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Biomedical subjects

H Chiu

Publications and source records attributed to H Chiu.

At least 19 recordsLinked to original sources
PubMed2004

Cytokines in Drosophila hematopoiesis and cellular immunity.

Hematopoiesis is a complex, multistep process in which progenitor cells undergo distinct cellular changes of proliferation and differentiation to give rise to mature blood cells in circulation. Many of the genetic and molecular events that drive these changes have been characterized in mammals, frogs, and zebra fish, and more recently in the insect model system Drosophila melanogaster. Blood cells in Drosophila are actively involved in fighting infections and the cellular immune responses are intimately tied to the process of hematopoiesis. In this article, we briefly review the fundamental similarities in Drosophila and mammalian hematopoiesis and highlight the potential roles of four cytokines/growth factors in Drosophila hematopoiesis and cellular immunity.

Animals↗
PubMed2004

Soy formula complicates management of congenital hypothyroidism.

AIMS: To test the hypothesis that feeding soy formula to infants with congenital hypothyroidism (CH) leads to prolonged increase of thyroid stimulating hormone (TSH). METHODS: The study was a review of 78 patients seen during their first year of life between 1990 and 1998. Data regarding clinical diagnosis, date of treatment initiation, TSH, levothyroxine dose, weight, length, and diet information from each visit were collected from the charts. RESULTS: There were eight patients in the soy diet group and 70 in the non-soy diet group. There was no significant difference between the two groups in the starting dose of levothyroxine or the change in this dose over one year. There was a significant difference between the two groups in the following areas: time to TSH normalisation, first TSH on treatment, percentage with increased TSH at 4 months of age, percentage with increased TSH throughout the first year of life, and in the overall trend of TSH at each visit. CONCLUSIONS: Infants fed soy formula had prolonged increase of TSH when compared to infants fed non-soy formula. These infants need close monitoring of free thyroxine and TSH measurements, and they may need increased levothyroxine doses to achieve normal thyroid function tests.

Child, Preschool↗
PubMed2001

Distinct roles of tumor necrosis factor-alpha and nitric oxide in acute liver injury induced by carbon tetrachloride in mice.

Macrophages are known to release a number of different inflammatory mediators with cytotoxic potential. In the present studies we analyzed the role of two macrophage-derived mediators, tumor necrosis factor-alpha (TNF-alpha) and nitric oxide, in liver injury induced by carbon tetrachloride (CCl4). Treatment of mice with CCl4 resulted in a dose- and time-dependent induction of centrilobular hepatic necrosis. This was observed within 12 h with 0.3 ml/kg CCl4 and was correlated with increases in serum transaminase levels. CCl4 administration also caused increases in hepatic TNF-alpha mRNA expression and serum TNF-alpha levels, as well as inducible nitric oxide synthase (NOS II) protein expression in the liver. To study the role of TNF-alpha and nitric oxide in hepatotoxicity, we used knockout mice lacking the gene for the 55-kDa TNF-alpha receptor (TNFR1/p55), the TNF-alpha cytokine, or NOS II. We found that CCl4 was significantly less effective in inducing hepatotoxicity in mice lacking TNFR1/p55 or the TNF-alpha cytokine. In contrast, CCl4-induced liver injury was increased in knockout mice lacking the gene for NOS II. This was associated with an increase in hepatic TNF-alpha mRNA expression and serum TNF-alpha levels. These data suggest that the hepatoprotective effects of nitric oxide in this model may be due in part to inhibition of TNF-alpha.

Acute Disease↗
PubMed2001

MgATP-Bound and nucleotide-free structures of a nitrogenase protein complex between the Leu 127 Delta-Fe-protein and the MoFe-protein.

A mutant form of the nitrogenase iron protein with a deletion of residue Leu 127, located in the switch II region of the nucleotide binding site, forms a tight, inactive complex with the nitrogenase molybdenum iron (MoFe) protein in the absence of nucleotide. The structure of this complex generated with proteins from Azotobacter vinelandii (designated the L127Delta-Av2-Av1 complex) has been crystallographically determined in the absence of nucleotide at 2.2 A resolution and with bound MgATP (introduced by soaking) at 3.0 A resolution. As observed in the structure of the complex between the wild-type A. vinelandii nitrogenase proteins stabilized with ADP.AlF(4-), the most significant conformational changes in the L127Delta complex occur in the Fe-protein component. While the interactions at the interface between the MoFe-protein and Fe-proteins are conserved in the two complexes, significant differences are evident at the subunit-subunit interface of the dimeric Fe-proteins, with the L127Delta-Av2 structure having a more open conformation than the wild-type Av2 in the complex stabilized by ADP.AlF(4-). Addition of MgATP to the L127Delta-Av2-Av1 complex results in a further increase in the separation between Fe-protein subunits so that the structure more closely resembles that of the wild-type, nucleotide-free, uncomplexed Fe-protein, rather than the Fe-protein conformation in the ADP.AlF(4-) complex. The L127Delta mutation precludes key interactions between the Fe-protein and nucleotide, especially, but not exclusively, in the region corresponding to the switch II region of G-proteins, where the deletion constrains Gly 128 and Asp 129 from forming hydrogen bonds to the gamma-phosphate and activating water for attack on this group, respectively. These alterations account for the inability of this mutant to support mechanistically productive ATP hydrolysis. The ability of the L127Delta-Av2-Av1 complex to bind MgATP demonstrates that dissociation of the nitrogenase complex is not required for nucleotide binding.

Adenosine Triphosphate↗
PubMed2001

Crystal structure of the all-ferrous [4Fe-4S]0 form of the nitrogenase iron protein from Azotobacter vinelandii.

The structure of the nitrogenase iron protein from Azotobacter vinelandii in the all-ferrous [4Fe-4S](0) form has been determined to 2.25 A resolution by using the multiwavelength anomalous diffraction (MAD) phasing technique. The structure demonstrates that major conformational changes are not necessary either in the iron protein or in the cluster to accommodate cluster reduction to the [4Fe-4S](0) oxidation state. A survey of [4Fe-4S] clusters coordinated by four cysteine ligands in proteins of known structure reveals that the [4Fe-4S] cluster of the iron protein has the largest accessible surface area, suggesting that solvent exposure may be relevant to the ability of the iron protein to exist in three oxidation states.

Amides↗
PubMed2001

Telepsychiatry in psychogeriatric service: a pilot study.

A pilot study on telepsychiatry was conducted in which a videoconferencing link was established between a regional hospital and a care and attention home. Using this system, a psychogeriatric outreach team provided 149 psychiatric assessments to 45 residents of the care and attention home over 11 months. Videoconferencing was found to be highly feasible. It was acceptable to staff and patients and more cost-effective than on-site visits.

Aged↗
PubMed2001

A psychiatric epidemiological study of postpartum Chinese women.

OBJECTIVE: Epidemiological studies in the 1980s have suggested that depression is rare in the Chinese population and there is no postpartum depression among Chinese women. However, subsequent small-scale studies of postpartum depression in China have yielded contradictory and inconsistent findings. Furthermore, after two decades of profound socioeconomic transformation, depression may no longer be rare in the contemporary population. The authors conducted a psychiatric epidemiological study among postpartum Chinese women using rigorous methodology and a representative sample. METHOD: A total of 959 consecutive women were recruited at the antenatal clinic of a university hospital in Hong Kong. At 3 months postpartum, the prevalence and incidence rates of depression were measured with a two-phase design. The participants were first stratified by means of the 12-item General Health Questionnaire. Subsequently, all high scorers and 10% of low scorers were assessed with the nonpatient version of the Structured Clinical Interview for DSM-III-R. The 1-month and 3-month prevalence and incidence rates were estimated by using reverse weighting. RESULTS: The 1-month prevalence rates for major and minor depression were 5.5% and 4.7%, respectively. At 3 months, the corresponding prevalence rates were 6.1% and 5.1%. Together, 13.5% of the participants suffered from one or more forms of psychiatric disorder in the first 3 months postpartum. CONCLUSIONS: Postpartum depression is common among contemporary Chinese women. A universal postpartum depression-screening program would be useful for early detection. Our data suggest that depression may no longer be rare in the Chinese population.

Adult↗
PubMed2001

Routine chest radiographs in pediatric intensive care units.

OBJECTIVES: To determine whether interventions were performed based on portable routine morning chest x-rays (CXRs) in pediatric intensive care unit (PICU) patients and to identify patient subgroups for whom the routine CXR is most useful. DESIGN: Prospective multiinstitutional study. Setting. PICUs of 15 tertiary care hospitals. Patients. PICU patients who received a routine morning CXR were included in the study. OUTCOME MEASURES: Recorded data included: weight, diagnosis, presence of active cardiopulmonary problems, length of stay, and number and type of devices. The number and types of interventions based on the interpretation of the CXR were recorded. RESULTS: Five hundred twelve routine CXRs were evaluated. The majority of the routine chest radiographs were obtained on patients who were admitted for cardiovascular disease (195/512; 38%) or respiratory failure (186/512; 36%), and 465/512 of the routine CXRs (91%) were performed on patients with one or more devices. Two hundred thirty-one of the 512 routine CXRs (45%) resulted in 1 or more interventions. One hundred fifty-five of the 284 routine CXRs (55%) obtained in children </=10 kg resulted in one or more interventions, compared with 61/152 (40%) and 15/76 (20%) of routine CXRs obtained in children 10 to 40 kg and >/=40 kg, respectively. The frequency of interventions increased from 19% in children with no devices to >50% in children with 2 or more devices. One or more interventions were performed in 27% of routine CXRs when no active cardiopulmonary problems were present, compared with 51% of routine CXRs when active cardiopulmonary problems were present. Diagnosis and length of intensive care unit stay at the time the routine CXR was obtained did not affect the percentage of CXRs that resulted in interventions. CONCLUSIONS: Routine CXRs are more likely to result in interventions in the smaller, critically ill child with one or more devices and if active cardiopulmonary problems are present.

Body Weight↗
PubMed2000

Memory and organizational strategies in chronic and acute schizophrenic patients.

The memory profile of acute and chronic schizophrenic patients was examined according to the information processing model, with which encoding, retention and retrieval processes of these patients were compared. The effects of an external organizational strategy on their verbal learning and memory were also examined. Twenty chronic and 20 acute schizophrenic patients were tested with a list learning task consisting of a random (i.e., words presented randomly) and a blocked (i.e., words presented in clusters) word-list. The schizophrenic patients, as compared with age- and education-matched normal control subjects, demonstrated impaired learning, and the duration of their illness was not a significant factor in the severity of their learning impairment. However, the acute and chronic schizophrenic patients seem able to retain most of the newly acquired materials, regardless of the presentation format, after 30 min. In addition, the learning and subjective organizational strategy of the chronic patients, but not that of the acute patients, improved significantly by the blocked presentation. However, semantic organization could facilitate both the chronic and acute schizophrenic patients to retain more newly learned items.

Acute Disease↗
PubMed2000

MRI of Enterovirus 71 myelitis with monoplegia.

We report two boys diagnosed as having herpangina and hand-foot-mouth disease complicated by monoplegia during the outbreak enterovirus infection in Taiwan in 1998. Enterovirus 71 was identified in the stool and throat swab; neither polio nor Coxsackie viruses was identified. MRI showed unilateral lesions in the anterior horns of the spinal cord at T11-12 and C2-5. Although the MRI findings and sites of these lesions were similar to those of poliovirus-associated poliomyelitis, the virological data indicated that these boys were infected with enterovirus type 71.

Diagnosis, Differential↗
PubMed2000

Functional heterogeneity of rat hepatic and alveolar macrophages: effects of chronic ethanol administration.

Chronic ethanol consumption is associated with increased incidence of hepatic and pulmonary infections. To determine if this is correlated with altered macrophage activity, we analyzed the functional properties of cells isolated sequentially from the liver and lung of rats fed a liquid diet containing ethanol (35% of calories) or malto-dextrin control for 9-12 weeks. Hepatic and alveolar macrophages from control animals were found to exhibit distinct morphologic and functional properties. Thus, hepatic macrophages were highly vacuolated and appeared larger and more irregular in shape than alveolar macrophages. These cells also displayed greater phagocytic activity and random migration. In contrast, lung macrophages produced more superoxide anion and nitric oxide, and exhibited enhanced chemotactic activity toward the complement fragment C5a. Whereas administration of ethanol to rats for 9-12 weeks resulted in decreased chemotaxis and superoxide anion production by alveolar macrophages, cell adhesion molecule expression was reduced in hepatic macrophages. Nitric oxide production and inducible nitric oxide synthase protein expression were decreased in both macrophage populations. These effects were not observed after 3-6 weeks of ethanol administration to rats. Our results suggest that changes in macrophage functioning may play a role in decreased host defense following chronic ethanol exposure.

Animals↗
PubMed1999

A breakdown of event schemas in patients with schizophrenia: an examination of their script for dining at restaurants

Event schemas, the conceptualization of past experience, in schizophrenic patients were examined based upon script theory. Forty schizophrenic patients and 40 age- and education-matched normal control subjects participated in this study. This experiment consisted of three tasks. In the recall task, subjects recalled a typical scenario of going to a formal restaurant. In the frequency judgment task, subjects determined whether the given events happen frequently, occasionally or rarely in a restaurant. In the sequencing task, the subjects put the randomly presented events in the correct order. The responses of the schizophrenic patients in the recall task, when compared with those of the normal control subjects, had significantly fewer concepts and a greater proportion of highest-frequency concepts. In addition, the sequence of their responses was less accurate than that of normal individuals. This abnormality is unlikely due primarily to a retrieval deficit (i.e. generating fewer concepts in the recall task) given that their performances on the frequency judgment and sequencing tasks, tasks that require less retrieval effort, were consistent with those of the recall task. These results suggest that event schemas in schizophrenic patients contain little detailed information and are incoherent in organization.

Journal Article↗
PubMed1999

Sleep paralysis in the elderly.

Isolated sleep paralysis (SP) is a common sleep phenomenon that is highly colored by indigenous beliefs. In Hong Kong Chinese, the 'ghost oppression phenomenon' (GO) has been shown to be descriptively identical to SP. The prevailing concept is that the majority of cases with SP have their onset during adolescence, but the lack of any systematic study on an older population means that late-onset cases can not be excluded. In a study investigating the prevalence of mental disorders in Chinese elderly aged above 70 y in Hong Kong, we employed the revised GO questionnaire to study the prevalence of SP in this group of elderly as well. One hundred and fifty-eight subjects were finally analyzed for the study. Almost 18% (95% C.I. 11.77%, 23.68%) of the subjects reported experiences of GO. Their description of the features of GO showed striking similarity to those of SP. There was a clear bimodal distribution of onset of GO with peaks during adolescence and after age 60 y. At least one-third of the cases were late onset. In concordance with the rapid eye movement (REM)/wakefulness dissociation hypothesis of SP, those elderly with GO+ experiences also had more frequent nocturnal sleep disturbances. A family history was reported in 10% of subjects.

Age of Onset↗
PubMed1998

No association detected between very-low-density lipoprotein receptor (VLDL-R) and late-onset Alzheimer's disease in Hong Kong Chinese.

The epsilon4 allele of apolipoprotein E (ApoE) is a risk factor in late-onset Alzheimer's disease (AD). As a receptor for ApoE, very-low-density lipoprotein receptor (VLDLR) might be involved in AD pathogenesis. A Japanese study [Okuizimi, K., et al., Nature Genet., 11 (1995) 207-209] has shown an increased 5 and decreased 8 CGG-repeat allele frequency in the 5' untranslated region of VLDLR in Japanese AD versus normal controls (N). Subsequent studies in Caucasian Americans failed to duplicate the result. We examined this polymorphism in pathologically- or clinically-diagnosed Chinese late-onset AD. Our data did not show a significant increase in the 5 CGG-repeat in AD, thus suggesting no association to VLDLR. However, our data did show that the allele frequencies for each CGG-repeat were similar in both Chinese and Japanese.

Age of Onset↗
PubMed1997

Simultaneous determination of imipramine, desipramine and their 2- and 10-hydroxylated metabolites in human plasma and urine by high-performance liquid chromatography.

A simultaneous assay for imipramine, desipramine and their 2- and 10-hydroxy-metabolites using high-performance liquid chromatography (HPLC) is described. The drugs and internal standard, pericyazine, were extracted from plasma or urine at pH 9.6 with diethyl ether and back-extracted into 0.1 M orthophosphoric acid. The recovery of the compounds ranged from 78.6% for imipramine to 94.3% for 2-hydroxydesipramine. The extracts were analysed by reversed-phase HPLC with electrochemical detection using a mobile phase of 30% acetonitrile in 0.1 M K2HPO4 at pH 6.0 delivered at 2 ml/min. All compounds were resolved in a run time of 15 min with lower limits of quantification of 1.5 ng/ml for hydroxy-metabolites and 3 ng/ml for imipramine and desipramine. The intra- and inter-day coefficients of variation at 50 ng/ml were 5.2% and 6.8%, respectively (n=8).

Adult↗
PubMed1997

Duration of immunity in foxes vaccinated orally with ERA vaccine in a bait.

Red foxes (Vulpes vulpes) vaccinated orally with the ERA strain of rabies vaccine in a bait were challenged after 83 mo. Ten of 11 foxes that had seroconverted following vaccination resisted challenge with a virulent rabies virus which produced clinical signs of rabies in 6 of 6 unvaccinated foxes. Five of 11 vaccinated animals retained titers of rabies virus neutralizing antibody throughout the period. Although 6 of 11 had no detectable antibody at the time of challenge, 5 of these 6 resisted challenge and had an anamnestic response, as indicated by elevated titers of antibody when measured at day 77 postchallenge. These results show that foxes can be immunized successfully with a single oral dose of ERA vaccine, probably with protection against a lethal rabies challenge, for at least 7 y.

Administration, Oral↗