TCF1-LEF1 co-expression identifies a multipotent progenitor cell (TH2-MPP) across human allergic diseases

Repetitive exposure to antigen in chronic infection and cancer drives T cell exhaustion, limiting adaptive immunity. In contrast, aberrant, sustained T cell responses can persist over decades in human allergic disease. To understand these divergent outcomes, we employed bioinformatic, immunophenotyping and functional approaches with human diseased tissues, identifying an abundant population of type 2 helper T (TH2) cells with co-expression of TCF7 and LEF1, and features of chronic activation. These cells, which we termed TH2-multipotent progenitors (TH2-MPP) could self-renew and differentiate into cytokine-producing effector cells, regulatory T (Treg) cells and follicular helper T (TFH) cells. Single-cell T-cell-receptor lineage tracing confirmed lineage relationships between TH2-MPP, TH2 effectors, Treg cells and TFH cells. TH2-MPP persisted despite in vivo IL-4 receptor blockade, while thymic stromal lymphopoietin (TSLP) drove selective expansion of progenitor cells and rendered them insensitive to glucocorticoid-induced apoptosis in vitro. Together, our data identify TH2-MPP as an aberrant T cell population with the potential to sustain type 2 inflammation and support the paradigm that chronic T cell responses can be coordinated over time by progenitor cells.

Making the Case for Virtual Surgical Planning: Bilateral Sequential Fibula Flaps with Immediate Dental Implants for Maxillectomy

SUMMARY

Oncologic maxillectomy defects requiring bony reconstruction are among the most challenging head and neck cases because of the complex three-dimensional geometry of the midface. Virtual surgical planning technology is advantageous in these cases because it provides superior positional precision and accuracy compared with traditional techniques and facilitates prosthodontic rehabilitation. Maxillary cancer recurrence after an initial fibula flap reconstruction presents a unique challenge. The authors report the first two cases of sequential fibula flaps after second or recurrent cancer of the maxilla. Virtual surgical planning facilitated resection with adequate tumor margins, optimized anatomic positioning of the fibula construct with three-dimensional printed plates, and enabled immediate functional dental implant placement.

Digital Transfer for Hand Reconstruction in Cleft Hand and Foot Differences

BACKGROUND

 Digital transfer for hand reconstruction in children with cleft hand and foot differences present unique challenges with anomalous anatomy and rare opportunities to dramatically improve function of one- or two-digit hands.

METHODS

 Medical records were reviewed for patients with cleft hand and foot treated at two pediatric institutions between 1996 and 2018. Hospital records, clinical photographs, radiographs, and alginate molds were available on all patients. Patient characteristics, indications for transfer, associated syndromes, donor and recipient anatomy, and complications were examined.

RESULTS

 Twenty digital transfers were identified in 16 patients. The mean age at time of transfer was 6 years (range: 3-18 years). Associated syndromes in this study included ectrodactyly ectodermal dysplasia clefting (EEC) syndrome and Goltz's syndrome. Recipient sites included the thumb (n = 17) and index ray (n = 3) in 10 hands with monodactyly, 6 hands with a two-digit ulnar syndactyly, and 3 hands with central deficiency and associated polydactyly or other anomalies. Donor sites included the great toe (n = 7), fifth toe (n = 9), great toe polydactyly (n = 2), thumb polydactyly (n = 1), and second toe (n = 1). All transfers survived. Revisions included tenolysis (n = 2), repeat fixation for nonunion or malunion (n = 2), and fusion for instability (n = 3).

CONCLUSION

 Digital transfer in cleft hand and foot patients is a functional endeavor. The transferred digits provide sensation, mobility, and stability for opposition. Technically challenging due to small structures and atypical anatomy, these rare cases represent unique opportunities to improve function and appearance in the pediatric hand. This is a therapeutic study and reflects level of evidence IV.

Epigenetic Control of Cdkn2a.Arf Protects Tumor-Infiltrating Lymphocytes from Metabolic Exhaustion

T-cell exhaustion in cancer is linked to poor clinical outcomes, where evidence suggests T-cell metabolic changes precede functional exhaustion. Direct competition between tumor-infiltrating lymphocytes (TIL) and cancer cells for metabolic resources often renders T cells dysfunctional. Environmental stress produces epigenome remodeling events within TIL resulting from loss of the histone methyltransferase EZH2. Here, we report an epigenetic mechanism contributing to the development of metabolic exhaustion in TIL. A multiomics approach revealed a Cdkn2a.Arf-mediated, p53-independent mechanism by which EZH2 inhibition leads to mitochondrial dysfunction and the resultant exhaustion. Reprogramming T cells to express a gain-of-function EZH2 mutant resulted in an enhanced ability of T cells to inhibit tumor growth in vitro and in vivo. Our data suggest that manipulation of T-cell EZH2 within the context of cellular therapies may yield lymphocytes that are able to withstand harsh tumor metabolic environments and collateral pharmacologic insults. SIGNIFICANCE: These findings demonstrate that manipulation of T-cell EZH2 in cellular therapies may yield cellular products able to withstand solid tumor metabolic-deficient environments. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/21/4707/F1.large.jpg.

Proteogenomic analysis of melanoma brain metastases from distinct anatomical sites identifies pathways of metastatic progression

Melanoma brain metastases (MBM) portend a grim prognosis and can occur in up to 40% of melanoma patients. Genomic characterization of brain metastases has been previously carried out to identify potential mutational drivers. However, to date a comprehensive multi-omics approach has yet to be used to analyze brain metastases. In this case report, we present an unbiased proteogenomics analyses of a patient's primary skin cancer and three brain metastases from distinct anatomic locations. We performed molecular profiling comprised of a targeted DNA panel and full transcriptome as well as proteomics using mass spectrometry. Phylogeny demonstrated that all MBMs shared a SMARCA4 mutation and deletion of 12q. Proteogenomics identified multiple pathways upregulated in the MBMs compared to the primary tumor. The protein, PIK3CG, was present in many of these pathways and had increased gene expression in metastatic melanoma tissue from the cancer genome atlas data. Proteomics demonstrated PIK3CG levels were significantly increased in all 3 MBMs and this finding was further validated by immunohistochemistry. In summary, this case report highlights the potential role of proteogenomics in identifying pathways involved in metastatic tumor progression. Furthermore, our multi-omics approach can be considered to aid in precision oncology efforts and provide avenues for therapeutic innovation.

Abstract 1029: Epigenetic control of tumor-infiltrating lymphocyte metabolic-exhaustion

Direct competition between tumor-infiltrating lymphocytes and cancer cells for metabolic resources often renders T cells dysfunctional. It is becoming clearer that T cell metabolic changes can precede functional exhaustion. In the case of solid tumors, the driving force of this dysfunction is thought to be a result of inhibitory metabolism (e.g. glucose deprivation and mitochondrial dysfunction). The mechanisms connecting inhibitory metabolism and T cell metabolic exhaustion are largely unknown. Interestingly, T cells undergo a loss of the histone methyltransferase EZH2 (H3K27me3) during tumor infiltration. Methyltransferases, like EZH2, depend on mitochondria to supply S-Adenosyl-L-Methionine (SAM), the primary methyl donor. We sought to determine if there was a link between EZH2 and mitochondrial function. In this work, we utilized highly specific EZH2 inhibitors to model acute inhibition of EZH2 in CD8+ and CD4+ T cells. Taking an unbiased, multi-omics approach (proteomics, RNAseq, ChIPseq) we fully interrogate the downstream consequences of EZH2 inhibition in T cells. The loss of H3K27me3 does indeed lead to an induction of mitochondrial dysfunction, which in turn, drives a dependency on glycolytic metabolism and sensitivity to glucose withdrawal. The metabolic shift phenotype was confirmed using extracellular metabolic flux analysis. In T cells, we found the loss of H3K27me3 repression of the Cdkn2aArf locus to be a major contributor to mitochondrial dysfunction, independent of the canonical role to stabilize p53. Furthermore, we show Arf-/- mice are resistant to EZH2-inhibition induced mitochondrial dysfunction. Reprogramming tumor-specific T cells to exogenously express a gain-of-function EZH2 mutant (Y641F) resulted in an enhanced ability of T cells to inhibit solid tumor growth. This work demonstrates the potential for manipulation of EZH2 in cellular therapies for solid tumors with harsh metabolic conditions and sheds light on the dynamic interplay of epigenetics and metabolic sufficiency.

Citation Format: Brian Koss, Bradley D. Shields, Erin M. Taylor, Aaron J. Storey, Stephanie D. Byrum, Allen J. Gies, Charity L. Washam, Samrat Roy Choudhury, Jeong Hyun Ahn, Hidetaka Uryu, Kimberly J. Krager, Tung-Chin Chiang, Samuel G. Mackintosh, Rick D. Edmondson, Nukhet Aykin-Burns, Gang Greg Wang, Alan J. Tackett. Epigenetic control of tumor-infiltrating lymphocyte metabolic-exhaustion [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1029.

Histone Modifications as Biomarkers for Immunotherapy

Recent advances in immunotherapy have revolutionized the treatment of certain cancers. Some patients show a durable response to these immunotherapies, while others show little benefit or develop resistance. Identification of biomarkers to predict responsiveness will be helpful for informing treatment strategies; and would furthermore lead to the identification of molecular pathways dysregulated in nonresponding patients that could be targeted for therapeutic development. Pathways of epigenetic modification, such as histone posttranslational modifications (PTMs), have been shown to be dysregulated in certain cancer and immune cells. Histones are abundant cellular proteins readily assayed with high-throughput technologies, making them attractive targets as biomarkers. We explore promising advancements for using histone PTMs as immunotherapy responsiveness biomarkers in both cancer and immune cells, and provide a methodological workflow for assaying histone PTMs in relevant samples.

Loss of E-Cadherin Inhibits CD103 Antitumor Activity and Reduces Checkpoint Blockade Responsiveness in Melanoma

Identifying controlling features of responsiveness to checkpoint blockade therapies is an urgent goal in oncology research. Our group and others have previously shown melanoma tumors resistant to checkpoint blockade display features of mesenchymal transition, including E-cadherin loss. Here, we present the first in vivo evidence that E-cadherin from tumor cells facilitate immune attack, using a B16F10 melanoma mouse model in which E-cadherin is exogenously expressed (B16.Ecad). We find, compared with vector control, B16.Ecad exhibits delayed tumor growth, reduced metastatic potential, and increased overall survival in vivo. Transplantation of B16.Ecad into Rag1^-/- and CD103^-/- mice abrogated the tumor growth delay. This indicates the anti-melanoma response against B16.Ecad is both immune and CD103⁺ mediated. Moreover, B16.Ecad showed increased responsiveness to combination immune checkpoint blockade (ICB) compared with vector control. This work establishes a rationale for ICB responses observed in high E-cadherin-expressing tumors and suggests therapeutic advancement through amplifying CD103⁺ immune cell subsets.Significance: These findings identify the mechanism behind checkpoint blockade resistance observed in melanoma that has undergone mesenchymal transition and suggest activation of CD103⁺ immune cells as a therapeutic strategy against other E-cadherin-expressing malignancies.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/6/1113/F1.large.jpg.

Quantitative microinjection using fluorescence calibration of streaming microdroplets on a superhydrophobic surface

A simple and reproducible procedure was developed to measure the volume of liquid microinjected into cells. A calibration curve of droplet fluorescence intensity versus volume was constructed by injecting a fluorescent dextran solution through a 125-150 µm diameter micropipette into an oil-filled culture dish to create a spray of varied-sized droplets. The droplets retained a spherical shape because they were in an oil medium and they settled onto a glass surface coated with a superhydrophobic surface. Fluorescent micrographs of the droplets were obtained and analyzed with Image-J software to quantify the fluorescence intensity and radius of each spherical droplet to produce the calibration curve. Subsequently, Dut-145 human prostate carcinoma cells were microinjected with the same fluorescent dextran solution and fluorescent micrographs of the cells were obtained using the identical exposure conditions used to photograph the droplets. The measured fluorescence intensity of the microinjected cells was entered into the formula for the regression line that was fit to the calibration curve allowing determination of the volume of solution injected into each cell. Thus, a mixture consisting of known concentrations of a test material of test material (macromolecules, drugs, etc.) and a fluorescent dextran, volumetric, tracer can be used to quantify the relationship between the amount of a microinjected material and subsequent effects on cells.

Skeletal Muscle PGC1α -1 Nucleosome Position and -260 nt DNA Methylation Determine Exercise Response and Prevent Ectopic Lipid Accumulation in Men

Endurance exercise has been shown to improve lipid oxidation and increase mitochondrial content in skeletal muscle, two features that have shown dependence on increased expression of the peroxisome proliferator-activated receptor-γ coactivator 1α (PGC1α). It is also hypothesized that exercise-related alterations in PGC1α expression occur through epigenetic regulation of nucleosome positioning in association with differential DNA methylation status within the PGC1α promoter. In this study, we show that when primary human myotubes from obese patients with type 2 diabetes are exposed to lipolytic stimulus (palmitate, forskolin, inomycin) in vitro, nucleosome occupancy surrounding the -260 nucleotide (nt) region, a known regulatory DNA methylation site, is reduced. This finding is reproduced in vivo in the vastus lateralis from 11 healthy males after a single, long endurance exercise bout in which participants expended 650 kcal. Additionally, we show a significant positive correlation between fold change of PGC1α messenger RNA expression and -1 nucleosome repositioning away from the -260 nt methylation site in skeletal muscle tissue following exercise. Finally, we found that when exercise participants are divided into high and low responders based on the -260 nt methylation status, the -1 nucleosome is repositioned away from the regulatory -260 nt methylation site in high responders, those exhibiting a significant decrease in -260 nt methylation, but not in low responders. Additionally, high but not low responders showed a significant decrease in intramyocellular lipid content after exercise. These findings suggest a potential target for epigenetic modification of the PGC1α promoter to stimulate the therapeutic effects of endurance exercise in skeletal muscle.

Abstract LB-206: Indicators of responsiveness to immune checkpoint inhibitors

Modulation of the immune system can produce anti-tumor responses in various cancer types, including melanoma. Recently, immune checkpoint inhibitors, in single agent and combination regimens, have produced durable and long-lasting clinical responses in a subset of metastatic melanoma patients. These monoclonal antibodies, developed against CTLA-4 and PD-1, block immune-inhibitory receptors on activated T-cells, amplifying the immune response. However, even when using anti-CTLA-4 and anti-PD-1 in combination, approximately half of patients exhibit innate resistance and suffer from disease progression. Currently, it is impossible to predict therapeutic response. Here, we report the first proteomic and histone epigenetic analysis of patient metastatic melanoma tumors taken prior to immune checkpoint inhibitor therapy, which revealed specific biological signatures that can stratify metastatic melanoma patients as responders or non-responders. Furthermore, our findings provide the first evidence of epigenetically-driven epithelial-mesenchymal transition, a known mechanism of immune-escape, in non-responding melanoma tumors. We identified elevated histone H3 lysine (27) trimethylation (H3K27me3), decreased E-cadherin, and other protein features indicating a more mesenchymal phenotype in non-responding tumors. Furthermore, we show E-cadherin is transcriptionally regulated by the EZH2-catalyzed H3K27me3 epigenetic mark in non-responding tumors. The repressive epigenetic mark H3K27me3, has known roles in melanoma pathogenesis and progression, but not in response to immunotherapies. Here, we provide the first report of an epigenetic program directly linking elevated levels of H3K27me3 to non-responding tumors. Our results have broad implications for immune checkpoint inhibitor therapy in a variety of carcinomas as patient specific responsiveness can be predicted through readily assayable proteins and histone epigenetic marks, and specific pathways activated in non-responders have been identified for therapeutic development to enhance responsiveness.

Citation Format: Bradley D. Shields, Fade Mahmoud, Erin M. Taylor, Stephanie D. Byrum, Deepanwita Sengupta, Brian Koss, Giulia Baldini, Seth Ransom, Kyle Cline, Samuel Mackintosh, Ricky Edmondson, Sara C. Shalin, Alan J. Tackett. Indicators of responsiveness to immune checkpoint inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-206. doi:10.1158/1538-7445.AM2017-LB-206

Indicators of responsiveness to immune checkpoint inhibitors

Modulation of the immune system can produce anti-tumor responses in various cancer types, including melanoma. Recently, immune checkpoint inhibitors (ICI), in single agent and combination regimens, have produced durable and long-lasting clinical responses in a subset of metastatic melanoma patients. These monoclonal antibodies, developed against CTLA-4 and PD-1, block immune-inhibitory receptors on activated T-cells, amplifying the immune response. However, even when using anti-CTLA-4 and anti-PD-1 in combination, approximately half of patients exhibit innate resistance and suffer from disease progression. Currently, it is impossible to predict therapeutic response. Here, we report the first proteomic and histone epigenetic analysis of patient metastatic melanoma tumors taken prior to checkpoint blockade, which revealed biological signatures that can stratify patients as responders or non-responders. Furthermore, our findings provide evidence of mesenchymal transition, a known mechanism of immune-escape, in non-responding melanoma tumors. We identified elevated histone H3 lysine (27) trimethylation (H3K27me3), decreased E-cadherin, and other protein features indicating a more mesenchymal phenotype in non-responding tumors. Our results have implications for checkpoint inhibitor therapy as patient specific responsiveness can be predicted through readily assayable proteins and histone epigenetic marks, and pathways activated in non-responders have been identified for therapeutic development to enhance responsiveness.

Surgeon-Based 3D Printing for Microvascular Bone Flaps

Background Three-dimensional (3D) printing has developed as a revolutionary technology with the capacity to design accurate physical models in preoperative planning. We present our experience in surgeon-based design of 3D models, using home 3D software and printing technology for use as an adjunct in vascularized bone transfer. Methods Home 3D printing techniques were used in the design and execution of vascularized bone flap transfers to the upper extremity. Open source imaging software was used to convert preoperative computed tomography scans and create 3D models. These were printed in the surgeon's office as 3D models for the planned reconstruction. Vascularized bone flaps were designed intraoperatively based on the 3D printed models. Results Three-dimensional models were created for intraoperative use in vascularized bone flaps, including (1) medial femoral trochlea (MFT) flap for scaphoid avascular necrosis and nonunion, (2) MFT flap for lunate avascular necrosis and nonunion, (3) medial femoral condyle (MFC) flap for wrist arthrodesis, and (4) free fibula osteocutaneous flap for distal radius septic nonunion. Templates based on the 3D models allowed for the precise and rapid contouring of well-vascularized bone flaps in situ, prior to ligating the donor pedicle. Conclusions Surgeon-based 3D printing is a feasible, innovative technology that allows for the precise and rapid contouring of models that can be created in various configurations for pre- and intraoperative planning. The technology is easy to use, convenient, and highly economical as compared with traditional send-out manufacturing. Surgeon-based 3D printing is a useful adjunct in vascularized bone transfer. Level of Evidence Level IV.

Effects of naltrexone are influenced by childhood adversity during negative emotional processing in addiction recovery

Naltrexone is an opioid receptor antagonist used in the management of alcohol dependence. Although the endogenous opioid system has been implicated in emotion regulation, the effects of mu-opioid receptor blockade on brain systems underlying negative emotional processing are not clear in addiction. Individuals meeting criteria for alcohol dependence alone (n=18, alcohol) and in combination with cocaine and/or opioid dependence (n=21, alcohol/drugs) and healthy individuals without a history of alcohol or drug dependence (n=21) were recruited. Participants were alcohol and drug abstinent before entered into this double-blind, placebo-controlled, randomized, crossover study. Functional magnetic resonance imaging was used to investigate brain response while viewing aversive and neutral images relative to baseline on 50 mg of naltrexone and placebo. We found that naltrexone modulated task-related activation in the medial prefrontal cortex and functional connectivity between the anterior cingulate cortex and the hippocampus as a function of childhood adversity (for aversive versus neutral images) in all groups. Furthermore, there was a group-by-treatment-by-condition interaction in the right amygdala, which was mainly driven by a normalization of response for aversive relative to neutral images under naltrexone in the alcohol/drugs group. We conclude that early childhood adversity is one environmental factor that influences pharmacological response to naltrexone. Pharmacotherapy with naltrexone may also have some ameliorative effects on negative emotional processing in combined alcohol and drug dependence, possibly due to alterations in endogenous opioid transmission or the kappa-opioid receptor antagonist actions of naltrexone.

Health Risk Factors and Desire to Change among Homeless Adults

OBJECTIVES

The prevalence of smoking, at-risk alcohol use, overweight/obesity, inadequate fruit and vegetable consumption, and inadequate physical activity was examined among homeless adults. Desire to change these modifiable health risk factors and the association between desire to change and self-rated health also were examined.

METHODS

A sample of 394 homeless adults completed computer-based questionnaires (read over headphones) that assessed sociodemographic characteristics, health risk factors, desire to address health risk factors, and self-rated health.

RESULTS

Participants were primarily men (71.8%) and African Americans (62.8%). Most participants were current smokers (75.9%), 31.0% were at-risk drinkers, 58.8% were over-weight or obese, 66.2% consumed fewer than 5 fruits and vegetables per day, and 29.9% had insufficient physical activity. With the exception of at-risk drinking, more than half of those with each health risk factor reported a desire to address that factor. Poorer self-rated health was associated with desire to reduce drinking (p = .023) and increase fruit and vegetable consumption (p = .027); it was marginally related to desire to lose weight (p = .057).

CONCLUSIONS

Although the prevalence of modifiable health risk factors in homeless adults is high, the desire to change many risk factors is also high, indicating the need for relevant interventions for homeless adults.

A Review of Mitochondrial-derived Fatty Acids in Epigenetic Regulation of Obesity and Type 2 Diabetes

Type 2 diabetes, the leading metabolic disease, is characterized by insulin resistance and is associated with obesity. The onset of type 2 diabetes is largely due to environmental inputs, such as high dietary fat content and decreased levels of exercise. Insulin resistance resulting from high fat diet is associated with skeletal muscle mitochondrial dysfunction, leading to alterations in lipid accumulation and specific species of intracellular fatty acids; whereas, exercise training augments insulin resistance while improving skeletal muscle mitochondrial function and producing beneficial fatty acid profiles. Additionally, high fat diets and exercise alter epigenetic modifications, including DNA methylation and histone acetylation, to produce differences in metabolic gene expression that are associated with insulin resistance and sensitivity, respectively. Recent evidence suggests that short chain fatty acids that act as histone deacetylase inhibitors prevent and ameliorate obesity and insulin resistance. Here, we discuss the potential of mitochondrial-derived fatty acids, especially short chain fatty acids, to epigenetically regulate obesity and type 2 diabetes.

Blastic plasmacytoid dendritic cell neoplasm in an elderly woman

Blastic plasmacytoid dendritic cell neoplasm (a.k.a. NK cell lymphoma, CD4+CD56+ haematodermic neoplasm) is a rare aggressive tumour that arises from plasmacytoid dendritic cell precursors. We report the first case from Malaysia of a 79-year-old Chinese woman who presented with purpuric plaques and nodules produced by pleomorphic CD4+, CD56+, CD68+, CD123+ and CD303+, but CD2APmononuclear cell infiltrates. Leukemic dissemination occurred and she succumbed to disease without treatment 4 weeks after diagnosis and 9 months after onset of cutaneous disease.

Multiple sclerosis susceptibility alleles in African Americans

Multiple sclerosis (MS) is an autoimmune demyelinating disease characterized by complex genetics and multifaceted gene-environment interactions. Compared to whites, African Americans have a lower risk for developing MS, but African Americans with MS have a greater risk of disability. These differences between African Americans and whites may represent differences in genetic susceptibility and/or environmental factors. SNPs from 12 candidate genes have recently been identified and validated with MS risk in white populations. We performed a replication study using 918 cases and 656 unrelated controls to test whether these candidate genes are also associated with MS risk in African Americans. CD6, CLEC16a, EVI5, GPC5, and TYK2 contained SNPs that are associated with MS risk in the African American data set. EVI5 showed the strongest association outside the major histocompatibility complex (rs10735781, OR=1.233, 95% CI=1.06-1.43, P-value=0.006). In addition, RGS1 seems to affect age of onset whereas TNFRSF1A seems to be associated with disease progression. None of the tested variants showed results that were statistically inconsistent with the effects established in whites. The results are consistent with shared disease genetic mechanisms among individuals of European and African ancestry.

Regulating private health insurance: The reality behind the rhetoric in Uganda

The continued preponderance of large health budget deficits in low-income countries has led to increasing international debate over the role that private health insurance could play in providing additional financing for health. However, the market failures inherent to insurance constitute a major concern and proponents are now advocating that states employ calculated regulations to offset these tendencies. This article uses an examination of the policy evolution of the Government of Uganda to demonstrate how one low-income country has heeded the call for regulation yet, so far, has remained unable to implement the resulting policies. In doing so, the case study exposes the contradiction underlying the impetus for the state to regulate private health insurance in low-income settings, namely, that while private health insurance is advanced as one response to the failure of the nation state and its inability to provide adequate health services for its population, the same 'failing' state is now being called upon to govern against the market failures inherent to the product.

Long-term trends in pH, aluminium and dissolved organic carbon in Scottish fresh waters; implications for brown trout (Salmo trutta) survival

Over the past 30 years upland streams and lochs in Scotland have shown significant signs of recovery from acidification, particularly in terms of declining concentrations of non-marine sulphate (nm-SO(4)). Long-term index sites in central and southwest Scotland reveal a significant decline in the concentration of biologically important components, notably acidity (H(+)) and labile (toxic) forms of aluminium (Al-L), whilst dissolved organic carbon (DOC) and complexed forms of aluminium (AL-NL) have increased significantly. Although these improvements should increase the probability of brown trout survival, and have resulted in increased acid neutralising capacity (ANC) in fishless streams to values close to current critical limits, there is still a relatively poor correlation between ANC and current fish status. Site to site variability appears to be linked to the relative contribution of (H(+)), Al-L and DOC within the critical ANC (ANC(CRIT)) range. It is proposed that ANC(CRIT) should cover a range of ANC values as a function of Al-L concentration. Based on field studies an empirical range of critical ANC values are suggested which better predict the presence of a sustainable brown trout population.

Quantifying the effects of forestry practices on the recovery of upland streams and lochs from acidification

Trends in long-term chemistry data are presented for 37 acidified upland streams and lochs, located in four areas (A, B, C and D) across Scotland, to provide a comparison between recovery rates of moorland catchments and forest catchments at different stages of the management cycle. For all sites, non-marine sulfate (nm-SO(4)) showed a significant decline in annual median concentrations, the greatest decline being in streams draining felled catchments, which showed a 50% greater decline than catchments with moorland or young, aggrading forests. A similar pattern was found for chloride (Cl) concentrations in Area C, which reflected the reduced interception of sea-salt aerosols following clearfelling. However, high elevation moorland sites in Area D also revealed significant declines in Cl while trends in aggrading forest sites in this area were insignificant. Alkalinity (ALK) and pH increased more at sites where felling had taken place than at moorland or young forest sites while aggrading forest catchments appeared to be most resistant to changes in pH and ALK. Associated with these acid-base changes was a corresponding decline in labile aluminium (Al-L) concentrations. The pattern of nitrate (NO(3)) change was especially affected by the timing of felling in forested catchments. Large negative trends in NO(3) at stream sites were associated with felling during the early part of the study period. This downward trend was further enhanced as NO(3) concentrations fell below pre-felling levels as the second rotation crop became established. Few forest sites showed significant increases in NO(3) due to felling in the latter part of the study period. Most moorland loch sites showed a small but significant increase in NO(3,) probably in response to similar increases in N deposition and/or climatic impacts. Dissolved organic carbon (DOC) increased significantly at both forest and moorland sites, however, the extent of these increasing trends appeared to be positively correlated with absolute DOC concentrations. Despite the complex response of streams and lochs during the various stages of the forest cycle, especially for NO(3), both forest and moorland catchments showed generally similar and rapid responses to reductions in S deposition. Nevertheless, forested sites are still more acid and have higher concentrations of toxic forms of Al than moorland sites. Although the proposed emission reductions in Europe are likely to result in a continuing decline in S and N loadings to catchments, the continuing policy of planting second rotation forests in these acidified catchments may, in the long-term, delay or halt chemical and biological recovery. However, in the short-term, any increase in the uptake of N deposition by aggrading forests should help to counteract the acidifying effects of a small increase in the interception of S and N compounds.

Is postnatal depression a risk factor for sudden infant death?

BACKGROUND

In New Zealand, an association has been shown between postnatal depression and sudden infant death syndrome (SIDS).

AIM

To replicate the New Zealand study.

DESIGN OF STUDY

Case-control study.

SETTING

The city of Sheffield, UK.

METHOD

The database of the Sheffield Child Development Study was used Demographic and obstetric data were collected and at one month postpartum the Edinburgh Postnatal Depression Scale (EPDS) was administered. Detailed information on the cause of all infant deaths was available.

RESULTS

There were 32,984 live births during the study period (from the year 1988 to 1993) and 42 babies died with the cause registered as SIDS. Multivariate analysis showed that smoking was the most important risk factorfor SIDS (odds ratio [OR] = 7.24, 95% confidence interval [95% CI] = 2.76 to 19.01), followed by a high EPDS (OR = 3.20, 95% CI = 1.46 to 6.99) and residence in an area of poverty (OR = 2.33, 95% CI = 1.06 to 5.11).

CONCLUSIONS

The Sheffield data confirm the New Zealand findings. A high EPDS score and, by implication, postnatal depression, may be risk factors for SIDS, however, there are many possible explanations for the association.

Two individuals with features of both xeroderma pigmentosum and trichothiodystrophy highlight the complexity of the clinical outcomes of mutations in the XPD gene

The xeroderma pigmentosum group D (XPD) protein is a subunit of transcription factor TFIIH with DNA helicase activity. TFIIH has two functions, in basal transcription and nucleotide excision repair. Mutations in XPD that affect DNA repair but not transcription result in the skin cancer-prone disorder, xeroderma pigmentosum (XP). If transcription is also affected, the result is the multi-system disorder trichothiodystrophy (TTD), in which there is no skin cancer predisposition, or in rare cases, XP combined with Cockayne syndrome. Up till now there have been no reports of combined clinical features of XP and TTD. We have now identified two patients with some features of both these disorders. One of these, XP189MA, a 3-year-old girl with sun sensitivity, mental and physical developmental delay, has XPD mutations not previously reported, and barely detectable levels of nucleotide excision repair. The other, XP38BR, a 28-year-old woman with sun sensitivity, pigmentation changes and skin cancers typical of XP, has a mutation that has been identified previously, but only in TTD patients with no features of XP. The level of repair of UV damage in XP38BR is substantially higher than that in other patients with the same mutation. With both patients, polarized light microscopy revealed a 'tiger-tail' appearance of the hair, and amino acid analysis of the hair shafts show levels of sulfur-containing proteins intermediate between those of normal and TTD individuals. Our findings highlight the complexities of genotype-phenotype relationships in the XPD gene.

Characterization of a novel human SMC heterodimer homologous to the Schizosaccharomyces pombe Rad18/Spr18 complex

The structural maintenance of chromosomes (SMC) protein encoded by the fission yeast rad18 gene is involved in several DNA repair processes and has an essential function in DNA replication and mitotic control. It has a heterodimeric partner SMC protein, Spr18, with which it forms the core of a multiprotein complex. We have now isolated the human orthologues of rad18 and spr18 and designated them hSMC6 and hSMC5. Both proteins are about 1100 amino acids in length and are 27-28% identical to their fission yeast orthologues, with much greater identity within their N- and C-terminal globular domains. The hSMC6 and hSMC5 proteins interact to form a tight complex analogous to the yeast Rad18/Spr18 heterodimer. In proliferating human cells the proteins are bound to both chromatin and the nucleoskeleton. In addition, we have detected a phosphorylated form of hSMC6 that localizes to interchromatin granule clusters. Both the total level of hSMC6 and its phosphorylated form remain constant through the cell cycle. Both hSMC5 and hSMC6 proteins are expressed at extremely high levels in the testis and associate with the sex chromosomes in the late stages of meiotic prophase, suggesting a possible role for these proteins in meiosis.

Retro-inverso prosaptide peptides retain bioactivity, are stable In vivo, and are blood-brain barrier permeable

Prosaptide (trademark of Myelos Corporation, San Diego, CA) peptides are based on the 14-amino-acid neurotrophic sequence of human prosaposin and, like the parent protein, have potent neurotrophic and neuroprotective properties. We previously examined the in vivo stability of a series of bioactive Prosaptide peptides and designed peptides with increased enzymatic stability in the central and peripheral nervous systems. In this article, we examined the stability, biological activity, and permeability of the blood-brain barrier to retro-inverso Prosaptide peptidomimetics. Retro-inversion both reverses the primary sequence and replaces L-amino acids with D-amino acids. We examined the bioactivity of five peptidomimetics, Prosaptides D1-D5. Prosaptide D1, a peptide containing all D-amino acids with the primary sequence intact, was inactive. However, four retro-inverso peptidomimetics, Prosaptides D2-D5 retained bioactivity in neurite outgrowth and [(35)S]GTPgammaS binding assays. We focused on Prosaptide D4 as a prototypical retro-inverso Prosaptide peptidomimetic for further study. (125)I-Prosaptide D4 remained intact in brain or serum for 60 min after i.v. administration and was transported across the blood-brain barrier with a unidirectional influx constant of 2.5 x 10(-4) ml. g(-1). min(-1). We conclude that retro-inverso Prosaptide peptidomimetics are excellent candidates for development as therapeutics for central nervous system neurodegeneration.

AIT-082, a cognitive enhancer, is transported into brain by a nonsaturable influx mechanism and out of brain by a saturable efflux mechanism

A fundamental feature of any drug designed to treat a disease of the central nervous system is the ability to cross the blood-brain barrier. Passage across the blood-brain barrier of AIT-082, a cognitive enhancer, was investigated in mice. [(14)C]AIT-082 crossed the blood-brain barrier in young male Swiss-Webster mice with a mean influx constant (K(i)) of 0.6 +/- 0.2 microl g(-1) min(-1). Furthermore, [(14)C]AIT-082 was transported into brain of both young and old male C57BL/6 mice with a K(i) of 0.35 +/- 0.06 and 0.33 +/- 0.02 microl g(-1) min(-1), respectively. There was no significant effect of age or strain on the movement of [(14)C]AIT-082 across the blood-brain barrier in mice. When 110- or 650-fold excess unlabeled AIT-082 was included in the injection solution, the K(i) was not significantly changed in either Swiss-Webster or C57BL/6 mice. This indicated that [(14)C]AIT-082 crossed the blood-brain barrier by a nonsaturable mechanism. The passage of AIT-082 into brain extracellular fluid was confirmed with capillary depletion and microdialysis. The efflux of [(14)C]AIT-082 from brain also was examined. After i.c.v. injection, [(14)C]AIT-082 levels in brain decreased over time with a t(1/2) of 20.0 +/- 1.0 min. Excess unlabeled AIT-082 (600-fold) increased the t(1/2) to 35.5 +/- 3.6 min. Together, these data indicate that AIT-082 moves into brain via a nonsaturable mechanism and is actively transported out of brain.

Designing stable blood-brain barrier-permeable prosaptide peptides for treatment of central nervous system neurodegeneration

Prosaposin-derived peptides have been proposed as potential therapeutics for neurodegenerative diseases. Previously, we reported that the minimal length for bioactivity was 12 amino acids, and key amino acids were described based on interspecies conservation. In this article, we have further investigated the sequence requirements for bioactive Prosaptide (Myelos Corporation) peptides in terms of length and amino acid identity. The use of Prosaptide peptides for treatment of central nervous system (CNS) disorders requires that they are stable in vivo. Although robust effects of our prototypical peptide Prosaptide TX14(A) have been shown in the peripheral nervous system, minimal success has been achieved when treating the CNS in rats and this may be due to instability of Prosaptide TX14(A) in brain. Herein, we demonstrate that, indeed, Prosaptide TX14(A) is rapidly degraded in the brain and we have attempted to design prosaptides with increased CNS stability. One peptide, Prosaptide TX15-2, shows increased stability in brain and may be of use in the treatment of CNS disorders. With the aim of designing Prosaptide peptides that may be systemically administered for CNS treatment, we have investigated the blood-brain barrier permeability of Prosaptide TX14(A) and TX15-2. Both of these peptides cross the blood-brain barrier via a nonspecific mechanism.

The cancer-free phenotype in trichothiodystrophy is unrelated to its repair defect

The DNA repair-deficient genetic disorders xeroderma pigmentosum (XP) and trichothiodystrophy (TTD) can both result from mutations in the XPD gene, the sites of the mutations differing between the two disorders. The hallmarks of XP are multiple pigmentation changes in the skin and a greatly elevated frequency of skin cancers, characteristics that are not seen in TTD. XP-D and most TTD patients have reduced levels of DNA repair, but some recent reports have suggested that the repair deficiencies in TTD cells are milder than in XP-D cells. We reported recently that inhibition of intracellular adhesion molecule-1 (ICAM-1) expression by UVB irradiation was similar in normal and TTD cells but increased in XP-D cells, suggesting a correlation between ICAM-1 inhibition and cancer proneness. In the first part of the current work, we have extended these studies and found several other examples, including XP-G and Cockayne syndrome cells, in which increased ICAM-1 inhibition correlated with cancer proneness. However, we also discovered that a subset of TTD cells, in which arg112 in the NH2-terminal region of the XPD protein is mutated to histidine, had an ICAM-1 response similar to that of XP-D cells. In the second part of the work, we have shown that TTD cells with this specific NH2-terminal mutation are more sensitive to UV irradiation than other TTDs, most of which are mutated in the COOH-terminal region, and are indistinguishable from XP-D cells in cell killing, incision breaks, and repair of cyclobutane pyrimidine dimers. Because the clinical phenotypes of these patients do not obviously differ from those of TTDs with mutations at other sites, we conclude that the lack of skin abnormalities in TTD is independent of the defective cellular responses to UV. It is likely to result from a transcriptional defect, which prevents the skin abnormalities from being expressed.

Do our patients understand? A comparison of understanding in adult inpatients and schoolchildren

AIM

To test the assumption that if an explanation about a resuscitation policy is understood by a 12-year-old then it will be understood by an adult patient.

METHOD

The comprehension of a paragraph about resuscitation by inpatients was compared to the comprehension of the same paragraph by 12-year-old schoolchildren.

RESULTS

The schoolchildren demonstrated better comprehension of a paragraph about resuscitation than the inpatients (p = 0.02).

CONCLUSIONS

Schoolchildren, aged 12, in a classroom setting show better comprehension than adult medical and surgical inpatients. This has implications about giving information to patients and seeking consent from them. Persons giving information to patients need to ensure the patients have understood it.

1st MRC Human Genetics Symposium: maintenance of genomic stability

This meeting served to juxtapose the fundamental studies on the distinct pathways which maintain genomic stability with work that addresses the phenotypic consequences of loss of genomic stability in humans. This created an exciting environment where we were prompted to think about the links between fundamental and applied research. It was also a forum where new ideas could be formed that will hopefully fuel interesting research in human disease. As we place the genome projects into perspective, the ideas arising from meetings such as the 1st MRC Human Genetics Symposium might be expected to guide studies that will reveal the molecular defects which underlie some of the more impenetrable phenotypes of human diseases.

Abnormally high nourishment during sensitive periods results in body weight changes across generations

OBJECTIVE

This study asked whether a brief period of overnutrition during a developmentally sensitive time could impact the individual's adult weight and that of succeeding generations.

RESEARCH METHODS AND PROCEDURES

Female rat pups (F1 generation) were randomly assigned to 1 of 3 groups: (1) a control group that was naturally reared by mothers; (2) another control group implanted with chronic gastric fistulas on postnatal day 4 and fed enough formula to match the growth of the mother-reared group; and (3) an experimental group gastrostomized and infused from day 8 through day 16 with a greater quantity of food than gastrostomy-reared controls (OF). On postnatal day 16, both gastrostomy-reared groups were returned to normal litters. Adult F1 females from overfed and mother-reared groups were bred with normal males to yield an F2 generation. F2 adult females were bred to normal males to produce an F3 generation.

RESULTS

When adult, the F1 experimental group was heavier than control groups. F2 adults from OF mothers were smaller than those from the control group. F3 animals from OF grandmothers were heavier at weaning than F3 descendants from mother-reared animals.

DISCUSSION

Excess nourishment during a developmentally sensitive period changed the metabolic phenotype of one generation so dramatically that the gestational development and subsequent phenotype of two succeeding generations were also changed. The experiment models fetal effects of gestational diabetes in humans and may help to elucidate how, independent of genetic anomalies, secular changes can be detected across generations.

Conservation of eukaryotic DNA repair mechanisms

PURPOSE

To discuss the evolutionary conservation of different DNA repair processes. The proteins that carry out base excision repair show a varying degree of structural conservation, but a high level of functional complementation between species, as might be expected for a sequential pathway. In nucleotide excision repair there is a high degree of structural conservation, but few examples of functional complementation because the process involves multiprotein complexes. Repair by homologous recombination involves proteins that are highly conserved structurally. The process of repair of DNA breaks by non-homologous end-joining is conserved in eukaryotes, but the level of sequence identity of several of the proteins is fairly low and some components involved in man do not appear to have sequence homologues in yeast.

CONCLUSIONS

All DNA repair processes are highly conserved. The degree of structural and functional conservation varies between the different processes.

Atm-dependent interactions of a mammalian chk1 homolog with meiotic chromosomes

BACKGROUND

Checkpoint pathways prevent cell-cycle progression in the event of DNA lesions. Checkpoints are well defined in mitosis, where lesions can be the result of extrinsic damage, and they are critical in meiosis, where DNA breaks are a programmed step in meiotic recombination. In mitotic yeast cells, the Chk1 protein couples DNA repair to the cell-cycle machinery. The Atm and Atr proteins are mitotic cell-cycle proteins that also associate with chromatin during meiotic prophase I. The genetic and regulatory interaction between Atm and mammalian Chk1 appears to be important for integrating DNA-damage repair with cell-cycle arrest.

RESULTS

We have identified structural homologs of yeast Chk1 in human and mouse. Chk1(Hu/Mo) has protein kinase activity and is expressed in the testis. Chk1 accumulates in late zygotene and pachytene spermatocytes and is present along synapsed meiotic chromosomes. Chk1 localizes along the unsynapsed axes of X and Y chromosomes in pachytene spermatocytes. The association of Chk1 with meiotic chromosomes and levels of Chk1 protein depend upon a functional Atm gene product, but Chk1 is not dependent upon p53 for meiosis I functions. Mapping of CHK1 to human chromosomes indicates that the gene is located at 11q22-23, a region marked by frequent deletions and loss of heterozygosity in human tumors.

CONCLUSIONS

The Atm-dependent presence of Chk1 in mouse cells and along meiotic chromosomes, and the late pachynema co-localization of Atr and Chk1 on the unsynapsed axes of the paired X and Y chromosomes, suggest that Chk1 acts as an integrator for Atm and Atr signals and may be involved in monitoring the processing of meiotic recombination. Furthermore, mapping of the CHK1 gene to a region of frequent loss of heterozygosity in human tumors at 11q22-23 indicates that the CHK1 gene is a candidate tumor suppressor gene.

Xeroderma pigmentosum and trichothiodystrophy are associated with different mutations in the XPD (ERCC2) repair/transcription gene

The xeroderma pigmentosum group D (XPD) protein has a dual function, both in nucleotide excision repair of DNA damage and in basal transcription. Mutations in the XPD gene can result in three distinct clinical phenotypes, XP, trichothiodystrophy (TTD), and XP with Cockayne syndrome. To determine if the clinical phenotypes of XP and TTD can be attributed to the sites of the mutations, we have identified the mutations in a large group of TTD and XP-D patients. Most sites of mutations differed between XP and TTD, but there are three sites at which the same mutation is found in XP and TTD patients. Since the corresponding patients were all compound heterozygotes with different mutations in the two alleles, the alleles were tested separately in a yeast complementation assay. The mutations which are found in both XP and TTD patients behaved as null alleles, suggesting that the disease phenotype was determined by the other allele. If we eliminate the null mutations, the remaining mutagenic pattern is consistent with the site of the mutation determining the phenotype.

Cell death prevention, mitogen-activated protein kinase stimulation, and increased sulfatide concentrations in Schwann cells and oligodendrocytes by prosaposin and prosaptides

Prosaposin, the precursor of saposins A, B, C, and D, was recently identified as a neurotrophic factor. Herein prosaposin was found to increase sulfatide concentrations in primary and transformed Schwann cells (iSC) and oligodendrocytes (differentiated CG4 cells). Of the four mature saposins, only saposin C was found to increase sulfatide concentrations in these cell types. A similar result was obtained by using peptides (prosaptides) encompassing the neurotrophic sequence located in the saposin C domain. Dose-response curves demonstrated maximal enhancement by saposin C and prosaptides at low nanomolar concentrations (5-10 nM). The increase in sulfatide concentration by a 14-mer prosaptide, TX14(A), in CG4 oligodendrocytes was about 3-fold greater than in primary Schwann cells. A mutant prosaptide with a single amino acid replacement of Asn --> Asp was inactive. Prosaptides did not induce cell proliferation of primary Schwann cells, iSC cells, or CG4 oligodendrocytes but nanomolar concentrations of prosaptides prevented cell death of iSC cells and CG4 oligodendrocytes. Immunoblot analysis demonstrated that phosphorylation of both mitogen-activated protein kinase p-42 and p-44 isoforms were enhanced 3- to 5-fold after 5 min of treatment with prosaptides at concentrations of 1-5 nM. These findings suggest that prosaposin and prosaptides bind to a receptor that initiates signal transduction to promote myelin lipid synthesis and prolong cell survival in both Schwann cells and oligodendrocytes. Prosaposin may function as a myelinotrophic factor in vivo during development and repair of myelinated nerves explaining the deficiency of myelin observed in prosaposin-deficient mice and humans.

Mechanisms involved in increased iron uptake across rat duodenal brush-border membrane during hypoxia

1. Chronic hypoxia enhances intestinal iron transport but the cellular processes involved are poorly understood. In order to assess the effects of 3 days of hypoxia on iron uptake across the duodenal brush-border membrane, we have measured the membrane potential difference (Vm) of villus-attached enterocytes by direct microelectrode impalement and have used semi-quantitative autoradiography to study changes in expression of iron uptake during enterocyte maturation. 2. Hypoxia increased duodenal Vm (-57.7 vs. -49.3 mV, P < 0.001). Ion substitution experiments revealed that hyperpolarization was due, at least in part, to a reduction in brush-border Na+ permeability. 3. Autoradiography revealed that hypoxia increased by 6-fold the rate of iron accumulation during enterocyte transit along the lower villus and enhanced by 3-fold the maximal accumulation of iron. Depolarization of the brush border, using a high-K(+)-containing buffer, caused a proportionally greater reduction in iron uptake in control compared with hypoxic tissue suggesting that the raised iron uptake is only partly driven by brush-border hyperpolarization. 4. We conclude that hypoxia increases the expression of iron transport in duodenal brush-border membrane and an enhanced electrical driving force may be involved in this response.

5-Azacytidine treatment of the fission yeast leads to cytotoxicity and cell cycle arrest

A fission yeast gene which shares considerable sequence homology with cytosine-specific DNA methyltransferases has recently been identified. This discovery has led us to investigate the effects of the treatment of fission yeast with the nucleoside analogue 5-azacytidine (5-azaC). 5-AzaC is known to inhibit cytosine methylation as a result of the formation of stable covalent complexes between DNA (cytosine-5) methyltransferases (C5 Mtases) and 5-azaC containing DNA. Here we demonstrate that 5-azaC treatment of Schizosaccharomyces pombe leads to reversible cell cycle arrest at the G2/M transition. This reversible arrest is dependent on the cell cycle checkpoint mechanisms which act to prevent the onset of mitosis in the presence of either damaged or unreplicated DNA. Treatment of S. pombe cell division cycle and checkpoint mutants indicates that 5-azaC causes DNA damage and is likely to inhibit a late stage in DNA replication. The data show that viability in the presence of the drug requires both the DNA damage and the replication checkpoint pathways to be functional. 5-AzaC also elicits a transcriptional response which is associated with DNA damage and the inhibition of DNA replication in fission yeast, and this response is absent in cells carrying G2 checkpoint mutations. The implications of these observations for both the use of 5-azaC in cancer chemotherapy and the existence of cytosine methylation in fission yeast are discussed.

The introduction and auditing of a formal do not resuscitate policy

AIMS

To introduce, to assess the use of and the staff understanding of a do not resuscitate policy.

METHODS

A policy was developed with legal, medical, nursing and ethical input. Two distinct methods for a do not resuscitate order were allowed. The first method is where the patient requests a do not resuscitate order. The second is the medically indicated do not resuscitate order. The policy was trialed on two floors at Dunedin Hospital and an audit performed. Information was collected on patients receiving do not resuscitate orders. The notes of all patients dying on these floors were reviewed. A questionnaire was sent to clinical staff working on the trial floors which included questions on their understanding of issues related to do not resuscitate orders.

RESULTS

86% of deaths had a do not resuscitate order, 26% in accordance with the formal policy. Thirty percent of the time there was no record of a discussion of the do not resuscitate order with the patient or their family. Problems identified by staff included difficulty with raising and discussing these orders with patients and their families. Staff misunderstanding of consent and responsibility for treatment decisions for mentally competent and incompetent patients was common.

CONCLUSIONS

There is a need for further staff education and discussion of the issues surrounding do not resuscitate orders. Discussion with patients and their families could be improved.

The Atr and Atm protein kinases associate with different sites along meiotically pairing chromosomes

A number of cell-cycle checkpoint genes have been shown to play important roles in meiosis. We have characterized the human and mouse counterpart of the Schizosaccharomyces pombe Rad3 protein, named Atr (for ataxia-telangiectasia- and rad3-related), and the protein that is mutated in ataxia-telangiectasia, Atm. We demonstrate that ATR mRNA and protein are expressed in human and mouse testis. More detailed analysis of specific cells in seminiferous tubules shows localization of Atr to the nuclei of cells in the process of meiosis I. Using immunoprecipitation and immunoblot analysis, we show that Atr and Atm proteins are approximately 300 and 350 kD relative molecular mass, respectively, and further demonstrate that both proteins have associated protein kinase activity. Further, we demonstrate that Atr and Atm interact directly with meiotic chromosomes and show complementary localization patterns on synapsing chromosomes. Atr is found at sites along unpaired or asynapsed chromosomal axes, whereas Atm is found along synapsed chromosomal axes. This is the first demonstration of a nuclear association of Atr and Atm proteins with meiotic chromosomes and suggests a direct role for these proteins in recognizing and responding to DNA strand interruptions that occur during meiotic recombination.

The genetics of the repair of 5-azacytidine-mediated DNA damage in the fission yeast Schizosaccharomyces pombe

We have recently demonstrated that Schizosaccharomyces pombe cells treated with the nucleoside analogue 5-azacytidine (5-azaC) require previously characterised G2 checkpoint mechanisms for survival. Here we present a survey of known DNA repair mutations which defines those genes required for survival in the presence of 5-azaC. Using a combination of single-mutant and epistasis analyses we find that the excision, mismatch and recombinational repair pathways are all required in some degree for the repair of 5-azaC-mediated DNA damage. There are distinct differences in the epistatic interactions of several of the repair mutations with respect to 5-azaC-mediated DNA damage relative to UV-mediated DNA damage.

Family structure, neonatal infection, and hay fever in adolescence

OBJECTIVE

To determine whether increased numbers of siblings and infection in early life protect against allergic sensitisation.

DESIGN

Historical cohort study.

SETTING

Sheffield, UK.

SUBJECTS

11,765 children aged 11-16 years for whom a history of neonatal infectious illness had been recorded systematically at 1 month of age.

METHODS

A history of hay fever and family structure was obtained by postal questionnaire; neonatal illness history was ascertained from health visitor records; 723 children underwent skin prick testing with mixed grass pollen extract.

RESULTS

The prevalence of hay fever was reduced (p < 0.0001) among children of younger mothers, and those from larger families. The number of older siblings exerted a stronger independent effect than the number of younger siblings (p < 0.001). Infants breast fed exclusively during the first month were at higher risk (p < 0.05) of subsequent hay fever, independent of demographic factors. Adolescents at high risk of hay fever by virtue of their family structure were more likely to be sensitised to grass pollen (p < 0.002). No significant relations emerged between hay fever and infection in the first month of life, even among children born in June.

CONCLUSIONS

The association of hay fever with family structure is not due to reporting bias and reflects an environmental influence on allergic sensitisation. The effects of sibship size, birth order, and infant feeding are consistent with a protective influence of postnatal infection. The first month of life and the first postnatal exposure to allergen are not the critical periods during which this protective effect is determined.

Blockade of human and porcine myocardial 5-HT4 receptors by SB 203186

We investigated the blockade of the positive inotropic effects of 5-hydroxytryptamine (5-HT) by SB 203 186 (piperidinoethyl-indole-3-carboxylate hydrochloride) and its affinity for 5-HT4 receptors of human right atrium and piglet left atrium. We also compared the blocking effects of SB 203 186 against 5-HT-evoked tachycardia in anaesthetised adult Yucatan minipigs as well as new-born Camborough piglets. SB 203 186 caused competitive antagonism of the positive inotropic effects of 5-HT in electrically paced atrial preparations of man (pKB = 8.9) and piglet (pKB = 8.5) at concentrations (up to 0.3 micromol/l) which were devoid of depressant or stimulant effects. The affinity of SB 203 186 for atrial 5-HT4 receptors was 30-160 times higher than that of tropisetron. 5-HT caused tachycardia with similar potency and efficacy in Yucatan minipigs and new-born Camborough piglets. SB 203 186 (0.1-3 mg/kg, i.v.) surmountably antagonised 5-HT-evoked tachycardia in anaesthetised Yucatan minipigs or new-born Camborough piglets with similar potency. The blocking potency of SB 203 186 in Yucatan minipigs was 17 times higher than that of tropisetron. Intraduodenally administered SB 203 186 (0.3-3 mg/kg) to new-born Camborough piglets produced blockade of 5-HT-evoked tachycardia which was maximal after 20 min and lasted for more than 3 h with 0.3 mg/kg. The antagonism produced by the SB 203 186 administration in new-born Camborough piglets was dose-related and threefold greater through the intravenous route than through the intraduodenal route. We conclude that SB 203 186 is an antagonist with nanomolar affinity for both human and porcine atrial 5-HT4 receptor. The in vivo results demonstrate that the sinoatrial 5-HT4 receptors function is similar in new-born Camborough piglets and adult Yucatan minipigs. Both porcine breeds are valid models for human atrial 5-HT4 receptors as demonstrated with the antagonist SB 203 186.