How do we get from hyperexcitability to excitotoxicity in amyotrophic lateral sclerosis?

Amyotrophic lateral sclerosis is a devastating neurodegenerative disease that, at present, has no effective cure. Evidence of increased circulating glutamate and hyperexcitability of the motor cortex in patients with amyotrophic lateral sclerosis have provided an empirical support base for the 'dying forward' excitotoxicity hypothesis. The hypothesis postulates that increased activation of upper motor neurons spreads pathology to lower motor neurons in the spinal cord in the form of excessive glutamate release, which triggers excitotoxic processes. Many clinical trials have focused on therapies that target excitotoxicity via dampening neuronal activation, but not all are effective. As such, there is a growing tension between the rising tide of evidence for the 'dying forward' excitotoxicity hypothesis and the failure of therapies that target neuronal activation. One possible solution to these contradictory outcomes is that our interpretation of the current evidence requires revision in the context of appreciating the complexity of the nervous system and the limitations of the neurobiological assays we use to study it. In this review we provide an evaluation of evidence relevant to the 'dying forward' excitotoxicity hypothesis and by doing so, identify key gaps in our knowledge that need to be addressed. We hope to provide a road map from hyperexcitability to excitotoxicity so that we can better develop therapies for patients suffering from amyotrophic lateral sclerosis. We conclude that studies of upper motor neuron activity and their synaptic output will play a decisive role in the future of amyotrophic lateral sclerosis therapy.

SF-CORNER (splenic flexure colorectal cancer): an international survey of operative approaches and outcomes for cancers of the splenic flexure

AIM

The optimum surgical approach to splenic flexure cancers (SFCs) remains uncertain. The aim of this survey was to explore the opinions of an international surgical community on the management and outcomes of SFC.

METHOD

A questionnaire was constructed comprising five sections (information about respondents; definition and prognosis of SFC; operative approach; approach in specific scenarios; outcomes) and circulated through an international dissemination committee and social media.

RESULTS

The survey received 576 responses over 4 weeks across 50 countries. There was no consensus regarding the definition of the splenic flexure, whilst the proportion of respondents who did and did not think that patients with SFC had a worse outcome was equal. The overall preferred operative approach was left hemicolectomy [203 (35.2%)], followed by segmental resection [167 (29%)], extended right hemicolectomy [126 (21.9%)] and subtotal colectomy [7 (12%)]. The stated pedicles for ligation varied between resection types and also within the same resection. One hundred and sixty-six (28.8%) respondents thought a segmental resection was associated with the worst survival and 190 (33%) thought it was associated with the best quality of life.

CONCLUSION

This survey confirms a lack of consensus across all aspects SFC treatment. The differing approaches described are likely to represent different beliefs around the variable anatomy of this region and the associated lymphatic drainage. Future studies are required to address such inconsistencies and identify the optimum surgical strategy, whilst also incorporating quality-of-life metrics and patient-reported outcomes. A one-size-fits-all approach is probably not appropriate with SFC, and a more bespoke approach is required.

TH1.2 Referral of patients with breast pain to breast clinic: a retrospective analysis

Aims

Previous literature provides evidence that in patients with breast pain and a normal breast examination, the incidence of ipsilateral breast cancer is approximately equivalent to the screening incidence. Isolated breast pain is not an indication for a suspected cancer pathway referral as per NICE guidance. We assessed all breast clinic referrals in one month for use of the appropriate referral pathway for patients with isolated breast pain, and correct primary care management of breast pain.

Methods

GP referral letters and breast clinic letters were analysed retrospectively using an electronic clinical data system for all 173 patients referred to breast clinic in September 2021, of which, 47 patients satisfied eligibility criteria. Letters were assessed for urgency of referral and documentation of GP interventions for breast pain (bra fitting advice, simple oral analgesics and topical NSAIDs).

Results

62% of patients presenting with isolated breast pain were referred under a USC or urgent referral pathway to breast clinic. Only one patient with breast pain as a symptom, had documented evidence of GP interventions for breast pain.

Conclusions

The majority of patients presenting with isolated breast pain were inappropriately referred under urgent pathways, potentially impeding capacity in breast clinic for patients that satisfied USC criteria. There was little evidence of GP interventions for breast pain which could negate need for a clinic appointment or alleviate symptoms in the interim. Further GP education could reduce inappropriate urgent referrals of patients with isolated breast pain and improve breast pain management.

Age, but Not Amyloidosis, Induced Changes in Global Levels of Histone Modifications in Susceptible and Disease-Resistant Neurons in Alzheimer's Disease Model Mice

There is increasing interest in the role of epigenetic alterations in Alzheimer’s disease (AD). The epigenome of every cell type is distinct, yet data regarding epigenetic change in specific cell types in aging and AD is limited. We investigated histone tail modifications in neuronal subtypes in wild-type and APP/PS1 mice at 3 (pre-pathology), 6 (pathology-onset) and 12 (pathology-rich) months of age. In neurofilament (NF)-positive pyramidal neurons (vulnerable to AD pathology), and in calretinin-labeled interneurons (resistant to AD pathology) there were no global alterations in histone 3 lysine 4 trimethylation (H3K4me3), histone 3 lysine 27 acetylation (H3K27ac) or histone 3 lysine 27 trimethylation (H3K27me3) in APP/PS1 compared to wild-type mice at any age. Interestingly, age-related changes in the presence of H3K27ac and H3K27me3 were detected in NF-labeled pyramidal neurons and calretinin-positive interneurons, respectively. These data suggest that the global levels of histone modifications change with age, whilst amyloid plaque deposition and its sequelae do not result in global alterations of H3K4me3, H3K27ac and H3K27me3 in NF-positive pyramidal neurons or calretinin-labeled interneurons.

The Impact of Change in the 2007 English Law on Mental Health Act Detentions

Background

The Mental Health Act (MHA) 2007 made some significant changes from the Mental Health Act 1983, including the fact that detention is now only allowed if an appropriate medical treatment is available to the patient at the time [1]. There was considerable concern at the time that the 2007 Act would lead to an increase in detentions.

Objective

The primary objective is to assess how the change in the English law with the MHA 2007 has affected the number of detentions under the MHA.

Methods

A retrospective, observational and noninterventional study used anonymised and routinely collected data regarding 11,509 people who were formally assessed under the Mental Health Act during the period of 2001–2011 in the county of Norfolk. This included 7885 assessments before the 2007 MHA and 3620 done after implementation.

Results

The proportion of people detained following assessment decreased from 53.2% before the 2007 MHA to 42.9% after implementation (P = .000). The total proportion of patients admitted (whether informally or detained) also decreased from 63.3% before the 2007 MHA to 52.8% thereafter (P = .000).

Conclusion

These results show a significant decrease in the rate of detentions under the MHA since the 2007 Act became law.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Cost analysis of an integrated care model in the management of acute exacerbations of chronic obstructive pulmonary disease

Home treatment models for acute exacerbations of chronic obstructive pulmonary disease (AECOPD) proved to be a safe alternative to hospitalization. These models have the potential to free up resources; however, in the United Kingdom, it remains unclear to whether they provide cost savings compared with hospital treatment. Over a 12-month period from August 2003, 130 patients were selected for the integrated care group (total admissions with AECOPD = 546). These patients were compared with 95 retrospective controls in the hospital treatment group. Controls were selected from admissions during the previous 12 months (total of 662 admissions) to match the integrated care group in age, sex, and postal code. Resource use data were collected for both groups and compared using National Health Service (NHS) perspective for cost minimization analysis. In the integrated care group (130 patients), 107 (82%) patients received home support with average length of stay 3.3 (SD 3.9) days compared with 10.4 (SD 7.7) in the hospital group (95 patients). Average number of visits per patients in the integrated care group was 3.08 (SD = 0.95; 95% CI = 2.9—3.2). Cost per patient in the integrated care group was £1653 (95% CI, £1521—1802) compared with £2256 (95% CI, £2126— 2407) in the hospital group. The integrated care group resulted in cost saving of approximately £600 (P < 0.001) per patient. This integrated care model for the management of patients with AECOPD offered cost savings of £600 per patient over the conventional hospital treatment model using the new NHS tariff from an acute trust provider perspective.

AAV-mediated delivery of interferon-β for the treatment of retinoblastoma in preclinical models

3565

Background: Interferon-β has anti-tumor properties against a variety of malignancies through direct cytotoxicity as well as immunological effects. In order to circumvent limitations of IFN-β therapy, we have developed an adeno-associated viral gene therapy approach to deliver IFN-β directly to tumors. In this study, we tested the efficacy of AAV mediated delivery of IFN-β in preclinical retinoblastoma models. Retinoblastoma is an ideal candidate for gene-therapy based anti-cancer treatments because viral infection and IFN-β delivery can be contained within the ocular environment thereby minimizing systemic toxicity. Methods: Retinoblastoma cell lines Weri and Y79 were treated in vitro with recombinant human Interferon-β and then subjected to Viacount assays, Nexin apoptosis assays, FACS cell cycle analysis, and immunolabeling for proliferation (BrdU) and apoptosis (caspase and TUNEL). An orthotopic Xenograft retinoblastoma rat model with luciferase reporter were established and treated with single subconjunctival injection of AAV-IFN-β gene therapy. Xenogen in vivo imaging was used to follow tumor volume. Blood and tissue samples (ELISA) were obtained to determine IFN-β levels. Results: Weri and Y79 cells showed maximum reduction in viability at 500 IU/ml and 2500 IU/ml respectively. Weri response was found to be cell death by Caspase and TUNEL assay. Y79 response was found to be due to suppression of proliferation as measured by BrdU incorporation and cell cycle analysis. In the retinoblastoma xenograft model there was no increase in tumor volume by serial in vivo imaging compared to control animals. Stable levels of IFN-β were maintained at 20 ng/ml >6weeks following injection. Plasma levels were undetectable 42 days following treatment. Conclusions: Retinoblastoma cell lines exhibit pleiotropic responses to IFN-β consistent with previous studies. Intravitreal injection of AAV-IFN-β resulted in efficient retinal infection and sustained IFN-β production. Viral spread outside of the eye was not detected. Using our retinoblastoma xenograft model we found that intravitreal injection of AAV-IFN-β had a potent anti-tumor effect in vivo. These data suggest that AAV mediated delivery of IFN-β may provide a complementary approach to systemic chemotherapy.

No significant financial relationships to disclose.

Evaluation of the ventricular assist device programme in the UK

OBJECTIVES

To summarise the relevant clinical effectiveness and cost-effectiveness literature, to collect data on survival, transplantation rates, health-related quality of life (HRQoL) and resource use for ventricular assist device (VAD) and non-VAD transplant candidates in the UK, and to construct cost-effectiveness and cost-utility models of VADs in a UK context. Also to investigate the factors that drive costs and survival.

DESIGN

A comprehensive systematic review was carried out. Data were collected from April 2002 to December 2004, with follow-up to March 2005. Cost-effectiveness and cost-utility models of VAD devices were developed based on UK activity and outcomes collected from April 2002 to March 2005.

SETTING

National Specialist Commissioning Advisory Group funded VAD implantation was carried out at the Freeman, Harefield and Papworth transplant centres in the UK.

PARTICIPANTS

Seventy patients were implanted with a VAD as a bridge to transplantation between April 2002 and December 2004. Non-VAD-supported transplant candidates (n = 250), listed at the three centres between April 2002 and December 2004, were divided into an inotrope-dependent group (n = 71) and a non-inotrope-dependent group (n = 179). Although patients in the inotrope-dependent group were closest to the VAD group they were less sick. The last group comprised a hypothetical worst case scenario, which assumed that all VAD patients would die in the intensive care unit (ICU) within 1 month without VAD technology.

INTERVENTIONS

Patients were included who were implanted with a VAD designed for circulatory support for more than 30 days, with intention to bridge to transplantation. A multistate model of VAD and transplant activity was constructed; this was populated by data from the UK.

MAIN OUTCOME MEASURES

Survival from VAD implant or from transplant listing for non-VAD patients to 31 March 2005. Serious adverse events and quality of life measures were used. Cognitive functioning was also assessed. Utility weights were derived from EuroQoL responses to estimate quality-adjusted life-years (QALYs). Incremental cost-effectiveness ratios (ICERs) were defined as the additional cost of VADs divided by additional QALYs. Time-horizons were 3 years, 10 years and the lifetime of the patients.

RESULTS

Of 70 VAD patients, 30 (43%) died pretransplant, 31 (44%) underwent transplantation, and four (6%) recovered and had the VAD removed. Five patients (7%) were still supported for median of 279 days at the end of March 2005. Successful bridge-to-transplantation/recovery rates were consistent with published rates. Survival from VAD implantation was 74% at 30 days and 52% at 12 months. There were 320 non-fatal adverse events in 62 patients during 300 months of VAD support, mostly in the first month after implantation. Commonly observed events were bleeding, infection and respiratory dysfunction. Twenty-nine (41%) patients were discharged from hospital with a VAD. The 1-year survival post-transplantation was 84%. For the inotrope-dependent and non-inotrope-dependent transplant candidates, death rates while listed were 10% and 8% and the median waiting times were 16 and 87 days, respectively. For transplant recipients, 1-year survival was 85% and 84%, respectively. Both VAD and non-VAD patients demonstrated similar significant improvements in their New York Heart Association class after transplantation. All patients had poor EQ-5D pretransplantation; after transplantation the groups had similar EQ-5D of 0.76 irrespective of time after surgery. HRQoL was poor in the first month for VAD patients but better for those who waited longer in all groups. VAD patients reported more problems with sleep and rest and with ambulation in the first month. Symptom scores were similar in all groups pretransplant. After transplantation all groups showed a marked and similar improvement in physical and psychosocial function. Mean VAD implant cost, including device, was pound 63,830, with costs of VAD support for survivors of pound 21,696 in month 1 and pound 11,312 in month 2. Main cost drivers were device itself, staffing, ICU stay, hospital stay and events such as bleeding, stroke and infection. For the base case, extrapolating over the lifetime of the patients the mean cost for a VAD patient was pound 173,841, with mean survival of 5.63 years and mean QALYs of 3.27. Corresponding costs for inotrope-dependent patients were pound 130,905, with mean survival 8.62 years and mean QALYs 4.99. Since inotrope-dependent patients had lower costs and higher QALYs than VAD patients, this group is said to be dominant. Non-inotrope-dependent transplant candidates had similar survival rates to those on inotropes but lower costs, also dominant. Compared with the worst case scenario the mean lifetime ICER for VADs was pound 49,384 per QALY. In a range of sensitivity analyses this ranged from pound 35,121 if the device cost was zero to pound 49,384. Since neither inotrope-dependent transplant candidates nor the worst case scenario were considered fair controls the assumption was investigated that, without VAD technology, there would be a mixture of these situations. For mixtures considered the ICER for VADs ranged from pound 79,212 per QALY to the non-VAD group being both cheaper and more effective.

CONCLUSIONS

There are insufficient data from either published studies or the current study to construct a fair comparison group for VADs. Overall survival of 52% is an excellent clinical achievement for those young patients with rapidly failing hearts. However, if the worst case scenario were plausible, and one could reliably extrapolate results to the lifetime of the patients, VADs would not be cost-effective at traditional thresholds. Further randomised controlled trials are required, using current second generation devices or subsequent devices and conducted in the UK.

Expression of Plasmodium falciparum trimeric G proteins and their involvement in switching to sexual development

Both cholera and pertussis toxins were used to label and study the expression of heterotrimeric G protein alpha subunits in Plasmodium falciparum extracts. Expression of these proteins is developmentally regulated throughout the erythrocytic cycle with peak expression during early asexual development and in mature sexual stages. Treatment of P. falciparum cultures with cholera toxin causes an increase in conversion to sexual development, and at the same concentration has a marginal inhibitory effect on asexual growth and division. Through precise synchronisation of the parasites' asexual cell cycle, we have defined the period of sensitivity to this induction at around the time of invasion, one cycle before the development of the sexual form. Fluorescent microscopy confirmed that access of the toxin to the parasite is limited to the invasive form--the free merozoite, while further labelling studies revealed expression of a single G protein alpha subunit in these stages. These observations are consistent with the view that a G protein-dependent signal transduction pathway is involved in coupling the parasite's environment to commitment to sexual development (gametocytogenesis). This means of artificially stimulating the pathways leading to sexual development can now be used to biochemically follow the activation of the signalling pathways involved.

Expression of Plasmodium falciparum trimeric G proteins and their involvement in switching to sexual development

Both cholera and pertussis toxins were used to label and study the expression of heterotrimeric G protein alpha subunits in Plasmodium falciparum extracts. Expression of these proteins is developmentally regulated throughout the erythrocytic cycle with peak expression during early asexual development and in mature sexual stages. Treatment of P. falciparum cultures with cholera toxin causes an increase in conversion to sexual development, and at the same concentration has a marginal inhibitory effect on asexual growth and division. Through precise synchronisation of the parasites' asexual cell cycle, we have defined the period of sensitivity to this induction at around the time of invasion, one cycle before the development of the sexual form. Fluorescent microscopy confirmed that access of the toxin to the parasite is limited to the invasive form - the free merozoite, while further labelling studies revealed expression of a single G protein alpha subunit in these stages. These observations are consistent with the view that a G protein-dependent signal transduction pathway is involved in coupling the parasite's environment to commitment to sexual development (gametocytogenesis). This means of artificially stimulating the pathways leading to sexual development can now be used to biochemically follow the activation of the signalling pathways involved.

Commitment to gametocytogenesis in Plasmodium falciparum

To achieve transmission, a subpopulation of asexually dividing bloodstream forms of the human malaria parasite Plasmodium falciparum withdraws from the cell cycle to develop into gametocytes - cells specialized for sexual reproduction and invasion of the mosquito vector. For natural selection to maximize transmission to new hosts, a balance must have evolved between asexual replication and sexual differentiation. Here, Mike Dyer and Karen Day consider observations on the process of commitment to gametocytogenesis and use this information as the framework for a model that begins to explain the control of the dynamics between asexual and sexual development.

Field evaluation of the ICT malaria P.f/P.v immunochromatographic test for detection of Plasmodium falciparum and Plasmodium vivax in patients with a presumptive clinical diagnosis of malaria in eastern Indonesia

In areas such as eastern Indonesia where both Plasmodium falciparum and Plasmodium vivax occur, rapid antigen detection tests for malaria need to be able to detect both species. We evaluated the new combined P. falciparum-P. vivax immunochromatographic test (ICT Malaria P.f/P.v.) in Radamata Primary Health Centre, Sumba, Indonesia, from February to May 1998 with 560 symptomatic adults and children with a presumptive clinical diagnosis of malaria. Blinded microscopy was used as the "gold standard," with all discordant and 20% of concordant results cross-checked blindly. Only 50% of those with a presumptive clinical diagnosis of malaria were parasitemic. The ICT Malaria P.f/P.v immunochromatographic test was sensitive (95. 5%) and specific (89.8%) for the diagnosis of falciparum malaria, with a positive predictive value (PPV) and a negative predictive value (NPV) of 88.1 and 96.2%, respectively. HRP2 and panmalarial antigen line intensities were associated with parasitemia density for both species. Although the specificity and NPV for the diagnosis of vivax malaria were 94.8 and 98.2%, respectively, the overall sensitivity (75%) and PPV (50%) for the diagnosis of vivax malaria were less than the desirable levels. The sensitivity for the diagnosis of P. vivax malaria was 96% with parasitemias of >500/microl but only 29% with parasitemias of <500/microl. Nevertheless, compared with the test with HRP2 alone, use of the combined antigen detection test would reduce the rate of undertreatment from 14.7 to 3.6% for microscopy-positive patients, and this would be at the expense of only a modest increase in the rate of overtreatment of microscopy-negative patients from 7.1 to 15. 4%. Cost remains a major obstacle to widespread use in areas of endemicity.

The biology of Plasmodium falciparum transmission stages

The most important function of any parasite is to secure transmission to new hosts. The gametocyte, the stage which has become developmentally committed to the sexual cycle, provides a critical link in the transmission of Plasmodium falciparum from the human host to the anopheline mosquito vector. It is therefore imperative that our determination to understand the biology of the gametocyte is greater than the technical obstacles which have resulted in the gametocyte being left very much out of the limelight by the intensive investigation of the asexual bloodstream parasite. Here we explore the areas of gametocyte biology which by nature of their relevance to control and pathology as well as basic biology, are the subjects of investigation in our laboratory. We also point out areas in need of particular attention.

Sezary cell leukaemia: a distinct T cell disorder or a variant form of T prolymphocytic leukaemia?

We report the clinical, ultrastructural, immunophenotypic and virological features of nine cases of a rare type of mature T cell disorder formerly designated Sezary cell leukaemia. All patients presented with lymphocytosis ranging from 12.7 to 133 x 10(9)/l, bone marrow infiltration, splenomegaly and lymphadenopathy. Skin involvement was absent at presentation but developed as a terminal event in two patients, one of whom showed a pattern of dermal infiltration different from that characteristic of Sezary syndrome. Cells from eight cases bore a mature T cell phenotype and electronmicroscopy revealed lymphocytes with cerebriform nuclei resembling Sezary cells. All cases except one were HTLV-I negative. Patients were treated with various chemotherapy regimens but with poor outcome, the median survival being 13 months. Laboratory and clinical data suggest great similarity between Sezary cell leukaemia and T prolymphocytic leukaemia (T-PLL), namely coexpression of CD4 and CD8 (3/9 cases), identical chromosomal abnormalities in the three cases studied (isochromosome 8q plus inversion 14 or t(X;14)(q28;q11)) and a remarkable sensitivity to CAMPATH-1H (complete remission of 21 months' duration in one patient), suggesting that this entity could be considered a variant form of T-PLL. The alternative diagnosis of adult T cell leukaemia/lymphoma could not be excluded in one patient in whom positive HTLV-I serology was documented.

Definition of acute biphenotypic leukemia

BACKGROUND AND OBJECTIVE

A minority of acute leukemias have features characteristic of both the myeloid and lymphoid lineages and for this reason are designated mixed-lineage, hybrid or biphenotypic acute leukemias (BAL). There have been difficulties in establishing whether BAL represents a distinct clinico-biological entity due to a lack of objective criteria for distinguishing BAL from acute myeloid leukemias (AML) or acute lymphoblastic leukemias (ALL) with aberrant expression of a marker from another lineage. In this work we analyze diagnostic criteria for BAL.

METHODS

We describe the features of 26 patients (19 adults and 7 children) with BAL diagnosed at the Royal Marsden Hospital. BAL was defined according to a scoring system devised by our group and the European Group for the Immunological Classification of Leukemia (EGIL). This system is based on the number and degree of specificity of the markers (lymphoid and myeloid) expressed by the blasts.

RESULTS

According to the FAB criteria, BAL may present as "ALL" or as one of the "AML" subtypes, often M1. It is not infrequent to identify two distinct blast populations: one of small size resembling lymphoblasts and the other larger. The most common immunophenotype is coexpression of B-lymphoid and myeloid markers and less frequently, T-lymphoid and myeloid markers. Cases with a B and T lymphoid phenotype or with trilineage differentiation are rare. BAL has a high incidence of clonal chromosomal abnormalities, the most common being the t(9;22) (q34;q11) (Ph chromosome) and structural abnormalities involving 11q23. Data are emerging that BAL has a negative prognosis in both children and adults and this may be related to the underlying chromosome abnormalities.

INTERPRETATION AND CONCLUSIONS

In summary, BAL is an uncommon type of leukemia which probably arises from a multipotent progenitor cell and carries a poor prognosis. Although there are no uniform criteria about whether to treat these patients as ALL or AML, it is likely that an intensive approach with high-dose therapy followed by bone marrow transplantation will be required to eradicate the disease permanently.

Expression and regulation of the rnc and pdxJ operons of Escherichia coli

Escherichia coli rnc-era-recO operon (rnc operon) expression is negatively autoregulated at the level of message stability by ribonuclease III (RNase III), which is encoded by the rnc gene. RNase III, a double-stranded RNA-specific endoribonuclease involved in rRNA and mRNA processing and degradation, cleaves a stemloop structure in the 5' untranslated leader, initiating rapid decay of the rnc operon mRNA. Here, we examine rnc operon expression and regulation in greater detail. Northern, primer extension, and lacZ fusion analyses show that a single promoter (rncP) specifies two principal mRNAs: the 1.9 kb rnc-era transcript and the less-abundant 3.7 kb RNA encoding rnc-era-recO and the downstream pdxJ and acpS genes. A 1.3 kb pdxJ-acpS RNA is transcribed from a promoter (pdxP) located within recO. About 70% of pdxJ transcription depends on transcription from rncP. Both promoters were characterized genetically. RNase III reduces 1.9 kb and 3.7 kb transcript levels and stability, and corresponding effects are seen with genetic fusions. These detailed studies enabled us to show that the first 378 nucleotides of the rnc transcript comprise a portable RNA stability element (rncO) that contains all of the cis-acting elements required for RNase III-initiated decay of the rnc mRNA as well as the heterologous lacZ transcript. Moreover, mutations in rncO that block RNase III cleavage also block control, showing that RNase III initiates mRNA decay by cleaving at a single site.

Fluorescence in situ hybridization analysis of t(3; 12)(q26; p13): a recurring chromosomal abnormality involving the TEL gene (ETV6) in myelodysplastic syndromes

We have identified a new recurrent reciprocal translocation between chromosome 3 and 12 with breakpoints at bands 3q26 and 12p13, t(3;12)(q26;p13) in the malignant cells from five patients with acute transformation of myelodysplastic syndrome or blast crisis of chronic myelogenous leukemia. t(3;12)(q26;p13) appears as a rare but nonrandom event present in various myeloid leukemia subtypes, which is frequently associated with dysplasia of megakaryocytes, multilineage involvement, short duration of any blastic phase, and a very poor prognosis. Here, we report the molecular cytogenetic analysis of the t(3;12). Fluorescence in situ hybridization results indicate that the 3q26 breakpoints are quite heterogeneous and occur 5' of MDS1, 3' of EVI1, or between MDS1 and EVI1. Our results are very similar to those observed in other 3q26 rearrangements in which breakpoints were shown to occur over considerable distances 5' and 3' of EVI1. Fluorescence in situ hybridization investigations proved that, in three myelodysplastic syndrome cases with t(3;12)(q26;p13), the 12p 13 breakpoint occurred within the TEL gene.

Analysis of a cation-transporting ATPase of Plasmodium falciparum

We have cloned and characterised one gene, PfATPase4 which encodes a P-type ATPase containing all the primary sequence motifs characteristic of this class of transmembrane ion transporters, and also a fragment of a second P. falciparum P-type ATPase pseudogene (PfATPase5). Analysis of conserved domains and motifs of specific ATPases reveals that PfATPase4 is most analogous to Ca2+ ATPases of the endoplasmic reticulum. The PfATPase4 gene gives rise to a transcript of 8 kb shortly after erythrocyte invasion. Although this mRNA is not detected in later stages, the protein detected immunologically at 190 kDa persists throughout and is detected in free merozoites. Immunofluorescence microscopy reveals that the PfATPase4 protein is concentrated in discrete compartments at the periphery of the parasite. Detailed sequence and structural analyses of these and the other P-type ATPases of P. falciparum described previously, reveals that they comprise an unusual family in several respects. Firstly, the large number of non-homologous genes so far characterised reflects the complexities of ionic regulation in the diverse environments encountered by the parasite. Secondly, the plasmodial P-type ATPase family may be classified both at primary sequence and structural levels into two distinct groups-those typical of P-type ATPases (including PfATPase4) and those which are much more divergent. A third complexity is illustrated by the fact that one of the other members [1] here termed PfATPase6, has an even greater similarity to the sarcoplasmic reticulum Ca2+ ATPases than does PfATPase4, which raises questions about the possible functional relationship between these two members.

Immunoblastic transformation of a Sezary syndrome in a black Caribbean patient without evidence of HTLV-I

We describe an unusual case of Sezary syndrome which transformed into a large T-cell non Hodgkin's lymphoma (immunoblastic) in a black man of Caribbean descent with negative HTLV-I serology and no evidence of HTLV-I infection by DNA analysis using sensitive techniques. The disease presented as a small-cell Sezary syndrome and transformed in an inguinal lymph node one year from diagnosis. Immunological markers in the small and large cells showed a mature T-cell phenotype CD4+, CD8- with expression of T-cell activation markers and a high proliferative rate. Ultrastructural analysis confirmed small Sezary cells with serpentine nucleus in the peripheral blood and immunoblasts in the lymph node. Cytogenetics demonstrated complex clonal chromosome abnormalities with involvement of 7q35, the locus for the beta chain of the T-cell receptor (TCR). Southern-blot analysis showed the same rearrangement of the TCR beta, gamma, delta chain genes in lymph node and peripheral blood cells. Antibodies to HTLV-I were not detected in the serum by ELISA and particle agglutination (PA) nor HTLV-I specific sequences were demonstrated by nested polymerase chain reaction with primers to the envelope proteins, LTR and tax/rex of HTLV-I in both tissues, blood and lymph node. The disease had an aggressive course and was refractory to therapy; the patient died of progressive disease 28 months from presentation. Two unusual features characterised this patient's illness: immunoblastic transformation of a Sezary syndrome in a patient of Afro-Caribbean origin without evidence of HTLV-I DNA sequences and negative HTLV-I serology and the atypical lymph node histology resembling ATLL.

Characterization of a t(10;11)(p13-14;q14-21) in the monoblastic cell line U937

Previous analysis of the monoblastic cell line U937 has shown that several sublines contain a rearranged chromosome arm 11q. In order to determine the true nature of the rearrangement, fluorescence in situ hybridization (FISH) was carried out with various combinations of single copy anonymous markers, clones containing genes, a chromosome 10 paint, and an 11 centromere specific sequence. The rearrangement was deduced to be a reciprocal translocation between chromosomes 10 and 11 described as t(10;11)(p13-14;q14-21). The breakpoint on chromosome 11 is telomeric to the INT2 gene and the pHS11 probe at 11q13, and centromeric to the marker D11S36 localized to 11q14.3-q22.1 and the MLL gene at 11q23. Similar translocations have been reported in various acute leukemias, principally of the monocytic lineage, and also in T-cell precursor acute lymphocytic leukemias. Further characterization of the genetic rearrangements in U937 may lead to the isolation of genes important in leukemogenesis and provide an in vitro system for their study.

Characterization and functional analysis of the rat endothelin-1 promoter

To define the molecular mechanisms of endothelin-1 (ET-1) gene regulation, we cloned, sequenced, and characterized the rat ET-1 promoter. A sequence consisting of the first 1329 bp of the rat ET-1 promoter was investigated in greater detail. Sequence analysis identified putative binding sites for a number of transcriptional factors that may be involved in ET-1 gene regulation. Several of these factors have been proposed earlier to be involved in cell-specific gene regulation and may be responsible for directing ET-1 expression in vivo. For functional analysis of the ET-1 promoter, we generated a reporter gene construct using luciferase as reporter gene under control of the promoter fragment isolated. The construct was transfected transiently into bovine aortic endothelial cells, and luciferase expression was evaluated. The results indicated that the promoter segment used showed high expression in endothelial cells comparable to that induced by viral promoters. Since ET-1 is regulated by a number of vasoactive substances, we studied the effect of angiotensin II on endothelin transcription. We could demonstrate a dose-dependent transcriptional activation of ET-1 transcription by angiotensin.

Ordering clone libraries in computational biology

We consider a probabilistic model, due to Lander and Waterman and to Alizadeh, Karp, Newberg and Weisser, for the physical mapping of DNA molecules. Within this model, we answer precisely a question of Alizadeh et al. concerning the minimum number of probes required to reconstruct the entire ordering of a given clone library with high probability. We also examine the related problem of determining the least number of probes required to construct a "tiling" for the library. We give a fairly precise characterization for this number.

Isolation and sequence analysis of a cDNA encoding an adenine nucleotide translocator from Plasmodium falciparum

A cDNA clone encoding the polypeptide for Plasmodium falciparum adenine nucleotide translocator (ANT) was isolated by screening a cDNA library with a 150 base pair fragment of genomic DNA which had been enzymatically amplified using two oligonucleotide primers designed from conserved regions of ANT's from other sources. The deduced amino acid sequence of the P. falciparum cloned insert was highly homologous to ANT of other organisms. Features of the sequence are discussed with reference to the targeting and membrane insertion of ANT. The protein has a molecular mass of 35 kDa as predicted from the 303 amino acids encoded in the open reading frame.

Lack of MDM2 amplification in human leukaemia

While deletion or mutation of the p53 gene is one of the most common molecular alterations detected in a wide variety of tumours, it has been shown to occur in only a relatively small percentage of the leukaemia cases examined. However, it may be that other components of the p53 pathway are involved. Amplification of the MDM2 gene has recently been demonstrated in human sarcomas resulting in an increase in MDM2 protein levels. This protein can bind to p53 preventing the transactivation of p53 responsive genes, thus mimicking mutation or deletion of p53. We have investigated the prevalence of MDM2 amplification in human leukaemias. 101 leukaemia or lymphoma samples and nine cell lines were studied using Southern blotting. In no case was MDM2 amplification present. We conclude that MDM2 amplification is not a common event in human leukaemias.

The probability of unique solutions of sequencing by hybridization

We determine the asymptotic limiting probability as m-->infinity that a random string of length m over some alphabet sigma can be determined uniquely by its substrings of length l. This is an abstraction of a problem faced when trying to sequence DNA clones by SBH.

Religious belief and attitudes to HIV/AIDS

This article discusses a research study into the effect of religious beliefs on attitudes to HIV/AIDS. The author sought to clarify the issues involved and to discover which 'elements' within a religious belief tend to dispose the adherent to negative attitudes towards a person with HIV/AIDS. Only 6 per cent of the variation in the subjects' attitudes, however, was attributable to the degree of scriptural influence in their lives.