The dispersion-brightness relation for fast radio bursts from a wide-field survey.

Despite considerable efforts over the past decade, only 34 fast radio bursts-intense bursts of radio emission from beyond our Galaxy-have been reported1,2. Attempts to understand the population as a whole have been hindered by the highly heterogeneous nature of the searches, which have been conducted with telescopes of different sensitivities, at a range of radio frequencies, and in environments corrupted by different levels of radio-frequency interference from human activity. Searches have been further complicated by uncertain burst positions and brightnesses-a consequence of the transient nature of the sources and the poor angular resolution of the detecting instruments. The discovery of repeating bursts from one source3, and its subsequent localization4 to a dwarf galaxy at a distance of 3.7 billion light years, confirmed that the population of fast radio bursts is located at cosmological distances. However, the nature of the emission remains elusive. Here we report a well controlled, wide-field radio survey for these bursts. We found 20, none of which repeated during follow-up observations between 185-1,097 hours after the initial detections. The sample includes both the nearest and the most energetic bursts detected so far. The survey demonstrates that there is a relationship between burst dispersion and brightness and that the high-fluence bursts are the nearby analogues of the more distant events found in higher-sensitivity, narrower-field surveys5.

Heterocyclic boronic acids display sialic acid selective binding in a hypoxic tumor relevant acidic environment.

Boronic acids are well known for their ability to reversibly interact with the diol groups found in sugars and glycoproteins. However, they are generally indiscriminate in their binding. Herein we describe the discovery of a group of heterocyclic boronic acids demonstrating unusually high affinity and selectivity for sialic acids (SAs or N-acetylneuraminic acid), which are sugar residues that are intimately linked with tumor growth and cancer progression. Remarkably, these interactions strengthen under the weakly acidic pH conditions associated with a hypoxic tumoral microenvironment. In vitro competitive binding assays uncovered a significantly higher ability of 5-boronopicolinic acid, one of the derivatives identified in this work as a strong SA-binder, to interact with cell surface SA in comparison to a gold-standard structure, 3-propionamidophenylboronic acid, which has proven to be an efficient SA-binder in numerous reports. This structure also proved to be suitable for further chemical conjugation with a well-preserved SA-binding capability. These findings suggest an attractive alternative to other ongoing boronic acid based chemistry techniques aiming to achieve tumor-specific chemotherapies and diagnoses.

Residues within the transmembrane domain of the glucagon-like peptide-1 receptor involved in ligand binding and receptor activation: modelling the ligand-bound receptor.

The C-terminal regions of glucagon-like peptide-1 (GLP-1) bind to the N terminus of the GLP-1 receptor (GLP-1R), facilitating interaction of the ligand N terminus with the receptor transmembrane domain. In contrast, the agonist exendin-4 relies less on the transmembrane domain, and truncated antagonist analogs (e.g. exendin 9-39) may interact solely with the receptor N terminus. Here we used mutagenesis to explore the role of residues highly conserved in the predicted transmembrane helices of mammalian GLP-1Rs and conserved in family B G protein coupled receptors in ligand binding and GLP-1R activation. By iteration using information from the mutagenesis, along with the available crystal structure of the receptor N terminus and a model of the active opsin transmembrane domain, we developed a structural receptor model with GLP-1 bound and used this to better understand consequences of mutations. Mutation at Y152 [transmembrane helix (TM) 1], R190 (TM2), Y235 (TM3), H363 (TM6), and E364 (TM6) produced similar reductions in affinity for GLP-1 and exendin 9-39. In contrast, other mutations either preferentially [K197 (TM2), Q234 (TM3), and W284 (extracellular loop 2)] or solely [D198 (TM2) and R310 (TM5)] reduced GLP-1 affinity. Reduced agonist affinity was always associated with reduced potency. However, reductions in potency exceeded reductions in agonist affinity for K197A, W284A, and R310A, while H363A was uncoupled from cAMP generation, highlighting critical roles of these residues in translating binding to activation. Data show important roles in ligand binding and receptor activation of conserved residues within the transmembrane domain of the GLP-1R. The receptor structural model provides insight into the roles of these residues.

Case report: foreign body in the palate of an infant.

Most foreign body aspirations occur in children younger than five years old, with 65% of deaths affecting infants younger than one year. A reasonably uncommon eventuality is attachment and retention of the foreign body to the oral mucosal tissues and in particular to the soft tissues of the hard palate. The following report discusses the unusual presentation of a foreign body in the palate of a child as well as the treatment carried out to facilitate the removal of the object. This report aims to highlight the importance of considering an impacted foreign body in the differential diagnosis of a palatal mass in an infant.

Heparanase expression and activity influences chondrogenic and osteogenic processes during endochondral bone formation.

Endochondral bone formation is a highly orchestrated process involving coordination among cell-cell, cell-matrix and growth factor signaling that eventually results in the production of mineralized bone from a cartilage template. Chondrogenic and osteogenic differentiation occur in sequence during this process, and the temporospatial patterning clearly requires the activities of heparin binding growth factors and their receptors. Heparanase (HPSE) plays a role in osteogenesis, but the mechanism by which it does so is incompletely understood. We used a combination of ex vivo and in vitro approaches and a well described HPSE inhibitor, PI-88 to study HPSE in endochondral bone formation. In situ hybridization and immunolocalization with HPSE antibodies revealed that HPSE is expressed in the peri-chondrium, peri-osteum, and at the chondro-osseous junction, all sites of key signaling events and tissue morphogenesis. Transcripts encoding Hpse also were observed in the pre-hypertrophic zone. Addition of PI-88 to metatarsals in organ culture reduced growth and suggested that HPSE activity aids the transition from chondrogenic to osteogenic processes in growth of long bones. To study this, we used high density cultures of ATDC5 pre-chondrogenic cells grown under conditions favoring chondrogenesis or osteogenesis. Under chondrogenic conditions, HPSE/Hpse was expressed at high levels during the mid-culture period, at the onset of terminal chondrogenesis. PI-88 addition reduced chondrogenesis and accelerated osteogenesis, including a dramatic up-regulation of osteocalcin levels. In normal growth medium, addition of PI-88 reduced migration of ATDC-5 cells, suggesting that HPSE facilitates cartilage replacement by bone at the chondro-osseous junction by removing the HS component of proteoglycans, such as perlecan/HSPG2, that otherwise prevent osteogenic cells from remodeling hypertrophic cartilage.

Comparison of sevoflurane and isoflurane in dogs anaesthetised for clinical surgical or diagnostic procedures.

OBJECTIVES: To assess attributes of sevoflurane for routine clinical anaesthesia in dogs by comparison with the established volatile anaesthetic isoflurane. METHODS: One hundred and eight dogs requiring anaesthesia for elective surgery or diagnostic procedures were studied. The majority was premedicated with 0.03 mg/kg of acepromazine and 0.01 mg/kg of buprenorphine or 0.3 mg/kg of methadone before induction of anaesthesia with 2 to 4 mg/kg of propofol and 0.5 mg/kg of diazepam. They were randomly assigned to receive either sevoflurane (group S, n=50) or isoflurane (group I, n=58) in oxygen and nitrous oxide for maintenance of anaesthesia. Heart rate, respiratory rate, indirect arterial blood pressure, haemoglobin saturation, vaporiser settings, end-tidal carbon dioxide and anaesthetic concentration and oesophageal temperature were measured. Recovery was timed. Data were analysed using analysis of variance and non-parametric tests. RESULTS: Heart rate (85 to 140/minute), respiratory rate (six to 27/minute) and systolic arterial blood pressure (80 to 150 mmHg) were similar in the two groups. End-tidal carbon dioxide between 30 and 60 minutes (group S 6.4 to 6.6 and group I 5.8 to 5.9 per cent) and vaporiser settings throughout (group S 2.1 to 2.9 and group I 1.5 to 1.5 per cent) were higher in group S. There was no difference in time to head lift (18+/-16 minutes), sternal recumbency (28+/-22 minutes) or standing (48+/-32 minutes). No adverse events occurred. CLINICAL SIGNIFICANCE: Sevoflurane appeared to be a suitable volatile anaesthetic for maintenance of routine clinical anaesthesia in dogs.

Comprehensive clinical management of polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) affects 6-7% of reproductive-aged women. Although the diagnostic criteria for PCOS have been debated, it is frequently characterized by hyperandrogenism (hirsutism, acne, male-pattern hair loss), oligo-anovulation, and polycystic ovaries on ultrasound. The reproductive and metabolic complications associated with the syndrome can be serious, so a comprehensive approach to the evaluation and treatment of affected women is important. Menstrual cycle control is necessary to prevent endometrial hyperplasia, and this can be accomplished with hormonal contraception, progesterone therapy, and weight loss (if overweight). In women desiring pregnancy, commonly used ovulation induction therapies include weight loss, clomiphene citrate, and/or metformin. Cosmetic issues such as hirsutism, acne and male-pattern hair loss can be challenging to cope with. Treatment options include estrogen-containing hormonal contraceptive agents, antiandrogens, and topical agents. More permanent hair reduction can be achieved with electrolysis and laser therapy. Evaluation of metabolic complications includes risk assessment for diabetes, dyslipidemia, hypertension, and nonalcoholic fatty liver disease. Women with PCOS should also be screened for sleep apnea, as this has been reported to occur more commonly in women with PCOS. Finally, mental health issues such as depression and eating disorders may be present. Many of the complications associated with PCOS can be managed with therapeutic lifestyle change, including a healthy diet, exercise, weight loss (if overweight), and psychological support. Pharmacological therapies are also available to effectively regulate menstrual cycles and manage cosmetic complications. This article will review the current diagnostic and therapeutic strategies in PCOS.

The DNA sequence and biological annotation of human chromosome 1.

The reference sequence for each human chromosome provides the framework for understanding genome function, variation and evolution. Here we report the finished sequence and biological annotation of human chromosome 1. Chromosome 1 is gene-dense, with 3,141 genes and 991 pseudogenes, and many coding sequences overlap. Rearrangements and mutations of chromosome 1 are prevalent in cancer and many other diseases. Patterns of sequence variation reveal signals of recent selection in specific genes that may contribute to human fitness, and also in regions where no function is evident. Fine-scale recombination occurs in hotspots of varying intensity along the sequence, and is enriched near genes. These and other studies of human biology and disease encoded within chromosome 1 are made possible with the highly accurate annotated sequence, as part of the completed set of chromosome sequences that comprise the reference human genome.

Prospective study of the effect of rectopexy on colonic motility in patients with rectal prolapse.

BACKGROUND: Patients with rectal prolapse have abnormal hindgut motility. This study examined the effect of rectal prolapse surgery on colonic motility. METHODS: Twelve patients undergoing sutured rectopexy were studied before and 6 months after surgery by colonic manometry, colonic transit study and clinical assessment of bowel function. The results were compared with those from seven control subjects. RESULTS: Before surgery colonic pressure was greater in patients than controls (P < 0.050). Controls responded to a meal stimulus by increasing colonic pressure; this increase was absent in patients. After rectopexy, colonic pressure reduced towards control values and patients' colonic pressure response to a meal returned. High-amplitude propagated contractions (HAPCs) were seen in all controls but in only three patients before and two patients after surgery. Three patients had prolonged colonic transit before and eight after rectopexy. CONCLUSION: Patients with rectal prolapse have abnormal colonic motility associated with reduced HAPC activity. Rectopexy reduces colonic pressure but fails to restore HAPCs, reduce constipation or improve colonic transit. These observations help explain the pathophysiology of constipation associated with rectal prolapse.

DNA sequence and analysis of human chromosome 9.

Chromosome 9 is highly structurally polymorphic. It contains the largest autosomal block of heterochromatin, which is heteromorphic in 6-8% of humans, whereas pericentric inversions occur in more than 1% of the population. The finished euchromatic sequence of chromosome 9 comprises 109,044,351 base pairs and represents >99.6% of the region. Analysis of the sequence reveals many intra- and interchromosomal duplications, including segmental duplications adjacent to both the centromere and the large heterochromatic block. We have annotated 1,149 genes, including genes implicated in male-to-female sex reversal, cancer and neurodegenerative disease, and 426 pseudogenes. The chromosome contains the largest interferon gene cluster in the human genome. There is also a region of exceptionally high gene and G + C content including genes paralogous to those in the major histocompatibility complex. We have also detected recently duplicated genes that exhibit different rates of sequence divergence, presumably reflecting natural selection.

The DNA sequence and analysis of human chromosome 13.

Chromosome 13 is the largest acrocentric human chromosome. It carries genes involved in cancer including the breast cancer type 2 (BRCA2) and retinoblastoma (RB1) genes, is frequently rearranged in B-cell chronic lymphocytic leukaemia, and contains the DAOA locus associated with bipolar disorder and schizophrenia. We describe completion and analysis of 95.5 megabases (Mb) of sequence from chromosome 13, which contains 633 genes and 296 pseudogenes. We estimate that more than 95.4% of the protein-coding genes of this chromosome have been identified, on the basis of comparison with other vertebrate genome sequences. Additionally, 105 putative non-coding RNA genes were found. Chromosome 13 has one of the lowest gene densities (6.5 genes per Mb) among human chromosomes, and contains a central region of 38 Mb where the gene density drops to only 3.1 genes per Mb.

Surgery for occult rectal prolapse.

OBJECTIVE: An 'occult' rectal prolapse may be diagnosed during investigation of altered bowel habit. It has been suggested that the outcome of surgery for these patients may be associated with results that are inferior to those achieved in patients with overt rectal prolapse. This study compares the results of surgery for 'occult' and overt rectal prolapse in terms of mortality, morbidity and change in bowel habit. PATIENTS AND METHODS: A retrospective review was undertaken of consecutive patients undergoing surgery for rectal prolapse during the decade 1988-98. Resection rectopexy was the treatment of choice except in patients with faecal incontinence who underwent sutured rectopexy. Those patients who were unfit for an abdominal operation were offered a perineal procedure. Outcome measures were mortality, morbidity, prolapse recurrence, constipation and faecal incontinence. Data were retrieved from case note review, clinical assessment, telephone consultation or postal questionnaire. RESULTS: Rectal prolapse surgery was undertaken in 69 patients with an overt prolapse and 74 patients with an 'occult' prolapse. Patients in the 'occult' prolapse group were significantly younger than those with overt prolapse (P = 0.0002). There were significantly more perineal procedures in the overt prolapse group compared with the 'occult' prolapse group (54% vs 5%, P = 0.0001). There were no deaths within 28 days of surgery. Major surgical complications occurred in 5 patients (3.5%). Seven patients (10%) experienced recurrent prolapse. Rectal prolapse surgery reduced the incidence of St. Mark's grade 4 faecal incontinence from 38% to 19% in the overt prolapse group (P = 0.023) and from 49% to 22% in the 'occult' prolapse group (P < 0.001). Following surgery the incidence of constipation increased in the 'occult' group from 39% to 50% but decreased in the overt prolapse group from 42% to 35%. CONCLUSIONS: Surgery for an 'occult' rectal prolapse is unlikely to benefit patients whose principle symptom is constipation. Approximately half of those patients whose 'occult' rectal prolapse is associated with faecal incontinence will have their bowel habit improved by prolapse surgery.

Strategy for selection of type of operation for rectal prolapse based on clinical criteria.

PURPOSE: Reports of outcome after surgery for rectal prolapse predominantly relate to single operative procedures. A single surgical operation is not appropriate for all patients with rectal prolapse. We describe a selective policy based on clinical criteria. METHODS: Patients were offered surgery according to the following broad clinical protocol. Those who were unfit for abdominal surgery had a perineal operation. The remainder had a suture abdominal rectopexy. A sigmoid resection was added for patients in whom incontinence was not a predominant symptom. RESULTS: Surgery was performed in 159 patients. Of these, 57 had a perineal operation, 65 had fixation rectopexy, and 37 had resection rectopexy. There were no in-hospital deaths, and major complications occurred in five patients (3.5 percent). Minimum follow-up was 3 years. Of the 143 patients with long-term follow-up, recurrence occurred in 7 (5 percent). Constipation increased from 41 to 43 percent (59-61/143) and incontinence decreased from 43 to 19 percent (61 to 27/143). CONCLUSIONS: A selective policy has improved outcome compared with reports of a single operation. Future studies might consider an objective method of selecting the type of operation for rectal prolapse.

The DNA sequence and analysis of human chromosome 6.

Chromosome 6 is a metacentric chromosome that constitutes about 6% of the human genome. The finished sequence comprises 166,880,988 base pairs, representing the largest chromosome sequenced so far. The entire sequence has been subjected to high-quality manual annotation, resulting in the evidence-supported identification of 1,557 genes and 633 pseudogenes. Here we report that at least 96% of the protein-coding genes have been identified, as assessed by multi-species comparative sequence analysis, and provide evidence for the presence of further, otherwise unsupported exons/genes. Among these are genes directly implicated in cancer, schizophrenia, autoimmunity and many other diseases. Chromosome 6 harbours the largest transfer RNA gene cluster in the genome; we show that this cluster co-localizes with a region of high transcriptional activity. Within the essential immune loci of the major histocompatibility complex, we find HLA-B to be the most polymorphic gene on chromosome 6 and in the human genome.

Yeast assays for G-protein-coupled receptors.

Yeast assays for G-protein-coupled receptors have many attractions due to their simplicity, low cost, and lack of endogenous receptors. Since the first report of functional coupling of the human beta 2 adrenergic receptor to the yeast pheromone-response pathway in 1990, the technology has developed to a point at which more than 30 heterologous GPCRs are now published to couple. Major breakthroughs have come from an understanding of receptor-G protein interactions, alongside advances in knowledge of the structure of heterotrimeric G proteins. Yeast screens have been used to identify ligands both from compound collections and through the autocrine expression of peptide libraries. Yeast genetics has also been applied to a functional analysis of GPCRs and peptide ligands. In this review we describe the historical development of yeast GPCR assay systems and their current applications.

Therapeutic uses of vitamin D analogues.

The vitamin D endocrine system has been implicated in numerous biological activities throughout the body. The breadth and magnitude of vitamin D activity suggest potential therapeutic applications for the treatment of several diseases and disorders, including hyperproliferative diseases, immune dysfunction, endocrine disorders, and metabolic bone diseases. However, therapy using natural vitamin D hormone, 1,25-dihydroxyvitamin D(3) (1,25[OH](2)D(3)) has been precluded in most cases because of the potent calcemic activity shown by this hormone. Newly developed vitamin D analogues with lower calcemic activity have been shown to retain many therapeutic properties of 1,25(OH)(2)D(3). Molecular studies discussed in this article provide insights into the unique target cell specificity afforded by these analogues. In particular, the importance of the nuclear vitamin D receptor (VDR), serum vitamin D-binding protein, 24-hydroxylase, and membrane receptor is noted because analogue selectivity, specificity, and potency are afforded through their molecular interactions. The nuclear VDR has been isolated from a variety of target cells and tissues, suggesting that vitamin D compounds may have therapeutic potential throughout several body systems. Five vitamin D analogues have been approved for use in patients: calcipotriol (Dovonex; Leo Pharmaceuticals, Copenhagen, Denmark) for the treatment of psoriasis, 19-nor-1,25(OH)(2)D(2) (Zemplar; Abbott Laboratories, Abbott Park, IL) for secondary hyperparathyroidism, doxercalciferol (Hectorol; Bone Care Int, Madison, WI) for reduction of elevated parathyroid hormone levels, 22-oxacalcitriol (Maxacalcitol; Chugai Pharmaceuticals, Tokyo, Japan), and alfacalcidol. Several other analogues are currently being tested in preclinical and clinical trials for the treatment of various types of cancer and osteoporosis, as well as immunosuppression. Understanding how analogues exert their selective actions may allow for the design of more effective and safer vitamin D compounds for the treatment of a wide range of clinical disorders.

Metabolism of an oxysterol, 7-ketocholesterol, by sterol 27-hydroxylase in HepG2 cells.

7-Ketocholesterol (7K) is a quantitatively important oxysterol in both atherosclerotic lesions and macrophage foam cells. We reported recently that radiolabeled 7K delivered to rodents in a modified lipoprotein or chylomicron remnant-like emulsion, both cleared predominantly by the liver, was rapidly excreted into the intestine as water-soluble products, presumably bile acids. Herein, we aimed to elucidate the early or initial reactions in 7K metabolism. The hypothesis was tested that sterol 27-hydroxylase, a mitochondrial cytochrome P450 and the first enzyme of the acidic bile acid pathway, is responsible for the initial metabolism of 7K by HepG2 cells, a human hepatoblastoma cell-line. The 27-hydroxylated product of 7K (27OH-7K) was shown to be the initial, lipid-soluble product of 7K metabolism. It was produced in mitochondrial incubations and whole cells and was readily released into the media from cells. Intact cells generated metabolites of 7K that had undergone conversion from lipid-soluble precursors to water-soluble products rapidly and extensively. Their production was ablated with cyclosporin A, a sterol 27-hydroxylase inhibitor. Furthermore, we demonstrated the effectiveness of two novel selective inhibitors of this enzyme, GW273297X and GI268267X. These inhibitors also ablated the production of water-soluble products by cells; and the inhibitor of choice, GW273297X, decreased the production of 27OH-7K in mitochondrial preparations. This is the first study to demonstrate that sterol 27-hydroxylase plays an important role in the metabolism of oxysterols such as 7K in liver cells.

Soluble recombinant HTLV-1 surface glycoprotein competitively inhibits syncytia formation and viral infection of cells.

Efficient entry into, and infection of, human cells by human T-cell leukaemia virus type-1 (HTLV-1) is mediated by the viral envelope glycoproteins, gp46 and gp21. The gp46 surface glycoprotein binds to an as yet unidentified cell surface receptor, thereby, allowing the gp21 transmembrane glycoprotein to initiate fusion of the viral and cellular membranes. In the absence of membrane fusion viral penetration and entry into the host cell cannot occur. The envelope glycoproteins are also a major target for neutralising antibodies and cytotoxic T lymphocytes following a protective immune response, and represent ideal constituents for a recombinant HTLV-1 vaccine. Given the importance of the envelope proteins in HTLV-1 pathogenesis there is increasing interest in obtaining sufficient quantities of these proteins for biochemical, biophysical and biological analyses. We have now developed a system for production of large amounts of a glycosylated and functional form of soluble recombinant gp46 (sRgp46), and have used this recombinant material for analysis of envelope function and receptor binding activity. We find that, the sRgp46 molecules expressed in our system are immunologically indistinguishable from the native virally expressed surface glycoproteins; that sRgp46 binds to T-cells in a dose dependent and saturable manner; and that cell surface binding by sRgp46 can be inhibited by neutralising antibodies. Importantly, we demonstrate that these sRgp46 molecules potently inhibit syncytia formation and viral infection of target cells, and that regions outwith the SU domain of envelope are not required for binding to target cells or for inhibiting membrane fusion. The sRgp46 produced in our study will provide new opportunities to investigate envelope-receptor interactions, and will be of utility in defining the conformationally sensitive antigenic determinants of the HTLV-1 surface glycoprotein.

Clinical and biochemical features, molecular diagnosis and long-term management of a case of cerebrotendinous xanthomatosis.

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive sterol storage disease characterised clinically by juvenile bilateral cataracts, progressive neurological dysfunction, and formation of tendon xanthomata. We describe the clinical and biochemical features, molecular diagnosis and long-term management of the first reported Australasian case of CTX. Molecular analysis confirmed the diagnosis of CTX and demonstrated that the patient was homozygous for a G-->A transition in the splice donor site of intron 4 of the sterol 27-hydroxylase gene. Serum cholestanol concentrations were decreased with the HMG-CoA reductase inhibitor simvastatin alone and greater reductions were achieved after the addition of the bile acid chenodeoxycholic acid; suggesting a synergistic effect of this combination. Despite serum cholestanol concentrations remaining within the low-normal range, there has been no significant improvement in mental and physical abilities or in EEG abnormalities with 5 years of treatment. Metabolism of radiolabeled 7-ketocholesterol to aqueous soluble products was absent in CTX-derived macrophages. Consistent with this finding, plasma 7 alpha-hydroxycholesterol, 7 beta-hydroxycholesterol, and 7-ketocholesterol concentrations were increased in the CTX subject compared with controls.