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In vivo ultrasound imaging with phased array transducers is of great importance for both clinical application and biomedical research. In this work, relaxor ferroelectric PMN-0.28PT single crystal with very high piezoelectric constant d33 ≥ 2000 pC/N and electromechanical coupling coefficient k33 â¼ 0.92 is used to fabricate high-frequency phased array transducers. A 128-element 20-MHz phased array transducer is successfully fabricated, and the optimized performance of -6 dB average bandwidth of â¼ 84 % and insertion loss of -43 dB are achieved. The axial and lateral imaging resolutions of the transducer are determined to be 81 µm and 243 µm, respectively. With Verasonics image platform, in vivo fisheye images are acquired, demonstrating the potential application of our developed high-frequency phased array transducer for biomedical research on small animals.
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Transductores , Animales , Diseño de Equipo , UltrasonografíaRESUMEN
Population divergence in geographic isolation is due to a combination of factors. Natural and sexual selection may be important in shaping patterns of population differentiation, a pattern referred to as 'isolation by adaptation' (IBA). IBA can be complementary to the well-known pattern of 'isolation by distance' (IBD), in which the divergence of closely related populations (via any evolutionary process) is associated with geographic isolation. The barn swallow Hirundo rustica complex comprises six closely related subspecies, where divergent sexual selection is associated with phenotypic differentiation among allopatric populations. To investigate the relative contributions of selection and geographic distance to genome-wide differentiation, we compared genotypic and phenotypic variation from 350 barn swallows sampled across eight populations (28 pairwise comparisons) from four different subspecies. We report a draft whole-genome sequence for H. rustica, to which we aligned a set of 9493 single nucleotide polymorphisms (SNPs). Using statistical approaches to control for spatial autocorrelation of phenotypic variables and geographic distance, we find that divergence in traits related to migratory behaviour and sexual signalling, as well as geographic distance, together explain over 70% of genome-wide divergence among populations. Controlling for IBD, we find 42% of genomewide divergence is attributable to IBA through pairwise differences in traits related to migratory behaviour and sexual signalling alone. By (i) combining these results with prior studies of how selection shapes morphological differentiation and (ii) accounting for spatial autocorrelation, we infer that morphological adaptation plays a large role in shaping population-level differentiation in this group of closely related populations.
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Evolución Biológica , Genética de Población , Selección Genética , Golondrinas/genética , Animales , Genoma , Geografía , Fenotipo , Aislamiento ReproductivoRESUMEN
The gonad-inhibiting hormone (GIH) belongs to a neuropeptide family synthesized and released in an X-organ sinus gland complex of crustacean eyestalks. GIH inhibits crustacean ovarian maturation by suppressing vitellogenin (Vtg) synthesis, whereas estrogen is responsible for the stimulation of vitellogenesis (not established). In this study, the effects of 17ß-estradiol (E2, 10(-6) M), estrogen receptor antagonist tamoxifen (TAM, 10(-6), 10(-7), and 10(-8) M), and the environmental estrogen nonylphenol (NP, 1 µg/L and 100 µg/L) on LvGIH expression in the eyestalks of shrimp were determined by quantitative real-time PCR. Results showed that LvGIH expression decreased significantly during the L. vannamei ovarian maturation cycle. E2 and NP significantly reduced LvGIH transcripts in vivo, but TAM neutralized the inhibitory action of E2 in a dose-dependent manner (P < 0.05). In addition, the LvGIH expression levels decreased significantly in a time-dependent manner (P < 0.05) when ovary fragments were cultured in vitro with E2. The results of this study suggested that estrogen regulates GIH expression in L. vannamei eyestalks. E2 promoted ovarian development not only by directly upregulating vitellogenesis in the hepatopancreas, but it was also capable of downregulating LvGIH expression, which indirectly resulted in the stimulation of L. vannamei vitellogenesis.
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Proteínas Portadoras/biosíntesis , Estradiol/farmacología , Hormonas de Invertebrados/biosíntesis , Penaeidae/efectos de los fármacos , Fenoles/farmacología , Animales , Proteínas Portadoras/genética , Antagonistas de Estrógenos/farmacología , Estrógenos/metabolismo , Femenino , Expresión Génica/efectos de los fármacos , Hormonas de Invertebrados/genética , Ovario/efectos de los fármacos , Ovario/metabolismo , Penaeidae/genética , Penaeidae/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Tamoxifeno/farmacología , Vitelogénesis/efectos de los fármacos , Vitelogeninas/metabolismoRESUMEN
Understanding the coercivity mechanism has a substantial impact on developing novel permanent materials. However, the current coercivity mechanisms used widely in permanent alloys cannot explain well the amorphous phase produced hard magnetic behavior of Nd-based bulk amorphous alloys (BAAs). Here, we propose that the coercivity in as-cast Nd60Fe30Al10 alloy is from the combination of magnetic interaction and strong pinning of domain walls. Moreover, the role of domain wall pinning is less affected after crystallization, while the magnetic interaction is dependent on the annealing temperature. Our findings give further insight into the coercivity mechanism of Nd-based bulk ferromagnets and provide a new idea to design prospective permanent alloys with coercivity from the combination of magnetic interaction and pinning of domain walls.
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BACKGROUND: Many bodies advise that people with bowel symptoms undergo colonoscopy to detect colorectal cancer. AIM: To determine which bowel symptoms predict cancer on colonoscopy. METHODS: Information was collected on symptoms, demographics and medical history from patients subsequently undergoing colonoscopy. Multiple logistic regression modelling was used to identify predictors of colorectal cancer. An ROC curve was estimated for each model, and the area under the curve (AUC) was computed. RESULTS: Cancer was found in 159 patients and no cancer or adenoma in 7577 patients. Bowel symptoms that predicted cancer were rectal bleeding, change in bowel habit and rectal mucus. Prediction was the strongest in patients who had symptoms at least weekly and commencing within the previous 12 months; abdominal pain was predictive only in such patients. The odds ratios never exceeded 4.27. A model based on age, gender, and medical history was highly predictive (AUC = 0.79). Adding symptoms to this model increased the AUC to 0.85. CONCLUSIONS: This model predicts patients in whom colonoscopy will have the highest yield. Conversely, colonoscopy can be avoided in people at low risk: in our study, 95% of cancers could have been detected by doing only 60% of the colonoscopies.
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Dolor Abdominal/etiología , Colonoscopía , Neoplasias Colorrectales/diagnóstico , Hemorragia Gastrointestinal/etiología , Adolescente , Adulto , Edad de Inicio , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Moco , Encuestas y Cuestionarios , Adulto JovenRESUMEN
Plasmapheresis remains the main treatment modality for patients with thrombotic thrombocytopenic purpura. We report a patient who had simultaneous onset of membranoproliferative glomerulonephritis and thrombotic thrombocytopenic purpura. She did not improve after 48 plasmapheresis sessions. A 6-week course of weekly intravenous doses of rituximab was then given. This achieved complete remission of her nephrotic syndrome and improvement in her renal function, so plasmapheresis was ceased. She had a low ADAMTS13 antigen level and a positive ADAMTS13 antibody, both of which reverted to normal after treatment with rituximab. This coincided with a rise in her hepatitis C virus RNA and liver transaminases. Liver biopsies did not reveal active fibrosis. Her hepatitis C virus RNA titre dropped afterwards, and she had no relapses of her thrombotic thrombocytopenic purpura and nephrotic syndrome, for more than 2 years after remission. The simultaneous onset and successful outcomes of both the membranoproliferative glomerulonephritis and thrombotic thrombocytopenic purpura illustrate the usefulness of rituximab. We discuss its use and risks, in the context of chronic hepatitis C infection.
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Anticuerpos Monoclonales/uso terapéutico , Glomerulonefritis Membranoproliferativa/tratamiento farmacológico , Glomerulonefritis Membranoproliferativa/epidemiología , Hepatitis C/epidemiología , Púrpura Trombocitopénica Trombótica/tratamiento farmacológico , Púrpura Trombocitopénica Trombótica/epidemiología , Proteínas ADAM/sangre , Proteína ADAMTS13 , Adulto , Alanina Transaminasa/sangre , Anticuerpos Monoclonales/administración & dosificación , Anticuerpos Monoclonales de Origen Murino , Arterias/patología , Comorbilidad , Creatinina/sangre , Femenino , Glomerulonefritis Membranoproliferativa/patología , Hepacivirus/genética , Humanos , Factores Inmunológicos/administración & dosificación , Factores Inmunológicos/uso terapéutico , Glomérulos Renales/patología , Hígado/patología , Plasmaféresis , Púrpura Trombocitopénica Trombótica/terapia , ARN Viral/sangre , Rituximab , Insuficiencia del TratamientoRESUMEN
Possible altered gene expression patterns in bladder turnout carcinogenesis in rat bladder cancers induced by BBN [N-butyl-N-(4-hydroxybutyl)nitrosamine] was examined by cDNA microarray analysis of gene expression profiles.Thirty Sprague-Dawley rats were given drinking water containing 0.05% BBN ad libitum for 24 to 28-weeks.Equal numbers of control rats were given tap water without BBN.After treatment,the rat bladders were excised for RNA extraction and histopathological examinations.Total RNAs were extracted from rat transitional cell carcinoma (TCC) tissues and micro-dissected normal rat bladder epithelia.The atlas glass rat microarray was used,which included oligonucleotides of 1081 rat genes.Some of the up-regulated genes in rat bladder TCCs were further confirmed by Northern blotting.Our results showed that the transcriptions of 30 genes were significantly elevated in the rat bladder TCCs,and these included fly proto-oncogene,Lipocortin 2,COX Ⅳ,COX Ⅴ a,and cathepsin D.Also,15 genes were significantly down-regulated in the rat bladder TCCs and they included B7.1,TNFrl,APOAI and VHL.The resuits of cDNA microarray analysis demonstrated that normal rat bladder epithelia and bladder TCC exhibited different and specific gene statement profiles.The increased expressions of the identified genes may play an important role in the chemically induced bladder carcinogenesis.
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Acute pain services in public hospitals in Hong Kong were studied. Audit data on the volume and quality of acute pain services were collected prospectively from 1997 to 1999, and data on related facilities were collected in 2000. About 20% of patients undergoing a major operation received an acute pain service; of these, 78.6% were satisfied with the treatment provided. In 2000, 86% (18/21) of hospitals providing anaesthetic services were running an acute pain service. Staffing was better in hospitals providing a high volume of acute pain services, ranging from a full-time specialist anaesthesiologist assisted by a half-time trainee to a half-time specialist assisted by a full- or half-time trainee. However, only four hospitals were staffed with pain nurses. In total, 57% of patients received intravenous patient-controlled analgesia and 32% epidural analgesia. The mean duration of acute pain service treatment was 3.1 days. Currently anaesthesiologist-based acute pain services take care of a limited number of patients. To expand the coverage, there should be a move towards an anaesthesiologist-led, pain nurse-based, acute pain service. The present shortage of pain nurses should be addressed.
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Servicio de Anestesia en Hospital , Dolor Postoperatorio/prevención & control , Analgesia Controlada por el Paciente , Servicio de Anestesia en Hospital/organización & administración , Hong Kong , Humanos , Auditoría Médica , Satisfacción del PacienteRESUMEN
OBJECTIVES: To assess the quality of anaesthetic services as defined in the six anaesthetic clinical indicators against preset standards and to identify risk factors for adverse events in the recovery room. DESIGN: Prospective study. SETTING: All public hospitals providing anaesthetic care in Hong Kong. PATIENTS: Eighteen thousand, seven hundred and fifty-nine patients receiving elective or emergency anaesthesia administered by anaesthetists from June 1998 to July 1998. MAIN OUTCOME MEASURES: Patient demographics, American Society of Anesthesiologists status, category and nature of operation, presence of preoperative anaesthetic visit in ward, type of anaesthesia, reasons for a recovery room stay of more than a 2-hour duration, intubation to relieve respiratory distress in the recovery room, presence of hypothermia in the recovery room for operations lasting more than 2 hours, and dental or ocular injuries attributable to anaesthesia. RESULTS: There are two major findings from this study. Firstly, a high incidence of hypothermia in the recovery room was reported. Secondly, a greater risk of prolonged stay in the recovery room was identified for patients older than 65 years, major operations, and anaesthetic techniques using combined general and regional anaesthesia. CONCLUSION: The six anaesthetic clinical indicators reflected the provision of anaesthetic care in public hospitals in Hong Kong. Good compliance to the preset standard of the anaesthetic clinical indicators was achieved during the study period.
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Anestesia/normas , Hospitales Públicos , Adolescente , Adulto , Anciano , Anestesia/estadística & datos numéricos , Niño , Preescolar , Femenino , Hong Kong , Humanos , Hipotermia/etiología , Lactante , Tiempo de Internación , Masculino , Persona de Mediana Edad , Evaluación de Procesos y Resultados en Atención de Salud , Estudios Prospectivos , Sala de Recuperación , Factores de RiesgoRESUMEN
Regulation of protein phosphatase 2A (PP2A) activity and NMDA receptor (NMDAR) phosphorylation state contribute to the modulation of synaptic plasticity, yet these two mechanisms have not been functionally linked. The NMDAR subunit NR3A is equipped with a unique carboxyl domain that is different from other NMDAR subunits. We hypothesized that the NR3A C-terminal intracellular domain might serve as synaptic anchor for the phosphatase in the developing CNS. A cDNA library was screened by the yeast two-hybrid method using the NR3A carboxyl domain as the bait. The catalytic subunit of the serine-threonine PP2A was found to be associated with the NR3A carboxyl domain. Immunoprecipitation studies indicated that the NR3A subunit formed a stable complex with PP2A in the rat brain in vivo. Association of PP2A with NMDARs led to an increase in the phosphatase activity of PP2A and the dephosphorylation of serine 897 of the NMDAR subunit NR1. Stimulation of NMDARs led to the dissociation of PP2A from the complex and the reduction of PP2A activity. A peptide corresponding to the PP2A-NR3A binding domain functioned as a negative regulator of PP2A activity. These data suggest that NMDARs are allosteric modulators of PP2A, which in turn controls their phosphorylation state. The data delineate a mechanistic model of the dynamic regulation of a PP2A-NMDAR signaling complex, mediated by the interaction of NR3A and PP2A, and suggest a novel NMDAR-mediated signaling mechanism in addition to the traditional ionotropic functions of NMDARs.
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Fosfoproteínas Fosfatasas/metabolismo , Subunidades de Proteína , Receptores de N-Metil-D-Aspartato/metabolismo , Transducción de Señal/fisiología , Regulación Alostérica/fisiología , Animales , Sitios de Unión/fisiología , Membrana Celular/química , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Células Cultivadas , Humanos , Riñón/citología , Riñón/efectos de los fármacos , Riñón/metabolismo , Sustancias Macromoleculares , Ratones , Mutagénesis Sitio-Dirigida , Plasticidad Neuronal/fisiología , Neuronas/citología , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Péptidos/farmacología , Fosfoproteínas Fosfatasas/antagonistas & inhibidores , Fosforilación/efectos de los fármacos , Pruebas de Precipitina , Unión Proteica/fisiología , Proteína Fosfatasa 2 , Estructura Terciaria de Proteína/fisiología , Ratas , Receptores de N-Metil-D-Aspartato/genética , Relación Estructura-Actividad , Fracciones Subcelulares/química , Transfección , Técnicas del Sistema de Dos HíbridosRESUMEN
A brief intellectual history of the indigenization movement in Asia leads to the thesis that the generation of psychological knowledge is culture dependent. Indigenous psychologies go further and insist on viewing a target group from the natives' own standpoint. Psychological decentering underlies conceptions of human existence rooted in Asian intellectual traditions, in particular, relatedness between persons predominates in Confucianism. These conceptions demand new approaches to knowledge generation that signify a paradigmatic shift from methodological individualism to methodological relationalism. An implication is that relationships precede situations in the study of personality and social behavior. We define personality as the sum total of common attributes manifest in, and abstracted from, a person's behavior directly or indirectly observed across interpersonal relationships and situations over time. We rely on the notion that there are identifiable levels of cognition to develop a metatheoretical framework for reconstructing selfhood. Confronting the subject-object dichotomy opens the door to investigations of transcendent consciousness; confronting the self-other demarcation underlying Western theories leads to the construction of self-in-relations.
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Cultura , Etnicidad , Personalidad , Comparación Transcultural , Humanos , Teoría PsicológicaRESUMEN
The purpose of this study was to assess HIV and AIDS knowledge and attitudes, source of HIV and AIDS information, and behaviours related to HIV and AIDS among Chinese adolescents in Hong Kong. Participants included 1259 (826 females and 433 males) Chinese adolescents in Hong Kong between 12-18 years of age. Findings revealed that over 80% of the adolescents had rarely or never discussed HIV and AIDS with their family or teacher, and the primary source of HIV and AIDS information was media sources such as television and newspapers. Findings revealed HIV and AIDS misinformation among both male and female adolescents in the areas of transmission, facts, personal vulnerability and attitudes. However, participants reported engaging in little at-risk behaviour associated with HIV and AIDS. Implications for HIV and AIDS education and prevention are discussed.
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Síndrome de Inmunodeficiencia Adquirida/psicología , Actitud Frente a la Salud , Etnicidad/psicología , Infecciones por VIH/psicología , Psicología del Adolescente , Adolescente , Niño , China/etnología , Femenino , Conductas Relacionadas con la Salud , Educación en Salud/normas , Conocimientos, Actitudes y Práctica en Salud , Hong Kong , Humanos , Masculino , Factores SexualesRESUMEN
Glucocorticoid excess inhibits somatic growth in man and laboratory animals. While the mechanism involved is likely to be multifactorial, indirect evidence suggesting the role of an enhanced endogenous somatostatin (SS) tone has been reported. However, there has been no direct evidence indicating an increased synthesis or secretion of hypothalamic SS. In this study, we investigated the effects of glucocorticoids on hypothalamic SS expression by measuring the peptide and mRNA content of SS in whole hypothalamic blocks of male Sprague-Dawley rats sacrificed 4 weeks after adrenalectomy or sham operation. Adrenalectomy decreased the SS content in the rat hypothalamus (p < 0.05), an effect which was reversed by dexamethasone treatment for 10 days. On the other hand, total hypothalamic SS mRNA levels were unaffected by adrenalectomy, but became significantly decreased following dexamethasone treatment (p < 0.05). Using in situ hybridization, this reduction in SS gene expression was shown to occur consistently in the periventricular nucleus and in the parvocellular subdivision of the paraventricular nucleus. The effects of adrenalectomy and dexamethasone on SS mRNA levels were further quantitated in hypothalamic fragments containing predominantly the periventricular and paraventricular nuclei. Somatostatin mRNA levels in these tissue fragments were marginally increased by adrenalectomy (p < 0.05), but showed a 50% reduction following dexamethasone treatment (p < 0.0001). In conclusion, our findings suggest that the inhibitory effect of glucocorticoids on somatic growth is probably not mediated via an effect on hypothalamic SS gene expression.
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Dexametasona/farmacología , Hipotálamo/metabolismo , ARN Mensajero/metabolismo , Somatostatina/genética , Adrenalectomía , Animales , Peso Corporal/efectos de los fármacos , Hormona del Crecimiento/sangre , Hormona del Crecimiento/metabolismo , Hipotálamo/efectos de los fármacos , Hibridación in Situ , Masculino , Núcleo Hipotalámico Paraventricular/efectos de los fármacos , Núcleo Hipotalámico Paraventricular/metabolismo , Ratas , Ratas Sprague-DawleyRESUMEN
The occurrence of 5-methoxytryptophol (5-MTL) in the quail retina was investigated by capillary column gas chromatography/mass spectrometry/selected ion monitoring using a deuterated internal standard. Based on ion intensity ratios in the mass spectra of pentafluoropropionyl and heptafluorobutyryl derivatives of 5-MTL and deuterated 5-MTL, 5-MTL was unequivocally identified in the quail retina. Similar to the circadian rhythm of retinal melatonin, retinal 5-MTL also exhibited a diurnal variation with high levels at mid-dark. However, no significant correlation between the diurnal levels of 5-MTL and melatonin was observed in the quail retina at mid-light or mid-dark.
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Indoles/análisis , Codorniz/metabolismo , Retina/análisis , Animales , Ritmo Circadiano , Deuterio , Fluorocarburos , Cromatografía de Gases y Espectrometría de Masas , Espectrometría de Masas , Melatonina/análisisRESUMEN
The changes in histamine and prostaglandins (PGE2 and PGF) in carrageenan-induced acute inflammation were studied in 6 day old air pouches in mice. A significant elevation of exudate histamine was found 1 hour after the carrageenan injection. Highest vascular permeability at the site of inflammation was also found at 1 hour. Both PGE2 and PGF showed steady increases in the pouch exudate and reached significantly higher levels at 24 hours. The present findings thus suggest that histamine is involved in the early phase of carrageenan-induced inflammation by enhancing vascular permeability. The increases in PGE2 and PGF appear to be closely correlated with the increased exudate cell accumulation. This leads us to suggest that they are likely to be involved in the exudate cell activity rather than in enhancing the vascular permeability which was found to decrease at 4 hours after the carrageenan injection.
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Dinoprostona/metabolismo , Histamina/metabolismo , Inflamación/metabolismo , Prostaglandinas F/metabolismo , Animales , Permeabilidad Capilar , Carragenina , Exudados y Transudados/citología , Femenino , Inflamación/inducido químicamente , Inflamación/patología , Cinética , Leucocitos/patología , RatonesRESUMEN
Apparent acidity constants obtained for various benzothiadiazine diuretics by semiaqueous potentiometric titrations gave satisfactory agreement with many values obtained by aqueous potentiometry. One suitable method for determining the acidity constants of sparingly soluble drugs, the solubility variation with pH technique, does not take into account instability problems. The preparation of decomposition products and the TLC analysis of sample solutions at various time intervals during solubility studies of methyclothiazide and bendroflumethiazide indicated that decomposition takes place during agitation and equilibration. This decomposition in buffers of pH 8 and higher was confirmed with the acidified p-dimethylaminobenzaldehyde test for primary aromatic amines.