Mechanical scission of a knotted polymer

Molecular knots and entanglements form randomly and spontaneously in both biological and synthetic polymer chains. It is known that macroscopic materials, such as ropes, are substantially weakened by the presence of knots, but until now it has been unclear whether similar behaviour occurs on a molecular level. Here we show that the presence of a well-defined overhand knot in a polymer chain substantially increases the rate of scission of the polymer under tension (≥2.6× faster) in solution, because deformation of the polymer backbone induced by the tightening knot activates otherwise unreactive covalent bonds. The fragments formed upon severing of the knotted chain differ from those that arise from cleavage of a similar, but unknotted, polymer. Our solution studies provide experimental evidence that knotting can contribute to higher mechanical scission rates of polymers. It also demonstrates that entanglement design can be used to generate mechanophores that are among the most reactive described to date, providing opportunities to increase the reactivity of otherwise inert functional groups.

Force-controlled release of small molecules with a rotaxane actuator

Force-controlled release of small molecules offers great promise for the delivery of drugs and the release of healing or reporting agents in a medical or materials context1-3. In polymer mechanochemistry, polymers are used as actuators to stretch mechanosensitive molecules (mechanophores)4. This technique has enabled the release of molecular cargo by rearrangement, as a direct5,6 or indirect7-10 consequence of bond scission in a mechanophore, or by dissociation of cage11, supramolecular12 or metal complexes13,14, and even by 'flex activation'15,16. However, the systems described so far are limited in the diversity and/or quantity of the molecules released per stretching event1,2. This is due to the difficulty in iteratively activating scissile mechanophores, as the actuating polymers will dissociate after the first activation. Physical encapsulation strategies can be used to deliver a larger cargo load, but these are often subject to non-specific (that is, non-mechanical) release3. Here we show that a rotaxane (an interlocked molecule in which a macrocycle is trapped on a stoppered axle) acts as an efficient actuator to trigger the release of cargo molecules appended to its axle. The release of up to five cargo molecules per rotaxane actuator was demonstrated in solution, by ultrasonication, and in bulk, by compression, achieving a release efficiency of up to 71% and 30%, respectively, which places this rotaxane device among the most efficient release systems achieved so far1. We also demonstrate the release of three representative functional molecules (a drug, a fluorescent tag and an organocatalyst), and we anticipate that a large variety of cargo molecules could be released with this device. This rotaxane actuator provides a versatile platform for various force-controlled release applications.

A novel candidate gene in autosomal dominant facial pruritus

Pruritus is a common and often debilitating symptom that is associated with dermatological conditions including eczema, allergic contact dermatitis, urticaria, some drug eruptions and less commonly systemic diseases and neuropathic causes¹ . We report here an unusual familial centrofacial pruritus without any history or clinical findings of a rash, affecting three siblings and their father. The index patient (ll-1; Figure 1a) was a 62-year-old female with a 20-year history of severe localised pruritus of the nose. Her predominant symptom was debilitating itch on the surface of the skin around her nasal bridge, nasal septum and the nasal alae. She had no associated nasal congestion, rhinorrhea, skin changes nor rash and there was no relation to seasons, being outdoors, time of day, occupation, or food intake. Possible triggers included a warm environment and exercise.

Intradermal testing for autoimmune progesterone dermatitis: should we be basing the diagnosis on it?

Autoimmune progesterone dermatitis (APD) is a rare skin disorder with varying presentations, resulting from hypersensitivity to endogenous progesterone during the luteal phase of the menstrual cycle. The diagnosis has been traditionally confirmed with intradermal progesterone testing (IPT) or intramuscular challenge with progesterone or its derivatives. We present a case of a 31-year-old woman with suspected APD who underwent IPT to progesterone. The patient's cyclical symptoms, positive skin reaction and symptoms following IPT were sufficient to make a diagnosis of APD. However, we also tested 10 healthy female controls without symptoms of APD, and found that 9 of these also developed positive skin reactions to intradermal progesterone at 15 min, 24 and 48 h, albeit to a lesser extent. Therefore, these results raise doubts about the validity of using IPT to make a diagnosis of APD. Further research on appropriate testing is needed.

Isotope Effect in the Activation of a Mechanophore

In mechanochemistry, molecules under tension can react in unexpected ways. The reactivity of mechanophores (mechanosensitive molecules) can be controlled using various geometric or electronic factors. Often these factors affect the rate of mechanical activation but sometimes give rise to alternative reaction pathways. Here we show that a simple isotope substitution (H to D) leads to a reversal of selectivity in the activation of a mechanophore. Remarkably this isotope effect is not kinetic in nature but emerges from dynamic effects in which deuteration reduces the ability of the reactant to follow a post-transition-state concerted trajectory on the bifurcated force-modified potential energy surface. These results give a new insight into the reactivity of molecules under tension.

Potential methanol toxicity and the importance of using a standardised alcohol-based hand rub formulation in the era of COVID-19

OBJECTIVES

Hand sanitisers are urgently needed in the time of COVID-19, and as a result of shortages, some people have resorted to making their own formulations, including the repurposing of distilleries. We wish to highlight the importance of those producing hand sanitisers to avoid methylated spirits containing methanol and to follow WHO recommended formulations.

METHODS

We explore and discuss reports of methanol toxicity through ingestion and transdermal absorption. We discuss the WHO formulations and explain the rationale behind the chosen ingredients.

SHORT CONCLUSION

We advise those producing hand sanitisers to follow WHO recommended formulations, and advise those producing hand sanitisers using methylated spirits, to avoid formulations which contain methanol.

Prevalence of endocrine and genetic abnormalities in boys evaluated systematically for a disorder of sex development

STUDY QUESTION

What is the likelihood of identifying genetic or endocrine abnormalities in a group of boys with 46, XY who present to a specialist clinic with a suspected disorder of sex development (DSD)?

SUMMARY ANSWER

An endocrine abnormality of the gonadal axis may be present in a quarter of cases and copy number variants (CNVs) or single gene variants may be present in about half of the cases.

WHAT IS KNOWN ALREADY

Evaluation of 46, XY DSD requires a combination of endocrine and genetic tests but the prevalence of these abnormalities in a sufficiently large group of boys presenting to one specialist multidisciplinary service is unclear.

STUDY, DESIGN, SIZE, DURATION

This study was a retrospective review of investigations performed on 122 boys.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All boys who attended the Glasgow DSD clinic, between 2010 and 2015 were included in the study. The median external masculinization score (EMS) of this group was 9 (range 1-11). Details of phenotype, endocrine and genetic investigations were obtained from case records.

MAIN RESULTS AND THE ROLE OF CHANCE

An endocrine abnormality of gonadal function was present in 28 (23%) with a median EMS of 8.3 (1-10.5) whilst the median EMS of boys with normal endocrine investigations was 9 (1.5-11) (P = 0.03). Endocrine abnormalities included a disorder of gonadal development in 19 (16%), LH deficiency in 5 (4%) and a disorder of androgen synthesis in 4 (3%) boys. Of 43 cases who had array-comparative genomic hybridization (array-CGH), CNVs were reported in 13 (30%) with a median EMS of 8.5 (1.5-11). Candidate gene analysis using a limited seven-gene panel in 64 boys identified variants in 9 (14%) with a median EMS of 8 (1-9). Of the 21 boys with a genetic abnormality, 11 (52%) had normal endocrine investigations.

LIMITATIONS, REASONS FOR CAUTION

A selection bias for performing array-CGH in cases with multiple congenital malformations may have led to a high yield of CNVs. It is also possible that the yield of single gene variants may have been higher than reported if the investigators had used a more extended gene panel.

WIDER IMPLICATIONS OF THE FINDINGS

The lack of a clear association between the extent of under-masculinization and presence of endocrine and genetic abnormalities suggests a role for parallel endocrine and genetic investigations in cases of suspected XY DSD.

STUDY FUNDING/COMPETING INTEREST(S)

RN was supported by the James Paterson Bursary and the Glasgow Children's Hospital Charity Summer Scholarship. SFA, RM and EST are supported by a Scottish Executive Health Department grant 74250/1 for the Scottish Genomes Partnership. EST is also supported by MRC/EPSRC Molecular Pathology Node and Wellcome Trust ISSF funding. There are no conflicts of interest.

TRIAL REGISTRATION NUMBER

None.

An assessment of the quality of the I-DSD and the I-CAH registries - international registries for rare conditions affecting sex development

BACKGROUND

With the proliferation of rare disease registries, there is a need for registries to undergo an assessment of their quality against agreed standards to ensure their long-term sustainability and acceptability.This study was performed to evaluate the I-DSD and I-CAH Registries and identify their strengths and weaknesses.

METHODS

The design and operational aspects of the registries were evaluated against published quality indicators. Additional criteria included the level of activity, international acceptability of the registries and their use for research.

RESULTS

The design of the I-DSD and I-CAH Registries provides them with the ability to perform multiple studies and meet the standards for data elements, data sources and eligibility criteria. The registries follow the standards for data security, governance, ethical and legal issues, sustainability and communication of activities. The data have a high degree of validity, consistency and accuracy and the completeness is maximal for specific conditions such as androgen insensitivity syndrome and congenital adrenal hyperplasia. In terms of research output, the external validity is strong but the wide variety of cases needs further review. The internal validity of data was condition specific and highest for conditions such as congenital adrenal hyperplasia. The shift of the registry from a European registry to an international registry and the creation of a discrete but linked CAH registry increased the number of users and stakeholders as well as the international acceptability of both registries.

CONCLUSIONS

The I-DSD and I-CAH registries comply with the standards set by expert organisations. Recent modifications in their operation have allowed the registries to increase their user acceptability.

Variations in the quality and sustainability of long-term glycaemic control with continuous subcutaneous insulin infusion

AIMS

To investigate the pattern of changes in HbA1c in people with Type 1 diabetes managed by long-term Continuous subcutaneous insulin infusion.

METHODS

We studied HbA1c changes using computerized clinic records in 35 adult people with Type 1 diabetes and an elevated HbA1c (≥ 64 mmol/mol, 8.0%) on multiple daily insulin injections, who were then switched to continuous subcutaneous insulin infusion for at least 5 years.

RESULTS

We identified three subgroups with similar baseline HbA1c but different long-term responses to pump therapy: group A--those with improvement followed by deterioration (57%); group B--those with improvement that was sustained throughout the 5 years (31%); and group C-those where HbA1c did not change significantly from baseline (12%). The patients in group C had a higher BMI: 31.0 ± 5.2 vs. 25.9 ± 3.3 vs. 25.2 ± 3.1 kg/m² (group C vs. group A and group B; P = 0.02).

CONCLUSIONS

Improved glycaemic control with continuous subcutaneous insulin infusion was maintained over 5 years by 88% of people with Type 1 diabetes in this study, but there were variations in the long-term efficacy, with some people improving and worsening, others maintaining strict control and a few subcutaneous insulin infusion 'non-responders'.

Factors associated with resistance to dementia despite high Alzheimer disease pathology

BACKGROUND

Autopsy series have shown that some elderly people remain with normal cognitive function during life despite having high burdens of pathologic lesions associated with Alzheimer disease (AD) at death. Understanding why these individuals show no cognitive decline, despite high AD pathologic burdens, may be key to discovery of neuroprotective mechanisms.

METHODS

A total of 36 subjects who on autopsy had Braak stage V or VI and moderate or frequent neuritic plaque scores based on Consortium to Establish a Registry for Alzheimer's Disease (CERAD) standards were included. Twelve had normal cognitive function and 24 a diagnosis of AD before death. Demographic characteristics, clinical and pathologic data, as well as antemortem brain volumes were compared between the groups.

RESULTS

In multiple regression analysis, antemortem hippocampal and total brain volumes were significantly larger in the group with normal cognitive function after adjusting for gender, age at MRI, time from MRI to death, Braak stage, CERAD neuritic plaque score, and overall presence of vascular disease.

CONCLUSION

Larger brain and hippocampal volumes were associated with preserved cognitive function during life despite a high burden of Alzheimer disease (AD) pathologic lesions at death. A better understanding of processes that lead to preservation of brain volume may provide important clues for the discovery of mechanisms that protect the elderly from AD.

Modelling the cost effectiveness of TNF-alpha antagonists in the management of rheumatoid arthritis: results from the British Society for Rheumatology Biologics Registry

OBJECTIVE

To evaluate the cost effectiveness of TNF-alpha antagonist therapies for rheumatoid arthritis (RA) in the United Kingdom using data from the British Society for Rheumatology Biologics Registry (BSRBR).

METHODS

A simulation model is constructed to quantify the cost effectiveness of the TNF-alpha antagonist therapies (infliximab, etanercept and adalimumab) as a group versus traditional disease-modifying anti-rheumatic drugs, with a time horizon over the full patient lifetime. Participants are UK NHS patients in the BSRBR with RA who have failed at least two traditional disease-modifying anti-rheumatic drugs. The BSRBR aims to recruit all RA patients starting on a TNF-alpha antagonist agent and follows them 6 monthly via consultant and patient administered questionnaires. Data collected include disease activity scores (DAS28), the Health Assessment Questionnaire and the SF-36. Costs include drug, monitoring and hospitalisations. Benefits are measured in disability and quality of life improvements. The main outcome measure is the incremental cost per quality adjusted life-year gained (discounted).

RESULTS

The basecase cost per quality adjusted life-year gained by using TNF-alpha antagonist therapies is estimated at pound23 882, with probabilistic uncertainty analysis suggesting that the probability that treatments are below 30,000 pounds per QALY is around 84%. The results are most sensitive to assumptions concerning long-term disability progression, discount rates and the validity or otherwise of SF6D derived utility measures. Subgroup analysis, monotherapy versus combination with methotrexate, and a limited analysis of sequential therapy with two TNF-alpha antagonist agents, suggest cost-effectiveness ratios around 20,000 pounds to 30,000 pounds.

CONCLUSIONS

The BSRBR data provide valuable evidence for estimating cost-effectiveness. The analysis concludes that current policies and practice for the use of TNF-alpha antagonist therapies, after RA patients have failed at least two traditional disease-modifying anti-rheumatic drugs, appear cost-effective in the context of the NICE re-appraisal of 2006 for England and Wales, thus supporting their decision to continue their reimbursement. Decision-makers worldwide might adapt this analysis because differential costs, discount rates and other factors could affect results. There remains uncertainty, particularly on long-term disease progression. Further data collection using the BSRBR is recommended, together with a revision to this analysis when data become available.

The efficacy of inhibiting tumour necrosis factor alpha and interleukin 1 in patients with rheumatoid arthritis: a meta-analysis and adjusted indirect comparisons

OBJECTIVE

New treatments that inhibit the cytokines tumour necrosis factor alpha (TNFalpha) and interleukin 1 (IL-1) in the treatment of rheumatoid arthritis have proven clinical effect against placebo and methotrexate (MTX) in several clinical trials in early and late-stage disease and different severity groups. Since there are no head-to-head randomized controlled trials directly comparing the currently available treatments, etanercept, adalimumab, infliximab or anakinra, we perform a meta-analysis that adjusts for differences between study characteristics, and allows indirect comparisons between treatments.

METHODS

Thirteen trials of cytokine antagonists were included from a systematic review of the literature. They reported the primary outcome of American College of Rheumatology (ACR) response criteria at 6 months or beyond. Meta-analytical methods are used to quantify relative treatment effects, using the log odds ratio of an ACR20 or ACR50 response at 6 months, whilst adjusting for study-level variables.

RESULTS

In each of the trials, cytokine treatment was efficacious in comparison with placebo or MTX. For each treatment, the inclusion of MTX in combination improved the response. After adjustment for study-level variables, we found TNFalpha antagonists to be more efficacious compared with anakinra (P < 0.05). Indirect comparisons between the three TNFalpha antagonists indicated no difference in efficacy. Sensitivity analysis using a different statistical model structure confirmed these results.

CONCLUSION

When the outcome of interest is the probability of an ACR20 or ACR50 response at 6 months we found: (i) treatment with the IL-1 antagonist anakinra is better than placebo; (ii) for each treatment, the use of combination MTX improves the probability of response; (iii) treatment with any of the TNFalpha antagonists is better than with the IL-1 antagonist anakinra; and (iv) all drugs in the TNFalpha antagonist class are no different from each other.

Quantitative MRI reveals aging-associated T2 changes in mouse models of Alzheimer's disease

In this study, we used MRI to analyze quantitative parametric maps of transverse (T(2)) relaxation times in a longitudinal study of transgenic mice expressing mutant forms of amyloid precursor protein (APP), presenilin (PS1), or both (PS/APP), modeling aspects of Alzheimer's disease (AD). The main goal was to characterize the effects of progressive beta-amyloid accumulation and deposition on the biophysical environment of water and to investigate if these measurements would provide early indirect evidence of AD pathological changes in the brains of these mice. Our results demonstrate that at an early age before beta-amyloid deposition, only PS/APP mice show a reduced T(2) in the hippocampus and cortex compared with wild-type non-transgenic (NTg) controls, whereas a statistically significant within-group aging-associated decrease in T(2) values is seen in the cortex and hippocampus of all three transgenic genotypes (APP, PS/APP, and PS) but not in the NTg controls. In addition, for animals older than 12 months, we confirmed our previous report that only the two genotypes that form amyloid plaques (APP and PS/APP) have significantly reduced T(2) values compared with NTg controls. Thus, T(2) changes in these AD models can precede amyloid deposition or even occur in AD models that do not deposit beta-amyloid (PS mice), but are intensified in the presence of amyloid deposition.

Costs and quality of life of multiple sclerosis in the United Kingdom

This cost-of-illness analysis for the United Kingdom is part of a Europe-wide study on the costs of multiple sclerosis (MS). The objective was to analyze the costs and quality of life (utility) related to the level of disease severity. People with MS from a database administered by a UK charity (the MS Trust) were asked to participate in the survey by answering a postal questionnaire. In addition to details on the disease (type of disease, relapses, level of functional disability), the questionnaire asked for information on all resource consumption, medical, non-medical, work absence and informal care as well as utility. The response rate was 19%, and a total of 2048 people were included. The mean age of the cohort was 51 years, and 23% of people were > or =60 years of age. Disease severity was concentrated in people with moderately severe MS (Expanded Disability Status Scale [EDSS] score of 4 to 6.5), with 21, 60 and 19% of people reporting mild, moderate and severe disease, respectively. Costs and utility are highly correlated with disease severity. Mean annual costs for all people in the study increase from approximately pound 12.000 at an EDSS score <4 to almost pound 60.000 at an EDSS score > or =7. In particular, employment rates are reduced from 82% in early disease to 2% at an EDSS score of 8, while the costs of inpatient care, investments, informal care and productivity losses increase by more than tenfold between an EDSS score of 0-1 and a score > or =7. Utility decreases from 0.92 at an EDSS score of 0 to a state worse than death in the most severe state (-0.18 at an EDSS score of 9). Compared to the results in an earlier cost study in the United Kingdom using a comparable methodology, costs have substantially increased, by roughly 40%. Part of the increase is due to a higher use of disease-modifying drugs and, possibly linked with this, a higher use of ambulatory care and services. Another part of the increase is most likely due to an increased age in the current sample, with more patients on early retirement due to MS and more intense use of informal care. However, another reason may lie in the methodology, e.g. different unit costs or differences in the sample distribution, despite a similar mean EDSS score of 5.1.

Low rates of cutaneous adverse reactions to alcohol-based hand hygiene solution during prolonged use in a large teaching hospital

We assessed cutaneous adverse reactions (CARs) to alcohol-based hand rub (ABHR) after the introduction of a hand hygiene culture change program at our institution. CARs were infrequent among exposed health care workers (HCWs) (13/2,750; 0.47%; 1 CAR per 72 years of HCW exposure) and were not influenced by the duration or intensity of ABHR use but were associated with the presence of irritant contact dermatitis.

PRNP H187R mutation associated with neuropsychiatric disorders in childhood and dementia

Described is a large family with an autosomal dominant dementia associated with an H187R mutation in the prion protein gene (PRNP). Clinical features include neuropsychiatric disturbances in childhood and adolescence, dementia in young adulthood with frontotemporal manifestations, and long disease duration. Neuropathology revealed atrophy and mild gliosis, whereas prion protein analysis revealed an abnormal conformer with unusual sensitivity to protease digestion. Mutations in PRNP may cause neuropsychiatric disorders that predate dementia by many years.

Imaging of iron oxide nanoparticles by MR and light microscopy in patients with malignant brain tumours

OBJECTIVE

Ferumoxtran-10 (Combidex), a dextran-coated iron oxide nanoparticle, provides enhancement of intracranial tumours by magnetic resonance (MR) for more than 24 h and can be imaged histologically by iron staining. Our goal was to compare ferumoxtran imaging and histochemistry vs. gadolinium enhancement in malignant brain tumours on preoperative and postoperative MR.

METHODS

Seven patients with primary and metastatic malignant tumours underwent MR imaging with gadolinium and ferumoxtran both pre- and postoperatively. Normalized signal intensities on the ferumoxtran-enhanced scans were determined in representative regions of interest. Resected tissue from six ferumoxtran patients and from three patients who did not receive ferumoxtran was assessed for localization of iron in tumour and reactive brain.

RESULTS

All malignant tumours (all of which enhanced by gadolinium MR) showed ferumoxtran accumulation with T1 and T2 signal changes, even using a 0.15 T intraoperative MR unit in one patient. Iron staining was predominantly in reactive cells (reactive astrocytes and macrophages) and not tumour cells. In five of the seven patients, including two patients who showed additional lesions, areas enhancing with ferumoxtran but not with gadolinium were observed. Comparison of the pre- and postoperative MR revealed residual ferumoxtran-enhancing areas in four of seven cases.

CONCLUSION

In malignant tumours, ferumoxtran may show areas of enhancement, even with a 0.15 T intraoperative MR, that do not enhance with gadolinium. Ferumoxtran-enhancing lesions have persistent increased T1 signal intensity for 2-5 days, which may provide advantages over gadolinium for postoperative imaging. Histochemistry for iron shows uptake of ferumoxtran in reactive cells (astrocytes and macrophages) rather than tumour cells.

Application of a non-linear image registration algorithm to quantitative analysis of T2 relaxation time in transgenic mouse models of AD pathology

Transgenic mouse models have been essential for understanding the pathogenesis of Alzheimer's disease (AD) including those that model the deposition process of beta-amyloid (Abeta). Several laboratories have focused on research related to the non-invasive detection of early changes in brains of transgenic mouse models of Alzheimer's pathology. Most of this work has been performed using regional image analysis of individual mouse brains and pooling the results for statistical assessment. Here we report the implementation of a non-linear image registration algorithm to register anatomical and transverse relaxation time (T2) maps estimated from MR images of transgenic mice. The algorithm successfully registered mouse brain magnetic resonance imaging (MRI) volumes and T2 maps, allowing reliable estimates of T2 values for different regions of interest from the resultant combined images. This approach significantly reduced the data processing and analysis time, and improved the ability to statistically discriminate between groups. Additionally, 3D visualization of intra-regional distributions of T2 of the resultant registered images provided the ability to detect small changes between groups that otherwise would not be possible to detect.

Endocytic disturbances distinguish among subtypes of Alzheimer's disease and related disorders

The endocytic pathway is important in amyloid precursor protein (APP) processing and beta-amyloid formation. Our studies have shown that endocytic pathway activation is a prominent and early feature of neurons in vulnerable regions of the brain in sporadic Alzheimer's disease. We report that endocytic pathway abnormalities are present not only in neurons, but in cerebral endothelia in Alzheimer's disease caused by certain APP mutations. The presence or absence of endocytic abnormalities distinguish subtypes of familial Alzheimer's disease linked to APP mutations from presenilin mutations, supporting the notion that different cellular pathways are involved in the altered processing of APP leading to increased beta-amyloid generation in certain of these different Alzheimer's disease subtypes.

Initial results of a study into the effectiveness of breast cancer screening in a population identified to be at high risk

BACKGROUND

Women are frequently referred to genetic clinics because of a family history of breast or ovarian cancer, conferring a moderate increased risk of the disease, but not sufficient in itself to indicate gene mutation analysis. One possible management strategy is to offer regular mammographic screening, possibly earlier in life and more frequently than in the general population. This strategy is used in many parts of the UK, although it has not been formally evaluated.

METHODS

In this paper we present some early results on the effectiveness of a programme of mammography in 2,998 women aged 19-71 with a moderate family history of breast cancer in Manchester. We estimated the test and programme sensitivity and sojourn time, using different statistical methods.

RESULTS

Fifty breast cancers were diagnosed. The incidence rate observed was 4.46 per thousand person-years. The incidence expected from the segregation analysis of Claus et al. was 3.75 per thousand person-years. Screen-detection rates at first and subsequent screens were 5.00 and 4.93 per thousand respectively. Interval cancer incidence in the first year following a negative screen was 0.91 per thousand person-years. Screening test sensitivity was estimated conservatively as 83%, programme sensitivity as 70%.

CONCLUSIONS

Early indications are that the programme is likely to be effective. Further follow-up, analysis of tumour size, node status and malignancy grade, and subsequent mortality from breast cancer is required to confirm this.

Cutaneous spectrum of coeliac disease

Coeliac disease is characterized by gluten intolerance and immunologically mediated damage to small intestinal mucosa. Patients classically present with gastrointestinal symptoms including chronic diarrhoea, steatorrhoea, weight loss, anorexia and abdominal distension. In a substantial proportion of cases however, gastrointestinal symptoms are minor or absent, and cutaneous manifestations may provide an early clue to diagnosis. Early recognition of coeliac disease, with appropriate implementation of a gluten-free diet, may reduce the incidence of benign and malignant complications associated with this condition.

Occupational skin disease in hairdressers

Hairdressers belong to an occupational group that is commonly affected by occupational skin disease, specifically contact dermatitis, which may be allergic or irritant and, less commonly, contact urticaria. Occupational contact dermatitis predominantly affects apprentices, and atopy is a recognized risk factor associated with a poor prognosis. Repetitive wet work leading to irritant contact dermatitis, followed by exposure to allergens and the development of allergic contact dermatitis, are the main factors contributing to occupational contact dermatitis. Once developed, it is often difficult to manage and is a cause of significant morbidity. Early education, training and prevention is the best approach to the management of this disorder that is endemic among hairdressers.

Reduction of use of latex gloves in food handlers: an intervention study

Frequent latex glove use is a risk factor for the development of latex allergy. With the increase in latex glove use, latex allergy has become more prevalent. There are a number of occupational groups in which the use of latex gloves is both inappropriate and even hazardous, including food handlers, where the hazard relates particularly to their latex-sensitive customers. The aim of this study was to assess both the use of latex gloves by food handlers and the impact of an intervention study on reducing latex glove use. This was done at the Queen Victoria Market in Melbourne, Australia. We found that 10 out of 30 stalls (33%) used latex gloves, and that following a short education program, this was reduced to 1 stall (3%, p=0.006). The potential to reduce latex glove use by using this intervention study was 93% (95% confidence interval of 54%-100%). We recommend that food handlers be educated during their training, not only about hygiene issues, but also about the appropriate type of glove to wear, in order to prevent both the development of a new occupational group at risk of becoming allergic to latex, but more importantly to protect their latex-sensitive customers.

Severe allergic contact dermatitis induced by paraphenylenediamine in paint-on temporary 'tattoos'

Paraphenylenediamine (PPD) is a black dye with well known sensitizing properties. Its increasing use as a skin paint to produce temporary 'tattoos' has led to recent reports of allergic contact dermatitis. Hitherto, such cases of allergic contact dermatitis due to PPD have been localized to the original site of application of the skin paint. We report two cases of severe allergic reactions to paint-on 'tattoos'. Both of these patients had no prior history of sensitivity to PPD, although case 2 had previously used permanent hair dyes. In both cases, the primary eruption at the 'tattoo' site was followed within days by a generalized eruption which ultimately required treatment with oral corticosteroids, because the initially prescribed topical corticosteroids proved ineffective.

Unexpected neurotoxicity of etoposide phosphate administered in combination with other chemotherapeutic agents after blood-brain barrier modification to enhance delivery, using propofol for general anesthesia, in a rat model

OBJECTIVE

Osmotic blood-brain barrier disruption (BBBD) increases brain and brain tumor delivery of chemotherapeutic agents, which results in increased efficacy against brain tumors. We previously noted that the use of propofol anesthesia for BBBD increased the percentage of successful disruptions, resulting in delivery of increased amounts of chemotherapeutic drugs. This study evaluated the neurotoxicity of combination chemotherapeutic administration with this enhanced delivery system.

METHODS

Osmotic BBBD was performed in Long-Evans rats with isoflurane (n = 11) or propofol (n = 90) anesthesia. Carboplatin and/or melphalan, methotrexate, or etoposide phosphate was administered intra-arterially (IA) after BBBD using propofol anesthesia. Animals were assessed for systemic and neurological toxicity. Animals were killed for neuropathological evaluation 30 days after treatment.

RESULTS

With propofol or isoflurane anesthesia, BBBD alone produced no systemic or neurological toxicity. Single agents were relatively non-neurotoxic when administered IA with BBBD, as were the combinations of carboplatin or melphalan with methotrexate. Etoposide phosphate in combination with any other agent was observed to be highly neurotoxic if both agents were administered after BBBD. Administration of etoposide phosphate before BBBD completely eliminated neurotoxicity, although acute pulmonary toxicity occurred with any combination of etoposide phosphate and methotrexate, regardless of the timing of administration.

CONCLUSION

Neurotoxicity was significantly increased for etoposide phosphate combination groups, particularly when both drugs were administered IA after BBBD. This increase in neurotoxicity may reflect on increase in drug delivery observed with propofol anesthesia. The neurotoxicity of IA administered etoposide phosphate with BBBD and propofol anesthesia could be minimized by administering etoposide phosphate IA before BBBD and administering carboplatin or melphalan IA after BBBD.

Safety and efficacy of a multicenter study using intraarterial chemotherapy in conjunction with osmotic opening of the blood-brain barrier for the treatment of patients with malignant brain tumors

BACKGROUND

The aim of this study was to determine the safety and efficacy of intraarterial chemotherapy with osmotic opening of the blood-brain barrier (BBB) for the treatment of malignant brain tumors when administered across multiple centers.

METHODS

Patients with primary central nervous system lymphoma (PCNSL), primitive neuroectodermal tumor (PNET), germ cell tumor, cancer metastasis to the brain, or low or high grade glioma were eligible. Prior to entry, magnetic resonance imaging or computed tomography brain scan, medical history, neurologic status, and Karnofsky performance status were reviewed at the coordinating center. Standardized anesthesia and intraarterial catheterization guidelines were followed by a multidisciplinary team at each center. Between March 1994 and November 1997, 5 universities treated 221 adult patients with intraarterial chemotherapy with or without osmotic opening of the BBB (2464 procedures).

RESULTS

Of evaluable patients with PCNSL, 40 of 53 (75%) achieved complete response (CR). All evaluable patients with PNET (n = 17), metastatic disease (n = 12), or germ cell tumor (n = 4) achieved stable disease (SD) or better. Of 57 evaluable patients with glioblastoma multiforme, 45 (79%) achieved SD or better. Asymptomatic subintimal tear occurred in 11 of 221 patients (5%), pulmonary embolism in 6 of 221 (2.7%), and renal toxicity in 4 of 221 (1.8%). One patient with extensive glioma expired within 48 hours after treatment.

CONCLUSIONS

Using standard guidelines and protocols, intraarterial chemotherapy with or without osmotic opening of the BBB is feasible across multiple centers with a low incidence of catheter-related complications. In patients with chemotherapy-sensitive tumors, such as PCNSL, PNET, germ cell tumor, and cancer metastasis to the central nervous system, enhanced delivery results in a high degree of tumor response, with an efficacy profile that is reproducible across multiple centers.

Some random-effects models for the analysis of matched-cluster randomised trials: application to the Swedish two-county trial of breast-cancer screening

BACKGROUND

In the Swedish two-county trial women aged 40-74 years from two counties in Sweden were randomised to invitation to mammographic screening for breast cancer.

METHODS

This paper uses random effects logistic regression models to analyse recent data from the trial. The analysis accounts for the structure of the trial, where small geographical units are randomised within larger geographical strata (blocks of two or three small units that are socio-economically similar).

RESULTS

Fixed effects and a variety of random effects models show a strong degree of agreement and yield a significant 29% or 30% reduction in breast-cancer mortality.

DISCUSSION

Fixed effects and random effects models agree for this example, because heterogeneity both between strata and within strata between clusters is small and because the effect of treatment does not vary much in different strata.

Peptide T blocks GP120/CCR5 chemokine receptor-mediated chemotaxis

We previously reported that certain short gp120 V2 region peptides homologous to vasaoactive intestinal peptide (VIP), such as "peptide T," were potent inhibitors of gp120 binding, infectivity, and neurotoxicity. The present study shows that synthetic V2-region-derived peptides have potent intrinsic chemotaxis agonist activity for human monocytes and also act as antagonists of high-affinity (0.1 pM) gp120-mediated monocyte chemotaxis. Selectivity is shown in that peptide T is more potent at suppressing M-tropic than T-tropic gp120 chemotaxis. Peptide T was also able to suppress monocyte chemotaxis to MIP-1beta, a chemokine with selectivity for CCR5 chemokine receptors, while chemotaxis of the more promiscuous ligand RANTES was not inhibited, nor was chemotaxis mediated by SDF-1alpha. In order to determine if peptide T mediated its gp120 antagonistic effects via modulation of CCR5 receptors, RANTES chemotaxis was studied using a CCR5 receptor-transfected HOS cell line. In this case, RANTES chemotaxis was potently inhibited by V2-region-derived short peptides. Peptide T also partially suppressed (125)I-MIP1-beta binding to human monocytes, suggesting action at a subset of MIP1-beta receptors. The V2 region of gp120 thus contains a potent receptor binding domain and synthetic peptides derived from this region modulate CCR5 chemokine receptor chemotactic signaling caused by either gp120 or chemokine ligands. The results have therapeutic implications and may explain recent clinical improvements, in that HIV/gp120 actions at CCR5 receptors, such as occur in the brain or early infection, would be susceptible to peptide T inhibition.

The proteolytic fragments of the Alzheimer's disease-associated presenilin-1 form heterodimers and occur as a 100-150-kDa molecular mass complex

Mutations in the presenilin (PS) genes are linked to early onset familial Alzheimer's disease (FAD). PS-1 proteins are proteolytically processed by an unknown protease to two stable fragments of approximately 30 kDa (N-terminal fragment (NTF)) and approximately 20 kDa (C-terminal fragment (CTF)) (Thinakaran, G., Borchelt, D. R., Lee, M. K., Slunt, H. H., Spitzer, L., Kim, G., Ratovitsky, T., Davenport, F., Nordstedt, C., Seeger, M., Hardy, J., Levey, A. I., Gandy, S. E., Jenkins, N. A., Copeland, N. G., Price, D. L., and Sisodia, S. S. (1996) Neuron 17, 181-190). Here we show that the CTF and NTF of PS-1 bind to each other. Fractionating proteins from 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid-extracted membrane preparations by velocity sedimentation reveal a high molecular mass SDS and Triton X-100-sensitive complex of approximately 100-150 kDa. To prove if both proteolytic fragments of PS-1 are bound to the same complex, we performed co-immunoprecipitations using multiple antibodies specific to the CTF and NTF of PS-1. These experiments revealed that both fragments of PS-1 occur as a tightly bound non-covalent complex. Upon overexpression, unclipped wild type PS-1 sediments at a lower molecular weight in glycerol velocity gradients than the endogenous fragments. In contrast, the non-cleavable, FAD-associated PS-1 Deltaexon 9 sediments at a molecular weight similar to that observed for the endogenous proteolytic fragments. This result may indicate that the Deltaexon 9 mutation generates a mutant protein that exhibits biophysical properties similar to the naturally occurring PS-1 fragments. This could explain the surprising finding that the Deltaexon 9 mutation is functionally active, although it cannot be proteolytically processed (Baumeister, R., Leimer, U., Zweckbronner, I., Jakubek, C., Grünberg, J., and Haass, C. (1997) Genes & Function 1, 149-159; Levitan, D., Doyle, T., Brousseau, D., Lee, M., Thinakaran, G., Slunt, H., Sisodia, S., and Greenwald, I. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 14940-14944). Formation of a high molecular weight complex of PS-1 composed of both endogenous PS-1 fragments may also explain the recent finding that FAD-associated mutations within the N-terminal portion of PS-1 result in the hyperaccumulation not only of the NTF but also of the CTF (Lee, M. K., Borchelt, D. R., Kim, G., Thinakaran, G., Slunt, H. H., Ratovitski, T., Martin, L. J., Kittur, A., Gandy, S., Levey, A. I., Jenkins, N., Copeland, N., Price, D. L., and Sisodia, S. S. (1997) Nat. Med. 3, 756-760). Moreover, these results provide a model to understand the highly regulated expression and processing of PS proteins.

Altered gene expression for calpain/calpastatin system in motor neuron degeneration (Mnd) mutant mouse brain and spinal cord

The calcium-activated neutral proteases (CANP, calpains) have been implicated in both acute and chronic neurodegenerative processes. In the present study, we analyzed the in situ mRNA expression of calpain I and II and their endogenous inhibitor, calpastatin, in the motor neuron degeneration (Mnd) mutant mouse, which exhibits progressive dysfunction of the spinal cord and brain. As the disease progresses, the mutants show increasingly pronounced motor abnormalities which coincide with swelling of the spinal motor neurons, neocortex, hippocampal CA regions and cerebellar Purkinje cells. In situ hybridization studies show that the Mnd mice have a significantly higher level of calpain I, calpain II and calpastatin than the congenic controls in the following brain regions and cell types: hippocampal CA3 region, pyramidal cells, cerebellar Purkinje cells and spinal cord motor neurons. However, no differences in calpain or calpastatin mRNA levels are observed in glial and cerebellar granule cells of Mnd and control mice. Western blots and competitive RT-PCR analyses of brain and spinal cord homogenates are confirmative. Such altered gene expression in specific cell types of brain and spinal cord suggests the involvement of the calpain/calpastatin system.

Cellular expression and proteolytic processing of presenilin proteins is developmentally regulated during neuronal differentiation

We have determined the expression of the Alzheimer's disease-associated proteins presenilin-1 and presenilin-2 in primary cultures of rat hippocampal neurons. Neurons highly express presenilin-1 and presenilin-2, whereas both proteins were not detected in astrocytes. Further, we have analyzed the subcellular localization and expression in rat hippocampal neurons during development. Although presenilin proteins were localized predominantly to the endoplasmic reticulum in nonneuronal cells transfected with presenilin cDNAs, in neurons, presenilin proteins were also found in compartments not staining with antibodies to grp78(BiP). Presenilin-1 and presenilin-2 were predominantly detected in vesicular structures within the somatodendritic compartment with much less expression in axons. Polarized distribution of presenilin-1 and presenilin-2 differs slightly, with more presenilin-2 expressed in axons compared with presenilin-1. Presenilin expression was found to be developmentally regulated. Presenilin expression strongly increased during neuronal differentiation until full morphological polarization and then declined. No full-length presenilin-1 or presenilin-2 could be detected within cell lysates. At early developmental stages the expected approximately 34-kDa N-terminal proteolytic fragment of presenilin-1 and the approximately 38-kDa fragment of presenilin-2 were detected. Later during differentiation we predominantly detected a approximately 38-kDa fragment for presenilin-1 and a approximately 42-kDa fragment for presenilin-2. By epitope mapping, we show that these slower migrating peptides represent N-terminal proteolytic fragments, cleaved C-terminal to the conventional site of processing. It is noteworthy that both presenilin-1 and presenilin-2 undergo alternative proteolytic cleavage at the same stage of neuronal differentiation. Regulation of presenilin expression and proteolytic processing might have implications for the pathological as well as the biological function of presenilins during aging in the human brain.

Subcellular colocalization of the cellular and scrapie prion proteins in caveolae-like membranous domains

Results of transgenetic studies argue that the scrapie isoform of the prion protein (PrPSc) interacts with the substrate cellular PrP (PrPC) during conversion into nascent PrPSc. While PrPSc appears to accumulate primarily in lysosomes, caveolae-like domains (CLDs) have been suggested to be the site where PrPC is converted into PrPSc. We report herein that CLDs isolated from scrapie-infected neuroblastoma (ScN2a) cells contain PrPC and PrPSc. After lysis of ScN2a cells in ice-cold Triton X-100, both PrP isoforms and an N-terminally truncated form of PrPC (PrPC-II) were found concentrated in detergent-insoluble complexes resembling CLDs that were isolated by flotation in sucrose gradients. Similar results were obtained when CLDs were purified from plasma membranes by sonication and gradient centrifugation; with this procedure no detergents are used, which minimizes artifacts that might arise from redistribution of proteins among subcellular fractions. The caveolar markers ganglioside GM1 and H-ras were found concentrated in the CLD fractions. When plasma membrane proteins were labeled with the impermeant reagent sulfo-N-hydroxysuccinimide-biotin, both PrPC and PrPSc were found biotinylated in CLD fractions. Similar results on the colocalization of PrPC and PrPSc were obtained when CLDs were isolated from Syrian hamster brains. Our findings demonstrate that both PrPC and PrPSc are present in CLDs and, thus, support the hypothesis that the PrPSc formation occurs within this subcellular compartment.

mu-calpain activation and calpain-mediated cytoskeletal proteolysis following traumatic brain injury

Increasing evidence suggests that excessive activation of the calcium-activated neutral protease mu-calpain could play a major role in calcium-mediated neuronal degeneration after acute brain injuries. To further investigate the changes of the in vivo activity of mu-calpain after unilateral cortical impact injury in vivo, the ratio of the 76-kDa activated isoform of mu-calpain to its 80-kDa precursor was measured by western blotting. This mu-calpain activation ratio increased to threefold in the pellet of cortical samples ipsilateral to the injury site at 15 min, 1 h, 3 h, and 6 h after injury and returned to control levels at 24-48 h after injury. We also investigated the effect of mu-calpain activation on proteolysis of the neuronal cytoskeletal protein alpha-spectrin. Immunoreactivity for alpha-spectrin breakdown products was detectable within 15 min after injury in cortical samples ipsilateral to the injury site. The levels of alpha-spectrin breakdown products increased in a biphasic manner, with a large increase between 15 min and 6 h after injury, followed by a smaller increase between 6 and 24 h after the insult. No further accumulation of alpha-spectrin breakdown products was observed between 24 and 48 h after injury. Histopathological examinations using hematoxylin and eosin staining demonstrated dark, shrunken neurons within 15 min after traumatic brain injury. No evidence of mu-calpain autolysis, calpain-mediated alpha-spectrin degradation, or hematoxylin and eosin neuronal pathology was detected in the contralateral cortex. Although mu-calpain autolysis and cytoskeletal proteolysis occurred concurrently with early morphological alterations, evidence of calpain-mediated proteolysis preceded the full expression of evolutionary histopathological changes. Our results indicate that rapid and persistent mu-calpain activation plays an important role in cortical neuronal degeneration after traumatic brain injury. Our data also suggest that specific inhibitors of calpain could be potential therapeutic agents for the treatment of traumatic brain injury in vivo.

Decreased receptor-mediated calcium response in prion-infected cells correlates with decreased membrane fluidity and IP3 release

The most characteristic neuropathologic features of prion diseases are accumulation of PrPSc in the brain and vacuolation of neurons. Neuronal vacuolation suggests plasma membrane dysfunction. In an earlier study, we found that bradykinin (Bk)-stimulated Ca2+ responses in scrapie-infected ScN2a cells were reduced by 30 to 50% compared with uninfected N2a cells. In this study, we investigated the cause. The IP3 second-messenger response to Bk stimulation was reduced 90%, indicating that a defect occurs in the plasma membrane. Receptor-binding assays showed a 3- to 4-fold increase in Bk receptor numbers on ScN2a cells; however, their binding affinity was reduced 5- to 13-fold, which may account for the decreased IP3 and Ca2+ responses. These results argue that scrapie causes a more fundamental change in the properties of the plasma membrane. We verified this by fluorescence recovery after photobleaching (FRAP) analysis with a lipid probe that measures lateral membrane fluidity. A 7-fold reduction of fluidity was found. These results support the hypothesis that the conversion of PrPc to PrPSc or the accumulation of PrPSc in scrapie-infected cells alters the composition of their plasma membranes that secondarily causes the abnormal receptor-mediated function.

The corporate assault on the Food and Drug Administration

Current "regulatory reform" in the U.S. Congress is seeking to eliminate the Food and Drug Administration. The author discusses the forces behind this reform and traces the impact of campaign contributions from various industries opposed to FDA regulations, stock held by members of Congress in companies regulated by the FDA, and a variety of organizations with ties to House Speaker Newt Gingrich that have received donations from industries that Gingrich has helped in their efforts to loosen FDA regulations. The article also examines the myth that the FDA is an overzealous watchdog imposing unnecessary burdens on the companies that it regulates. The controversy over the cow hormone rBGH is given as an example.

Regional differences in gene expression for calcium activated neutral proteases (calpains) and their endogenous inhibitor calpastatin in mouse brain and spinal cord

The family of calpains (CANP or calcium activated neutral proteases) and their endogenous inhibitor calpastatin have been implicated in many neural functions; however, functional distinctions between the major calpain isoforms, calpain I and II, have not been clearly established. In the present study we analyzed the gene expression patterns for calpain I and II and calpastatin in mouse brain and spinal cord by measuring both their mRNA and protein levels. Our results show that the overall mRNA level measured by competitive reverse transcription polymerase chain reaction for calpain II is 15-fold higher and for calpastatin is three-fold higher than that for calpain I. Overall, both mRNA and protein expression levels for the calpains and calpastatin showed no significant difference between the spinal cord and the brain. The cellular distributions of mRNA for calpain I or calpastatin, measured by in situ hybridization, are relatively uniform throughout the brain. In contrast, calpain II gene expression is selectively higher in certain neuron populations including pyramidal neurons of the hippocampus and the deep neocortical layers, Purkinje cells of cerebellum, and motor neurons of the spinal cord. The motor neurons were the most enriched in calpain message. Motor neurons possessed 10-fold more calpain II mRNA than any other spinal cord cell type. The differential distribution of the two proteases in the brain and the spinal cord at the mRNA level indicates that the two calpain genes are differentially regulated, suggesting that they play different physiological roles in neuronal activities and that they may participate in the pathogenesis of certain regional neurological degenerative diseases.