Phenotype and Variant Spectrum in the LAMB3 Form of Amelogenesis Imperfecta

Amelogenesis imperfecta (AI) is a heterogeneous group of inherited disorders characterized by abnormal formation of dental enamel, either in isolation or as part of a syndrome. Heterozygous variants in laminin subunit beta 3 ( LAMB3) cause AI with dominant inheritance in the absence of other cosegregating clinical features. In contrast, biallelic loss-of-function variants in LAMB3 cause recessive junctional epidermolysis bullosa, characterized by life-threatening skin fragility. We identified 2 families segregating autosomal dominant AI with variable degrees of a distinctive hypoplastic phenotype due to pathogenic variants in LAMB3. Whole exome sequencing revealed a nonsense variant (c.3340G>T, p.E1114*) within the final exon in family 1, while Sanger sequencing in family 2 revealed a variant (c.3383-1G>A) in the canonical splice acceptor site of the final exon. Analysis of cDNA from family 2 revealed retention of the final intron leading to a premature termination codon. Two unerupted third molar teeth from individual IV:5 in family 2 were subject to computerized tomography and scanning electron microscopy. LAMB3 molar teeth have a multitude of cusps versus matched controls. LAMB3 enamel was well mineralized but pitted. The architecture of the initially secreted enamel was abnormal, with cervical enamel appearing much less severely affected than coronal enamel. This study further defines the variations in phenotype-genotype correlation for AI due to variants in LAMB3, underlines the clustering of nonsense and frameshift variants causing AI in the absence of junctional epidermolysis bullosa, and highlights the shared AI phenotype arising from variants in genes coding for hemidesmosome proteins.

The effect of luminal content and rate of occlusion on the interpretation of colonic manometry

BACKGROUND

Manometry is commonly used for diagnosis of esophageal and anorectal motility disorders. In the colon, manometry is a useful tool, but clinical application remains uncertain. This uncertainty is partly based on the belief that manometry cannot reliably detect non-occluding colonic contractions and, therefore, cannot identify reliable markers of dysmotility. This study tests the ability of manometry to record pressure signals in response to non-lumen-occluding changes in diameter, at different rates of wall movement and with content of different viscosities.

METHODS

A numerical model was built to investigate pressure changes caused by localized, non-lumen-occluding reductions in diameter, similar to those caused by contraction of the gut wall. A mechanical model, consisting of a sealed pressure vessel which could produce localized reductions in luminal diameter, was used to validate the model using luminal segments formed from; (i) natural latex; and (ii) sections of rabbit proximal colon. Fluids with viscosities ranging from 1 to 6800 mPa s(-1) and luminal contraction rates over the range 5-20 mmHg s(-1) were studied.

KEY RESULTS

Manometry recorded non-occluding reductions in diameter, provided that they occurred with sufficiently viscous content. The measured signal was linearly dependent on the rate of reduction in luminal diameter and also increased with increasing viscosity of content (R(2) = 0.62 and 0.96 for 880 and 1760 mPa s(-1), respectively).

CONCLUSIONS & INFERENCES

Manometry reliably registers non-occluding contractions in the presence of viscous content, and is therefore a viable tool for measuring colonic motility. Interpretation of colonic manometric data, and definitions based on manometric results, must consider the viscosity of luminal content.

Abstract P4-17-03: Towards the standardisation of outcome reporting in reconstructive breast surgery: Initial results of the BRAVO (Breast Reconstruction and Valid Outcome) Study–A multicentre consensus process to develop a core outcome set for reconstructive breast surgery

Introduction: Appropriate outcome selection is essential if research is to guide decision-making for patients, professionals and policy makers. Systematic reviews evaluating the clinical, cosmetic and patient-reported outcomes of breast reconstruction, however, have demonstrated marked heterogeneity of outcome reporting such that results from individual studies cannot be compared or combined. Standardising end-points by developing and using core outcome sets - an agreed minimum set of outcomes that should be measured and reported in all research and audit studies – is one way by which outcome reporting may be improved. We therefore report the initial results of the BRAVO (Breast Reconstruction and Valid Outcomes) Study which aims to use a scientifically rigorous Delphi consensus process to develop a core outcome set for reconstructive breast surgery.

Methods: The Delphi process involves the sequential completion of questionnaires to allow stakeholder opinions to be synthesised using item responses to prioritise outcome domains.

The questionnaire was developed from a long list of 148 outcomes generated from literature reviews and qualitative work with stakeholders. The outcomes were categorised into 34 domains in six categories (short-term complications; late complications; symptoms; psychosocial issues; practical issues and cosmesis) and each domain operationalised.

Key stakeholders were identified as patients, surgeons, specialist nurses and psychologists and participants were sampled purposively to ensure a breadth of perspectives. Each participant was sent a questionnaire and asked to prioritise the outcomes on a nine-point likert scale from 1(not important) to 9(extremely important).

The number of respondents in each group rating each outcome as not important(scores 1–3); equivocal(scores 4–6) or very important(score 7–9) were calculated for each item and compared between groups. The proportions of respondents rating each item as very important(score 7–9) was used to rank the items.

Results: 213 of the 430 questionnaires were returned(126/274 patients and 87/156 professionals) giving a response rate of 49.5%.

Patient participants had a median age of 53.4 years(range 34–76) and had undergone a full range of reconstructive procedures. The professional group included 39 breast surgeons, 20 plastic surgeons and 18 clinical nurse specialists.

There was agreement between 7 of the 10 outcomes that each group rated most highly. Items with consensus included patient-reported cosmesis, cosmetic satisfaction and early complications. Patients, but not professionals, considered generic complications such as bleeding to be important while professionals valued psychosocial issues such as self-esteem more highly than patients.

Conclusions: Patients and professionals prioritise similar outcomes, but areas of discrepancy with regard to complications and psychosocial outcomes remain. A further Delphi round asking participants to re-prioritise outcomes and a consensus meeting to ratify the final decisions will be necessary to determine a final core outcome set for reconstructive breast surgery.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-17-03.

Anti-acrolein treatment improves behavioral outcome and alleviates myelin damage in experimental autoimmune encephalomyelitis mouse

Oxidative stress is considered a major contributor in the pathology of multiple sclerosis (MS). Acrolein, a highly reactive aldehyde byproduct of lipid peroxidation, is thought to perpetuate oxidative stress. In this study, we aimed to determine the role of acrolein in an animal model of MS, experimental autoimmune encephalomyelitis (EAE) mice. We have demonstrated a significant elevation of acrolein protein adduct levels in EAE mouse spinal cord. Hydralazine, a known acrolein scavenger, significantly improved behavioral outcomes and lessened myelin damage in spinal cord. We postulate that acrolein is an important pathological factor and likely a novel therapeutic target in MS.

Regional variation in the neurochemical coding of the myenteric plexus of the human colon and changes in patients with slow transit constipation

There are differences in the structure and function between regions of the colon. In patients with slow transit constipation the activity of all regions is markedly slowed. Counts of colonic neurones in slow transit constipation have been semiquantitative and led to varying results. We have applied new methods of quantification of markers in whole mounts of the colonic myenteric plexus to compare density of innervation between regions and between normal patients and those undergoing resection for severe constipation. Whole mounts of colonic myenteric plexus were made from specimens removed for cancer treatment (controls) and cases of severe constipation. All neurones were labelled by anti-human neuronal protein antibodies. Neurones synthesizing acetyl choline were labelled for choline acetyltransferase (ChAT) and those for nitric oxide by antisera to nitric oxide synthase (NOS). Four populations of neurones were distinguished and quantified according to the two selective markers, ChAT and NOS. In the normal major populations were NOS alone (51% of ascending colon neurones and 44% of descending colon neurones) and ChAT alone (41% ascending colon, 48% descending colon). Nitric oxide synthase/ChAT and NOS-/ChAT-comprised only small populations. In all regions in severe constipation, the percentage of NOS-only colonic myenteric neurones was raised (54% ascending colon, 49% descending colon) and ChAT only was reduced (36% ascending colon, 42% descending colon). The other populations were not changed. Accurate quantification of neuronal populations in whole mounts of human colon reveals inter-regional differences in innervation and marked changes in innervation in cases of very severe constipation.

Do medical students with A-level mathematics have a better understanding of the principles behind evidence-based medicine?

With the advent of evidence-based medicine, medical students, doctors and other healthcare professionals are required to be more skilled in the interpretation and manipulation of numerical data. The authors observed that undergraduate students without A-level mathematics expressed concern as to their ability to cope with an epidemiology and biostatistics course. It was hypothesized that these anxieties reflected differences in attitudes to numerical manipulation rather than any real lack of competence. Mean exam performance scores were compared for 498 first-year medical students between 2000 and 2002 depending on whether the students did or did not have A-level mathematics. The data revealed no difference in performance. Students without mathematics A-level scored marginally worse (-1.1%, 95% CI -3.1% to 0.8%, p=0.20) but were no more likely to fail the exam (odds ratio=0.98, 95% CI 0.40 to 2.6, p=0.9). It is concluded that some students experience 'numerophobia'-- a perceived and, it is thought, disproportionate fear of numbers and simple mathematical manipulation. This may act as a psychological barrier for future evidence-based practitioners.

Impact on T-cell depletion and CD34+ cell recovery using humanised CD52 monoclonal antibody (CAMPATH-1H) in BM and PSBC collections; comparison with CAMPATH-1M and CAMPATH-1G

BACKGROUND

Ex vivo T-cell depletion of allogeneic BM (BM) grafts can effectively reduce graft versus host disease (GvHD) and may also apply to transplantation of allogeneic peripheral blood stem cell (PBSC) transplants.

METHODS

Here we have evaluated T-cell depletion and progenitor cell recovery by antibody-mediated cells lysis using three CD52 monoclonal antibodies (MAbs) at different concentrations and cell densities.

RESULTS

CAMPATH-1M was superior to CAMPATH-1H for T-cell depletion of BM samples. Treatment with CAMPATH-1M resulted in up to 2.55 log depletion of CD3+ cells, with recoveries of >or=45% CD34+ cells, >or=67% CFU-GM and >or=65% BFU-E. CAMPATH-1H treatment resulted in up to 1.64 log depletion of CD3+ cells and similar recoveries of CD34+ cells, CFU-GM and BFU-E as seen with CAMPATH-1M. Depletion of CD19+ cells was similar to that observed for CD3+ cells while natural killer (NK) cells were relatively spared compared with the T and B cell populations. Log depletions of T cells from PBSC, as determined by immunofluorescence studies and limiting dilution analyses, were similar using CAMPATH-1M, -1H, and -1G. There were also no differences in the depletion of CD19+ cells or NK cells using the three MAbs. Similar results were obtained for recoveries of CD34+ cells, CFU-GM and BFU-E using all three MAbs, although the recovery of CD34+ cells using the highest concentration of MAbs was significantly greater in CAMPATH-1H treated samples. Increasing the number of PBSC treated with CAMPATH-1H and -1M had no effect on the log depletion of T, B or NK cells and there were no major differences in the log depletions achieved with CAMPATH-1H or -1M. Likewise, the higher PBSC density had no effect on the recoveries of CD34+ cells or committed progenitors and once again CAMPATH-1H gave similar recoveries to those obtained using CAMPATH-1M.

DISCUSSION

Although CAMPATH-1M resulted in greater ex vivo T-cell depletion of BM than CAMPATH-1H, in all other respects, the humanised CAMPATH-1H was just as effective as CAMPATH-1M and -1G.

Guidelines and educational outreach visits from community pharmacists to improve prescribing in general practice: a randomised controlled trial

OBJECTIVES

To evaluate the effectiveness of guidelines with or without one-to-one educational outreach visits by community pharmacists in improving general practice prescribing for non-steroidal anti-inflammatory drugs (NSAIDs).

METHODS

Cluster randomised trial of 20 general practices within Avon, England. Practices were randomised to three groups: control; mailed guidelines; mailed guidelines plus educational outreach visits. General practitioners (GPs) in the latter group received two one-to-one outreach visits from community pharmacists. Changes in prescribing were measured using outcomes derived from prescribing analysis and cost (PACT) data. The primary outcome measure was change in the volume of prescribing for ibuprofen, diclofenac and naproxen as a percentage of total NSAID prescribing. Six secondary outcomes included other measures of prescribing quality and volume. A cost-benefit analysis was performed.

RESULTS

No significant differences were observed for the primary outcome measure: practices receiving outreach visits prescribed only 2.1% [95% confidence interval (CI): -0.8 to 5.0] more of the three recommended NSAIDs than the control practices did and 1.6% (95% CI: -1.4 to 4.7) more than practices that received guidelines only. Following adjustment for multiple comparisons, only one secondary outcome showed a statistically significant difference between the groups: the proportion of prescribing of the five most frequently used drugs was 2.2% (95% CI: 0.9 to 3.6) higher in the educational outreach group compared with the control group. A net increase in costs was shown with both interventions.

CONCLUSIONS

Although good prescribing at baseline in the participating practices limited the capacity for improvement, this trial provides no evidence that guidelines with or without educational outreach visits from community pharmacists lead to substantial improvements in prescribing behaviour.

Retrograde tracing of enteric neuronal pathways

Neuroanatomical tracing techniques, and retrograde labelling in particular, are widely used tools for the analysis of neuronal pathways in the central and peripheral nervous system. Over the last 10 years, these techniques have been used extensively to identify enteric neuronal pathways. In combination with multiple-labelling immunohistochemistry, quantitative data about the projections and neurochemical profile of many functional classes of cells have been acquired. These data have revealed a high degree of organization of the neuronal plexuses, even though the different classes of nerve cell bodies appear to be randomly assorted in ganglia. Each class of neurone has a predictable target, length and polarity of axonal projection, a particular combination of neurochemicals in its cell body and distinctive morphological characteristics. The combination of retrograde labelling with targeted intracellular recording has made it possible to target small populations of cells that would rarely be sampled during random impalements. These neuroanatomical techniques have also been applied successfully to human tissue and are gradually unravelling the complexity of the human enteric nervous system.

Two p16 (CDKN2A) germline mutations in 30 Israeli melanoma families

Germline mutations in the p16 (CDKN2A) tumour suppressor gene have been linked to inherited predisposition to malignant melanoma (MM). Variable frequencies of p16 germline mutations were reported in different collections of melanoma families but it can be as high as 50%. Here we describe the results of p16 mutation screening in 30 melanoma kindreds in Israel. The entire coding region of the p16 gene, including exons 1, 2 and 3, flanking exon/intron junctions, and a portion of the 3' untranslated (UTR) region of the gene were examined by single-stranded conformation polymorphism (SSCP) analysis and direct sequencing. Two p16 germline mutations were identified: G101W, which has been previously observed in a number of melanoma kindreds, and G122V, a novel missense mutation. Thus, the frequency of mutations identified in this collection of Israeli families was 7%. Functional analysis indicated that the novel G122V variant retained some capacity to interact with cyclin dependent kinases (CDKs) in vitro, yet it was significantly impaired in its ability to cause a G1 cell cycle arrest in human diploid fibroblasts. This partial loss of function is consistent with the predicted impact of G122V substitution on the 3-dimensional structure of the p16 protein.

Invasive Haemophilus influenzae disease in adults

We reviewed retrospectively all invasive Haemophilus influenzae (Hi) infections in adults ascertained from reference laboratory records and notifications from five NHS regions over the 5 years from 1 October 1990, a period encompassing the introduction of routine Hib childhood immunization (October 1992). A total of 446 cases were identified, a rate of 0.73 infections per 10(5) adults per annum. Though numbers of Hib infections in adults fell after the introduction of Hib vaccines for children (P = 0.035), and there was no increase in infections caused by other capsulated Hi serotypes, total numbers of invasive Hi infections increased due to a large rise in infections caused by non-capsulated Hi (ncHi) strains (P = 0.0067). There was an unexpectedly low rate of infections in those aged 75 years or more (P < 0.0001). The commonest clinical presentations were pneumonia with bacteraemia (227/350, 65%) and bacteraemia alone (62/350, 18%) and the highest rates of disease were in the 65-74 years age group (P < 0.0001). Clinical presentation was not influenced by the capsulation status of the invading Hi strain. 103/350 cases (29%) died within 1 month, and 207/350 (59%) within 6 months of their Hi infection. Case fatality rates were high in all age groups. Pre-existing diseases were noted in 220/350 cases and were associated with a higher case fatality rate (82% vs. 21%, P < 0.0001). After the introduction of Hib immunization in children, invasive Hib infections in unimmunized adults also declined, but the overall rate of invasive Hi disease in adults increased, with most infections now caused by non-capsulated strains. Physicians and microbiologists should be aware of the changing epidemiology, the high associated mortality and high risk of underlying disease. Invasive haemophilus infections in adults should be investigated and treated aggressively.

Threonine dehydrogenase is a minor degradative pathway of threonine catabolism in adult humans

The threonine dehydrogenase (TDG) pathway is a significant route of threonine degradation, yielding glycine in experimental animals, but has not been accurately quantitated in humans. Therefore, the effect of a large excess of dietary threonine, given either as free amino acid (+Thr) or as a constituent of protein (+P-Thr), on threonine catabolism to CO(2) and to glycine was studied in six healthy adult males using a 4-h constant infusion of L-[1-(13)C]threonine and [(15)N]glycine. Gas chromatography-combustion isotope ratio mass spectrometry was used to determine [(13)C]glycine produced from labeled threonine. Threonine intakes were higher on +Thr and +P-Thr diets compared with control (126, 126, and 50 micromol x kg(-1) x h(-1), SD 8, P < 0.0001). Threonine oxidation to CO(2) increased threefold in subjects on +Thr and +P-Thr vs. control (49, 45, and 15 micromol x kg(-1) x h(-1), SD 6, P < 0.0001). Threonine conversion to glycine tended to be higher on +Thr and +P-Thr vs. control (3.5, 3.4, and 1.6 micromol x kg(-1) x h(-1), SD 1.3, P = 0.06). The TDG pathway accounted for only 7-11% of total threonine catabolism and therefore is a minor pathway in the human adult.

Evidence for regulation of amelogenin gene expression by 1,25-dihydroxyvitamin D(3) in vivo

The unique hereditary enamel defect clearly related to the disturbance of one enamel matrix protein is X-linked amelogenesis imperfecta (AI), in which several mutations of amelogenin gene have been identified. The clinical phenotype of many of these subjects shows similarities with enamel defects related to rickets. Therefore, we hypothesized that rachitic dental dysplasia is related to disturbances in the amelogenin pathway. In order to test this hypothesis, combined qualitative and quantitative studies in experimental vitamin D-deficient (-D) rat model systems were performed. First, Western blot analysis of microdissected enamel matrix (secretion and maturation stages) showed no clear evidence of dysregulation of amelogenin protein processing in -D rats as compared with the controls. Second, the ultrastructural investigation permitted identification of the internal tissular defect of rachitic enamel, the irregular absence of intraprismatic enamel observed in -D animals, suggesting a possible link between prism morphogenesis and vitamin D. In addition, the steady-state levels of amelogenin mRNAs measured in microdissected dental cells was decreased in -D rats and up-regulated by an unique injection of 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)). The present study shows evidences that amelogenin expression is regulated by vitamin D. This is the first study of an hormonal regulation of tooth-specific genes.

Functional evaluation of tumour-specific variants of p16INK4a/CDKN2A: correlation with protein structure information

Inherited mutations in the CDKN2A/INK4a/MTS1 tumour suppressor gene on chromosome 9p21 are associated with familial predisposition to melanoma and other tumour types. Nonsense and missense mutations are also found in a variety of sporadic cancers, and over 140 sequence variants have already been recorded in the literature. In assessing the relevance of these variants and for counselling members of affected families, it is important to distinguish inactivating mutations from harmless polymorphisms. Existing functional assays have frequently reached conflicting conclusions and no single test appears adequate. Here we evaluate a number of alternatives including a novel assay based on retroviral delivery of p16INK4a cDNAs into human diploid fibroblasts. Among the 17 sequence variants analysed, three distinct categories can be distinguished: those that abrogate the binding of p16INK4a to CDK4 and CDK6, those that alter the properties of the protein without preventing it from interacting with CDKs, and those that have no discernible effect on protein function. These distinctions can be rationalized by considering the impact of the amino acid changes on the three-dimensional structure of the protein.

The effect of oestrogen supplementation on post-menopausal urinary stress incontinence: a double-blind placebo-controlled trial

OBJECTIVE

To investigate the effect of hormone replacement therapy on post-menopausal urinary stress incontinence.

DESIGN

Double-blind, placebo-controlled, randomised trial.

SETTING

University associated teaching hospital.

POPULATION

Post-menopausal women with genuine stress incontinence, not taking hormone replacement therapy.

METHODS

Randomisation to six months therapy with oestradiol valerate 2 mg daily or placebo. Assessment prior to treatment and upon study completion with the SF-36 health status questionnaire, the Bristol Female Lower Urinary Tract Symptoms questionnaire, a one week urinary diary, one hour perineal pad test, cystometry and urethral profilometry.

RESULTS

Sixty-seven women consented to participate, 33 were randomised to receive oestradiol. Mean age was 63 years. Five women failed to undergo repeat assessment, three of whom were receiving oestrogen. Six women receiving oestradiol experienced breakthrough bleeding during the six months and were subsequently treated with additional monthly progestogen. No significant effect of oestrogen over placebo was observed for any subjective or objective clinical outcome.

CONCLUSIONS

This trial is one of the largest controlled studies yet reported, with the longest duration of treatment. No improvement in post-menopausal stress incontinence was demonstrated after six months therapy with oestradiol. This concurs with another study reported recently; it seems unlikely that oestrogen has a significant role to play in this condition.

An in vitro study of the use of photodynamic therapy for the treatment of natural oral plaque biofilms formed in vivo

Seven-day oral plaque biofilms have been formed on natural enamel surfaces in vivo using a previously reported in situ device. The devices are then incubated with a cationic Zn(II) phthalocyanine photosensitizer and irradiated with white light. Confocal scanning laser microscopy (CSLM) of the biofilms shows that the photosensitizer is taken up into the biomass of the biofilm and that significant cell death is caused by photodynamic therapy (PDT). In addition, the treated biofilms are much thinner than the control samples and demonstrate a different structure from the control samples, with little evidence of channels and a less dense biomass. Transmission electron microscopy (TEM) of the in vivo-formed plaque biofilms reveals considerable damage to bacteria in the biofilm, vacuolation of the cytoplasm and membrane damage being clearly visible after PDT. These results clearly demonstrate the potential value of PDT in the management of oral biofilms.

Flexibility of the major antigenic loop of foot-and-mouth disease virus bound to a Fab fragment of a neutralising antibody: structure and neutralisation

The interaction of foot-and-mouth disease virus (FMDV) serotype C (clone C-S8c1) with a strongly neutralising monoclonal antibody (MAb) 4C4 has been studied by combining data from cryoelectron microscopy and x-ray crystallography. The MAb 4C4 binds to the exposed flexible GH-loop of viral protein 1 (VP1), which appears to retain its flexibility, allowing movement of the bound Fab. This is in striking contrast to MAb SD6, which binds to the same GH-loop of VP1 but exhibits no movement of the bound Fab when observed under identical conditions. However, MAbs 4C4 and SD6 have very similar neutralisation characteristics. The known atomic structure of FMDV C-S8c1 and that of the 4C4 Fab cocrystallised with a synthetic peptide corresponding to the GH-loop of VP1 were fitted to the cryoelectron microscope density map. The best fit of the 4C4 Fab is compatible only with monovalent binding of the MAb in agreement with the neutralisation data on 4C4 MAbs, Fab2s, and Fabs. The position of the bound GH-loop is related to other known positions of this loop by a hinge rotation about the base of the loop. The 4C4 Fab appears to interact almost exclusively with the G-H loop of VP1, making no other contacts with the viral capsid.

Threonine kinetics in preterm infants fed their mothers' milk or formula with various ratios of whey to casein

BACKGROUND

Plasma threonine concentrations are elevated in infants fed formula containing a whey-to-casein protein ratio of 60:40 compared with concentrations in infants fed formula containing a ratio of 20:80 or human milk (60:40).

OBJECTIVE

We studied whether degradation of excess threonine was lower in formula-fed infants than in infants fed their mothers' milk.

DESIGN

Threonine kinetics were examined in 17 preterm infants (gestational age: 31+/-2 wk: birth weight: 1720+/-330 g) by using an 18-h oral infusion of [1-13C]threonine at a postnatal age of 21+/-11 d and weight of 1971+/-270 g. Five infants received breast milk. Formula-fed infants (n = 12) were randomly assigned to receive 1 of 3 formulas (5.3 g protein/MJ) that differed only in the whey-to-casein ratio (20:80, 40:60, and 60:40).

RESULTS

Threonine intake increased significantly in formula-fed infants with increasing whey content of the formula (48.5, 56.4, and 63.2 micromol.kg(-1).h(-1), respectively; pooled SD: 2.2; P = 0.0001), as did plasma threonine concentrations (228, 344, and 419 micromol/L, respectively; pooled SD: 75; P = 0.03). Despite a generous threonine intake by infants fed breast milk (58.0+/-16.0 micromol.kg(-1).h(-1), plasma threonine concentrations remained low (208+/-41 micromol/L). Fecal threonine excretion and net threonine tissue gain, estimated by nitrogen balance, did not differ significantly among groups. Threonine oxidation did not differ significantly among formula-fed infants but was significantly lower in formula-fed infants fed than in infants fed breast milk (17.1% compared with 24.3% of threonine intake, respectively).

CONCLUSION

Formula-fed infants have a lower capacity to oxidize threonine than do infants fed breast milk.

A rapid and reliable method for NO quantification and 15NO/14NO determination using isotope ratio mass spectrometry: an application for the detection of NO synthesis in propionibacteria

For the last decade, numerous studies have focused on the positive or toxic effects of nitric oxide (NO) in procaryotic and eucaryotic cells. This gas has fundamental roles in neurotransmission, vasodilatation, cytotoxicity, and intestinal motility. The ability to produce NO by intestinal microflora or probiotic bacteria is unknown. In this preliminary study, we present a rapid and reproducible procedure for NO quantification and 15NO/14NO determination (based on the reaction between nitrite and acidic potassium iodide) by isotope ratio mass spectrometry. Using this method, we have demonstrated for the first time in vitro production of NO by a dietary bacterium (Propionibacterium acidipropionici, Pa 1) under anaerobic culture conditions. Using different sources of nitrogen, we have clearly shown that propionibacteria can synthesize NO from reduction of nitrate or nitrite. In our experimental conditions, NO synthase was not involved in NO production by propionibacteria.

The alternative product from the human CDKN2A locus, p14(ARF), participates in a regulatory feedback loop with p53 and MDM2

The two distinct proteins encoded by the CDKN2A locus are specified by translating the common second exon in alternative reading frames. The product of the alpha transcript, p16(INK4a), is a recognized tumour suppressor that induces a G1 cell cycle arrest by inhibiting the phosphorylation of the retinoblastoma protein by the cyclin-dependent kinases, CDK4 and CDK6. In contrast, the product of the human CDKN2A beta transcript, p14(ARF), activates a p53 response manifest in elevated levels of MDM2 and p21(CIP1) and cell cycle arrest in both G1 and G2/M. As a consequence, p14(ARF)-induced cell cycle arrest is p53 dependent and can be abrogated by the co-expression of human papilloma virus E6 protein. p14(ARF) acts by binding directly to MDM2, resulting in the stabilization of both p53 and MDM2. Conversely, p53 negatively regulates p14(ARF) expression and there is an inverse correlation between p14(ARF) expression and p53 function in human tumour cell lines. However, p14(ARF) expression is not involved in the response to DNA damage. These results place p14(ARF) in an independent pathway upstream of p53 and imply that CDKN2A encodes two proteins that are involved in tumour suppression.

Expression of biologically active recombinant porcine GM-CSF by baculovirus gene expression system

The full length porcine granulocyte/macrophage colony stimulating factor (GM-CSF) cDNA, including secretion signal peptide coding region was recloned into baculovirus transfer vector pAcYM1. The vector was then transfected with Autographica californica nuclear polyhedrosis virus (AcNPV) DNA into SF21AE cells and the recombinant virus AcPGM was recovered. Recombinant porcine GM-CSF (rpGM-CSF) was obtained from the serum-free culture medium of Tn5 cells infected with the AcPGM virus, and was shown to be a glycosylated 21 kDa protein as confirmed by tunicamycin treatment and [3H]-glucosamine uptake. The biological activities of rpGM-CSF in AcPGM-infected cell culture supernatants were demonstrated by porcine bone marrow cell proliferation and haematopoietic cell colony formation assays. The use of rpGM-CSF enabled us to culture porcine monocytes/macrophage and dendritic-like cells, derived from either porcine bone marrow or peripheral blood, for up to 4 months.

Inhibitors of cyclin-dependent kinases induce features of replicative senescence in early passage human diploid fibroblasts

After a limited number of population doublings (PDs), cultures of normal mammalian diploid cells undergo an irreversible growth arrest known as replicative senescence [1]. As well as contributing to cellular ageing, senescence is viewed as an important mechanism of tumour suppression by preventing the emergence of immortal cell clones [2-4]. Senescent cells have a number of characteristics that distinguish them from cycling or quiescent cells including elevated levels of two cyclin-dependent kinase (Cdk) inhibitors, p16INK4a and p21CIP1 [5-11]. Here, we demonstrate that both of these Cdk inhibitors, as well as other members of their protein families (the INK4 and CIP/KIP families, respectively [12]), induce several facets of the senescent phenotype when ectopically expressed in young human diploid fibroblasts. These include a reduced proliferative capacity, an altered size and shape, the presence of underphosphorylated retinoblastoma protein (pRb), increased expression of plasminogen activator inhibitor (PAI-1) and the appearance of senescence-associated beta-galactosidase (SA-beta-gal) activity [2,3,13-15]. A 20 amino acid peptide from p16INK4a that inhibits Cdks active in the G1 phase of the cell cycle [16] produces similar effects in a dose-dependent manner suggesting that, in primary fibroblasts, inhibition of G1-specific Cdk activity is sufficient to induce phenotypic changes that normally occur at the end of their finite lifespan.

Germline mutations of the CDKN2 gene in UK melanoma families

Germline mutations in CDKN2 on chromosome 9p21, which codes for the cyclin D kinase inhibitor p16, and more rarely, mutations in the gene coding for CDK4, the protein to which p16 binds, underlie susceptibility in some melanoma families. We have sequenced all exons of CDKN2 and analysed the CDK4 gene for mutations in 27 UK families showing evidence of predisposition to melanoma. Five different germline mutations in CDKN2 were found in six families. Three of the mutations (Met53Ile, Arg24Pro and 23ins24) have been reported previously. We have identified two novel CDKN2 mutations (88delG and Ala118Thr) which are likely to be associated with the development of melanoma, because of their co-segregation with the disease and their likely functional effect on the CDKN2 protein. In binding assays the protein expressed from the previously described mutation, Met53Ile, did not bind to CDK4/CDK6, confirming its role as a causal mutation in the development of melanoma. Ala118Thr appeared to be functional in this assay. Arg24Pro appeared to bind to CDK6, but not to CDK4. No mutations were detected in exon 2 of CDK4, suggesting that causal mutations in this gene are uncommon. The penetrance of these mutant CDKN2 genes is not yet established, nor is the risk of non-melanoma cancer to gene carriers.

Accumulation of p16INK4a in mouse fibroblasts as a function of replicative senescence and not of retinoblastoma gene status

Viral transformation of mouse and human fibroblasts has very different effects on the composition of cyclin-dependent kinase (Cdk) complexes. In human cells transformed by the large T-antigen of simian virus 40 (SV40 T-Ag) and human tumour cell lines that lack a functional retinoblastoma gene product (pRb) no cyclin D1-Cdk4 complexes can be detected because all the available Cdk4 is associated with the Cdk-inhibitor p16INK4a. In contrast, SV40-transformed mouse cells and fibroblasts from Rh1-nullizygous mouse embryos contain normal levels of cyclin D1-Cdk4 complexes. To investigate this species difference, we have compared the biochemical properties and expression of mouse p16INK4a with that of its human counterpart. There is a marked increase in p16 RNA and protein levels as primary embryo fibroblasts approach their finite lifespan in culture, but mouse p16 expression does not appear to be influenced by the status of pRb. Transformed or spontaneously immortalized mouse cells therefore do not achieve the very high levels of p16 characteristic of pRb-negative human cell lines. We suggest that these differences may be related to the different frequencies with which mouse and human cells can be immortalized in culture.

A randomized controlled trial of antibiotics on symptom resolution in patients presenting to their general practitioner with a sore throat

BACKGROUND

Sore throat is a common symptom presented to general practitioners (GPs), and there remains controversy about the appropriate use of antibiotics.

AIM

To compare, in a randomized controlled trial, the effectiveness of penicillin, cefixime and placebo on symptom resolution in patients presenting with a sore throat in general practice.

METHOD

Twenty-two GPs in Avon recruited 154 patients, aged 16-60 years, presenting to their GP with a sore throat, and for whom the GP would normally prescribe an antibiotic. Patients were randomized to one of three groups: penicillin V 250 mg four times a day; cefixime 200 mg daily; and placebo. Each was prescribed for five days. The main outcome measures were a diary of symptom resolution over seven days and eradication of group A beta-haemolytic streptococcus (GABHS).

RESULTS

Of the 103 (67%) patients who completed symptom diaries, 40 were allocated to receive penicillin, 29 cefixime and 34 placebo. In the analysis including all patients, symptom resolution was greater by day 3 in the cefixime group than in the placebo group. Penicillin did not improve symptom resolution by day 3 compared with placebo, and cefixime was not statistically significantly different from penicillin. There were significant differences in the proportion of patients using analgesia at day 3, with the proportion being lowest in the cefixime group. The results for the subgroup of patients without GABHS were similar to those for all patients; in particular, the only statistically significant difference was between cefixime and placebo. Although numbers were too small for statistical significance, among patients with GABHS the effects of penicillin and cefixime were similarly raised in relation to placebo.

CONCLUSION

Compared with placebo, cefixime can improve the rate of resolution of symptoms in patients with a sore throat who are selected for antibiotic treatment by their GP. The unexpected finding that cefixime was of benefit compared with placebo for patients without GABHS suggests that bacteria other than GABHS may be important in the pathogenesis of sore throat.

Structure of the complex of an Fab fragment of a neutralizing antibody with foot-and-mouth disease virus: positioning of a highly mobile antigenic loop

Data from cryo-electron microscopy and X-ray crystallography have been combined to study the interactions of foot-and-mouth disease virus serotype C (FMDV-C) with a strongly neutralizing monoclonal antibody (mAb) SD6. The mAb SD6 binds to the long flexible GH-loop of viral protein 1 (VP1) which also binds to an integrin receptor. The structure of the virus-Fab complex was determined to 30 A resolution using cryo-electron microscopy and image analysis. The known structure of FMDV-C, and of the SD6 Fab co-crystallized with a synthetic peptide corresponding to the GH-loop of VP1, were fitted to the cryo-electron microscope density map. The SD6 Fab is seen to project almost radially from the viral surface in an orientation which is only compatible with monovalent binding of the mAb. Even taking into account the mAb hinge and elbow flexibility, it is not possible to model bivalent binding without severely distorting the Fabs. The bound GH-loop is essentially in what has previously been termed the 'up' position in the best fit Fab orientation. The SD6 Fab interacts almost exclusively with the GH-loop of VP1, making very few other contacts with the viral capsid. The position and orientation of the SD6 Fab bound to FMDV-C is in accord with previous immunogenic data.

The Bristol Female Lower Urinary Tract Symptoms questionnaire: development and psychometric testing

OBJECTIVE

To develop a questionnaire that is sensitive to changes in the symptomatology of the female lower urinary tract, particularly urinary incontinence, providing an instrument that can characterize symptom severity, impact on quality of life and evaluate treatment outcome.

PATIENTS, SUBJECTS AND METHODS

Items covering as wide a range of urinary symptoms as possible were devised after consultation with clinicians and a health scientist, a literature review and discussion with patients. Additional items assessed the degree of 'bother' that symptoms were causing. Eighty-five women with clinical symptoms attending for urodynamic assessment and 20 women with none were asked to self-complete the questionnaire. The instrument's validity was assessed by interviewing patients and measuring levels of missing data, comparing symptom scores between clinical and non-clinical populations and comparison with frequency/volume charts and data from pad tests. The instrument's reliability was assessed by measuring both internal consistency and stability, using a 2-week test-retest analysis.

RESULTS

The questionnaire was completed by the patients with a mean of only 2% of items missing; most questions were easily understood. Construct validity was good, with the instrument easily differentiating clinical and non-clinical populations. Criterion validity, as tested against frequency/volume charts and pad-test data, was acceptable, with Kappa coefficients of 0.29-0.79 for frequency/volume data and Spearman rank correlations of 0.50-0.97 and 0.31-0.67 for frequency/volume and pad-test data, respectively. The reliability of the instrument was good; a Cronbach's alpha of 0.78 indicated that the symptom questions had high internal consistency, while stability was excellent, with 78% of symptoms and problems answered identically on two occasions, and Spearman rank correlations of 0.86 and 0.90, respectively.

CONCLUSION

The instrument has good psychometric validity and reliability. The stability demonstrated at baseline and the ability to differentiate clearly between community and clinical populations suggest that it should be ideal for measuring changes following therapeutic intervention. The addition of life-impact items and a 'bother' factor may provide the opportunity to identify those women who wish treatment for their symptoms; this dimension requires further exploration.

Perioperative low-molecular-weight heparin. Is it effective and safe

In previous randomised clinical trials of thromboprophylaxis after total hip replacement, low-molecular-weight heparin has been given for an arbitrary 7 to 14 days. The risk factors are mainly perioperative and it is possible that a shorter course may be adequate. We assessed the safety and effectiveness of a three-day course. We assessed 156 primary THR patients after randomisation to either a control group or to receive enoxaparin at 12 hours preoperatively and 12 and 36 hours postoperatively. Thrombosis was diagnosed by routine venography. Haemorrhagic side-effects were assessed by measurement of blood loss, and soft-tissue side-effects by descriptive scores for wound discharge and bruising of the leg. The prevalence of calf thrombosis was 15.4% in the enoxaparin group and 32.1% in the control group (p = 0.01); the prevalence of proximal thrombosis was 15.4% and 17.9% respectively (not significant). There was no difference in haemorrhagic side-effects or wound discharge, but there was more bruising in the enoxaparin group.

Perioperative low-molecular-weight heparin. Is it effective and safe

In previous randomised clinical trials of thromboprophylaxis after total hip replacement, low-molecular-weight heparin has been given for an arbitrary 7 to 14 days. The risk factors are mainly perioperative and it is possible that a shorter course may be adequate. We assessed the safety and effectiveness of a three-day course. We assessed 156 primary THR patients after randomisation to either a control group or to receive enoxaparin at 12 hours preoperatively and 12 and 36 hours postoperatively. Thrombosis was diagnosed by routine venography. Haemorrhagic side-effects were assessed by measurement of blood loss, and soft-tissue side-effects by descriptive scores for wound discharge and bruising of the leg. The prevalence of calf thrombosis was 15.4% in the enoxaparin group and 32.1% in the control group (p = 0.01); the prevalence of proximal thrombosis was 15.4% and 17.9% respectively (not significant). There was no difference in haemorrhagic side-effects or wound discharge, but there was more bruising in the enoxaparin group.

Synthesis of linoleate and alpha-linolenate by chain elongation in the rat

The objective was to determine whether rats could synthesize longer chain polyunsaturates from hexadecadienoate (16:2n-6) and hexadecatrienoate (16:3n-3). Rats were gavaged with uniformly 13C-labelled hexadecadienoate or hexadecatrienoate, euthanized 24 h later, and total lipids were extracted from liver and carcass. Gas chromatography/combustion/isotope ratio mass spectrometry was used to measure 13C levels in individual liver, carcass, and whole body fatty acids. 13C Enrichment was present in desaturated and chain-elongated polyunsaturates, including linoleate, arachidonate, alpha-linolenate, and docosahexaenoate at 12-13% of the dose of tracer given. 13C Enrichment from hexadecatrienoate was highest in carcass and liver alpha-linolenate, representing 3.5 and 17.9% of the total alpha-linolenate pool, respectively. For linoleate, arachidonate, or docosahexaenoate, the contribution of 13C did not exceed 0.2% of the total body pool. Green leafy vegetables common in the human diet were shown to contain up to 1.2% of total fatty acids as hexadecadienoate and 11.6% as hexadecatrienoate. Hence, humans consuming green vegetables probably synthesize a small proportion of their total body content of linoleate and alpha-linolenate.

The gastrointestinal handling and metabolism of [1-13C]palmitic acid in healthy women

The gastrointestinal handling and metabolism of [1-13C]palmitic acid given as the free fatty acid was examined in six healthy women by measuring the excretion of 13C-label in stool and in breath as 13CO2. The gastrointestinal handling of [1-13C]palmitic acid was compared with the apparent absorption of dietary lipid by measuring lipid losses in stool. The variation both within and between subjects was determined by repeating the study in the same individuals on separate occasions. The time course for excretion of label in stool over the five-day study period followed a common pattern, with most of the label excreted over the first two days of the stool collection. 13C-Label excreted in stool over the five-day study period was 14.3 +/- 9.8% of that administered and on repeating the trial was 31.6 +/- 24.7% (not significantly different due to variability); there was poor agreement within subjects. Lipid excreted in stool expressed as a percentage of ingested lipid was 5.2 +/- 4.4% in Trial 1 and 5.9 +/- 4.0% in Trial 2, and was the same in each individual on repeating the trial. There was no clear relationship between the excretion of 13C-label and lipid in stool (Trial 1: R = -0.43, P > 0.40; Trial 2: R = -0.02, P > 0.97). On the first occasion, 22.0 +/- 4.5% of the administered label was excreted on breath over the 15-h study period and on repeating the trial was 15.8 +/- 9.5% (not significantly different) with poor repeatability in a given individual.(ABSTRACT TRUNCATED AT 250 WORDS)

Amplification of chromosome band 11q13 and a role for cyclin D1 in human breast cancer

In this paper we describe how research on the mouse mammary tumor virus model of breast cancer resulted in the identification of an amplified region of DNA on human chromosome 11 band q13. This amplification occurs in approximately 15% of primary breast cancers. Several candidate oncogenes map within the amplicon but by analysing expression of these genes a strong case can be made for a role for cyclin D1 in tumorigenesis. Immunohistochemical staining indicates that cyclin D1 is expressed at elevated levels in around 40% of breast cancers, including those with the 11q13 amplification. The potential function of cyclin D1 as a regulator of early cell division cycle events would be consistent with a role in neoplasia.

Chromosome 11q13 markers and D-type cyclins in breast cancer

One in six primary human breast cancers has DNA amplification centered on the cyclin D1 gene (CCND1) on chromosome 11q13. This genetic abnormality is preferentially associated with estrogen-receptor positive tumors and may define a sub-class of patients with an adverse prognosis. Although CCND1 has the credentials of a cellular oncogene, being a target for chromosomal translocation and retroviral integration, the 11q13 amplicon encompasses several other markers and CCND1 is not the only candidate for the key gene on the amplified DNA. To assess their relative importance, we have constructed a physical map of the amplified DNA and compared the extent and frequency of amplification across the region. Since it is likely that the gene providing the selective force for amplification will be expressed at elevated levels, we have also examined expression of both RNA and protein. By these criteria, cyclin D1 remains the strongest candidate for the key oncogene on the amplicon and we are currently investigating the functional consequences of its over-expression.

Utilization of uniformly labeled 13C-polyunsaturated fatty acids in the synthesis of long-chain fatty acids and cholesterol accumulating in the neonatal rat brain

Polyunsaturated fatty acids are needed for normal neonatal brain development, but the degree of conversion of the 18-carbon polyunsaturated fatty acid precursors consumed in the diet to their respective 20- and 22-carbon polyunsaturates accumulating in the brain is not well known. In the present study, in vivo 13C nuclear magnetic resonance spectroscopy was used to monitor noninvasively the brain uptake and metabolism of a mixture of uniformly 13C-enriched 16- and 18-carbon polyunsaturated fatty acid methyl esters injected intragastrically into neonatal rats. In vivo NMR spectra of the rat brain at postnatal days 10 and 17 had larger fatty acid signals than in uninjected controls, but changes in levels of individual fatty acids could not be distinguished. One day after injection of the U-13C-polyunsaturated fatty acid mixture, 13C enrichment (measured by isotope ratio mass spectrometry) was similar in brain phospholipids, free fatty acids, free cholesterol, and brain aqueous extract; 13C enrichment remained high in the phospholipids and cholesterol for 15 days. 13C enrichment was similar in the main fatty acids of the brain within 1 day of injection but 15 days later had declined in all except arachidonic acid while continuing to increase in docosahexaenoic acid. These changes in 13C enrichment in brain fatty acids paralleled the developmental changes in brain fatty acid composition. We conclude that, in the neonatal rat brain, dietary 16- and 18-carbon polyunsaturates are not only elongated and desaturated but are also utilized for de novo synthesis of long-chain saturated and monounsaturated fatty acids and cholesterol.

The Ets1 transcription factor is widely expressed during murine embryo development and is associated with mesodermal cells involved in morphogenetic processes such as organ formation

The Ets family of genes encodes a class of transcription factors. Ets1 is predominantly expressed in the lymphoid organs of neonatal and adult mice, whereas Ets2 is expressed in every organ examined. In this study, we investigate the expression of Ets1 and Ets2 during murine embryonic development. Our data show that Ets1 expression increases in embryos after implantation and during organogenesis such that it is expressed in all the organs of day-15 embryos studied. In later fetal stages, Ets1 expression is predominant in the lymphoid tissues, brain, and organs that are undergoing branching morphogenesis (e.g., lung) but is dramatically reduced in other organs such as the stomach and intestine. In neonatal development, Ets1 is expressed only in the lymphoid organs and brain. In situ hybridization analysis demonstrates that expression of Ets1 occurs in mesenchymal cells of developing organs, in the nervous system, and in forming bone. Furthermore, expression of Ets1 is upregulated in P19 cells induced to differentiate into mesoderm-like cells. Ets2, on the other hand, is expressed in differentiated and undifferentiated P19 and F9 cells and in all organs of embryonic, neonatal, and adult mice studied. These data suggest that Ets1 plays an important role in mesodermal cells associated with morphogenetic processes such as organ formation and tissue modeling, whereas Ets2 plays a more fundamental role in cells.

Activation of both Wnt-1 and Fgf-3 by insertion of mouse mammary tumor virus downstream in the reverse orientation: a reappraisal of the enhancer insertion model

In retrovirus-induced tumors, proviral DNA is commonly found next to or within a cellular proto-oncogene such that transcription of the gene is influenced by the viral promoter or enhancer. Extensive surveys of naturally occurring tumors reveal that proviruses integrated on the 3' side of the gene are usually in the same transcriptional orientation, suggesting a model in which the bidirectional viral enhancer acts primarily on the closest promoters. Here we describe a virally induced mammary tumor that appears to contradict these ideas since the Wnt-1/int-1 and Fgf-3/int-2 proto-oncogenes have both been activated by mouse mammary tumor virus (MMTV) DNA integrated 3' of the gene in the opposite transcriptional orientation. However, by cloning the relevant DNAs, we show that these are not simple proviral insertions. In the Wnt-1 locus, there is an additional LTR immediately adjacent to the 3' end of the MMTV provirus, while in Fgf-3, the provirus has sustained a deletion that removes the 5' LTR, gag, and most of pol. These structural alterations can be reconciled with the enhancer insertion model by postulating that the viral enhancer can only function if it is not transcribed.

Amplified region of chromosome band 11q13 in breast and squamous cell carcinomas encompasses three CpG islands telomeric of FGF3, including the expressed gene EMS1

DNA markers that map within the karyotypically defined band q13 on human chromosome 11 are amplified in a subset of mammary and squamous cell carcinomas. It is assumed that the amplified DNA includes a critical gene (or genes) whose overexpression provides a selective force in the development of the tumor. To help identify such genes, we have begun to construct a physical map of CpG islands in the region, making use of a squamous cell carcinoma cell line (UMSCC2) in which the 11q13 region is amplified 11-fold. We previously described the proximal end of this amplicon and the order of markers extending approximately 800 kb centromeric of the FGF3 locus (formerly INT2). We now report the use of chromosome jumping techniques to define additional CpG islands that lie distal to FGF3. These map within the amplified region in UMSCC2 cells and the most telomeric corresponds to the EMS1 gene. The data imply that the amplified DNA in UMSCC2 cells extends for over 1,500 kb and includes at least 7 potential genes. EMS1 and CCND1 (formerly PRAD1), the best candidates for the key gene on the 11q13 amplicon, are > or = 800 kb apart.

Proviral insertions near cyclin D1 in mouse lymphomas: a parallel for BCL1 translocations in human B-cell neoplasms

By isolating genomic DNA clones that encompass the mouse Cyl-1 (cyclin D1) locus, we have identified a putative CpG island close to the 5' end of the gene. Pulsed-field gel electrophoresis with probes derived from either the 5' or 3' side of the CpG island established physical linkage to two independent markers on mouse chromosome 7, in a region that is syntenic with human chromosome 11q13. On the 3' side, Cyl-1 is approximately 75 kb from Hst-1 and Int-2, although there is an additional CpG island in the intervening DNA, while on the 5' side, Cyl-1 is less than 300 kb from Fis-1, an integration site for Friend murine leukaemia virus. As there is no intervening CpG island, proviral insertions at Fis-1 could influence the expression of Cyl-1 and we describe two virally induced tumours in which this appears to be the case. The data suggest that proviral insertions near Cyl-1 in mouse lymphomas are functionally equivalent to the BCL1 translocations that activate cyclin D1 expression in human B-cell malignancies.