ABSTRACT
INTRODUCTION: Type 2 diabetes mellitus (T2DM) is becoming increasingly common among children and adolescents worldwide, including those in Hong Kong. This study analysed the characteristics and prevalence of microvascular complications among paediatric T2DM patients in Hong Kong at diagnosis and 2 years after diagnosis. METHODS: All patients aged <18 years who had been diagnosed with DM at public hospitals in Hong Kong were recruited into the Hong Kong Childhood Diabetes Registry. Data collected at diagnosis and 2 years after diagnosis were retrospectively retrieved from the Registry for patients diagnosed from 2014 to 2018. RESULTS: Median haemoglobin A1c (HbA1c) levels were 7.5% (n=203) at diagnosis and 6.5% (n=135) 2 years after diagnosis; 59.3% of patients achieved optimal glycaemic control (HbA1c level <7%) at 2 years. A higher HbA1c level at diagnosis was associated with worse glycaemic control at 2 years (correlation coefficient=0.39; P<0.001). The presence of dyslipidaemia (adjusted odds ratio [aOR]=3.19; P=0.033) and fatty liver (aOR=2.50; P=0.021) at 2 years were associated with suboptimal glycaemic control. Diabetic neuropathy and retinopathy were rare in our cohort, but 18.6% of patients developed microalbuminuria (MA) within 2 years after diagnosis. Patients with MA had a higher HbA1c level at 2 years (median: 7.2% vs 6.4%; P=0.037). Hypertension was a risk factor for MA at 2 years, independent of glycaemic control (aOR=4.61; P=0.008). CONCLUSION: These results highlight the importance of early diagnosis and holistic management (including co-morbidity management) for paediatric T2DM patients.
Subject(s)
Diabetes Mellitus, Type 2 , Glycated Hemoglobin , Glycemic Control , Registries , Humans , Hong Kong/epidemiology , Diabetes Mellitus, Type 2/complications , Male , Female , Child , Adolescent , Glycated Hemoglobin/analysis , Retrospective Studies , Diabetic Angiopathies/epidemiology , Diabetic Angiopathies/diagnosis , Prevalence , Blood Glucose/analysis , Risk Factors , Child, PreschoolABSTRACT
Sensitive probing of temperature variations on nanometre scales is an outstanding challenge in many areas of modern science and technology. In particular, a thermometer capable of subdegree temperature resolution over a large range of temperatures as well as integration within a living system could provide a powerful new tool in many areas of biological, physical and chemical research. Possibilities range from the temperature-induced control of gene expression and tumour metabolism to the cell-selective treatment of disease and the study of heat dissipation in integrated circuits. By combining local light-induced heat sources with sensitive nanoscale thermometry, it may also be possible to engineer biological processes at the subcellular level. Here we demonstrate a new approach to nanoscale thermometry that uses coherent manipulation of the electronic spin associated with nitrogen-vacancy colour centres in diamond. Our technique makes it possible to detect temperature variations as small as 1.8 mK (a sensitivity of 9 mK Hz(-1/2)) in an ultrapure bulk diamond sample. Using nitrogen-vacancy centres in diamond nanocrystals (nanodiamonds), we directly measure the local thermal environment on length scales as short as 200 nanometres. Finally, by introducing both nanodiamonds and gold nanoparticles into a single human embryonic fibroblast, we demonstrate temperature-gradient control and mapping at the subcellular level, enabling unique potential applications in life sciences.
Subject(s)
Fibroblasts/cytology , Metal Nanoparticles/chemistry , Nanodiamonds/chemistry , Thermometers , Thermometry/instrumentation , Thermometry/methods , Cell Survival , Color , Gold , Humans , Nanotechnology/instrumentation , Nitrogen , Single-Cell Analysis , TemperatureABSTRACT
BACKGROUND: Exploration of the information and participation needs of psychiatric inpatients is an important step for the implementation of recovery-oriented mental health service. The objective of this study was to explore the information and participation needs of Chinese psychiatric inpatients in the largest psychiatric hospital in Hong Kong. METHODS: The study was divided into two parts. In the first part, eight focus groups with patients, patients' relatives and healthcare professionals were held to identify 22 items of information needs and 16 items of participation needs of Chinese psychiatric inpatients. Basing on the items identified in the first part of the study, a questionnaire was developed to survey on the importance of the different information and participation needs in the second part of the study. Participants were asked to rate in rank order their perceived importance of the items in the questionnaire survey. RESULTS: A hundred and eighty three Chinese psychiatric inpatients completed the questionnaire and the majority of them suffered from schizophrenia (68.3 %). For information needs, the top three needs rated by patients as the most important in descending order were: "Information on the classifications of mental illnesses, signs and symptoms and factors contributing to relapse", "Information on the criteria and arrangements for discharge", and "Information on the importance of psychiatric drug taking and its side effects". For participation needs, the top three needs rated by patients as the most important in descending order were: "Enquiring about personal needs and arrangements", "Keeping in touch with the outside world", and "Learning and practising self-management". CONCLUSIONS: This study reveals that Chinese psychiatric inpatients are concerned about information on their mental illness and its treatments as well as the criteria for discharge. On the other hand, patients are concerned about their personal needs, their self-management, as well as their keeping in touch with the outside world during their hospitalisation. Moreover, patients with different socio-demographic and clinical characteristics have different information and participation needs. The results of the present study serve as a reference for designing guidelines, strategies, and programmes to meet the information needs and participation needs of psychiatric inpatients in Hong Kong.
Subject(s)
Asian People/psychology , Health Services Needs and Demand/standards , Inpatients/psychology , Mental Disorders/therapy , Mental Health Services/standards , Mental Health/standards , Adolescent , Adult , Female , Focus Groups/methods , Focus Groups/standards , Hong Kong/epidemiology , Hospitals, Psychiatric/standards , Humans , Male , Mental Disorders/epidemiology , Mental Disorders/psychology , Middle Aged , Schizophrenia/epidemiology , Schizophrenia/therapy , Self Care/methods , Self Care/psychology , Self Care/standards , Surveys and Questionnaires , Young AdultABSTRACT
We report the first example of a novel two-photon active, biocompatible, and macrophage cell-membrane permeable carbazole-based cyanine fluorophore for the detection of three biologically important ROS, namely, ËOH, O2(-) and OCl(-) in solution. This versatile probe shows cellular protection not only in stimulated macrophages from phorbol-12-myristate-13-acetate-induced morphological changes but also lipopolysaccharide-induced cytotoxicity by quenching with the O2(-) and OCl(-) production, respectively. Such protection could be visualized by a distinct change in the fluorescence intensity of the probe.
Subject(s)
Carbocyanines/pharmacology , Cytoprotection/drug effects , Fluorescent Dyes/pharmacology , Macrophages/cytology , Macrophages/drug effects , Photons , Reactive Oxygen Species/metabolism , Animals , Carbazoles/chemistry , Carbocyanines/chemistry , Fluorescent Dyes/chemistry , HeLa Cells , Humans , Lipopolysaccharides/pharmacology , Macrophages/metabolism , Mice , Oxidative Stress/drug effects , Phorbol Esters/pharmacology , RAW 264.7 CellsABSTRACT
The response of Grapholita molesta (Busck) males to three-component sex pheromone blends containing a 100% ratio of the major sex pheromone component, (Z)-8-dodecenyl acetate and a 10% ratio of (Z)-8-dodecenol, but with varying ratios of (E)-8-dodecenyl acetate (0.4, 5.4, 10.4, 30.4, and 100.1% E-blends) was tested with populations in eight stone and pome fruit orchards in Europe, Asia, and North and South America. Traps baited with the 5.4% E-blend caught significantly more males than traps with any other blend with all populations. Significantly more males were caught in traps baited with the 10.4% E-blend than in traps with the remaining blends, except with the 0.4% E-blend in Turkey. Significant differences in male moth catches occurred between the other blends with the 0.4>30.4% E-blend, and the 30.4>100.1% E-blend. Male moth catches with the 100.1% E-blend only differed from the hexane control in Chile. No apparent differences were noted to these blends in populations collected from pome or stone fruits. Flight tunnel assays to synthetic blends with a subset of populations were similar to the field results, but the breadth of the most attractive E-blends was wider. Flight tunnel assays also demonstrated a high level of male-female cross-attraction among field-collected populations. Female gland extracts from field-collected populations did not show any significant variation in their three-component blends. The only exceptions in these assays were that long-term laboratory populations were less responsive and attractive, and produced different blend ratios of the two minor components than recently collected field populations.
Subject(s)
Animal Communication , Moths/physiology , Sex Attractants/pharmacology , Sexual Behavior, Animal , Animals , Female , Food Chain , Geography , Male , Malus/physiology , Prunus/physiologyABSTRACT
We demonstrate an all-optical method for magnetic sensing of individual molecules in ambient conditions at room temperature. Our approach is based on shallow nitrogen-vacancy (NV) centers near the surface of a diamond crystal, which we use to detect single paramagnetic molecules covalently attached to the diamond surface. The manipulation and readout of the NV centers is all-optical and provides a sensitive probe of the magnetic field fluctuations stemming from the dynamics of the electronic spins of the attached molecules. As a specific example, we demonstrate detection of a single paramagnetic molecule containing a gadolinium (Gd(3+)) ion. We confirm single-molecule resolution using optical fluorescence and atomic force microscopy to colocalize one NV center and one Gd(3+)-containing molecule. Possible applications include nanoscale and in vivo magnetic spectroscopy and imaging of individual molecules.
ABSTRACT
OBJECTIVE: To review the performance of non-invasive prenatal testing (NIPT) by low-coverage whole-genome sequencing of maternal plasma DNA at a single center. METHODS: The NIPT result and pregnancy outcome of 1982 consecutive cases were reviewed. NIPT was based on low coverage (0.1×) whole-genome sequencing of maternal plasma DNA. All subjects were contacted for pregnancy and fetal outcome. RESULTS: Of the 1982 NIPT tests, a repeat blood sample was required in 23 (1.16%). In one case, a conclusive report could not be issued, probably because of an abnormal vanished twin fetus. NIPT was positive for common trisomies in 29 cases (23 were trisomy 21, four were trisomy 18 and two were trisomy 13); all were confirmed by prenatal karyotyping (specificity=100%). In addition, 11 cases were positive for sex-chromosomal abnormalities (SCA), and nine cases were positive for other aneuploidies or deletion/duplication. Fourteen of these 20 subjects agreed to undergo further investigations, and the abnormality was found to be of fetal origin in seven, confined placental mosaicism (CPM) in four, of maternal origin in two and not confirmed in one. Overall, 85.7% of the NIPT-suspected SCA were of fetal origin, and 66.7% of the other abnormalities were caused by CPM. Two of the six cases suspected or confirmed to have CPM were complicated by early-onset growth restriction requiring delivery before 34 weeks. Fetal outcome of the NIPT-negative cases was ascertained in 1645 (85.15%). Three chromosomal abnormalities were not detected by NIPT, including one case each of a balanced translocation, unbalanced translocation and triploidy. There were no known false negatives involving the common trisomies (sensitivity=100%). CONCLUSIONS: Low-coverage whole-genome sequencing of maternal plasma DNA was highly accurate in detecting common trisomies. It also enabled the detection of other aneuploidies and structural chromosomal abnormalities with high positive predictive value.
Subject(s)
Chromosome Disorders/diagnosis , DNA/blood , Down Syndrome/diagnosis , Mothers , Prenatal Diagnosis , Trisomy/diagnosis , Chromosome Disorders/blood , Chromosome Disorders/genetics , Chromosomes, Human, Pair 13/genetics , Chromosomes, Human, Pair 18/genetics , DNA Methylation , Down Syndrome/blood , Down Syndrome/genetics , Female , Genetic Markers , Genetic Testing/methods , Humans , Infant, Newborn , Karyotyping , Maternal Age , Polymorphism, Genetic , Pregnancy , Prenatal Diagnosis/methods , Reproducibility of Results , Sequence Analysis, DNA/methods , Trisomy/genetics , Trisomy 13 Syndrome , Trisomy 18 SyndromeABSTRACT
BACKGROUND: Primary percutaneous coronary intervention (PCI) in patients with ST-elevation myocardial infarction (STEMI) significantly reduces mortality and morbidity, particularly when door-to-balloon (D2B) time is < 90 min. We sought to minimize preventable delays by instituting an on-site cardiology team-based approach in the emergency department (ED). METHODS: The on-site group comprised 146 consecutive patients with STEMI undergoing primary PCI after implementation of the on-site strategy. This new patient care model was compared with the conventional care administered before instituting the on-site cardiology team-based strategy in ED, which included 90 patients (interim group) receiving primary PCI at a catheterization room in the same building as the ED, and 147 patients (pre-on-site group) undergoing primary PCI at a catheterization room two blocks away from the ED. RESULTS: Median D2B time decreased from 107 min in the pre-on-site group to 72 min in the interim group, and to 47 min in the on-site group, respectively (p < 0.001). The percentage of D2B times < 90 min increased from 34% to 78% and 96%, respectively among the three groups (p < 0.001). Hospitalization costs were significantly reduced in the on-site and interim vs. pre-on-site groups ($5944, $5999, and $6581, respectively; p = 0.008). In-hospital mortality did not differ significantly among the three groups (4.8%, 2.2%, and 6.1%, respectively; p = 0.387). CONCLUSIONS: Institution of an on-site cardiology team-based approach in the ED significantly reduces D2B time in STEMI patients eligible for primary PCI.
Subject(s)
Angioplasty, Balloon, Coronary/standards , Emergency Medical Services/standards , Myocardial Infarction/therapy , Patient Transfer/standards , Adult , Aged , Aged, 80 and over , Angioplasty, Balloon, Coronary/statistics & numerical data , Emergency Medical Services/statistics & numerical data , Female , Humans , Male , Middle Aged , Patient Transfer/statistics & numerical data , Taiwan , Time Factors , Treatment OutcomeABSTRACT
This study aimed to explore the perceptions and experiences of swallowing difficulties in irradiated survivors of nasopharyngeal carcinoma (NPC). Qualitative semi-structured interviews were conducted with 60 post-irradiation NPC patients after they had answered a set of self-report questions. The interviews were transcribed verbatim for analysis. Results of the self-report data showed that in response to a global question 'Do you have any swallowing difficulties?' eight-five per cent of the respondents reported a certain degree of difficulty. The qualitative interview findings, however, suggested that this figure might have been underestimated. Patient interpretations of swallowing difficulties had excluded part of the symptoms. Some respondents who claimed to have no difficulty swallowing, in fact, were suffering from oral retention of food bolus, regurgitation of food or liquids through the nose, and/or even choking. The risk of aspiration was generally neglected. Informants' concerns focused more on the threat of cancer recurrence, thus paid less attention to the radiation-induced swallowing complication. Respondents did not possess sufficient knowledge to judge their swallowing abilities at a general level. This study suggests ways to enhance patient-provider communication and health education to improve patient knowledge.
Subject(s)
Deglutition Disorders/psychology , Nasopharyngeal Neoplasms/radiotherapy , Survivors/psychology , Adult , Aged , Deglutition Disorders/etiology , Female , Humans , Male , Middle Aged , Nasopharyngeal Neoplasms/psychology , Quality of Life , Surveys and QuestionnairesABSTRACT
The rate of disappearance of intracisternally administered [(3)H]norepinephrine from rat brain gradually declines as a multiphasic exponential function of time. Conversion to [(3)H]normetanephrine accounts for a larger fraction of the [(3)H]norepinephrine released in the brain shortly after its intracisternal injection than that released at later times. Pools of norepinephrine in the brain thus appear to differ in their turnover rates and pathways of metabolism. The pool of norepinephrine with a rapid rate of turnover and an appreciable conversion to normetanephrine, identified by the techniques reported here, may correspond to a pool of newly synthesized norepinephrine in the brain.
Subject(s)
Brain/metabolism , Norepinephrine/metabolism , Brain Chemistry , Cisterna Magna , Injections , Norepinephrine/administration & dosage , Normetanephrine/metabolism , Time Factors , TritiumSubject(s)
Gene Expression , Interleukin-8/metabolism , MAP Kinase Signaling System , Matrix Metalloproteinase 9/genetics , Pseudomonas Infections/genetics , RNA, Messenger/metabolism , Anthracenes/pharmacology , Bronchi , Cells, Cultured , Epithelial Cells , Flavonoids/pharmacology , Humans , Interleukin-8/genetics , MAP Kinase Signaling System/drug effects , Matrix Metalloproteinase 2/genetics , Matrix Metalloproteinase 2/metabolism , Matrix Metalloproteinase 9/metabolism , Mitogen-Activated Protein Kinase Kinases/metabolism , NF-kappa B/antagonists & inhibitors , NF-kappa B/genetics , Phosphorylation , Protein Kinase Inhibitors/pharmacology , Pseudomonas Infections/metabolism , Pseudomonas aeruginosa , Pyrrolidines/pharmacology , Thiocarbamates/pharmacologyABSTRACT
A gene critical to esophageal cancer has been identified. Functional studies using microcell-mediated chromosome transfer of intact and truncated donor chromosomes 3 into an esophageal cancer cell line and nude mouse tumorigenicity assays were used to identify a 1.61 Mb tumor suppressive critical region (CR) mapping to chromosome 3p14.2. This CR is bounded by D3S1600 and D3S1285 microsatellite markers. One candidate tumor suppressor gene, ADAMTS9, maps to this CR. Further studies showed normal expression levels of this gene in tumor-suppressed microcell hybrids, levels that were much higher than observed in the recipient cells. Complete loss or downregulation of ADAMTS9 gene expression was found in 15 out of 16 esophageal carcinoma cell lines. Promoter hypermethylation was detected in the cell lines that do not express this gene. Re-expression of ADAMTS9 was observed after demethylation drug treatment, confirming that hypermethylation is involved in gene downregulation. Downregulation of ADAMTS9 was also found in 43.5 and 47.6% of primary esophageal tumor tissues from Hong Kong and from the high-risk region of Henan, respectively. Thus, this study identifies and provides functional evidence for a CR associated with tumor suppression on 3p14.2 and provides the first evidence that ADAMTS9, mapping to this region, may contribute to esophageal cancer development.
Subject(s)
ADAM Proteins/genetics , Carcinoma, Squamous Cell/genetics , Chromosomes, Human, Pair 3 , Esophageal Neoplasms/genetics , Genes, Tumor Suppressor , ADAMTS9 Protein , Base Sequence , Chromosome Mapping , DNA , DNA Methylation , Gene Expression Regulation, Neoplastic , Humans , In Situ Hybridization, Fluorescence , Molecular Sequence DataABSTRACT
BACKGROUND AND PURPOSE: Ever since the discovery of photodynamic therapy, there has been a continuous search for more potent photosensitizers. Towards that end, we have synthesized a number of novel phthalocyanine derivatives. The unsymmetrical bisamino silicon(IV) phthalocyanine BAM-SiPc is one of the most potent compounds. In in vitro cell culture, it exhibits high phototoxicity against a number of cancer cell lines. EXPERIMENTAL APPROACH: In the present investigation, the in vivo effect of BAM-SiPc was studied in the tumour-bearing nude mice model. The biodistribution of BAM-SiPc was followed to evaluate its tumour selectivity and rate of clearance. The tumour volume in the hepatocarcinoma HepG2- and the colorectal adenocarcinoma HT29-bearing nude mice was measured after photodynamic therapy. The level of intrinsic toxicity induced was also investigated. Finally, the metabolism of BAM-SiPc in the 'normal' WRL68 liver cells and the hepatocarcinoma HepG2 cells was compared. KEY RESULTS: The results not only showed significant tumour regression of HepG2 and growth inhibition of HT29 in the tumour-bearing nude mice, but also no apparent hepatic or cardiac injury with the protocol used. Histological analyses showed that apoptosis was induced in the solid tumour. BAM-SiPc could be metabolized by WRL68 liver cells but not by the hepatocarcinoma HepG2 cells. Unfortunately, BAM-SiPc did not show any specific targeting towards the tumour tissue. CONCLUSIONS AND IMPLICATIONS: The efficiency of BAM-SiPc in inhibiting tumour growth makes it a good candidate for further evaluation. Enhancement of its uptake in tumour tissue by conjugation with biomolecules is currently under investigation.
Subject(s)
Indoles/therapeutic use , Neoplasms, Experimental/therapy , Organosilicon Compounds/therapeutic use , Photochemotherapy , Photosensitizing Agents/therapeutic use , Animals , Cell Line, Tumor , HT29 Cells , Humans , In Situ Nick-End Labeling , In Vitro Techniques , Indoles/pharmacokinetics , Liver/pathology , Mice , Mice, Nude , Neoplasm Transplantation , Neoplasms, Experimental/metabolism , Neoplasms, Experimental/pathology , Organosilicon Compounds/pharmacokinetics , Photosensitizing Agents/pharmacokinetics , Tissue DistributionABSTRACT
Pigs have recently become very popular for use not only in xenotransplantation field, but in regeneration studies as well, sometimes with pigs being used as the scaffold. We have already presented our findings related to the pig immune system against human cells, including the complement systems, natural antibodies (NAs), and NK cells. In this study, we investigated the pig innate immunological reaction against human cells further. Our investigations included issues such as the production of NAs in newborns, day 0 and day 1, and sow colostrum. The alternative pathway for pig complement reacted with human cells, and pig NK cells and macrophages directly injured human aortic endothelial cells. Pig serum clearly contains the natural antibodies IgG and IgM to human peripheral blood mononuclear cells (PBMCs). Pig plasma from day 1 newborns contained almost the same levels of these natural antibodies to human PBMCs as those of sow plasma. On the other hand, pig plasma from day 0 newborns did not contain IgG and IgM to human PBMCs. In addition, sow colostrum clearly contained both IgG and IgM to human PBMCs. As expected, the pig innate immunity system reacted to human cells, including natural antibodies. However, the NAs of pigs, both IgM and IgG, against human cells do not exist in pig serum at day 0, but at day 1 and in mother's milk, indicating that NAs in newborns did not come from the placenta but from sow colostrum.
Subject(s)
Colostrum/immunology , Immunity, Innate/immunology , Swine/immunology , Transplantation Immunology/immunology , Transplantation, Heterologous , Animals , Animals, Newborn , Female , Humans , Immunoglobulin G/blood , Immunoglobulin G/immunology , Immunoglobulin M/blood , Immunoglobulin M/immunology , Leukocytes, Mononuclear/immunology , PregnancyABSTRACT
BACKGROUND AND OBJECTIVES: This retrospective study analysed a case series of subjects with citrin deficiency, and aims to present the molecular and clinical characterization of this disease in the Hong Kong Chinese population for the first time. PATIENTS AND METHODS: Data from medical records of eighteen patients with citrin deficiency (years 2006-2015) were retrieved. Demographic data, biochemical parameters, radiological results, genetic testing results, management, and clinical outcome were collected and analysed. RESULTS: Eighteen patients with diagnosis of citrin deficiency were recruited. All 18 patients carried at least one common pathogenic variant c.852_855delTATG in SLC25A13. Prolonged jaundice (neonatal intrahepatic cholestasis caused by citrin deficiency, NICCD) was the most common presenting symptom, in conjunction with elevated plasma citrulline, threonine, alkaline phosphatase, and alpha-fetoprotein levels. The abnormal biochemical parameters including liver derangement returned to normal range in most of the cases by 6â¯months of age after the introduction of a lactose-free formula. There were a few cases with atypical presentations. Two subjects did not present with NICCD, and were subsequently diagnosed later in life after their siblings presented with symptoms of citrin deficiency at one month of age and subsequently received a molecular diagnosis. One patient with citrin deficiency also exhibited multiple liver hemangioendotheliomas, which subsided gradually after introduction of a lactose-free formula. Only one patient from this cohort was offered expanded metabolic screening at birth. She was not ascertained by conducted newborn screening and was diagnosed upon presentation with cholestatic jaundice by 1â¯month of age. CONCLUSION: This is the first report of the clinical and molecular characterization of a large cohort of patients with citrin deficiency in Hong Kong. The presentation of this cohort of patients expands the clinical phenotypic spectrum of NICCD. Benign liver tumors such as hemangioendotheliomas may be associated with citrin deficiency in addition to the well-known association with hepatocellular carcinoma. Citrin deficiency may manifest in later infancy period with an NICCD-like phenotype. Furthermore, this condition is not always ascertained by expanded newborn metabolic screening testing.
ABSTRACT
A genomic clone encoding the Drosophila U1 small nuclear ribonucleoprotein particle 70K protein was isolated by hybridization with a human U1 small nuclear ribonucleoprotein particle 70K protein cDNA. Southern blot and in situ hybridizations showed that this U1 70K gene is unique in the Drosophila genome, residing at cytological position 27D1,2. Polyadenylated transcripts of 1.9 and 3.1 kilobases were observed. While the 1.9-kilobase mRNA is always more abundant, the ratio of these two transcripts is developmentally regulated. Analysis of cDNA and genomic sequences indicated that these two RNAs encode an identical protein with a predicted molecular weight of 52,879. Comparison of the U1 70K proteins predicted from Drosophila, human, and Xenopus cDNAs revealed 68% amino acid identity in the most amino-terminal 214 amino acids, which include a sequence motif common to many proteins which bind RNA. The carboxy-terminal half is less well conserved but is highly charged and contains distinctive arginine-rich regions in all three species. These arginine-rich regions contain stretches of arginine-serine dipeptides like those found in transformer, transformer-2, and suppressor-of-white-apricot proteins, all of which have been identified as regulators of mRNA splicing in Drosophila melanogaster.
Subject(s)
Drosophila melanogaster/genetics , Genes , Ribonucleoproteins/genetics , Amino Acid Sequence , Animals , Base Sequence , Blotting, Northern , Blotting, Southern , Cloning, Molecular , DNA/genetics , Gene Expression , Gene Library , Humans , Molecular Sequence Data , Molecular Weight , Oligonucleotide Probes , Poly A/genetics , RNA/genetics , RNA, Messenger , Ribonucleoproteins, Small Nuclear , Sequence Homology, Nucleic Acid , XenopusABSTRACT
The effects of branchpoint sequence, the pyrimidine stretch, and intron size on the splicing efficiency of the Drosophila white gene second intron were examined in nuclear extracts from Drosophila and human cells. This 74-nucleotide intron is typical of many Drosophila introns in that it lacks a significant pyrimidine stretch and is below the minimum size required for splicing in human nuclear extracts. Alteration of sequences of adjacent to the 3' splice site to create a pyrimidine stretch was necessary for splicing in human, but not Drosophila, extracts. Increasing the size of this intron with insertions between the 5' splice site and the branchpoint greatly reduced the efficiency of splicing of introns longer than 79 nucleotides in Drosophila extracts but had an opposite effect in human extracts, in which introns longer than 78 nucleotides were spliced with much greater efficiency. The white-apricot copia insertion is immediately adjacent to the branchpoint normally used in the splicing of this intron, and a copia long terminal repeat insertion prevents splicing in Drosophila, but not human, extracts. However, a consensus branchpoint does not restore the splicing of introns containing the copia long terminal repeat, and alteration of the wild-type branchpoint sequence alone does not eliminate splicing. These results demonstrate species specificity of splicing signals, particularly pyrimidine stretch and size requirements, and raise the possibility that variant mechanisms not found in mammals may operate in the splicing of small introns in Drosophila and possibly other species.
Subject(s)
DNA Transposable Elements , Drosophila Proteins , Introns , Peptide Hydrolases , RNA Splicing , Regulatory Sequences, Nucleic Acid , Animals , Base Sequence , Cell Nucleus/metabolism , Consensus Sequence , DNA , Drosophila , Electrophoresis, Polyacrylamide Gel , HeLa Cells , Humans , Molecular Sequence Data , Mutation , Proteins/genetics , Retroelements , Species SpecificityABSTRACT
Heterocyclic architectures offer powerful creative possibilities to a range of chemistry end-users. This is particularly true of heterocycles containing a high proportion of sp3-carbon atoms, which confer precise spatial definition upon chemical probes, drug substances, chiral monomers and the like. Nonetheless, simple catalytic routes to new heterocyclic cores are infrequently reported, and methods making use of biomass-accessible starting materials are also rare. Here, we demonstrate a new method allowing rapid entry to spirocyclic bis-heterocycles, in which inexpensive iron(III) catalysts mediate a highly stereoselective C-C bond-forming cyclization cascade reaction using (2-halo)aryl ethers and amines constructed using feedstock chemicals readily available from plant sources. Fe(acac)3 mediates the deiodinative cyclization of (2-halo)aryloxy furfuranyl ethers, followed by capture of the intermediate metal species by Grignard reagents, to deliver spirocycles containing two asymmetric centres. The reactions offer potential entry to key structural motifs present in bioactive natural products.