GABA(B) receptors function as a heteromeric assembly of the subunits GABA(B)R1 and GABA(B)R2

The principal inhibitory neurotransmitter GABA (gamma-aminobutyric acid) exerts its effects through two ligand-gated channels, GABA(A) and GABA(C) receptors, and a third receptor, GABA(B) , which acts through G proteins to regulate potassium and calcium channels. Cells heterologously expressing the cloned DNA encoding the GABA(B)R1 protein exhibit high-affinity antagonist-binding sites, but they produce little of the functional activity expected from studies of endogenous GABA(B) receptors in the brain. Here we describe a new member of the GABA(B) polypeptide family, GABA(B)R2, that shows sequence homology to GABA(B)R1. Neither GABA(B)R1 nor GABA(B)R2, when expressed individually, activates GIRK-type potassium channels; however, the combination of GABA(B)R1 and GABA(B)R2 confers robust stimulation of channel activity. Both genes are co-expressed in individual neurons, and both proteins co-localize in transfected cells. Moreover, immunoprecipitation experiments indicate that the two polypeptides associate with each other, probably as heterodimers. Several G-protein-coupled receptors (GPCRs) exist as high-molecular-weight species, consistent with the formation of dimers by these receptors, but the relevance of these species for the functioning of GPCRs has not been established. We have now shown that co-expression of two GPCR structures, GABA(B)R1 and GABA(B)R2, belonging to the same subfamily is essential for signal transduction by GABA(B) receptors.

Gene expression analysis by massively parallel signature sequencing (MPSS) on microbead arrays

We describe a novel sequencing approach that combines non-gel-based signature sequencing with in vitro cloning of millions of templates on separate 5 microm diameter microbeads. After constructing a microbead library of DNA templates by in vitro cloning, we assembled a planar array of a million template-containing microbeads in a flow cell at a density greater than 3x10(6) microbeads/cm2. Sequences of the free ends of the cloned templates on each microbead were then simultaneously analyzed using a fluorescence-based signature sequencing method that does not require DNA fragment separation. Signature sequences of 16-20 bases were obtained by repeated cycles of enzymatic cleavage with a type IIs restriction endonuclease, adaptor ligation, and sequence interrogation by encoded hybridization probes. The approach was validated by sequencing over 269,000 signatures from two cDNA libraries constructed from a fully sequenced strain of Saccharomyces cerevisiae, and by measuring gene expression levels in the human cell line THP-1. The approach provides an unprecedented depth of analysis permitting application of powerful statistical techniques for discovery of functional relationships among genes, whether known or unknown beforehand, or whether expressed at high or very low levels.

Characterization of dystrophin in muscle-biopsy specimens from patients with Duchenne's or Becker's muscular dystrophy

A deficiency of the protein dystrophin has recently been shown to be the probable cause of Duchenne's muscular dystrophy. We sought to determine the relation between the clinical phenotype and the status of dystrophin in muscle-biopsy specimens from 103 patients with various neuromuscular disorders. We found very low levels (less than 3 percent of normal levels) or no dystrophin in the severe Duchenne phenotype (35 of 38 patients), low concentrations of dystrophin in the intermediate (outlier) phenotype (4 of 7), and dystrophin of abnormal molecular weight in the mild Becker phenotype (12 of 18). Normal levels of dystrophin of normal molecular weight were found in nearly all the patients (38 of 40) with 20 other neuromuscular disorders we studied. These data show the clinical consequences of both quantitative alterations (in Duchenne's and intermediate dystrophy) in a single protein. The biochemical assay for dystrophin should prove helpful in delineating myopathies that overlap clinically with Duchenne's and Becker's dystrophies, and it shows promise as an accurate diagnostic tool.

Role of the mouse ank gene in control of tissue calcification and arthritis

Mutation at the mouse progressive ankylosis (ank) locus causes a generalized, progressive form of arthritis accompanied by mineral deposition, formation of bony outgrowths, and joint destruction. Here, we show that the ank locus encodes a multipass transmembrane protein (ANK) that is expressed in joints and other tissues and controls pyrophosphate levels in cultured cells. A highly conserved gene is present in humans and other vertebrates. These results identify ANK-mediated control of pyrophosphate levels as a possible mechanism regulating tissue calcification and susceptibility to arthritis in higher animals.

Fas preassociation required for apoptosis signaling and dominant inhibition by pathogenic mutations

Heterozygous mutations encoding abnormal forms of the death receptor Fas dominantly interfere with Fas-induced lymphocyte apoptosis in human autoimmune lymphoproliferative syndrome. This effect, rather than depending on ligand-induced receptor oligomerization, was found to stem from ligand- independent interaction of wild-type and mutant Fas receptors through a specific region in the extracellular domain. Preassociated Fas complexes were found in living cells by means of fluorescence resonance energy transfer between variants of green fluorescent protein. These results show that formation of preassociated receptor complexes is necessary for Fas signaling and dominant interference in human disease.

Deficiency in mural vascular cells coincides with blood-brain barrier disruption in Alzheimer's disease

Neurovascular dysfunction contributes to Alzheimer's disease (AD). Cerebrovascular abnormalities and blood-brain barrier (BBB) damage have been shown in AD. The BBB dysfunction can lead to leakage of potentially neurotoxic plasma components in brain that may contribute to neuronal injury. Pericytes are integral in maintaining the BBB integrity. Pericyte-deficient mice develop a chronic BBB damage preceding neuronal injury. Moreover, loss of pericytes was associated with BBB breakdown in patients with amyotrophic lateral sclerosis. Here, we demonstrate a decrease in mural vascular cells in AD, and show that pericyte number and coverage in the cortex and hippocampus of AD subjects compared with neurologically intact controls are reduced by 59% and 60% (P < 0.01), and 32% and 33% (P < 0.01), respectively. An increase in extravascular immunoglobulin G (IgG) and fibrin deposition correlated with reductions in pericyte coverage in AD cases compared with controls; the Pearson's correlation coefficient r for the magnitude of BBB breakdown to IgG and fibrin vs. reduction in pericyte coverage was -0.96 (P < 0.01) and -0.81 (P < 0.01) in the cortex, respectively, and -0.86 (P < 0.01) and -0.98 (P < 0.01) in the hippocampus, respectively. Thus, deficiency in mural vascular cells may contribute to disrupted vascular barrier properties and resultant neuronal dysfunction during AD pathogenesis.

Evidence for impaired T cell DNA methylation in systemic lupus erythematosus and rheumatoid arthritis

Procainamide and hydralazine inhibit T cell DNA methylation and induce autoreactivity in cloned CD4+ T cells. These drugs also induce an autoimmune syndrome, suggesting a possible relationship between DNA hypomethylation, T cell autoreactivity, and certain autoimmune diseases. To test this relationship, DNA methylation was studied in T cells from patients with rheumatoid arthritis and patients with systemic lupus erythematosus, and was found to be impaired. These results support a relationship between DNA hypomethylation and some forms of autoimmune disease.

Overproduction of protein kinase C causes disordered growth control in rat fibroblasts

We have generated a series of rat fibroblast cell lines that stably overexpress a full-length cDNA encoding the beta 1 form of protein kinase C (PKC). These cell lines contain a 20- to 53-fold increase in PKC activity and exhibit dramatically enhanced morphologic changes following exposure to the tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA). They grow to a high saturation density in monolayer cultures and, when maintained at postconfluence, develop small, dense foci. In contrast to control cells, which display complete anchorage dependence, PKC-overproducing cells form small colonies in soft agar in the absence of TPA and large colonies in the presence of TPA. Thus, the mere overproduction of a single form of PKC is sufficient to confer multiple growth abnormalities in rat fibroblasts. These results provide direct evidence that PKC plays a critical role in growth control and that it mediates several of the cellular effects of the phorbol ester tumor promoters. They also suggest that the activation of PKC may be of central importance in the process of multistage carcinogenesis.

Physiotherapy for adult patients with critical illness: recommendations of the European Respiratory Society and European Society of Intensive Care Medicine Task Force on Physiotherapy for Critically Ill Patients

The Task Force reviewed and discussed the available literature on the effectiveness of physiotherapy for acute and chronic critically ill adult patients. Evidence from randomized controlled trials or meta-analyses was limited and most of the recommendations were level C (evidence from uncontrolled or nonrandomized trials, or from observational studies) and D (expert opinion). However, the following evidence-based targets for physiotherapy were identified: deconditioning, impaired airway clearance, atelectasis, intubation avoidance, and weaning failure. Discrepancies and lack of data on the efficacy of physiotherapy in clinical trials support the need to identify guidelines for physiotherapy assessments, in particular to identify patient characteristics that enable treatments to be prescribed and modified on an individual basis. There is a need to standardize pathways for clinical decision-making and education, to define the professional profile of physiotherapists, and increase the awareness of the benefits of prevention and treatment of immobility and deconditioning for critically ill adult patients.

Late presentation of HIV infection: a consensus definition

OBJECTIVES

Across Europe, almost a third of individuals infected with HIV do not enter health care until late in the course of their infection. Surveillance to identify the extent to which late presentation occurs remains inadequate across Europe and is further complicated by the lack of a common clinical definition of late presentation. The objective of this article is to present a consensus definition of late presentation of HIV infection.

METHODS

Over the past year, two initiatives have moved towards a harmonized definition. In spring 2009, they joined efforts to identify a common definition of what is meant by a 'late-presenting' patient.

RESULTS

Two definitions were agreed upon, as follows. Late presentation: persons presenting for care with a CD4 count below 350 cells/μL or presenting with an AIDS-defining event, regardless of the CD4 cell count. Presentation with advanced HIV disease: persons presenting for care with a CD4 count below 200 cells/μL or presenting with an AIDS-defining event, regardless of the CD4 cell count.

CONCLUSION

The European Late Presenter Consensus working group believe it would be beneficial if all national health agencies, institutions, and researchers were able to implement this definition (either on its own or alongside their own preferred definition) when reporting surveillance or research data relating to late presentation of HIV infection.

Expression of a truncated, kinase-defective TGF-beta type II receptor in mouse skeletal tissue promotes terminal chondrocyte differentiation and osteoarthritis

Members of the TGF-beta superfamily are important regulators of skeletal development. TGF-betas signal through heteromeric type I and type II receptor serine/threonine kinases. When over-expressed, a cytoplasmically truncated type II receptor can compete with the endogenous receptors for complex formation, thereby acting as a dominant-negative mutant (DNIIR). To determine the role of TGF-betas in the development and maintenance of the skeleton, we have generated transgenic mice (MT-DNIIR-4 and -27) that express the DNIIR in skeletal tissue. DNIIR mRNA expression was localized to the periosteum/perichondrium, syno-vium, and articular cartilage. Lower levels of DNIIR mRNA were detected in growth plate cartilage. Transgenic mice frequently showed bifurcation of the xiphoid process and sternum. They also developed progressive skeletal degeneration, resulting by 4 to 8 mo of age in kyphoscoliosis and stiff and torqued joints. The histology of affected joints strongly resembled human osteo-arthritis. The articular surface was replaced by bone or hypertrophic cartilage as judged by the expression of type X collagen, a marker of hypertrophic cartilage normally absent from articular cartilage. The synovium was hyperplastic, and cartilaginous metaplasia was observed in the joint space. We then tested the hypothesis that TGF-beta is required for normal differentiation of cartilage in vivo. By 4 and 8 wk of age, the level of type X collagen was increased in growth plate cartilage of transgenic mice relative to wild-type controls. Less proteoglycan staining was detected in the growth plate and articular cartilage matrix of transgenic mice. Mice that express DNIIR in skeletal tissue also demonstrated increased Indian hedgehog (IHH) expression. IHH is a secreted protein that is expressed in chondrocytes that are committed to becoming hypertrophic. It is thought to be involved in a feedback loop that signals through the periosteum/ perichondrium to inhibit cartilage differentiation. The data suggest that TGF-beta may be critical for multifaceted maintenance of synovial joints. Loss of responsiveness to TGF-beta promotes chondrocyte terminal differentiation and results in development of degenerative joint disease resembling osteoarthritis in humans.

Impaired auditory recognition of fear and anger following bilateral amygdala lesions

The amygdalar complex is a medial temporal lobe structure in the brain which is widely considered to be involved in the neural substrates of emotion. Selective bilateral damage to the human amygdala is rare, offering a unique insight into its functions. There is impairment of social perception after amygdala damage, with defective recognition of facial expressions of emotion. Among the basic emotions, the processing of fear and anger has been shown to be disrupted by amygdala damage. Although it remains puzzling why this not found in all cases, the importance of the amygdala in negative emotion, and especially fear, has been confirmed by conditioning, memory and positron emission tomography (PET) experiments. Central to our understanding of these findings is the question of whether the amygdala is involved specifically in the perception of visual signals of emotion emanating from the face, or more widely in the perception of emotion in all sensory modalities. We report here a further investigation of one of these rare cases, a woman (D.R.) who has impaired perception of the intonation patterns that are essential to the perception of vocal affect, despite normal hearing. As is the case for recognition of facial expressions, it is recognition of fear and anger that is most severely affected in the auditory domain. This shows that the amygdala's role in the recognition of certain emotions is not confined to vision, which is consistent with its being involved in the appraisal of danger and the emotion of fear.

American College of Sports Medicine position stand. The Female Athlete Triad

The Female Athlete Triad is a syndrome occurring in physically active girls and women. Its interrelated components are disordered eating, amenorrhea, and osteoporosis. Pressure placed on young women to achieve or maintain unrealistically low body weight underlies development of the Triad. Adolescents and women training in sports in which low body weight is emphasized for athletic activity or appearance are at greatest risk. Girls and women with one component of the Triad should be screened for the others. Alone or in combination, Female Athlete Triad disorders can decrease physical performance and cause morbidity and mortality. More research is needed on its causes, prevalence, treatment, and consequences. All individuals working with physically active girls and women should be educated about the Female Athlete Triad and develop plans to prevent, recognize, treat, and reduce its risks.

Age at natural menopause and risk of cardiovascular disease

BACKGROUND

Early natural menopause has been postulated to increase the risk of cardiovascular disease.

OBJECTIVE

To examine the relation of age at natural menopause with risk of coronary heart disease (CHD) and stroke in the Nurses' Health Study.

METHODS

Analysis was restricted to 35 616 naturally postmenopausal women who never used estrogen replacement therapy and with no diagnosed cardiovascular disease at baseline, followed up from 1976 to 1994. Information on menopausal status, age at menopause, and other risk factors was obtained in 1976 and updated every 2 years by mailed questionnaires.

RESULTS

During 354326 person-years of follow-up, we documented 757 incident cases of CHD and 350 incident cases of stroke. After adjusting for age, smoking status, and other cardiovascular risk factors, the relative risks (RRs) across categories of age at natural menopause (<40, 40-44, 45-49, 50-54, and > or = 55 years) were 1.53, 1.42, 1.10, 1.00 (reference), and 0.95, respectively; the RR for each 1-year decrease in age at natural menopause was 1.03 (95% confidence interval, 1.01-1.05). Elevated risk with younger age at menopause was observed among current smokers (RR, 1.04 [95% CI, 1.01-1.07] for each 1-year decrease in age at natural menopause) but not among never smokers (RR, 1.00; 95% CI, 0.96-1.04). Age at natural menopause was not significantly associated with ischemic stroke (RR, 1.01; 95% CI, 0.97-1.04) or hemorrhagic stroke (RR, 1.03; 95% CI, 0.97-1.10).

CONCLUSIONS

We observed an overall significant association between younger age at menopause and higher risk of CHD among women who experienced natural menopause and never used hormone therapy. This increased risk was observed among current smokers but not among never smokers. The apparent elevated risk of CHD with decreased age at natural menopause among smokers might reflect residual confounding by smoking.

Ligand-independent activation of the glucocorticoid receptor by beta2-adrenergic receptor agonists in primary human lung fibroblasts and vascular smooth muscle cells

The glucocorticoid receptor (GR) is a ubiquitously expressed transcription factor present in most cell types. Upon ligand binding, the GR is activated and translocates into the nucleus where it transmits the anti-inflammatory actions of glucocorticoids. Here, we describe the ligand-independent activation of GR by the beta2-adrenergic receptor (beta2-AR) agonists, salbutamol and salmeterol, in primary human lung fibroblasts and vascular smooth muscle cells. Immunohistochemistry demonstrated expression of GR and the beta2-AR by fibroblasts and vascular smooth muscle cells. Treatment of the cells with the beta2-AR agonists, salbutamol or salmeterol, resulted in translocation of GR into the nucleus beginning at 30 min, as shown by immunohistochemistry and Western blotting of cytosolic and nuclear cell extracts. In comparison, activation of GR induced by the corticosteroids dexamethasone and fluticasone occurred at the same time after treatment (30 min) but resulted in a more complete depletion of GR from the cytosolic compartment. Electrophoretic mobility shift assays confirmed that nuclear GR, activated by both beta2-AR agonists and glucocorticoids, actively bound to the GR consensus sequence (GR element). Functional activation of the GR was confirmed by a Luciferase reporter gene assay, using a GR driven promoter fragment from the p21((WAF1/CIP1)) gene. The effects of the beta2-AR agonists, salbutamol and salmeterol, were dependent upon binding to the beta2-AR, because blocking of beta2-AR with propranolol abrogated GR activation. GR activation appeared to involve cAMP. In summary, these data show that beta2-AR agonists are potent activators of GR. Ligand-independent activation of GR by beta2-AR agonists may substantially mediate the anti-inflammatory actions of these drugs observed in vitro and in vivo.

The beta-adrenoceptor

The human beta-adrenoceptor is a member of the seven-transmembrane family of receptors, encoded by a gene on chromosome 5. beta-Adrenoceptors have been classified into beta1, beta2, and beta3 subgroups, with beta2-receptors being widely distributed in the respiratory tract, particularly in airway smooth muscle. Intracellular signaling following beta2-adrenoceptor activation is largely affected through a trimeric Gs protein coupled to adenylate cyclase. Cyclic AMP (cAMP) induces airway relaxation through phosphorylation of muscle regulatory proteins and attenuation of cellular Ca2+ concentrations. Alternative cAMP-independent pathways involving activation of membrane maxi-K+ channels and coupling through Gi to the MAP kinase system have also been described. Site-directed mutagenesis has identified Asp 113 and Ser 204/207 within the third and fourth membrane domains as the active site of the beta2-receptor, critical for beta2-agonist binding and activity. beta2-Agonists have been characterized as those that directly activate the receptor (albuterol), those that are taken up into a membrane depot (formoterol), and those that interact with a receptor-specific auxiliary binding site (salmeterol). These differences in mechanism of action are reflected in the kinetics of airway smooth muscle relaxation and bronchodilation in patients with asthma. beta-Adrenoceptor desensitization associated with beta2-agonist activation is a consequence of phosphorylation by beta-ARK and uncoupling of the receptor from Gs following beta-arrestin binding, of internalization and recycling of the receptor through processes of sequestration and resensitization and downregulation, modulated by an effect on receptor gene expression. The degree of receptor desensitization appears to differ, depending on the cell or tissue type, and is reflected in the different profiles of clinical tolerance to chronic beta2-agonist therapy. A number of polymorphisms of the beta2-receptor have been described that appear to alter the behavior of the receptor following agonist exposure. These include Arg-Gly 16, Glu-Gln 27, and Thr-lle 164. The Gly 16 receptor downregulates to a greater extent and is associated with increased airway hyperreactivity, nocturnal symptoms, and more severe asthma. The Glu 27 form appears to protect against downregulation and is associated with less reactive airways. An individual can be homozygous or heterozygous for given polymorphisms, and large populations will have to be studied to determine their importance to the asthma phenotype.

Anti-transforming growth factor (TGF)-beta antibodies inhibit breast cancer cell tumorigenicity and increase mouse spleen natural killer cell activity. Implications for a possible role of tumor cell/host TGF-beta interactions in human breast cancer progression

TGF-beta effects on angiogenesis, stroma formation, and immune function suggest its possible involvement in tumor progression. This hypothesis was tested using the 2G7 IgG2b, which neutralizes TGF-beta 1, -beta 2, and -beta 3, and the MDA-231 human breast cancer cell line. Inoculation of these cells in athymic mice decreases mouse spleen natural killer (NK) cell activity. Intraperitoneal injections of 2G7 starting 1 d after intraperitoneal inoculation of tumor cells suppressed intraabdominal tumor and lung metastases, whereas the nonneutralizing anti-TGF-beta 12H5 IgG2a had no effect. 2G7 transiently inhibited growth of established MDA-231 subcutaneous tumors. Histologically, both 2G7-treated and control tumors were identical. Intraperitoneal administration of 2G7 resulted in a marked increase in mouse spleen NK cell activity. 2G7 did not inhibit MDA-231 primary tumor or metastases formation, nor did it stimulate NK cell-mediated cytotoxicity in beige NK-deficient nude mice. Finally, serum-free conditioned medium from MDA-231 cells inhibited the NK cell activity of human blood lymphocytes. This inhibition was blocked by the neutralizing anti-TGF-beta 2G7 antibody but not by a nonspecific IgG2. These data support a possible role for tumor cell TGF-beta in the progression of mammary carcinomas by suppressing host immune surveillance.

Barriers and facilitators to implementing screening and brief intervention for alcohol misuse: a systematic review of qualitative evidence

BACKGROUND

This review aimed to synthesize qualitative evidence for barriers and facilitators to effective implementation of screening and brief intervention for alcohol misuse in adults and children over 10 years.

METHODS

A search of medical and social science databases was carried out and augmented by hand-searching of reference lists and contents of key journals. Qualitative evidence was synthesized thematically.

RESULTS

A total of 47 papers varying in design and quality were included in the review. Most evaluated implementation in primary care settings. Implementation was reported to be limited by lack of resources, training and support from management, as well as workload. The appropriateness of context in which discussions take place was reported as an acceptability factor for patients and practitioners. Health professionals require sufficient knowledge about alcohol guidelines and risk in order to implement screening and intervention to those most in need.

CONCLUSIONS

Whilst brief screening and brief intervention have been shown to be effective in some settings, this review has identified a number of barriers and facilitators to implementation. Adequate resources, training and the identification of those at risk without stereotyping are the main facilitators in primary care. More research is needed to assess implementation in other settings.

Face processing impairments after amygdalotomy

We report an investigation of face processing impairments in D.R., a 51-year-old woman with a partial bilateral amygdalotomy. D.R. was able to recognize pre-operatively familiar faces, but she showed generalized problems of name retrieval and a more circumscribed deficit affecting the recognition of faces learnt post-operatively. In contrast to her poor memory for new faces, D.R.'s ability to match simultaneously presented photographs of unfamiliar faces was unimpaired. However, D.R. also experienced deficits in expression processing which compromised the recognition of emotion from people's faces: she was poor both at matching and at identifying photographs of emotional facial expressions. In addition, her interpretation of eye gaze direction was defective, showing a more general problem in reading social signals from the face. The presence of impairments affecting the learning of new faces and the comprehension of gaze direction and facial expressions of emotion is consistent with the hypothesis of a role for the amygdala in learning and social behaviour.

Captopril inhibits angiogenesis and slows the growth of experimental tumors in rats

Captopril, an inhibitor of angiotensin converting enzyme, is widely used clinically to manage hypertension and congestive heart failure. Here captopril is shown to be an inhibitor of angiogenesis able to block neovascularization induced in the rat cornea. Captopril acted directly and specifically on capillary endothelial cells, inhibiting their chemotaxis with a biphasic dose-response curve showing an initial decrease at clinically achievable doses under 10 microM and a further slow decline in the millimolar range. Captopril inhibition of endothelial cell migration was not mediated by angiotensin converting enzyme inhibition, but was suppressed by zinc. Direct inhibition by captopril of zinc-dependent endothelial cell-derived 72-and 92-kD metalloproteinases known to be essential for angiogenesis was also seen. When used systemically on rats captopril inhibited corneal neovascularization and showed the antitumor activity expected of an inhibitor of angiogenesis, decreasing the number of mitoses present in carcinogen-induced foci of preneoplastic liver cells and slowing the growth rate of an experimental fibrosarcoma whose cells were resistant to captopril in vitro. These data define this widely used drug as a new inhibitor of neovascularization and raise the possibility that patients on long term captopril therapy may derive unexpected benefits from its antiangiogenic activities.

Fluorescence lifetime imaging

We describe a new fluorescence imaging methodology in which the image contrast is derived from the fluorescence lifetime at each point in a two-dimensional image and not the local concentration and/or intensity of the fluorophore. In the present apparatus, lifetime images are created from a series of images obtained with a gain-modulated image intensifier. The frequency of gain modulation is at the light-modulation frequency (or a harmonic thereof), resulting in homodyne phase-sensitive images. These stationary phase-sensitive images are collected using a slow-scan CCD camera. A series of such images, obtained with various phase shifts of the gain-modulation signal, is used to determine the phase angle and/or modulation of the emission at each pixel, which is in essence the phase or modulation lifetime image. An advantage of this method is that pixel-to-pixel scanning is not required to obtain the images, as the information from all pixels is obtained at the same time. The method has been experimentally verified by creating lifetime images of standard fluorophores with known lifetimes, ranging from 1 to 10 ns. As an example of biochemical imaging we created life-time images of Yt-base when quenched by acrylamide, as a model for a fluorophore in distinct environments that affect its decay time. Additionally, we describe a faster imaging procedure that allows images in which a specific decay time is suppressed to be calculated, allowing rapid visualization of unique features and/or regions with distinct decay times. The concepts and methodologies of fluorescence lifetime imaging (FLIM) have numerous potential applications in the biosciences. Fluorescence lifetimes are known to be sensitive to numerous chemical and physical factors such as pH, oxygen, temperature, cations, polarity, and binding to macromolecules. Hence the FLIM method allows chemical or physical imaging of macroscopic and microscopic samples.

CACP, encoding a secreted proteoglycan, is mutated in camptodactyly-arthropathy-coxa vara-pericarditis syndrome

Altered growth and function of synoviocytes, the intimal cells which line joint cavities and tendon sheaths, occur in a number of skeletal diseases. Hyperplasia of synoviocytes is found in both rheumatoid arthritis and osteoarthritis, despite differences in the underlying aetiologies of the two disorders. We have studied the autosomal recessive disorder camptodactyly-arthropathy-coxa vara-pericarditis syndrome (CACP; MIM 208250) to identify biological pathways that lead to synoviocyte hyperplasia, the principal pathological feature of this syndrome. Using a positional-candidate approach, we identified mutations in a gene (CACP) encoding a secreted proteoglycan as the cause of CACP. The CACP protein, which has previously been identified as both 'megakaryocyte stimulating factor precursor' and 'superficial zone protein', contains domains that have homology to somatomedin B, heparin-binding proteins, mucins and haemopexins. In addition to expression in joint synovium and cartilage, CACP is expressed in non-skeletal tissues including liver and pericardium. The similarity of CACP sequence to that of other protein families and the expression of CACP in non-skeletal tissues suggest it may have diverse biological activities.

Complete sequencing shows a role for MSX1 in non-syndromic cleft lip and palate

MSX1 has been proposed as a gene in which mutations may contribute to non-syndromic forms of cleft lip and/or cleft palate. Support for this comes from human linkage and linkage disequilibrium studies, chromosomal deletions resulting in haploinsufficiency, a large family with a stop codon mutation that includes clefting as a phenotype, and the Msx1 phenotype in a knockout mouse. This report describes a population based scan for mutations encompassing the sense and antisense transcribed sequence of MSX1 (two exons, one intron). We compare the completed genomic sequence of MSX1 to the mouse Msx1 sequence to identify non-coding homology regions, and sequence highly conserved elements. The samples studied were drawn from a panethnic collection including people of European, Asian, and native South American ancestry. The gene was sequenced in 917 people and potentially aetiological mutations were identified in 16. These included missense mutations in conserved amino acids and point mutations in conserved regions not identified in any of 500 controls sequenced. Five different missense mutations in seven unrelated subjects with clefting are described. Evolutionary sequence comparisons of all known Msx1 orthologues placed the amino acid substitutions in context. Four rare mutations were found in non-coding regions that are highly conserved and disrupt probable regulatory regions. In addition, a panel of 18 population specific polymorphic variants were identified that will be useful in future haplotype analyses of MSX1. MSX1 mutations are found in 2% of cases of clefting and should be considered for genetic counselling implications, particularly in those families in which autosomal dominant inheritance patterns or dental anomalies appear to be cosegregating with the clefting phenotype.