from the NCEPOD study. Following exclusion of 2309, details of 16 788 patients were analysed (derivation cohort 11 219, validation cohort 5569). A model of 45 risk factors was refined on repeated regression analyses to develop a model comprising six variables: American Society of Anesthesiologists Physical Status (ASA-PS) grade, urgency of surgery (expedited, urgent, immediate), high-risk surgical specialty (gastrointestinal, thoracic, vascular), surgical severity (from minor to complex major), cancer and age 65 years or over. In the validation cohort, the SORT was well calibrated and demonstrated better discrimination than the ASA-PS and Surgical Risk Scale; areas under the receiver operating characteristic (ROC) curve were 0·91 (95 per cent c.i. 0·88 to 0·94), 0·87 (0·84 to 0·91) and 0·88 (0·84 to 0·92) respectively (P < 0·001).

Conclusion

The SORT allows rapid and simple data entry of six preoperative variables, and provides a percentage mortality risk for individuals undergoing surgery.

Correct and incorrect use of child restraints: Results from an urban survey in New Zealand

This study describes the incorrect use of child restraints among car drivers with young children and examines factors that may influence their misuse. A cross-sectional survey was undertaken in supermarket car parks with car drivers travelling with children under the age of 8 years. The main measure was errors in child restraint use. Short interviews were conducted with 1113 drivers with a close inspection of the child restraints used in the vehicles. Only 4% of children were unrestrained but 64% of drivers made at least one error in restraint use. Most respondents thought using a restraint was easy, but 65% of these drivers made at least one error. Child restraints are used, but many are incorrectly fitted and/or have the child incorrectly placed in them. Correct use is a moderately complex task. Restraint systems need to be designed to minimize the opportunity for error and maximize safety.

Playing conditions, player preparation and rugby injury: a case-control study

This paper investigates the effect of player preparation, ground conditions and weather conditions upon the injury risk for Rugby Union players. A population-based case-control study was performed using a sample (n= 1043) of New Zealand Rugby Union players aged 16 y and above. Details concerning game preparation (warm-up and usual position), and ground and weather conditions (precipitation, wind and temperature) were obtained from the players. If players were injured during the season (n= 624) they were asked to provide details about the game in which they were last injured. Uninjured players (n= 419) provided details about the last game in which they played. Injuries were more likely to occur when games were played on hard grounds or in calm or warm conditions. Playing out of position and the duration of warming up did not significantly alter the risk of injury. When player preparation, ground and weather conditions, grade, age, playing position and rugby experience were simultaneously controlled for, hard ground and the absence of wind were associated with increased risk. The influence of these factors may be indirect, through adaptation to the conditions in which a game is played.

Tackling Rugby injury: lessons learned from the implementation of a five-year sports injury prevention program

Rugby Union football is a very popular sport in New Zealand but of all the major sports played in that country, it has the highest reported incidence of injury. In 1995, a national rugby injury prevention program was instigated to address this problem. Known as Tackling Rugby Injury, this multifaceted program was implemented over a five-year period. The program was based on the results of a prospective cohort study of rugby injury, known as the Rugby Injury and Performance Project (RIPP), and was organised around seven themes, five relating to the prevention of injury: coaching, fitness, injury management, tackling, and foul play, and two relating to the implementation and evaluation of the program. The purpose of this paper is to describe the lessons learned from the implementation of Tackling Rugby Injury. Qualitative research methods were used to describe the process of implementation, including informant interviews, participant observation, and the scrutiny of written, visual and archival material. Among the lessons learned were the importance of basing injury prevention strategies on scientific evidence rather than popular belief, the difficulty in implementing complex interventions, the advantages of a formal agreement between partners in the implementation of a program, the central role played by coaches in promoting injury prevention strategies, and the value of describing the process of implementation as well as monitoring injury outcomes and changes in knowledge, attitudes and behaviour. It is hoped that other sports wishing to develop injury prevention programs can learn from this experience.

Examining child restraint use and barriers to their use: lessons from a pilot study

OBJECTIVE

To determine the suitability of four research methods to measure the rate of child restraint device (CRD) use and incorrect use in New Zealand and obtain data on barriers to CRD use.

DESIGN AND SETTING

To assess the rates of CRD use among vehicles carrying children 8 years of age and under, two methods were piloted-namely, an unobtrusive observational survey and a short interview and close inspection. A self administered questionnaire and focus group interviews were also piloted to assess CRD use, reasons for use and non-use, and to obtain information on barriers to their use. Respondents to all methods except the focus groups were approached in supermarket car park sites at randomly selected times. Focus groups were established with parents identified through early childhood organisations. All methods were assessed on criteria related to efficiency, representativeness, and ability to obtain the necessary data.

RESULTS

The observational survey provided a simple method for identifying rates of CRD use, while the self administered questionnaire obtained data on demographic characteristics and reported the installation and use/non-use of CRDs. The interview/inspection addressed all the questions of both the above methods and enabled incorrect CRD use to be examined. The focus groups provided the most meaningful information of all methods on barriers to CRD use.

DISCUSSION

and conclusion: Advantages and limitations of these methods are discussed and some refinements of the original instruments are proposed. The interview/inspection and focus group methods were identified as being more appropriate for efficiently obtaining reliable data on CRD use and identification of barriers to CRD use.

The Spir actin organizers are involved in vesicle transport processes

The p150-Spir protein, which was discovered as a phosphorylation target of the Jun N-terminal kinase, is an essential regulator of the polarization of the Drosophila oocyte. Spir proteins are highly conserved between species and belong to the family of Wiskott-Aldrich homology region 2 (WH2) proteins involved in actin organization. The C-terminal region of Spir encodes a zinc finger structure highly homologous to FYVE motifs. A region with high homology between the Spir family proteins is located adjacent (N-terminal) to the modified FYVE domain and is designated as "Spir-box." The Spir-box has sequence similarity to a region of rabphilin-3A, which mediates interaction with the small GTPase Rab3A. Coexpression of p150-Spir and green fluorescent protein-tagged Rab GTPases in NIH 3T3 cells revealed that the Spir protein colocalized specifically with the Rab11 GTPase, which is localized at the trans-Golgi network (TGN), post-Golgi vesicles, and the recycling endosome. The distinct Spir localization pattern was dependent on the integrity of the modified FYVE finger motif and the Spir-box. Overexpression of a mouse Spir-1 dominant interfering mutant strongly inhibited the transport of the vesicular stomatitis virus G (VSV G) protein to the plasma membrane. The viral protein was arrested in membrane structures, largely colocalizing with the TGN marker TGN46. Our findings that the Spir actin organizer is targeted to intracellular membrane structures by its modified FYVE zinc finger and is involved in vesicle transport processes provide a novel link between actin organization and intracellular transport.

Barriers to safe hot tap water: results from a national study of New Zealand plumbers

INTRODUCTION

Many countries still have unacceptably high hospitalizations and deaths from scalds from hot tap water. Prevention strategies implemented in some countries may not work in others. Legislation aimed at changing environments that are conducive to hot tap water scalds may not be effective in many situations for a number of reasons, including lack of acceptability and practicality.

METHOD

A qualitative study of a purposefully selected group of craftsman plumbers across New Zealand was conducted using a structured format with open ended questions. The questionnaire was administered by telephone. Information was sought on the opinions, knowledge, and practice of these plumbers regarding hot tap water safety in homes.

RESULTS

Several barriers to hot tap water safety in homes were identified by the plumbers. These included common characteristics of homes with unsafe hot tap water, such as hot water systems heated by solid fuel, and public ignorance of hot tap water safety. Other factors that emerged from the analysis included a lack of knowledge by plumbers of the hazards of hot tap water, as well as a lack of importance given to hot tap water safety in their plumbing practice. Shower performance and the threat to health posed by legionella were prioritized over the prevention of hot tap water scalds.

CONCLUSION

The findings of this study allow an understanding of the practical barriers to safe hot tap water and the context in which interventions have been applied, often unsuccessfully. This study suggests that plumbers can represent a barrier if they lack knowledge, skills, or commitment to hot tap water safety. Conversely, they represent a potential source of advocacy and practical expertise if well informed, skilled, and committed to hot tap water safety.

Illuminating the human genome

The identification and analysis of novel genes and their encoded protein products remains a vigorous area of research in biology today. Worldwide genomic and cDNA sequencing projects are now identifying new molecules every day and the need for methodologies to functionally characterise these proteins has never been greater. The distinct compartmental arrangement of eukaryotic cells helps define the processes which occur within or in proximity to these membranes, and as such provides one means of inferring protein function. We describe here some of the methods recently reported in the literature, which use the subcellular localisation of proteins as a first step towards their further characterisation.

Being in the right location at the right time

Taking each coding sequence from the human genome in turn and identifying the subcellular localization of the corresponding protein would be a significant contribution to understanding the function of each of these genes and to deciphering functional networks. This article highlights current approaches aimed at achieving this goal.

A national confidential enquiry into community acquired pneumonia deaths in young adults in England and Wales. British Thoracic Society Research Committee and Public Health Laboratory Service

BACKGROUND

The aim of this study was to describe the frequency, causal pathogens, management, and outcome of a population of young adults who died from community acquired pneumonia (CAP).

METHODS

Pneumonia deaths in England and Wales in adults aged 15-44 were identified between September 1995 and August 1996. Patients with underlying chronic illness including HIV infection were excluded. Clinical details for each case were collected from the hospital and general practitioner records.

RESULTS

Death from CAP was identified in 27 previously well young adults (1.2 per million population per year). Twenty were known to have consulted a GP for this illness. Nine received antibiotics before hospital admission. A causative pathogen was identified in 17 cases (Streptococcus pneumoniae in eight). Bacteraemia was present in seven. All patients who reached a hospital ward received antibiotics (69% within two hours of admission). The British Thoracic Society antibiotic guidelines for severe CAP were followed in only 10 cases. Cardiac arrest at home or on arrival at hospital occurred in six cases, one of whom was successfully resuscitated. Of the remaining 21 patients, 71% had two or more markers of severe CAP. All 22 who were admitted reached an intensive care unit, but 11 of these required transfer to another hospital for some aspect of intensive care. One third of patients died within 24 hours of presenting to the hospital.

CONCLUSIONS

Death from CAP in previously fit young adults still occurs. While some deaths might be preventable by better patient management, most are unlikely to be preventable by current management practices.

Systematic subcellular localization of novel proteins identified by large-scale cDNA sequencing

As a first step towards a more comprehensive functional characterization of cDNAs than bioinformatic analysis, which can only make functional predictions for about half of the cDNAs sequenced, we have developed and tested a strategy that allows their systematic and fast subcellular localization. We have used a novel cloning technology to rapidly generate N- and C-terminal green fluorescent protein fusions of cDNAs to examine the intracellular localizations of > 100 expressed fusion proteins in living cells. The entire analysis is suitable for automation, which will be important for scaling up throughput. For > 80% of these new proteins a clear intracellular localization to known structures or organelles could be determined. For the cDNAs where bioinformatic analyses were able to predict possible identities, the localization was able to support these predictions in 75% of cases. For those cDNAs where no homologies could be predicted, the localization data represent the first information.

Smoothed Particle Hydrodynamics Simulations of Apsidal and Nodal Superhumps

In recent years, a handful of systems have been observed to show "negative" (nodal) superhumps, with periods slightly shorter than the orbital period. It has been suggested that these modes are a consequence of the slow retrograde precession of the line of nodes in a disk tilted with respect to the orbital plane. Our simulations confirm and refine this model: they suggest a roughly axisymmetric, retrogradely precessing, tilted disk that is driven at a period slightly less than half the orbital period as the tidal field of the orbiting secondary encounters, in turn, the two halves of the disk above and below the midplane. Each of these passings leads to viscous dissipation on one face of an optically thick disk-observers on opposite sides of the disk would each observe one brightening per orbit, but 180 degrees out of phase with each other.

Evidence for a COP-I-independent transport route from the Golgi complex to the endoplasmic reticulum

The cytosolic coat-protein complex COP-I interacts with cytoplasmic 'retrieval' signals present in membrane proteins that cycle between the endoplasmic reticulum (ER) and the Golgi complex, and is required for both anterograde and retrograde transport in the secretory pathway. Here we study the role of COP-I in Golgi-to-ER transport of several distinct marker molecules. Microinjection of anti-COP-I antibodies inhibits retrieval of the lectin-like molecule ERGIC-53 and of the KDEL receptor from the Golgi to the ER. Transport to the ER of protein toxins, which contain a sequence that is recognized by the KDEL receptor, is also inhibited. In contrast, microinjection of anti-COP-I antibodies or expression of a GTP-restricted Arf-1 mutant does not interfere with Golgi-to-ER transport of Shiga toxin/Shiga-like toxin-1 or with the apparent recycling to the ER of Golgi-resident glycosylation enzymes. Overexpression of a GDP-restricted mutant of Rab6 blocks transport to the ER of Shiga toxin/Shiga-like toxin-1 and glycosylation enzymes, but not of ERGIC-53, the KDEL receptor or KDEL-containing toxins. These data indicate the existence of at least two distinct pathways for Golgi-to-ER transport, one COP-I dependent and the other COP-I independent. The COP-I-independent pathway is specifically regulated by Rab6 and is used by Golgi glycosylation enzymes and Shiga toxin/Shiga-like toxin-1.

Ricin A chain utilises the endoplasmic reticulum-associated protein degradation pathway to enter the cytosol of yeast

Cytotoxic proteins such as ricin A chain (RTA) have target substrates in the cytosol and therefore have to reach this cellular compartment in order to act. RTA is thought to translocate into the cytosol from the lumen of the endoplasmic reticulum (ER), although how it traverses the ER membrane has not been established. Using yeast mutants defective in various aspects of the ER-associated protein degradation (ERAD) pathway, we show that RTA introduced into the yeast ER subverts this pathway to enter the cytosol via the Sec61p translocon. A significant proportion of the exported RTA avoided proteasomal degradation. These data are consistent with the contention that the RTA component from ricin endocytosed by mammalian cells may likewise exploit ERAD to translocate into the cytosol.

The KDEL retrieval system is exploited by Pseudomonas exotoxin A, but not by Shiga-like toxin-1, during retrograde transport from the Golgi complex to the endoplasmic reticulum

To investigate the role of the KDEL receptor in the retrieval of protein toxins to the mammalian cell endoplasmic reticulum (ER), lysozyme variants containing AARL or KDEL C-terminal tags, or the human KDEL receptor, have been expressed in toxin-treated COS 7 and HeLa cells. Expression of the lysozyme variants and the KDEL receptor was confirmed by immunofluorescence. When such cells were challenged with diphtheria toxin (DT) or Escherichia coli Shiga-like toxin 1 (SLT-1), there was no observable difference in their sensitivities as compared to cells which did not express these exogenous proteins. By contrast, the cytotoxicity of Pseudomonas exotoxin A (PE) is reduced by expressing lysozyme-KDEL, which causes a redistribution of the KDEL receptor from the Golgi complex to the ER, and cells are sensitised to this toxin when they express additional KDEL receptors. These data suggest that, in contrast to SLT-1, PE can exploit the KDEL receptor in order to reach the ER lumen where it is believed that membrane transfer to the cytosol occurs. This contention was confirmed by microinjecting into Vero cells antibodies raised against the cytoplasmically exposed tail of the KDEL receptor. Immunofluorescence confirmed that these antibodies prevented the retrograde transport of the KDEL receptor from the Golgi complex to the ER, and this in turn reduced the cytotoxicity of PE, but not that of SLT-1, to these cells.

Comparative personal exposures to organic dusts and endotoxin

The aims of the study were to provide valid comparative data for personal exposures to dust and endotoxins for different occupations and to calculate comparative data for the contamination of organic dusts with endotoxin. Nine different occupational settings were studied, drawn from the textile, agricultural and animal handling industries. Samples were collected by personal sampling techniques, using the Institute of Occupational Medicine (IOM) sampling head, glass fibre filters and rechargeable sampling pumps. The dust exposures were calculated by gravimetric analysis and using the calculated volume of air sampled were expressed as mg/m3. Endotoxin exposures were measured using a simple water extraction from the collected dusts, followed by a quantitative turbidimetric assay. Results were expressed as ng/m3, using the calculated volume of air sampled. In addition, the levels of the contamination of dusts with endotoxin for individual industries were expressed as ng/mg of collected dust. Two hundred and fifty-nine samples, collected from 9 different industries and across 36 different sites were analysed. This represented a sampling rate of 25% for the total work force. The average sampling time was 4.62 h. For all the dusts collected, a significant correlation between the collected dust and endotoxin was seen (r = 0.7 and p < 0.001). The highest dust exposures occurred during cleaning activities (grain handling: 72.5 mg/m3). The individuals exposed to the highest median level of dust and endotoxin were the animal handlers (poultry handlers, dust: 11.53 mg/m3, endotoxin: 71,995 ng/m3). Weaving and mushroom cultivation had the lowest exposures for dust and endotoxins. The mostly highly contaminated dusts (median values expressed as ng of endotoxin per mg of collected dust) were found in the animal handling (poultry: 1,030 ng/mg, swine: 152 ng/mg) and cotton spinning (522 ng/mg) industries. Processing of cotton and wool fibres was found to reduce the levels of contamination of dusts with endotoxin. In the study, valid comparative data for personal exposures to organic dusts and endotoxins have been presented. The highest exposures were found amongst animal handlers and during cleaning activities. The results highlight that dust exposures are greater in a number of industries than the set exposure standards. In addition, endotoxin exposures are found to be greater than levels at which harmful effects have been demonstrated.

Evaluating Tackling Rugby Injury: the pilot phase for monitoring injury

OBJECTIVE

To assess the suitability of two previously unused data sources for monitoring rugby injury throughout New Zealand.

METHOD

Interviews were conducted with respondents sampled from players registered with the Rugby Football Unions (RFUs) and players claiming for rugby injuries from the Accident Rehabilitation and Compensation Insurance Corporation (ACC) in Auckland and Dunedin.

RESULTS

Of the 500 RFU players sampled, 63% were interviewed and of these 39 (12%) had been injured playing rugby union. Of the 456 ACC claimants sampled, 66% were interviewed and 265 (88%) had been injured playing rugby union.

CONCLUSION

Identifying injured players through ACC claims was more efficient, both procedurally and because a smaller sample size was required to detect changes in incidence.

IMPLICATIONS

With no routine surveillance of sports injury being undertaken, recording sporting codes in national injury surveillance systems would assist the monitoring of sports injury.

Do radiographic features of acute infection influence management of lower respiratory tract infections in the community?

Community-acquired lower respiratory tract infection (LRTI) is a common clinical problem, and a chest radiograph is the most common investigation. This study investigated why general practitioners (GPs) request radiographs and whether radiographic features of LRTI affect management. The 12 month study included GP-requested chest radiographs performed at the Manchester Royal Infirmary. The GPs of patients with radiographic evidence of LRTI were sent a questionnaire. Radiographs (n=2,538) were performed in patients aged >15 yrs. One hundred and eleven (4.4%) chest radiographs showed evidence of LRTI, and 97 (87%) were included in the analysis. Fifty-six (62%) had their radiograph requested at the second or third visit. Forty-five (58%) radiographs were performed to confirm infection. In 47 (48%) of cases the GP felt the radiograph had affected treatment. An effect on treatment was significantly more common in patients not receiving antibiotics prior to the radiograph. Twenty-nine (32%) of GPs felt a normal radiograph would have affected management, most often with respect to antibiotic prescriptions (17 (58%)). Where the radiologist's report suggested a repeat radiograph or hospital referral, this was significantly more likely to have occurred. The commonest reason for a radiograph in patients with suspected lower respiratory tract infection is to confirm the infection. In the opinion of the general practitioner the results of the radiograph do affect patient treatment. The wording of the radiologists report is associated with patient management.

Educating future physicians for Ontario

In 1987, Ontario's physicians conducted a strike, ultimately not successful, over the issue of "extra billing." The fact that the Ontario public did not support this action reflected a major gap between the profession's view of itself and the public's view of the profession. In 1990, the province's five medical schools launched a collaborative project to determine more specifically what the people of Ontario expect of their physicians, and how the programs that prepare future physicians should be changed in response. The authors report on the first five years of that ongoing project. Consumer groups were asked to state their views concerning the current roles of physicians, future trends that would affect these roles, changes in roles they wished to see, and suggestions for changes in medical education. Methods used included focus groups, key informant interviews, an extensive literature review, and surveys, including a survey of health professionals. Concurrently, inter-university working groups prepared tools and strategies for strengthening faculty development, assessing student performance, and preparing future leadership for Ontario's medical education system. Eight specific physician roles were identified: medical expert, communicator, collaborator, health advocate, learner, manager ("gatekeeper"), scholar, and "physician as person." Educational strategies to help medical students learn to assume these eight roles were then incorporated into the curricula of the five participating medical schools. The authors conclude that the project shows that it is feasible to learn specifically what society expects of its physicians, to integrate this knowledge into the process of medical education reform, and to implement major curriculum changes through a collaborative, multi-institutional consortium within a single geopolitical jurisdiction.

Prevalence and predictors of work related respiratory symptoms in workers exposed to organic dusts

OBJECTIVES

The aims of this study were to document the prevalence of work related upper and lower respiratory tract symptoms in workers exposed to organic dusts and to identify variables predictive of their occurrence.

METHODS

A cross sectional survey with an administered questionnaire (a previously validated adaptation of the Medical Research Council (MRC) respiratory questionnaire) was performed. Symptoms were classified as work related by their periodicity. Demographic data, smoking habits, and occupational histories were recorded. Personal exposures to dust and endotoxin were measured and individual subjects ascribed an exposure value specific to occupation, site and industry. Cox's regression techniques were used to identify variables predictive of work related upper and lower respiratory tract symptoms. Information was stored using Dbase 3 and analysed with SPSS.

RESULTS

1032 Workers (93% of the target population) were studied in nine different industries. The highest prevalences of work related lower respiratory tract symptoms (38.1%), upper respiratory tract symptoms (45.2%), and chronic bronchitis (15.5%) were found among poultry handlers. White workers were significantly more likely to complain of upper and lower respiratory tract symptoms. An individual in the swine confinement industry had a symptom complex compatible with byssinosis. Increasing current personal exposures to dust or endotoxin were found to be predictive of upper and lower respiratory tract symptoms, chronic bronchitis, and byssinosis. In a univariate analysis a relation between current exposures and the organic dust toxic syndrome was found. Present smoking and previously documented respiratory tract illness were significantly predictive of work related lower respiratory tract symptoms. Women were more likely to report work related upper respiratory tract symptoms.

CONCLUSIONS

People exposed to organic dusts may have a high prevalence of work related respiratory tract symptoms which are related to dust exposures and smoking habits. Action should be taken to reduce exposures to dust and endotoxin and stopping smoking should be promoted among workers exposed to organic dusts to reduce morbidity.

Negative, positive, and disorganized symptom dimensions in schizophrenia, major depression, and bipolar disorder

We compared the factor structure of positive and negative symptoms in schizophrenia (N = 214), major depression (N = 97), and bipolar disorder (N = 58) to determine whether schizophrenia factors would generalize to mood disorders. A study of schizophrenia and mood disorders identified patients whose symptoms were evaluated with the Scale for the Assessment of Negative Symptoms and the Scale for the Assessment of Positive Symptoms. We conducted principal component analyses with orthogonal rotation on the global ratings. The factor structure replicated earlier findings of three factors (negative, positive, and disorganization) in groups with schizophrenia, combined mood disorders, and psychotic symptoms, regardless of diagnosis. An additional negative symptom factor was found in the major depression group. The bipolar group did not have a disorganization factor. Similar symptom factors in schizophrenia and mood disorders suggest a continuity in the major affective and psychotic disorders that appears to reflect the underlying dimension of a psychotic process.

Expression of mutant dynamin protects cells against diphtheria toxin but not against ricin

Diphtheria toxin is believed to enter sensitive mammalian cells via receptor-mediated endocytosis from clathrin-coated pits, while ricin can enter via both clathrin-dependent and clathrin-independent endocytosis. The present study has confirmed this by determining the toxin sensitivity of COS-7y cells which were transiently overexpressing a trans dominant negative mutant of dynamin, a GTPase required for the budding of clathrin-coated vesicles from the plasma membrane. Cells overexpressing wild-type dynamin showed normal receptor-mediated endocytosis of transferrin and remained sensitive to both diphtheria toxin and ricin. Cells overexpressing a mutant dynamin defective in GTP binding and hydrolysis were unable to endocytose transferrin and were protected against diphtheria toxin, but they remained completely sensitive to ricin intoxication. Treating non-transfected cells or cells overexpressing mutant dynamin with nystatin caused a redistribution of the caveolae membrane marker protein VIP21-caveolin from the cell surface to intracellular locations, but did not affect their sensitivity to ricin. The redistribution of caveolin seen after nystatin treatment may reflect the disappearance of caveolae. If this is the case, caveolae are not responsible for the endocytosis of ricin. An alternative clathrin-independent route may operate for ricin, since cellular uptake, intracellular transport, and translocation into the cytosol remain unaffected when clathrin-dependent endocytosis is effectively blocked.

Testing for interaction between maternal smoking and TGFA genotype among oral cleft cases born in Maryland 1992-1996

OBJECTIVE

Infants born in Maryland between June 1992 and June 1996 were used in a case-control study of nonsyndromic oral clefts to test for effects of maternal smoking and a polymorphic genetic marker at the transforming growth factor alpha (TGFA) locus, both of which have been reported to be risk factors for these common birth defects.

DESIGN AND SETTING

Cases were infants with an oral cleft ascertained through three comprehensive treatment centers, with additional ascertainment through a registry of birth defects maintained by the Maryland Health Department. Controls were healthy infants. Medical history information on infants and mothers were collected, along with DNA samples.

PATIENTS, PARTICIPANTS

Among 286 cases contacted (72% ascertainment), there were 192 nonsyndromic isolated oral clefts (106 M; 86 F) available for this case-control study.

MAIN OUTCOME MEASURES

The largest group of 149 Caucasian nonsyndromic cases and 86 controls was used to test for association with maternal smoking and genotype at the Taq1 polymorphism in TGFA.

RESULTS

While this modest sample had limited statistical power to detect gene-environment interaction, there was a significant marginal increase in risk of having an oral cleft if the mother smoked (odds ratio = 1.75, 95% CI = 1.01 to 3.02). We could not demonstrate statistical interaction between maternal smoking and TGFA genotype in this study, however, and the observed increase in the C2 allele among cases was not statistically significant.

CONCLUSIONS

We could not confirm either the reported association between oral clefts and TGFA genotype or its interaction with maternal smoking. However, these data do show an increased risk if the mother smoked during pregnancy, and this effect was greatest among infants with a bilateral cleft and no close family history of clefts.

Revisiting the factor structure for positive and negative symptoms: evidence from a large heterogeneous group of psychiatric patients

OBJECTIVE

The factor structures of individual positive and negative symptoms as well as global ratings were examined in a diagnostically heterogeneous group of subjects.

METHOD

Subjects were identified through a clinical and family study of patients with major psychoses at a VA medical center and evaluated with the Scale for the Assessment of Negative Symptoms and the Scale for the Assessment of Positive Symptoms. For the examination of global-level factor structures (N = 630), both principal-component analysis and factor analysis with orthogonal rotation were used. Factor analysis was used for the examination of item-level factor structures as well (N = 549).

RESULTS

The principal-component analysis of global ratings revealed three factors: negative symptoms, positive symptoms, and disorganization. The factor analysis of global ratings revealed a negative symptom factor and a positive symptom factor. The item-level factor analysis revealed two negative symptom factors (diminished expression and disordered relating), two positive symptom factors (bizarre delusions and auditory hallucinations), and a disorganization factor.

CONCLUSIONS

The generation of additional meaningful factors at the item level suggests that important information about symptoms is lost when only global ratings are viewed. Future work should explore clinical and pathological correlates of the more differentiated item-level symptom dimensions.

Chronic bronchitis in textile workers

BACKGROUND

Exposure to cotton is known to produce a specific occupational disease known as byssinosis. A large population of textile workers was investigated to determine whether such exposure was also associated with chronic bronchitis once other possible aetiological factors had been accounted for.

METHODS

A total of 2991 workers were investigated for the presence of symptoms compatible with chronic bronchitis. An MRC adapted respiratory questionnaire and MRC definition of chronic bronchitis were used for diagnostic labelling. Current and lifetime exposure to dust was estimated by personal and work area sampling, and the use of records of retrospective dust levels previously measured over the preceding 10 years. Airborne endotoxin exposure was measured using a quantitative turbidometric assay. Lung function tests were performed to measure forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). A control group of workers exposed to man-made fibre textiles was identified. The comparative prevalence of chronic bronchitis in the two populations was assessed, allowing for sex, age, smoking habit, and ethnic origin. Two case referent studies were also performed; cases of chronic bronchitis were separately matched with controls from the cotton and control populations to determine the effect of the symptomatic state on lung function.

RESULTS

After controlling for smoking (pack years), workers in a cotton environment were significantly more likely to suffer from chronic bronchitis and this was most marked in workers over 45 years of age (odds ratio 2.51 (CI 1.3 to 4.9); p < 0.01). Regression analysis of all possible influencing parameters showed that cumulative exposure to cotton dust was significantly associated with chronic bronchitis after the effects of age, sex, smoking, and ethnic group were accounted for (p < 0.0005). In the intra-cotton population case control study a diagnosis of chronic bronchitis was associated with a small decrement in lung function compared with controls: percentage predicted FEV1 in cases 81.4% (95% CI 78.3 to 84.6), controls 86.7% (84.9 to 88.5); FVC in cases 89.9% (95% CI 87.0 to 92.9), controls 94.6% (92.8 to 96.4). After controlling for cumulative past exposure and pack years of smoking the effect of the diagnostic state remained significant for both FEV1 (p < 0.01) and FVC (p < 0.05).

CONCLUSIONS

Chronic bronchitis is more prevalent in cotton workers than in those working with man-made fibre and exposure is additive to the effect of smoking. The diagnosis of chronic bronchitis is associated with a small but significant decrement in lung function.

Free ricin A chain reaches an early compartment of the secretory pathway before it enters the cytosol

During the intoxication of mammalian cells by ricin, the catalytically active A chain must cross the membrane of an intracellular compartment in order to reach its ribosomal substrates in the cytosol. The actual site of ricin A chain translocation is unclear, and conflicting views hold that it enters the cytosol from endosomes or from an early compartment of the secretory pathway, possibly the lumen of the endoplasmic reticulum. Here we show that treating cells with brefeldin A, or transiently overexpressing mutant GTPases known to inhibit biochemical complexes mediating anterograde and retrograde transport between the endoplasmic reticulum and the Golgi complex, protected cells from intoxication by free ricin A chain. These data indicate that ricin A chain, either free or as part of intact ricin, reaches an early compartment of the secretory pathway before translocation into the cytosol occurs.

Reconstruction of radionuclide releases from the Hanford Site, 1944-1972

Historic releases of key radionuclides were estimated as a first step in determining the radiation doses that resulted from Hanford Site operations. The Hanford Site was built in southcentral Washington State during World War II to provide plutonium for the U.S. nuclear weapons program. As part of the Hanford Environmental Dose Reconstruction (HEDR) Project, releases to the Columbia River of 24Na, 32P, 46Sc, 51Cr, 56Mn, 65Zn, 72Ga, 76As, 90Y, 131I, 239Np, and nonvolatile gross beta activity from operation of eight Hanford single-pass production reactors were estimated. Releases of 90Sr, 103Ru, 106Ru, 131I, 144Ce, and 239Pu to the atmosphere from operation of chemical separation facilities were also estimated. These radionuclides and the atmospheric and Columbia River pathways were selected for study because scoping studies showed them to be the largest contributors to dose from Hanford operations. The highest doses resulted from releases to the atmosphere of 131I from chemical separations plants in the pre-1950 period. Prior to 1950, the technology for limiting iodine releases had not been developed. Hence, a very detailed reconstruction of the hourly 131I release history was achieved for 1944-1949 using Monte Carlo methods. Atmospheric releases of the other radionuclides were estimated on a monthly basis for 1944-1972 using deterministic calculations. Monthly releases to the Columbia River for 1944-1971 were based on Monte Carlo methods.

Mortality among patients with schizophrenia

Results from a 40-year followup study of psychotic patients are presented to illustrate some of the major findings and unanswered questions about excess mortality in schizophrenia and to suggest analytical approaches that take full account of the potential effects of sample heterogeneity. In this study, hospital-diagnosed schizophrenia patients were at increased mortality risk whether or not they met research criteria for schizophrenia. In addition, mortality outcomes of several major diagnostic groups were similar despite substantial clinical and demographic differences between the groups at baseline. These results suggest that both diagnosis-specific and nondiagnostic factors are needed to account for excess mortality in patients with major psychiatric disorders. The issue of heterogeneity is also crucial for the clinical purposes of predicting and ultimately reducing the mortality risk of psychiatric patients, for example, in delineating profiles of high-risk patients who are not necessarily typical of other patients with the same diagnosis.

Catalytic and cytotoxic activities of recombinant ricin A chain mutants with charged residues added at the carboxyl terminus

Ricin A chain (RTA) mutants which had been modified by the addition of three lysine residues, three lysines and an alanine, or six histidine residues at the carboxyl terminus were expressed in Escherichia coli. The recombinant proteins were purified to homogeneity by ion-exchange chromatography on CM-Sepharose CL-6B. The 28S ribosomal RNA N-glycosidase activities of the three RTA mutants were indistinguishable from each other and from the activity of wild-type recombinant RTA. The RTA mutants were not impaired, compared with wild-type RTA, in their ability to reassociate with ricin B chain to form ricin holotoxin. Holotoxins containing mutant RTAs were as readily dissociated into subunits under reducing conditions as native holotoxin, and the RTA mutants were indistinguishable from wild-type RTA in the extent of their interaction with biological membranes. Ricin holotoxins containing the RTA mutants were, however, less cytotoxic to Vero cells than ricin containing wild-type RTA. At equivalent concentrations, a time course assay showed that holotoxin containing the mutant RTAs took longer to kill target cells than that containing wild-type recombinant RTA, suggesting that the mutant forms of RTA are less efficiently processed or translocated across an intracellular membrane than is wild-type RTA.

Point mutations in the hydrophobic C-terminal region of ricin A chain indicate that Pro250 plays a key role in membrane translocation

A series of mutations have been made in the carboxyl terminus of ricin A chain, centred on the hydrophobic region between amino acid residues Val245 and Val256. The mutant ricin A chains were expressed to a high level in an Escherichia coli system and the proteins purified to homogeneity. The enzymic activity of each of these A chain molecules was tested on rabbit reticulocyte ribosomes; in all cases, the activities were found to be comparable to wild-type recombinant ricin A chain. Following reassociation of these A chains to ricin B chain, Vero cells were challenged with these holotoxins and the cytotoxicities determined. Mutant ricin A chain with Ile247-->Ala was unable to reassociate and form holotoxin, indicating the importance of this residue in the interaction with ricin B chain. Mutant ricin A chain with Pro250-->Ala readily reassociated with ricin B chain, forming holotoxin with a 170-fold reduction in cytotoxicity to Vero cells. Other mutations in this region also produced A chain proteins which gave marked reductions in holotoxin cytotoxicity. We propose therefore that the C-terminal hydrophobic region of ricin A chain may be involved in membrane interactions prior to the translocation of this subunit into the cytosol, and that Pro250 plays a key role in one or both of these steps.

Ricin cytotoxicity is sensitive to recycling between the endoplasmic reticulum and the Golgi complex

Cytotoxic proteins that kill mammalian cells by catalytically inhibiting protein synthesis must enter the cytosol in order to reach their substrates. With the exception of diphtheria toxin, which enters the cytosol from acidified endosomes, the intracellular site of translocation of other toxins including ricin, Escherichia coli Shiga-like toxin-1, and Pseudomonas exotoxin A is likely to involve early compartments of the secretory pathway. We have used a molecular approach to identify the site and mechanism of toxin delivery to the cytosol by transiently expressing mutant GTPases that inhibit the assembly of biochemical complexes mediating anterograde and retrograde transport in the exocytic and endocytic pathways. The results provide evidence to suggest that receptors actively recycling between the endoplasmic reticulum and terminal Golgi compartments are essential for toxin translocation to the cytosol from the endoplasmic reticulum. The rapid kinetics of intoxication demonstrate a substantial level of bidirectional membrane flow and sorting through the early secretory pathway.

Mathematical models of complex dose-response relationships: implications for experimental design in psychopharmacologic research

We develop a mathematical model to account for the complex relationship between drug dose and clinical response in psychopharmacologic research. The model specifies relationships among drug dose, drug bioavailability, pharmacokinetic factors, course moderators, clinical response and the heterogeneity of the disorder, and allows for the derivation of results that have implications for experimental design in psychopharmacologic research. These results form the basis for computer simulations which indicate that random assignment to two fixed doses is more powerful and less sensitive to heterogeneity than assignment to clinically determined doses. Fixed dose designs, however, tend to overestimate the magnitude of drug bioavailability-clinical response relationships. Clinically determined dose designs are useful in some experimental situations; their effectiveness is enhanced by systematically reducing the clinically determined dose. Larger dose reductions improve the ability to detect bioavailability-clinical response relationships.

The role of gender in identifying subtypes of schizophrenia: a latent class analytic approach

Past literature suggests that schizophrenic men and women may be at different risks for developing different subtypes of schizophrenia. This hypothesis was tested using data from the well-known retrospective cohort family studies, the Iowa 500 and the Iowa non-500. The sample consisted of 171 male and 161 female DSM-III schizophrenic patients and 713 of their first-degree relatives. First, bivariate tests for gender differences were conducted regarding family morbidity, age of onset, premorbid history, season of birth, and expression of deficit and affective symptoms. Restricted maximum likelihood latent class analysis was then used to test whether there was a subgroup of schizophrenic men who were more likely to have a low familial risk for schizophrenia or schizophrenia spectrum disorders, deficit symptoms, poor premorbid history, and birth in the winter months, suggesting possible early environmental insults, compared to schizophrenic women. Results showed that although men were more likely to meet these criteria, women also met them, thus suggesting gender differences in the prevalence of the subtype. Schizophrenic women were more likely to express a form of the illness characterized by dysphoria, persecutory delusions, and a higher family morbidity risk for schizophrenia than schizophrenic men. Results for spectrum disorders among relatives were equivocal with regard to gender.

Outcome studies of schizoaffective disorders

Outcome studies of schizoaffective disorder have taught us much about the long-term consequences of the syndrome, and they have provided some indication of the potential usefulness of maintaining "schizoaffective disorder" as a diagnostic category separate from schizophrenia and major affective disorder. In a review of outcome studies that compared schizoaffective patients to schizophrenic or affective patients, we found consistent results despite wide variations in diagnostic criteria, length of followup, and demographic characteristics. Global measures of outcome show that schizophrenic patients are more impaired than schizoaffective patients, who in turn are more impaired than affective patients. However, studies of specific outcome domains such as symptomatology, social functioning, and occupational functioning indicate that schizoaffective disorder is heterogeneous and that subtyping by polarity (e.g., schizoaffective-manic vs. schizoaffective-depressed) accounts for some of this variance. The consistency of these findings in the face of methodological variability suggests that it would be premature to classify schizoaffective patients with schizophrenia or affective disorder, but also that strict diagnostic criteria for schizoaffective disorder are at best preliminary and need to be thoroughly validated.

Beta-adrenoceptor blockade and suxamethonium-induced rise in plasma potassium

The effects of beta-adrenergic blockade on the suxamethonium-induced rise in arterial plasma potassium were studied in patients who presented for open heart surgery. No potentiation of the immediate rise in plasma potassium was observed.

Cardiac surgery in Jehovah's witnesses. A review of 36 cases

Between January 1971 and January 1985, 31 Jehovah's witnesses underwent 24 bypass and 12 non-bypass cardiothoracic operations at the National Heart Hospital. Fifty-eight% of the group were under 16 years of age. There was one death in the non-bypass group unrelated to blood loss. Six deaths occurred in the bypass group. In one of these, blood loss contributed to the cause of death and in two patients, blood loss was directly related to the cause of death. The anaesthetic management of Jehovah's witnesses undergoing cardiac surgery is discussed.

Ten-year follow-up of drug abusers with acute or chronic psychosis

To assess whether long-term outcome of former drug abuse patients who had psychotic symptoms was related to duration of psychosis before hospitalization, the authors rated the psychiatric, occupational, and residential outcome of 101 former drug abuse patients based on interviews conducted ten years after their admission to a psychiatric hospital. At admission, 45 had had psychotic symptoms for six months or more; 26 had had psychotic symptoms for less than six months; and 30 had not been psychotic. Seventy-one former psychiatric patients who had had a psychotic illness but had not abused drugs were also interviewed and rated. Drug abusers with chronic psychosis had significantly worse psychiatric outcome than the other drug abusers and significantly worse occupational outcome than acutely psychotic drug abusers. The authors conclude that drug abusers with chronic psychotic symptoms are a distinct subgroup of drug abusers who suffer from major psychotic illness.

Characterization of chemical waste site contamination and determination of its extent using bioassays

Bioassays were used in a three-phase research project to (a) assess the comparative sensitivity of test organisms to known classes of chemicals, (b) determine if the chemical components in field soil and water samples of unknown chemical composition could be inferred from laboratory studies using pure chemicals and (c) investigate kriging (a relatively new statistical "mapping" technique) and bioassays as methods to define the areal extent of chemical contamination. The algal assay generally was most sensitive to samples of pure chemicals, soil elutriates and water from eight sites with known chemical contamination. Bioassays of nine samples of unknown chemical composition from the Rocky Mountain Arsenal site showed that a lettuce seed soil contact phytoassay was most sensitive. Preliminary evidence suggests that bioassays might be a useful tool in broadly identifying classes of toxic components of contaminated soil. Nearly pure formulations of insecticides and herbicides were less toxic than were their counterpart commercial formulations. This finding indicates that chemical analysis alone may fail to correctly rate the severity of possible environmental toxicity. Finally, we demonstrate that the lettuce seed phytoassay and kriging techniques can be used to map contamination in a portion of the Rocky Mountain Arsenal site and aid in cleanup decisions.

A family study of sex differences in the diagnosis of atypical schizophrenia

It has been hypothesized that women are more likely than men to have atypical schizophrenia. Among 984 relatives of patients with typical and atypical schizophrenia, the odds of having atypical schizophrenia did not differ by sex.

Are there sex differences in the long-term outcome of schizophrenia? Comparisons with mania, depression, and surgical controls

Female schizophrenics have been reported to have a better prognosis than male schizophrenics. However, earlier reports rarely used either operational criteria for schizophrenia or appropriate comparison groups. Using data collected as part of a long-term follow-up and family study, the authors examined outcome by sex of 186 schizophrenics, 212 depressives, 86 manics, and 145 surgical controls. When the authors controlled for differences in the age and sex distributions of the diagnostic groups, sex did not make a significant contribution to the explanation of outcome differences between diagnoses or within diagnoses. Examination of outcomes within diagnoses revealed only a nonsignificant trend for female manics to have a better long-term outcome than male manics.

Contamination of internal jugular cannulae

137 internal jugular vein cannulae from 113 patients undergoing open heart surgery were cultured using standard broth culture and a semiquantitative culture technique. 60 of the cannulae were placed using an aseptic technique and 77 using a standard non sterile technique. Significant contamination was found in 18.3% of the cannulae in the aseptic group and 15.6% in the standard group. The contaminating organism was Staphylococcus epidermidis in 87.1% of cases. No advantage in using an aseptic technique of cannula insertion was demonstrated. It was concluded that the major source of contamination was elsewhere.

Kriging for estimating spatial pattern of contaminants: Potential and problems

This paper discusses and illustrates the use of kriging techniques for estimating the spatial pattern of contaminants in environmental media, particularly soil. The assumptions underlying kriging are reviewed as are some advantages and disadvantages of the method. Lognormal kriging (kriging applied to logarithmic-transformed data) is illustrated using a set of radionuclide soil concentrations at a nuclear testing area on the Nevada Test Site. This example shows how lognormal kriging can be used to estimate average concentrations at points or for blocks of land, concentration contours over space, confidence bands about these contours, and radionuclide inventory in soil. The validity of kriging estimates depends on the accurate estimation and modeling of the spatial correlation structure of the phenomenon. Accuracy is especially important when lognormal kriging is used and estimates of means and their standard deviations are required in the original, untransformed scale. This paper illustrates the bias that can result when a changing correlation structure over space is ignored.