Examining the quality of work-life of paramedics in northern Ontario, Canada: A cross-sectional study

BACKGROUND: Paramedics are exposed to multiple stressors in the workplace. They are more likely to develop occupational-related stress conditions compared to other occupations. This study focused on understanding the factors affecting QoWL of paramedics in northern Ontario, Canada; a particular focus was on understanding the personal and organizational factors, such as practicing community paramedicine (CP), which may be associated with Quality of Work Life (QoWL). METHODS: Paramedic QoWL was assessed using an online survey that was distributed to approximately 879 paramedics across northern Ontario. The survey included the 23-Item Work- Related Quality of Work Life Scale. Data analysis involved linear regressions with nine predictor variables deemed to be related to QoWL for paramedics with QoWL and its six subscales as dependent variables. Multiple linear regressions were used to assess the personal and organizational factors, such as practicing of CP, which predicted QoWL. RESULTS: One hundred and ninety-seven paramedics completed the questionnaire. Overall, the mean QoWL score of all paramedic participants was 73.99, and this average compared to relevant published norms for other occupations. Factors that were most associated with higher QoWL were, experience practicing CP (p < 0.05), number of sick days/year (p < 0.01), and higher self- rated mental health (p < 0.001). CONCLUSIONS: Higher paramedic QoWL appears to be associated with many factors such as number of sick days per year, self-rated mental health, and participation in CP. EMS organizations should consider establishing necessary workplace health promotion strategies that are targeted at improving QoWL for paramedics.

676 OPTIMISING ENGAGEMENT OF OLDER ADULTS IN AN ONLINE PHYSICAL ACTIVITY PROGRAMME TO IMPROVE COGNITION: A QUALITATIVE STUDY

Introduction

Maintaining physical activity is a modifiable risk factor for cognitive impairment. However, despite numerous public health interventions, older adults do not routinely meet activity guidelines. Online interventions offer an alternative means of engaging with this group. The role of an online intervention holds particular value in the context of a global pandemic where people have become accustomed to digital living. Furthermore, such an intervention negates barriers frequently faced by older adults in attending face to face interventions, whilst providing an economically viable option. This study explored the factors which maximise engagement in an online programme to promote physical activity.

Methods

A qualitative study was conducted with adults aged 50 and over. Individual were recruited through the online UK PROTECT study cohort. Four focus groups (n = 21) examined key contributors to engagement with a digital programme to promote physical activity. Iterative Categorization was utilised to identify categories and themes of the focus group data. Semi-structured interviews were subsequently conducted (n = 5) whereby participants were asked to comment on a concept-stage online intervention.

Results

Four major themes emerged from the focus group data: interaction at the fore, incentives as foundations, fitting around me and identity is critical. The semi-structured interviews identified further key areas of programme acceptability and specific needs for enhancing engagement.

Conclusions

Older adults are open to using digital physical activity programmes, with the recent COVID-19 pandemic driving an appetite for online delivery. Any intervention must be tailored to individual usability preferences and take account of the fitness, health and lifestyle needs specific to older adults. Furthermore, the conceptual-stage intervention used in this study was found to be acceptable, with key changes needed to maximise engagement.

Conventional oxygen therapy versus CPAP as a ceiling of care in ward-based patients with COVID-19: a multi-centre cohort evaluation

BACKGROUND

Continuous positive airway pressure (CPAP) therapy is commonly used for respiratory failure due to severe COVID-19 pneumonitis, including in patients deemed not likely to benefit from invasive mechanical ventilation (nIMV). Little evidence exists demonstrating superiority over conventional oxygen therapy, whilst ward-level delivery of CPAP presents practical challenges. We sought to compare clinical outcomes of oxygen therapy versus CPAP therapy in patients with COVID-19 who were nIMV.

METHODS

This retrospective multi-centre cohort evaluation included patients diagnosed with COVID-19 who were nIMV, had a treatment escalation plan of ward-level care and clinical frailty scale ≤ 6. Recruitment occurred during the first two waves of the UK COVID-19 pandemic in 2020; from 1^st March to May 31^st, and from 1^st September to 31^st December. Patients given CPAP were compared to patients receiving oxygen therapy that required FiO₂ ≥0_.4 for more than 12 hours at hospitals not providing ward-level CPAP. Logistic regression modelling was performed to compare 30-day mortality between treatment groups, accounting for important confounders and within-hospital clustering.

FINDINGS

Seven hospitals provided data for 479 patients during the UK COVID-19 pandemic in 2020. Overall 30-day mortality was 75.6% in the oxygen group (186/246 patients) and 77.7% in the CPAP group (181/233 patients). A lack of evidence for a treatment effect persisted in the adjusted model (adjusted odds ratio 0.84 95% CI 0.57-1.23, p=0.37). 49.8% of patients receiving CPAP-therapy (118/237) chose to discontinue it.

INTERPRETATION

No survival difference was found between using oxygen alone or CPAP to treat patients with severe COVID-19 who were nIMV. A high patient-initiated discontinuation rate for CPAP suggests a significant treatment burden. Further reflection is warranted on the current treatment guidance and widespread application of CPAP in this setting.

FUNDING

L Pearmain is supported by the MRC (MR/R00191X/1). TW Felton is supported by the NIHR Manchester Biomedical Research Centre.

132 Physical Function Comparison of Acutely Unwell COVID-Negative Older Adults Pre-Pandemic and Through-Pandemic; “Covid-Protected”

Introduction

The risk of severe morbidity after COVID-19 infection is high in older adults (Lithander et al, 2020). Subsequent responsive UK Government guidance for older adults included self-isolation during the pandemic. It is therefore hypothesised that during the pandemic older adults are inadvertently deconditioned due to iatrogenic factors such as inactivity, social isolation, hospital-avoidance and malnutrition, and present with reduced resilience to illness and lower levels of function. The OPU continued to admit COVID-negative, or recently termed “COVID-protected”, patients throughout the pandemic. Data captured prior to, and during the COVID-19 pandemic has been compared to explore the implications on older adults, and elicit whether they are protected from the consequences of the pandemic?

Method

Demographic and physical function data (average 6 m gait-speed, Elderly Mobility Scale) were captured pre- and through-pandemic for all patients admitted to a COVID-negative OPU ward over a one month period. Ethical review was provided through local Trust governance process.

Results

Pre-pandemic 2019 (n = 67, mean(±SD) age 82.7(±8.2) years, 61%, hospital length-of-stay (LOS) 7.9(±7.3) days, hospital mortality-rate 7.2%) and through-pandemic 2020 (n = 73, 83.1(±8.3) years, 59%♀, LOS 9.0(±9.1) days, hospital mortality-rate 7.5%) data were captured during July 2019 and May 2020 respectively. There were no between-group differences in age [t(−.313) = 138, p = 0.755], gender [X², 1 df, p = 0.782], LOS [t(0.78) = 134, p = 0.44], or hospital mortality-rate [X² 1 df, p = 0.96]. Through-pandemic patients had a significantly slower 6 m gait-speed (0.11(±0.05) m.s-1) than pre-pandemic (0.16(±0.24) m.s-1); [t(2.74) = 93, p = 0.007] and lower median (IQR) Elderly Mobility Scale (4(6 IQR) vs 9 (12 IQR) [u = 866, p = 0.015]).

Conclusion

Our data indicates this relatively short period of self-isolation might have significant implications on the physical function of older adults. The likely mechanism is iatrogenic deconditioning. Critical Public Health and policy responses are required to mitigate these unforeseen risks by deploying prehabilitative counter-measures and accurately targeted hospital and community rehabilitation.

The effect of DAFNE education, continuous subcutaneous insulin infusion, or both in a population with type 1 diabetes in Scotland

AIM

To investigate the effect of DAFNE and continuous subcutaneous insulin infusion in clinical practice.

METHODS

Within NHS Lothian, continuous subcutaneous insulin infusion started in 2004 and DAFNE education began in 2006. We extracted anonymized data from the national database for all those aged > 18 years with type 1 diabetes having a Dose Adjustment For Normal Eating course or continuous subcutaneous insulin infusion start date (n = 4617).

RESULTS

In total, 956 persons received DAFNE education, and 505 had received an insulin pump, 208 of whom had DAFNE education followed by insulin pump. Mean (SD) HbA_1c before DAFNE education was 68 (15) mmol/mol (8.4% [1.4%]) and 66 (13) mmol/mol (8.2% [1.2%]) before continuous subcutaneous insulin infusion. In the year following DAFNE education, the mean fall in within-person HbA_1c was 3.8 mmol/mol (95% CI 4.0 to 3.4; 0.3% [0.4% to 0.3%]). Those with the poorest control (HbA_1c ≥ 85 mmol/mol [9.9%]) experienced the largest decline (15.7 mmol/mol [1.4%]). Those in the lowest HbA_1c band at initiation (< 53 mmol/mmol [7.0%]) experienced a rise. In the year following continuous subcutaneous insulin infusion initiation there was a mean fall in within-person HbA_1c of 6.6 mmol/mol (6.8 to 6.4; 0.6% [0.6% to 0.6%]). In those with the poorest control (HbA_1c ≥ 85 mmol/mol [9.9%]), the mean fall in HbA_1c was 22.2 mmol/mol (23 to 21; 2.0% [2.1% to 1.9%]). Continuous subcutaneous insulin infusion effectiveness was not different with or without DAFNE education. The effects of both interventions were sustained over 5 years.

CONCLUSIONS

Both DAFNE education and insulin pump therapy had the greatest effect on HbA_1c in those with higher baseline values. There was little difference to attained HbA_1c when Dose Adjustment For Normal Eating education was introduced before insulin pump therapy.

Antibacterials dispensed in the community comprise 85%-95% of total human antibacterial consumption

WHAT IS KNOWN AND OBJECTIVE

Interventions intended to slow the emergence and spread of antibacterial resistance through enhanced antimicrobial stewardship will be more effective if informed by an accurate knowledge of current patterns of antibacterial consumption. For example, knowledge of the relative magnitude of community antibacterial consumption in relation to hospital antibacterial consumption within each nation or region should help guide decisions about the relative importance of community and hospital antimicrobial stewardship programmes. It is commonly stated that community antibacterial consumption comprises approximately 80% of total national antibacterial consumption. We aimed to determine this proportion across a large range of nations.

METHODS

We measured community and hospital antibacterial consumption in New Zealand during 2015, from both reimbursement and purchase data, and compared the New Zealand data with those reported from a large range of other nations during similar time periods.

RESULTS AND DISCUSSION

Community antibacterial consumption comprised approximately 85%-95% of total antibacterial consumption in all nations for which data were available, and in New Zealand comprised a higher proportion than in any other nation. The proportion of total antibacterial consumption comprised by community consumption was significantly higher in countries with relatively high levels of total antibacterial consumption than in countries with relatively low levels of total antibacterial consumption.

WHAT IS NEW AND CONCLUSION

The high proportion of total antibacterial consumption comprised by community antibacterial consumption suggests devoting particular attention to improved community antimicrobial stewardship. These results suggest that improving antimicrobial stewardship in the community may provide greater overall benefits in combating antibacterial resistance than improving antimicrobial stewardship in hospitals.

Cytomegalovirus infection is associated with an increase in systolic blood pressure in older individuals

BACKGROUND

Cytomegalovirus (CMV) is a chronic infection that is widely distributed in the population. CMV infects a range of tissues, including endothelium, and viral replication is suppressed by the host immune system. Infection is associated with increased risk of mortality from vascular disease in older people, but the mechanisms behind this have not been determined.

AIM

We investigated the association between CMV infection and cardiovascular phenotype in a cohort of healthy elderly donors.

DESIGN

CMV serostatus and cardiovascular parameters were determined in the Lothian Birth cohort, which comprises 1091 individuals aged 70 years in whom many environmental, biochemical and radiological correlates of vascular function have been determined.

METHODS

CMV serostatus was determined by enzyme-linked immunosorbant assay and correlated with a range of biochemical and phenotypic measures.

RESULTS

Sixty-five percent of participants were CMV seropositive, which indicates chronic infection. The mean sitting systolic blood pressure (SBP) was 149.2 mmHg in CMV seropositive individuals compared with 146.2 mmHg in CMV seronegative subjects (SD 18.7 vs. 19.7; P < 0.017). This association between CMV infection and SBP was not attenuated after adjustment for a wide range of biological and socio-economic factors.

CONCLUSIONS

These data show that CMV infection is associated with an increase in SBP in individuals at age 70 years. The magnitude is comparable to environmental variables such as obesity, diabetes or high salt intake. This is the first evidence to show that a chronic infection may be an important determinant of blood pressure and could have significant implications for the future management of hypertension.

Comparison of the Band Gap of Porous Silicon as Measured by Photoelectron Spectroscopy and Photoluminescence

The peak energy of the room temperature photoluminescence of porous silicon is compared with the bandgap determined from photoelectron spectroscopy measurements for a series of porous silicon samples prepared under different conditions. The photoluminescence bandgap is found to be smaller than the photoelectron spectroscopy bandgap, but exhibits the same trend with preparation conditions. The width of both the photoluminescence spectrum and the L-absorption edge increases when the current density during the preparation is increased or the sample is allowed to soak in HF after preparation.

Immunodeficiency in ataxia telangiectasia is correlated strongly with the presence of two null mutations in the ataxia telangiectasia mutated gene

Immunodeficiency affects over half of all patients with ataxia telangiectasia (A-T) and when present can contribute significantly to morbidity and mortality. A retrospective review of clinical history, immunological findings, ataxia telangiectasia mutated (ATM) enzyme activity and ATM mutation type was conducted on 80 consecutive patients attending the National Clinic for Ataxia Telangiectasia, Nottingham, UK between 1994 and 2006. The aim was to characterize the immunodeficiency in A-T and determine its relationship to the ATM mutations present. Sixty-one patients had mutations resulting in complete loss of ATM kinase activity (group A) and 19 patients had leaky splice or missense mutations resulting in residual kinase activity (group B). There was a significantly higher proportion of patients with recurrent sinopulmonary infections in group A compared with group B (31 of 61 versus four of 19 P = 0.03) and a greater need for prophylactic antibiotics (30 of 61 versus one of 19 P = 0.001). Comparing group A with group B patients, 25 of 46 had undetectable/low immunoglobulin A (IgA) levels compared with none of 19; T cell lymphopenia was found in 28 of 56 compared with one of 18 and B cell lymphopenia in 35 of 55 compared with four of 18 patients (P = 0.00004, 0.001 and 0.003 respectively). Low IgG2 subclass levels and low levels of antibodies to pneumococcal polysaccharide were more common in group A than group B (16 of 27 versus one of 11 P = 0.01; 34/43 versus six of 17 P = 0.002) patients. Ig replacement therapy was required in 10 (12.5%) of the whole cohort, all in group A. In conclusion, A-T patients with no ATM kinase activity had a markedly more severe immunological phenotype than those expressing low levels of ATM activity.

Grand Rounds at the British Hypertension Society: renal artery stenosis

Renal artery angioplasty for renovascular hypertension is a controversial subject with considerable data but few certainties. This article is a summary of the Grand Round on Renovascular Hypertension held at the British Hypertension Society Annual Conference in September 2006.

High-risk febrile neutropenia in Auckland 2003-2004: the influence of the microbiology laboratory on patient treatment and the use of pathogen-specific therapy

BACKGROUND

International guidelines recommend routine microbiological assessment of patients with febrile neutropenia, but do not recommend a change from broad-spectrum antibiotic therapy to pathogen-specific therapy when a clinically relevant organism has been isolated. The aim of the study was to determine the aetiology of febrile neutropenia in adult haematology patients at Auckland City Hospital, to document the changes in treatment made following isolation of a clinically relevant organism and to assess adverse outcomes in any patient who received pathogen-specific therapy after a positive culture result.

METHODS

The results of all microbiological tests together with antibiotic therapy were recorded from consecutive patients with fever and a neutrophil count <0.5 x 10(9)/L over 1 year beginning in May 2003.

RESULTS

One thousand one hundred and ninety-six specimens were collected from 81 patients during 116 episodes of febrile neutropenia. A pathogen was isolated from blood cultures in 40 episodes: Gram-positive cocci accounted for 46% of isolates and Gram-negative bacilli for 35%. Isolation of a pathogen from blood cultures resulted in a change of treatment in 25 of 40 (62.5%, 95%CI 46-77%) episodes. In 12 of these episodes, antibiotic therapy was optimized to a single pathogen-specific agent. No adverse events or subsequent changes in antibiotic therapy occurred in any of these 12 patients. Isolation of a pathogen from specimens other than blood seldom led to a change in therapy.

CONCLUSION

Isolation of a pathogen from blood cultures often allows antibiotic therapy to be simplified to a pathogen-specific regimen. Further study of this approach is warranted.

Perspective: determinants of the severity of poliovirus outbreaks in the post eradication era

The potential consequences of the reintroduction of poliovirus in the post-eradication era range from trivial (no or self-limited transmission and no clinical cases) to very serious (return of continued transmission of polioviruses and abandonment of the poliomyelitis eradication goal). This paper summarises the key determinants of such outcomes and identifies factors relating to infection surveillance, to vaccination policies at the time of OPV cessation and beyond, and to the still-unknown implications of these policies for infection transmission in environments with poor sanitation, as particularly important. Explicit consideration of these issues should encourage studies on the effectiveness of IPV vaccines in reducing poliovirus transmission in tropical environments, and should influence the location and containment requirements of facilities for vaccine production and storage, and for poliovirus-related research, in the era after cessation of OPV.

Use of a preprinted sticker to improve the prescribing of prophylactic antibiotics for hip fracture surgery

PROBLEM

Antibiotic prophylaxis has been shown to reduce the number of postoperative infections following surgery for hip fracture. At Auckland Hospital the policy for antibiotic prophylaxis for hip fracture surgery is for the patient to receive the first dose of antibiotic at the induction of anaesthesia followed by two more doses at 8 hour intervals. A previous audit found that patients often received too many doses of antibiotic. A retrospective audit was performed of 100 patients undergoing surgery for a hip fracture. The primary problem was over-prescribing; 68 patients (68%) received more than three doses. The number of patients who received three doses according to the guidelines was 29 (29%, 95% CI 21 to 40).

SETTING

Auckland Hospital which provides acute orthopaedic services for a population of 500,000.

STRATEGY FOR CHANGE

A sticker was introduced with the prescription printed on it. The sticker was applied to the medication chart by the anaesthetist when the initial dose of antibiotic was given. Charts of a further 100 patients were reviewed after the introduction of the sticker and compared with those from another hospital in Auckland where the sticker was not used.

EFFECTS OF CHANGE

The number of patients who received three doses, in accordance with the guidelines, improved to 74 (74%, 95% CI 64 to 82, p<0.001). These changes were observed even though the sticker was only used in 44 patients (44%, 95% CI 34 to 54). At the other hospital the number of patients who received three doses was 10 (20%, 95% CI 10 to 42) and 13 (26%, 95% CI 15 to 40, p = 0.37) for the same two periods.

LESSONS LEARNT

The use of a preprinted sticker is a simple intervention which improves the use of antibiotic prophylaxis at the time of surgery. This improvement occurred even though the sticker was used in slightly fewer than half the cases.

Use of a preprinted sticker to improve the prescribing of prophylactic antibiotics for hip fracture surgery

PROBLEM

Antibiotic prophylaxis has been shown to reduce the number of postoperative infections following surgery for hip fracture. At Auckland Hospital the policy for antibiotic prophylaxis for hip fracture surgery is for the patient to receive the first dose of antibiotic at the induction of anaesthesia followed by two more doses at 8 hour intervals. A previous audit found that patients often received too many doses of antibiotic. A retrospective audit was performed of 100 patients undergoing surgery for a hip fracture. The primary problem was over-prescribing; 68 patients (68%) received more than three doses. The number of patients who received three doses according to the guidelines was 29 (29%, 95% CI 21 to 40).

SETTING

Auckland Hospital which provides acute orthopaedic services for a population of 500,000.

STRATEGY FOR CHANGE

A sticker was introduced with the prescription printed on it. The sticker was applied to the medication chart by the anaesthetist when the initial dose of antibiotic was given. Charts of a further 100 patients were reviewed after the introduction of the sticker and compared with those from another hospital in Auckland where the sticker was not used.

EFFECTS OF CHANGE

The number of patients who received three doses, in accordance with the guidelines, improved to 74 (74%, 95% CI 64 to 82, p<0.001). These changes were observed even though the sticker was only used in 44 patients (44%, 95% CI 34 to 54). At the other hospital the number of patients who received three doses was 10 (20%, 95% CI 10 to 42) and 13 (26%, 95% CI 15 to 40, p = 0.37) for the same two periods.

LESSONS LEARNT

The use of a preprinted sticker is a simple intervention which improves the use of antibiotic prophylaxis at the time of surgery. This improvement occurred even though the sticker was used in slightly fewer than half the cases.

Ross River virus transmission, infection, and disease: a cross-disciplinary review

Ross River virus (RRV) is a fascinating, important arbovirus that is endemic and enzootic in Australia and Papua New Guinea and was epidemic in the South Pacific in 1979 and 1980. Infection with RRV may cause disease in humans, typically presenting as peripheral polyarthralgia or arthritis, sometimes with fever and rash. RRV disease notifications in Australia average 5,000 per year. The first well-described outbreak occurred in 1928. During World War II there were more outbreaks, and the name epidemic polyarthritis was applied. During a 1956 outbreak, epidemic polyarthritis was linked serologically to a group A arbovirus (Alphavirus). The virus was subsequently isolated from Aedes vigilax mosquitoes in 1963 and then from epidemic polyarthritis patients. We review the literature on the evolutionary biology of RRV, immune response to infection, pathogenesis, serologic diagnosis, disease manifestations, the extraordinary variety of vertebrate hosts, mosquito vectors, and transmission cycles, antibody prevalence, epidemiology of asymptomatic and symptomatic human infection, infection risks, and public health impact. RRV arthritis is due to joint infection, and treatment is currently based on empirical anti-inflammatory regimens. Further research on pathogenesis may improve understanding of the natural history of this disease and lead to new treatment strategies. The burden of morbidity is considerable, and the virus could spread to other countries. To justify and design preventive programs, we need accurate data on economic costs and better understanding of transmission and behavioral and environmental risks.

A 90-kD phospholipase D from tobacco binds to microtubules and the plasma membrane

The organization of microtubule arrays in the plant cell cortex involves interactions with the plasma membrane, presumably through protein bridges. We have used immunochemistry and monoclonal antibody 6G5 against a candidate bridge protein, a 90-kD tubulin binding protein (p90) from tobacco BY-2 membranes, to characterize the protein and isolate the corresponding gene. Screening an Arabidopsis cDNA expression library with the antibody 6G5 produced a partial clone encoding phospholipase D (PLD), and a full-length gene was obtained by sequencing a corresponding expressed sequence tag clone. The predicted protein of 857 amino acids contains the active sites of a phospholipid-metabolizing enzyme and a Ca(2+)-dependent lipid binding domain and is identical to Arabidopsis PLD delta. Two amino acid sequences obtained by Edman degradation of the tobacco p90 are identical to corresponding segments of a PLD sequence from tobacco. Moreover, immunoprecipitation using the antibody 6G5 and tobacco BY-2 protein extracts gave significant PLD activity, and PLD activity of tobacco BY-2 membrane proteins was enriched 6.7-fold by tubulin-affinity chromatography. In a cosedimentation assay, p90 bound and decorated microtubules. In immunofluorescence microscopy of intact tobacco BY-2 cells or lysed protoplasts, p90 colocalized with cortical microtubules, and taxol-induced microtubule bundling was accompanied by corresponding reorganization of p90. Labeling of p90 remained along the plasma membrane when microtubules were depolymerized, although detergent extraction abolished the labeling. Therefore, p90 is a specialized PLD that associates with membranes and microtubules, possibly conveying hormonal and environmental signals to the microtubule cytoskeleton.

A 90-kD phospholipase D from tobacco binds to microtubules and the plasma membrane

The organization of microtubule arrays in the plant cell cortex involves interactions with the plasma membrane, presumably through protein bridges. We have used immunochemistry and monoclonal antibody 6G5 against a candidate bridge protein, a 90-kD tubulin binding protein (p90) from tobacco BY-2 membranes, to characterize the protein and isolate the corresponding gene. Screening an Arabidopsis cDNA expression library with the antibody 6G5 produced a partial clone encoding phospholipase D (PLD), and a full-length gene was obtained by sequencing a corresponding expressed sequence tag clone. The predicted protein of 857 amino acids contains the active sites of a phospholipid-metabolizing enzyme and a Ca(2+)-dependent lipid binding domain and is identical to Arabidopsis PLD delta. Two amino acid sequences obtained by Edman degradation of the tobacco p90 are identical to corresponding segments of a PLD sequence from tobacco. Moreover, immunoprecipitation using the antibody 6G5 and tobacco BY-2 protein extracts gave significant PLD activity, and PLD activity of tobacco BY-2 membrane proteins was enriched 6.7-fold by tubulin-affinity chromatography. In a cosedimentation assay, p90 bound and decorated microtubules. In immunofluorescence microscopy of intact tobacco BY-2 cells or lysed protoplasts, p90 colocalized with cortical microtubules, and taxol-induced microtubule bundling was accompanied by corresponding reorganization of p90. Labeling of p90 remained along the plasma membrane when microtubules were depolymerized, although detergent extraction abolished the labeling. Therefore, p90 is a specialized PLD that associates with membranes and microtubules, possibly conveying hormonal and environmental signals to the microtubule cytoskeleton.

A 90-kD phospholipase D from tobacco binds to microtubules and the plasma membrane

The organization of microtubule arrays in the plant cell cortex involves interactions with the plasma membrane, presumably through protein bridges. We have used immunochemistry and monoclonal antibody 6G5 against a candidate bridge protein, a 90-kD tubulin binding protein (p90) from tobacco BY-2 membranes, to characterize the protein and isolate the corresponding gene. Screening an Arabidopsis cDNA expression library with the antibody 6G5 produced a partial clone encoding phospholipase D (PLD), and a full-length gene was obtained by sequencing a corresponding expressed sequence tag clone. The predicted protein of 857 amino acids contains the active sites of a phospholipid-metabolizing enzyme and a Ca(2+)-dependent lipid binding domain and is identical to Arabidopsis PLD delta. Two amino acid sequences obtained by Edman degradation of the tobacco p90 are identical to corresponding segments of a PLD sequence from tobacco. Moreover, immunoprecipitation using the antibody 6G5 and tobacco BY-2 protein extracts gave significant PLD activity, and PLD activity of tobacco BY-2 membrane proteins was enriched 6.7-fold by tubulin-affinity chromatography. In a cosedimentation assay, p90 bound and decorated microtubules. In immunofluorescence microscopy of intact tobacco BY-2 cells or lysed protoplasts, p90 colocalized with cortical microtubules, and taxol-induced microtubule bundling was accompanied by corresponding reorganization of p90. Labeling of p90 remained along the plasma membrane when microtubules were depolymerized, although detergent extraction abolished the labeling. Therefore, p90 is a specialized PLD that associates with membranes and microtubules, possibly conveying hormonal and environmental signals to the microtubule cytoskeleton.

Serial renal biopsy in systemic lupus erythematosus

OBJECTIVE

To examine the role of sequential renal biopsies in patients with systemic lupus erythematosus (SLE), with regard to indications, morphologic change over time, and the clinical utility of repeat biopsies.

METHODS

Patients with repeat renal biopsies were identified from the University of Toronto Lupus Clinic Database and their biopsies were reviewed blindly by a committee, using the WHO classification as well as activity and chronicity indices. Reasons for obtaining biopsy were documented, and therapeutic decisions following repeat biopsy were tabulated.

RESULTS

Fifty-seven patients (49 F/9 M) had at least 2 renal biopsies between 1970 and 1994. The mean interval between biopsies was 4.2 years. The major reason for obtaining the first biopsy was disease diagnosis (32/57), while the majority of repeat biopsies were performed to discern the cause of increasing proteinuria (45/57). A comparison of the WHO classification of initial and repeat biopsies showed evolution to another class in 23 instances, but more commonly a change within a class was seen. A decrease in proliferative lesions (classes III and IV and subsets of V) was noted on repeat biopsies. The chronicity index increased significantly (p = 0.0001) and the activity index decreased (p = 0.064) between biopsies. Seventy-seven percent of patients had a change in treatment based on biopsy results.

CONCLUSION

The major reason for repeat renal biopsy in patients with SLE was proteinuria. Renal morphology in patients with SLE can change with time, particularly in terms of chronicity and activity features. Repeat biopsies in patients with SLE appear to have clinical utility.

Abscisic acid stimulation of phospholipase D in the barley aleurone is G-protein-mediated and localized to the plasma membrane

We have previously determined that phospholipase D (PLD) is activated by abscisic acid (ABA), and this activation is required for the ABA response of the cereal aleurone cell. In this study, ABA-stimulated PLD activity was reconstituted in vitro in microsomal membranes prepared from aleurone protoplasts. The transient nature (20 min) and degree (1.5- to 2-fold) of activation in vitro were similar to that measured in vivo. Stimulation by ABA was only apparent in the membrane fraction and was associated with a fraction enriched in plasma membrane. These results suggest that an ABA receptor system and elements linking it to PLD activation are associated with the aleurone plasma membrane. The activation of PLD in vitro by ABA was dependent on the presence of GTP. Addition of GTPgammaS transiently stimulated PLD in an ABA-independent manner, whereas treatment with GDPbetaS or pertussis toxin blocked the PLD activation by ABA. Application of pertussis toxin to intact aleurone protoplasts inhibited the ability of ABA to activate PLD as well as antagonizing the ability of ABA to down-regulate gibberellic acid-stimulated alpha-amylase production. All of these data support the hypothesis that ABA stimulation of PLD activity occurs at the plasma membrane and is mediated by G-protein activity.

Mosquito isolates of Ross River virus from Cairns, Queensland, Australia

During 1996-1998 60,619 mosquitoes were collected around Cairns, Australia and processed for Alphavirus isolation. Thirty-three isolates of Ross River (RR) virus were made from 9 species, Aedes imprimens, Aedes kochi, Aedes notoscriptus, Aedes vigilax, Culex annulirostris, Culex gelidus, Mansonia septempunctata, Verrallina (formerly Aedes) carmenti, and Verrallina lineatus. Attempts to isolate RR virus from 121 Aedes aegypti were unsuccessful. Twenty-six (79%) of the isolates came from within 1 km of a colony of spectacled flying-foxes, Pteropus conspicillatus. The minimum infection rate for these mosquitoes was 1.0 compared with 0.2 per 1,000 for mosquitoes trapped at all other sites. Ross River virus has not previously been isolated from Ae. imprimens, Cx. gelidus, Ma. septempunctata, Ve. carmenti, or Ve. lineatus. This is also the first isolation of an arbovirus from Cx. gelidus in Australia. In conclusion, the vector status of Ve. carmenti, Ae. aegypti and Ma. septempunctata warrants further study. This study also provides evidence that P. conspicillatus may be a reservoir host.

Transcription of the human c-Src promoter is dependent on Sp1, a novel pyrimidine binding factor SPy, and can be inhibited by triplex-forming oligonucleotides

The tyrosine kinase pp60(c-src) has been implicated in the regulation of numerous normal physiological processes as well the development of several human cancers. However, the mechanisms regulating its expression have not been addressed. In the present study, we report the presence of two Sp1/Sp3 binding sites and three polypurine:polypyrimidine (Pu:Py) tracts in the c-Src promoter that are essential for controlling expression. We demonstrate that Sp1, but not Sp3, is capable of activating the c-Src promoter and that Sp3 is also capable of inhibiting Sp1-mediated transactivation. The presence of multiple Pu:Py tracts conferred S1 sensitivity on plasmids in vitro, suggesting they are capable of adopting non B-DNA conformations. These tracts specifically bind a nuclear factor we named SPy (Src pyrimidine binding factor), which demonstrates both novel double- and single-stranded binding specificities. Mutations eliminating SPy binding compromised Src transcriptional activity, especially in concert with additional mutations affecting Sp1 binding, suggesting the two factors may cooperate in regulating c-Src expression. Finally, we demonstrate that triplex-forming oligonucleotides designed to target both Sp1 and SPy binding sites can down-regulate c-Src expression in vitro, suggesting a potential therapeutic approach to controlling c-Src expression in diseases where aberrant expression or activity has been documented.

Abscisic acid signal transduction in guard cells is mediated by phospholipase D activity

In guard cells, the plant hormone abscisic acid (ABA) inhibits stomatal opening and induces stomatal closure through the coordinated regulation of ion transport. Despite this central role of ABA in regulating stomatal function, the signal transduction events leading to altered ion fluxes remain incompletely understood. We report that the activity of the enzyme phospholipase D (PLD) transiently increased in guard cell protoplasts at 2.5 and 25 min after ABA application. Treatment of guard cell protoplasts with phosphatidic acid (PtdOH), one of the products of PLD activity, led to an inhibition of the activity of the inward K+ channel. PtdOH also induced stomatal closure and inhibited stomatal opening when added to epidermal peels. Application of 1-butanol (1-buOH), a selective inhibitor of PtdOH production by PLD, inhibited the increase in PtdOH production elicited by ABA. 1-BuOH treatment also partially prevented ABA-induced stomatal closure and ABA-induced inhibition of stomatal opening. This inhibitory effect of buOH was enhanced by simultaneous application of nicotinamide, an inhibitor of cADP ribose action. These results suggest that in the guard cell, ABA activates the enzyme PLD, which leads to the production of PtdOH. This PtdOH is then involved in triggering subsequent ABA responses of the cell via a pathway operating in parallel to cADP ribose-mediated events.

Neonatal suck reflex pattern does not predict apnea

Respiration and suck are gestational age-dependent reflexes modulated in the brain stem. To determine if the suck reflex pattern could be used to predict apnea, the relationship between the two was examined in 28 neonates. The suck reflex was quantified with respect to burst-pause rhythm, amplitude of negative suck pressure, and synchrony of the negative-positive pressure. Apneas were counted 5 days prior to and following measurement of the suck reflex pattern. Increasing gestational age correlated with a lower frequency of apnea (P < .01) and higher suck scores (P < .01). A mature suck reflex pattern, however, failed to predict the occurrence of apnea.

Attachment organizations in children with difficult life circumstances

The purpose of this study was to use the Attachment Q-Set to create categories of attachment organization that were conceptually consistent with organizational categories derived from other attachment assessments, reliable, and valid. We were particularly interested in creating categories that would describe insecure attachment organizations in children from difficult life circumstances. Our sample of relationships included 3062 teacher-child relationships. Children ranged in age from toddlers to kindergartners and were diverse in ethnic background. Two percent of the children were diagnosed with severe social and emotional problems and enrolled in a therapeutic preschool. Sixteen percent were enrolled in intervention programs on the basis of family poverty and another 34% of the children attended subsidized child care programs for low-income children. All of the children's child-teacher relationships were assessed with the Attachment Q-Set (AQS). Independent observers observed or rated children's peer play. Teachers completed behavior problem questionnaires and Student Teacher Relationships Scales. Using the AQS we created five subscales and six attachment organizational categories. These subscales and organizational categories were associated in theoretically meaningful ways with measures of behavior problems, social competence with peers, and teacher perceptions of child-teacher relationship.

The human c-Src proto-oncogene promoter contains multiple targets for triplex-forming oligonucleotides

The overexpression and activation of the human c-Src proto-oncogene is closely associated with cancer of the colon and breast. Characterization of the 5' region of the c-Src gene revealed that the promoter is very GC rich, regulated by the Sp family of transcription factors, and contains four perfect homopolypurine/homopolypyrimidine tracts (Pu:Py tracts). These Pu:Py tracts (TC1, TC1.1, TC2, and TC3) are located near or overlap critical Spl binding sites required for full activation of the gene. Triplex-forming oligonucleotides (TFOs) can be targeted to such sequences with high affinity to form intermolecular triple-helical DNA and modulate transcriptional activity. We therefore designed a series of antiparallel purine-based TFOs and measured their ability to form triplexes with the c-Src promoter Pu:Py tracts using comigration, bandshift, and chemical footprint techniques. With one interesting exception, all of the TFOs were found to bind with specificity and high affinity (67 nM-28 nM) to their target sequences at physiologic pH. These results indicate that the c-Src gene can successfully form stable triplexes under physiologic conditions and is, therefore, an excellent candidate for triplex-mediated transcriptional downregulation.

Thermodynamic and kinetic studies of the formation of triple helices between purine-rich deoxyribo-oligonucleotides and the promoter region of the human c-src proto-oncogene

The thermodynamic and kinetic parameters of triplex formation between four purine-rich oligonucleotides and a 22 bp pyrimidine. purine tract in the promoter region of the c-src gene were determined by fluorescence polarization studies. Three of these four oligonucleotides were 11 nt in length, corresponding to the left, central or right portion of the tract, while the fourth was a 22mer covering the whole tract. Binding constants ( Ka) were measured as a function of Mg2+ concentration (0-10 mM) and temperature (0-41 degrees C). In 10 mM Mg2+, K a for the left, central and right 11mers were 0.26, 0.75 and 1.4 x 10(8)/M, respectively, while for the 22mer the value was 1.8 x 10(8)/M at 22 degrees C. Under the same conditions, Ka was estimated by an electrophoretic band shift technique. The agreement between the two methods was acceptable for the 22mer but not for the 11mers. Kinetic measurements demonstrated that the rate of dissociation of the 22mer from the triplex was significantly slower than that of the 11mers, providing an explanation for the observed discrepancy. The entropy and enthalpy of triplex formation were calculated from van't Hoff plots. In all cases the entropy was favourable, especially for the 22mer and for the 11mer with the lowest guanine content. The enthalpy was unfavourable for the 22mer and most favourable for the 11mer with the highest guanine content. These results provide a thermodynamic explanation for length and sequence effects on the formation of purine.pyrimidine.purine triplexes.

Domestic Aedes aegypti breeding site surveillance: limitations of remote sensing as a predictive surveillance tool

This project tested aerial photography as a surveillance tool in identifying residential premises at high risk of Aedes aegypti breeding by extending the use of a recently developed, ground-based, rapid assessment technique, the modified Premise Condition Index (PCI2). During 1995, we inspected 360 premises in Townsville, Australia for Ae. aegypti breeding, and PCI2 scores were recorded. The PCI2 values were also estimated from 1:3,000 color and infrared aerial photograph interpretation for the same premises. We found that shade levels can be accurately identified from both color and infrared images, and the PCI2 can be accurately identified from infrared photographs. Yard conditions, however, cannot be accurately identified from either aerial photograph type. The airborne PCI2 did not significantly correlate with breeding measures, and logistic regression further demonstrated that neither aerial photograph type allows the accurate prediction of Ae. aegypti breeding risk. Therefore, the ability of low-level aerial photography to enhance Ae. aegypti breeding site surveillance is at present limited, with ground surveillance remaining our most reliable tool for identifying the probability of Ae. aegypti breeding in the residential environment.

Abscisic acid signal transduction in the barley aleurone is mediated by phospholipase D activity

The plant hormones abscisic acid (ABA) and gibberellic acid (GA) are important regulators of the dormancy and germination of seeds. In cereals, GA enhances the synthesis and secretion of enzymes (principally alpha-amylases) in the aleurone cells of the endosperm, which then mobilize the storage reserves that fuel germination. ABA inhibits this enhanced secretory activity and delays germination. Despite the central role of ABA in regulating germination, the signal transduction events leading to altered gene expression and cellular activity are essentially unknown. We report that the application of ABA to aleurone protoplasts increased the activity of the enzyme phospholipase D (PLD) 10 min after treatment. The product of PLD activity, phosphatidic acid (PPA), also increased transiently at this time. The application of PPA to aleurone protoplasts led to an ABA-like inhibition of alpha-amylase production, and induction of the ABA up-regulated proteins ASI (amylase subtilisin inhibitor) and RAB (responsive to ABA). Inhibition of PLD activity by 0.1% 1-butanol during the initial 20 min of ABA treatment resulted in inhibition of ABA-regulated processes. This inhibition coincided with the timing of PLD activation by ABA and was overcome by simultaneous addition of PPA. These results suggest that ABA activates the enzyme PLD to produce PPA that is involved in triggering the subsequent ABA responses of the aleurone cell.

An audit of in-patients aged 18-65 in acute psychiatric wards who are inappropriately placed three months after admission

OBJECTIVE

To identify acute psychiatric patients considered inappropriately placed three months after admission and expedite a more suitable placement by improving liaison with social work.

DESIGN

A survey established the point prevalence of inappropriately placed patients. Changes in usual practice were implemented with the identification of a named social worker for each ward and the introduction of a 'contact sheet' which updated the progress of these patients monthly. A repeat survey one year later assessed the impact of these changes.

SETTING

Gartnavel Royal Hospital, Greater Glasgow Community and Mental Health NHS Trust.

SUBJECTS

Patients aged 18-65 in the acute psychiatric wards who were resident beyond three months.

RESULTS

Use of the contact sheet and improved liaison with a named social worker did not shorten the length of stay of the inappropriately placed patients. Conversely, their mean value for in-patient weeks on the dates surveyed increased from 41.8 in 1994 to 64.7 in 1995. (p = 0.05, 95% confidence intervals from -1 to 42. The length of stay of patients who were still considered to be appropriately placed beyond three months after admission decreased from a mean of 47.7 to 31.9 weeks. (p > 0.5, 95% confidence intervals from -16 to 16). By 1995 the mean length of stay was significantly greater for inappropriately placed patients (p = 0.008, 95% confidence intervals from 10 to 47).

CONCLUSIONS

Improved liaison with social work at an operational level was not sufficient to solve the problem of inappropriately placed patients on acute wards. Additional factors such as limited access to rehabilitation placements and patients having complex physical or behavioural problems made placement elsewhere difficult. Such patients with unmet needs place increasing strain on acute psychiatric beds. A reappraisal of current services is required.

The significance of anticardiolipin antibodies in patients with lupus nephritis

The objective of this study was to determine whether anticardiolipin antibodies (ACL) in SLE patients are associated with a specific pattern of lupus nephritis and/or with renal microvascular changes. Patients with SLE, followed prospectively between June 1991-May 1994 at The Wellesley Hospital Lupus Clinic, who underwent a renal biopsy were included. The ACL was measured by the ELISA according to international standardized method. Renal biopsy morphology was assessed using the WHO criteria for the classification of lupus nephritis. Renal vascular changes included glomerular hyaline thrombi, intimal fibrosis and intraluminal thrombi of renal arterioles. There were 23 SLE patients. The mean age at diagnosis of SLE was 28.2 years and the mean disease duration was 6.3 years. Of these 10 (43%) had high levels of ACL. No difference in the frequency of severe nephritis (Class III and IV) was identified amongst patients with and without ACL. Mesangial nephritis was more common in patients with ACL 40% vs 0, p = 0.02). Glomerular hyaline thrombi occurred in 3 (13%) patients. None of them had positive ACL. Renal vascular lesions included intimal proliferation in 4 (ACL + , 1) occluded lumens by thrombi in 2 (ACL + 1). Our data indicate that the development of glomerular and/or microvascular changes is not related to the presence of ACL.

A controlled trial of cyclosporine in patients with progressive membranous nephropathy. Canadian Glomerulonephritis Study Group

A controlled trial of cyclosporine in patients diagnosed with progressive membranous nephropathy (MGN) was carried out to determine whether cyclosporine (D) would be more effective than placebo (P) in reducing the rate of deterioration in renal function. Patients (N = 64) with MGN were placed on a restricted protein diet (< or = 0.9 g/kg) and followed closely for 12 months (Part 1). Patients at high risk of progression based on an absolute loss in creatinine clearance (CCr) of > or = 8 ml/min and persistent nephrotic range proteinuria (Pr) were selected and randomly assigned to either (D) (N = 9) or (P) (N = 8) for 12 months (Part 2). No differences in the two groups were noted at entry. After 12 months, the improvement in CCr slope in ml/min/month was significantly greater in the D patients (D + 2.1 vs. P + 0.5, mean difference 1.6; 95% CI 0.3 to 3.0, P < 0.02). This improvement was maintained in six of eight D (75%) over a mean follow-up period of 21 months. Daily Pr also improved with D (by month 3, D - 4.5 g/day vs. P + 0.7 g/day, P = 0.02) and was sustained in six of eight (75%) D patients. When Pr was expressed as a function of their concurrent CCr, the D versus P patients' time to halving was faster (P = 0.02) and absolute number higher (4/9 D vs 0/8 P). In the D group a trend towards worse hypertension and an increase in the number of transient rises in serum creatinine were noted.(ABSTRACT TRUNCATED AT 250 WORDS)

Familial Dandy-Walker malformation associated with macrocephaly, facial anomalies, developmental delay, and brain stem dysgenesis: prenatal diagnosis and postnatal outcome in brothers. A new syndrome?

Brothers are reported with an apparently new constellation of manifestations including Dandy-Walker complex (DWC), migrational brain disorder, macrocephaly, and facial anomalies. The first brother presented at birth, the second was detected prenatally with DWC and the pregnancy terminated. Fetal brain histopathology showed DWC associated with brainstem dysgenesis. Inheritance is likely autosomal or X-linked recessive. An extensive review of the differential diagnosis of DWC is provided.

Motor development, infantile reactions and postural responses of preterm, at-risk infants

Eighty-nine low-birthweight, preterm infants were enrolled in a longitudinal study to describe motor development, infantile reactions and postural responses during the first chronological year of life and to determine the relationship between these behaviors. There was a clear trend from prevalence of primitive patterns, such as the asymmetric tonic neck reflex, towards a prevalence of mature postural reactions such as the Landau, righting and protective extension reflexes. Statistical analysis suggested that a relationship exists between infantile patterns, automatic postural reactions and motor development that is similar to that accepted as normal in term infant development, when allowance is made for preterm birth. Correlations were also obtained between integration of the tonic labyrinthine response and the presence of the asymmetric tonic neck pattern at the time of hospital discharge and later achievement of motor milestones. These relationships warrant further investigation.

Long-term benefits of angiotensin-converting enzyme inhibitor therapy in patients with severe immunoglobulin a nephropathy: a comparison to patients receiving treatment with other antihypertensive agents and to patients receiving no therapy

Of 531 cases of immunoglobulin A nephropathy in the Toronto Glomerulonephritis Registry, 115 were determined by retrospective analysis to have proteinuria > or = 1 g/d. These patients have been followed a minimum of 3 months (range, 3 to 121 months). Monitoring in the registry included routine blood pressure estimates and renal function status by serum creatinine, creatinine clearance, and proteinuria. These patients were grouped and examined retrospectively into three categories (1) hypertensive on angiotensin-converting enzyme (ACE) inhibitor therapy (ACEi), (2) hypertensive on other medication, and (3) no hypertension (NT). Despite comparable renal function abnormalities, the 27 ACEi patients, when compared with the 55 patients receiving other medication, experienced a significantly slower rate of decline in renal function as measured by slope of creatinine clearance (-0.4 mL/min/mo v-1.0 mL/min/mo; P = 0.007), longer time to a loss of one third of baseline creatinine clearance (P = 0.004), and a higher percentage of remission in proteinuria (18.5% v 1.8%; P = 0.003). A subsequent comparison was made between the NT and ACEi groups and, despite a much lower initial serum creatinine, less severe pathology, and a longer observation period in the NT group, both the rate of decline of creatinine clearance (-0.5 mL/min/mo v -0.4 mL/min/mo; P = 0.9) and the percentage of patients progressing to renal failure (21.2% v 18.5; P = 0.8) were not different. The remission rate of proteinuria was superior in the ACEi-treated group compared with the NT group.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical variability within Brachmann-de Lange syndrome: a proposed classification system

Seven patients, including two sibs, with the Brachmann-de Lange syndrome (BDLS) are presented as representative of the different types of BDLS in a proposed classification system. Type I ("classic") patients have the characteristic facial and skeletal changes of BDLS using the criteria in the diagnostic index of Preus and Rex. Type I is distinguished from the other subtypes by prenatal growth deficiency (< 2.5 S.D. below mean for gestation) becoming more severe postnatally (< 3.5 S.D. below the mean), moderate to profound psychomotor retardation, and major malformations which result in severe disability or death. Type II ("mild") BDLS patients have similar facial and minor skeletal abnormalities to those seen in type I; however, these changes may develop with time or may be partially expressed. Patients with type II BDLS are distinguished from those with other types by mild to borderline psychomotor retardation, less severe pre- and postnatal growth deficiency, and the absence of (or loss severe) major malformations. Behavioral problems can be a significant clinical problem in type II BDLS. Type III ("phenocopies") BDLS includes patients who have phenotypic manifestations of BDLS which are causally related to chromosomal aneuploidies or teratogenic exposures.

Trisomy 4 in a fetus with cyclopia and other anomalies

We report on an 18-week fetus with cyclopia, alobar holoprosencephaly, complex congenital heart defect, anal atresia, oligosyndactyly, cystic hygroma, and skeletal abnormalities with trisomy 4. Structural anomalies were detected on routine ultrasound of the pregnancy of a 17-year-old G3 P1 TAB1 woman with sickle cell trait. Trisomy 4 conceptuses usually miscarry in the first trimester. We are aware of no other reports of a fetus with trisomy 4 and cyclopia. Causal association of chromosome abnormalities and holoprosencephaly sequence may be more apparent in embryos and early fetuses than term fetuses because of poor viability of affected conceptuses.

The Effects of Transition Metal Substitutions in the NbTe4-TaTe4 Charge-Density Wave System

At room temperature, the structures of TaTe4 and NbTe4 are modulated by the presence of a charge-density wave which in the former compound is commensurate with the parent lattice and in the latter incommensurate. In addition, a series of incommensurate mixed crystals ( Tal-xNbx )Te4 (0 ≤ x ≤) exist in which the modulation wavevector increases as a function of x. In this paper, we report the occurrence of a systematic variation in the period of the charge-density wave upon substitution of the transition metal elements Ti, Zr or V for either Nb or Ta. Electron diffraction experiments reveal that, in TaTe4, substitutions of Group 4 elements Ti and Zr result in an incommensurate modulation with a decrease in the modulation wavevector q. In NbTe4, substitutions of Ti or Zr also reduce q, in this case towards the commensurate value, and, at sufficiently high concentrations, a commensurate phase is stabilized at room temperature. Vanadium substitutions in NbTe4 result in a slight increase in q. Satellite dark-field images reveal the presence of defects in the modulation structures of the doped crystals. The above results are discussed in terms of the factors which determine the charge-density wave periodicity in the NbTe4-TaTe4 system.

Pigmented lesions of the retinal pigment epithelium and familial adenomatous polyposis

Bilateral pigmented fundus lesions were found in 65 out of 72 patients with familial adenomatous polyposis, an additional five patients having unilateral lesions. With a family history of familial adenomatous polyposis, the occurrence of multiple bilateral fundus lesions indicates the presence of the abnormal gene, as does the occurrence of oval pigmented lesions with surrounding pale haloes. The absence of pigmented fundus lesions does not exclude the abnormal genotype, while the presence of occasional pigmented spots can be found in an appreciable percentage of the population. Ocular examination would, however, appear to be valuable in screening those at risk, with a positive yield in most carriers of the gene for familial adenomatous polyposis.