Biomedical subjects

X Chu

Publications and source records attributed to X Chu.

At least 37 records · Page 2Linked to original sources

PubMed1999

Effects of changes in travel patterns on highway fatalities.

This paper estimates the number of deaths that may have been avoided in 1995 because of changes in selected travel patterns during the period from 1969 to 1995 in the US. Four travel patterns are considered, including distributions of travel between urban and rural areas, between interstates and other roadways, between night and day time hours, and between female and male drivers. At the 1995 mobility level, changes in the selected travel patterns during the period from 1969 to 1995 may have avoided up to 9970 deaths in 1995 alone. These deaths avoided represent over 12% of the total number of deaths avoided in 1995 as a result of overall improvements in highway safety during the same period in this country.

Accidents, Traffic↗

PubMed1999

The localization and expression of the class II starch synthases of wheat.

The starch granules of hexaploid wheat (Triticum aestivum) contain a group of three proteins known as SGP-1 (starch granule protein-1) proteins, which have apparent molecular masses of 100, 108, and 115 kD. The nature and role of these proteins has not been defined previously. We demonstrate that these polypeptides are starch synthases that are present in both the starch granule and the soluble fraction at the early stages of wheat endosperm development, but that are exclusively granule bound at mid and late endosperm development. A partial cDNA clone encoding a fragment of the 100-kD protein was obtained by screening a wheat endosperm cDNA expression library using monoclonal antibodies. Three classes of cDNA were subsequently isolated from a wheat endosperm cDNA library by nucleic acid hybridization and were shown to encode the 100-, 108-, and 115-kD proteins. The cDNA sequences are highly homologous to class II starch synthases and have the highest homology with the maize SSIIa (starch synthase IIa) gene. mRNA for the SGP-1 proteins was detected in the leaf, pre-anthesis florets, and endosperm of wheat and is highly expressed in the leaf and in the grain during the early to mid stages of development. We discuss the roles of the SGP-1 proteins in starch biosynthesis in wheat.

Amino Acid Sequence↗

PubMed1999

Unique regulation of CYP17 expression in the trophectoderm of the preattachment porcine blastocyst.

Expression of the gene encoding cytochrome P450 17alpha-hydroxylase, CYP17, is necessary for adrenal and gonadal steroidogenesis in most species. However, some animals, such as the pig, express CYP17 in the trophectoderm of the preattachment blastocyst, an event associated with estrogen synthesis and the establishment of pregnancy. How trophoblastic expression of CYP17 is regulated in the porcine blastocyst remains unknown and forms the basis of the following studies. The porcine CYP17 gene, including the complete coding and several kilobases of 5'-flanking regions, was cloned and sequenced. Blastocysts were examined by Northern analysis to verify the level of CYP17 transcript, and tissue-specific expression in the trophectoderm was confirmed by in situ hybridization. Primer extension, S1 nuclease protection, and 5'-rapid amplification of cDNA ends confirmed a common proximal transcription start site in adrenals and gonads (-48 bp) but identified a unique distal start site used in porcine trophectoderm (-182 bp). Additionally, reporter analysis of the CYP17 regulatory region demonstrated that constructs (-27 to -718 bp) were unresponsive to forskolin when expressed in porcine trophoblast cells, suggesting that trophoblast may not be able to respond to cAMP induction of this gene. The identification of this distal, previously undescribed, transcriptional start site suggests that unique mechanisms control the expression of CYP17 in porcine trophectoderm and possibly other genes important in implantation and early placental development.

Adrenal Cortex↗

PubMed1999

[Two high performance fighter pilots with low +Gz tolerance rectified by centrifuge training].

OBJECTIVE: To demonstrate the effects of training on rectifying two high performance fight aircraft pilots with low +Gz tolerance. METHODS: Anti-G straining maneuver (AGSM) and pressure breathing for +Gz (PBG) maneuver were trained during centrifuge +Gz stress. RESULTS: After training, the +Gz tolerances with AGSM, and with PBG and anti-G suit were enhanced by 3.0 ~ 3.25 G and 2.75 ~ 3.0 G, respectively. The combined +Gz tolerance was higher than the relaxed +Gz tolerance by 4.25 ~ 4.5 G. Both two pilots had passed the 8 G 10 s SACM +Gz profile and reached the standard of training.

Acceleration↗

PubMed1999

[Comparative study of three different chemotherapy protocols for advanced non-small-cell lung cancer].

OBJECTIVE: To compare the efficacy and toxicity of three different chemotherapy protocols for advanced non-small-cell lung cancer (NSCLC). METHODS: The clinical data of 93 cases with advanced NSCLC treated with (1) ifosfamide plus vindesine plus cisplatin (IVP, 31 cases), (2) mitomycin C plus vindesine plus cisplatin (MVP, 30 cases), and (3) cyclophosphamide plus adriamycin plus cisplatin (CAP, 32 cases) were analysed. RESULTS: The response rate was 48.4% in patients treated with IVP, 40.0% in those treated with MVP, and 28.1% in those with CAP, respectively. The major toxic reactions in the three groups were tolerable myelo-suppression and hair loss. CONCLUSION: IVP and MVP are effective and safe chemotherapeutic protocols for the treatment of advanced NSCLC patients.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1999

[Integrated protection capability afforded by a new type capstan anti-G equipment and anti-G straining maneuver].

Objective. To investigate the integrated protection capability afforded by a new type capstan anti-G equipment and anti-G straining maneuver, as a result we discussed the feasibility of protection for 8 G 10 s (rapid onset runs at 2 G/s) acceleration using an associated precept with the above both anti-G measures. Method. This study was accomplished using the human centrifuge with rapid onset at 2 G/s. First, we determined the relaxed +Gz tolerance of nine male aviation students, and then determined theirs most + Gz tolerance while thereinto the five aviation students using a new type capstan anti-G suit (NKH) + a new type anti-G valve (NKT) + L-1 anti-G straining maneuver (L-1) and the other four aviation students using a new type capstan counterpressure suit (NDC) + the new type anti-G valve (NKT) + L-1. Result. The most +Gz tolerance of five students was 8.80 +/- 0.27 G while using NKH + NKT + L-1 and was higher than their relaxed +Gz tolerance at 4.60 +/- 0.42 G (P< 0.01) and that the most +Gz tolerance of four students was 8.75 +/- 0.50 G while using NDC + NKT + L-1 and was higher than their relaxed +Gz tolerance at 4.50 +/- 0.46 G (P< 0.01). Conclusion. Pilot will be capable against the 8 G 10 s (rapid onset runs at 2 G/s) effectively using the new type capstan anti +/- G equipment and anti +/- G straining maneuver, and the provided precept has availability.

Acceleration↗

PubMed1999

[Technical consideration of setting up a specification for human centrifuge evaluation of anti-G equipment].

Anti-G equipment needs to be evaluated using human centrifuge before further developed. However, there isn't a general specification for human centrifuge evaluation of anti-G equipment. From related literature and from our over thirty years experience in this area, we sum up to five aspect technical consideration below: human centrifuge, medical specification for using human in +Gz stress experiment, anti-G equipment experimental assembly, principle should be abided by during human centrifuge evaluation of anti-G equipment. We hope that the technical considerations mentioned in the paper should be helpful to the work of setting up a specification for human centrifuge evaluation anti-G equipment. After we have a specification, the research will be conducted orderly and the anti-G [correction of an-G] equipment will be developed sequentially.

Acceleration↗

PubMed1998

Stress-induced neuroendocrine modulation of viral pathogenesis and immunity.

Physical restraint (RST) was used to examine the interactions among the hypothalamic-pituitary-adrenal (HPA) axis, sympathetic nervous system, and the immune response to infection. In these studies, mice were infected with either herpes simplex virus (HSV) or influenza A/PR8 virus so that the impact of neuroendocrine activation could be assessed on disease pathophysiology and anti-viral immunity. RST suppressed lymphadenopathy in draining lymph nodes, reduced mononuclear cellular infiltration in the lungs, and suppressed virus-specific cytokine and cytolytic T-cell responses. Blockade of type II glucocorticoid receptors (by RU486) restored cellularity and cytokine responses to both organs in restraint-stressed, infected mice. Thus, the HPA axis modulated cell trafficking and T-cell cytokine responses. However, RU486 treatment failed to restore cytolytic T-cell responses. Blockade of beta-adrenergic receptors (by nadolol), in combination with RU486 treatment, fully restored cytolytic T-cell responses, suggesting that catecholamines were involved in suppressing the virus-specific CD8+ cytolytic T-cell response. RST also modulated the local development or expression of antibody-secreting cells (ASC) in the lungs draining lymph nodes, and spleen following infection of restrained mice. RST significantly suppressed the number of virus-specific ASC (IgM, IgG and subclasses IgG1 and IgG2a) in the lungs, mediastinal (MLN) lymph nodes and spleen, while it enhanced the responses in the superficial cervical (SCV) lymph nodes. This observation of differential modulation of ASC responses in the MLN and SCV lymph nodes supports the concept of tissue-specific immunoregulation in response to stress.

Animals↗

PubMed1998

Profound inhibition of cardiomotor neurons in the rat rostral ventrolateral medulla by nociceptin (orphanin FQ).

Nociceptin (orphanin FQ), the newly discovered endogenous ligand for the opioid receptor like-1 receptor, profoundly inhibited spontaneous discharges of neurons in the rostral ventrolateral medulla (RVLM) in rat brain slices. This inhibition was concentration-dependent (0.3, 1, 3 and 10 nM) and insensitive to pharmacological blockade of traditional opioid receptors by naloxone. Moreover, nociceptin injected into the RVLM (10 nM, 0.1 microliter) in anesthetized rats decreased arterial blood pressure and heart rate by 31% and 15%, respectively. The data obtained in vitro and in vivo suggest that nociceptin has powerful effects on the RVLM neurons involving central control of cardiovascular activity. The negative regulation of cardiovascular activity by nociceptin is not mediated through typical naloxone-sensitive opioid receptors.

Animals↗

PubMed1998

Multiplicity of biliary excretion mechanisms for the camptothecin derivative irinotecan (CPT-11), its metabolite SN-38, and its glucuronide: role of canalicular multispecific organic anion transporter and P-glycoprotein.

A frequent dose-limiting effect of irinotecan (CPT-11) is its gastrointestinal toxicity (diarrhea), which is thought to be related to biliary excretion of CPT-11 and its metabolites. Accordingly, we have investigated the mechanism of biliary excretion of these compounds. In vivo pharmacokinetic studies revealed that the biliary excretion of the four anionic forms of CPT-11 and its metabolites was reduced in Eisai hyperbilirubinemic rats, which carry a mutation of the hepatic canalicular multispecific organic anion transporter (cMOAT) gene. The protein encoded by this gene is expressed on the bile canalicular membrane and is responsible for the transport of organic anions into bile. Detailed analysis using isolated liver bile canalicular membrane vesicles to identify transport systems showed that cMOAT is responsible for biliary excretion of the low-affinity component of the carboxylate form of CPT-11 and the high-affinity component of both the lactone and carboxylate forms of SN-38 glucuronide. The carboxylate form of SN-38 is transported by cMOAT alone. Transport of the high-affinity component of CPT-11 was inhibited by verapamil and PSC-833, but their effect on the transport of its low-affinity component was minimal. In addition, ATP dependence in the uptake of CPT-11 by membrane vesicles obtained from a P-glycoprotein (P-gp)-overexpressing cell line was observed. Thus P-gp may be responsible for transport of the high-affinity component of the carboxylate form of CPT-11.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1998

[Experimental study on therapeutical effect of Chinese medicine on polymyositis in guinea pigs].

OBJECTIVE: To study the therapeutical effects of Radix Bupleuri and Ramulus Cinnamomi on virus polymyositis in guinea pigs. METHODS: Forty polymyositis guinea pigs induced by Coxsackievirus B1 were divided at random into A(n = 15), B(n = 15), C(n = 10) groups. A, B groups were treated with Radix Bupleuri and Ramulus Cinnamomi respectively. C group received no treatment. Sign, muscle enzyme spectrum and pathological changes were compared. RESULTS: A and B groups became better. C group showed an aggravating trend (P < 0.05). CONCLUSION: Radix Bupleuri and Ramulus Cinnamomi had therapeutic effect on polymyositis in guinea pigs.

Animals↗

PubMed1998

[Simultaneous determinations of carbamate pesticides in cereal by high performance liquid chromatography with post-column fluorescence derivatization].

A liquid chromatographic method for the simultaneous determination of carbamate pesticides in cereal by Waters Carbamate Analysis System with post-column fluorescence derivatization is described. The cereal sample homogenate was extracted with acetone and water. The extract was partitioned between 5% sodium chloride solution and dichloromethane. The dichloromethane layer was concentrated to dryness. The residue was dissolved in n-hexane and extracted with acetonitrile (saturated with n-hexane). The acetonitrile layer was decreased with n-hexane (saturated with acetonitrile), then the acetonitrile layer was concentrated to dryness. The residue was dissolved in methanol. It's the test solution for HPLC. Nine carbamate pesticides and their three metabolites were separated by Waters Carbamate Column with gradient elution. Two steps underwent in the post-column system: hydrolysis by NaOH solution and the reaction of the product with o-phthalaldehyde and 2-mercaptoethanol. The resulting fluorescence derivative was detected at 445 nm (excitation at 339 nm). The selectivity, reproducibility and sensitivity of proposed method are better than those reported with other methods. The detection limits was 5 micrograms/kg of samples.

Carbamates↗

PubMed1998

[Determination of digoxin-like immunoreactive substances in sera of 15 elder patients with cardiac insufficiency].

The presence of a higher concentration of digoxin-like immunoreactive substances (DLIS) in human serum have been reported in a number of pathophysiological conditions. DLIS can react with anti-digoxin antibodies when determination of serum digoxin was performed with immunoassay. It may falsely elevate the serum digoxin concentration and is troublesome in the therapeutic monitoring of digoxin. The apparent digoxin concentrations (DLIS) in serum were determined in 15 elder patients with cardiac insufficiency by fluorescence polarization immunoassay (FPIA). The lowest measurable concentration, defined as the concentration that could be distinguished from zero with 95% confidence, was 0.256 nmol.L-1. Steroids and drugs commonly administered with digoxin showed no significant cross-reactivity. In these patients, the positive ratio for determination of DLIS was 46.7% (7 in 15 cases), and its mean serum concentration was 0.55 +/- 0.44 nmol.L-1 (range 0.26-1.52 nmol.L-1). The results were well consistent with that obtained by Dasgupta et al. In conclusion, there are certain increased concentrations of DLIS in the sera of elder patients with cardiac insufficiency, suggesting that digoxin levels measured by immunoassay method must be interpreted carefully in these patients after treatment with digoxin or other digitalis preparations.

Aged↗

PubMed1997

An Expression for the Dispersion Force between Colloidal Particles

A result for the integral of R-12 over two spheres of radii a and b is given. This result, together with Hamaker's result for the integral of R-6, leads to an expression for the integral of the Lennard-Jones potential over two spheres that is suitable for calculations involving colloidal particles.

Journal Article↗

PubMed1997

Dextromethorphan metabolic phenotyping in a Chinese population.

AIM: To establish a phenotyping of dextromethorphan (DM) oxidation polymorphism in a native Chinese population. METHODS: The urine concentrations of DM and its metabolite dextrophan (DX) were assayed by HPLC and metabolic ratios (MR) were calculated in 120 unrelated native Chinese subjects after ingestion of DM 20 mg. RESULTS: The incidence of poor metabolizers was 0.8% (one in 120 subjects). There were distinct dimodal distributions which divided extensive metabolizers into 43 intermediate metabolizers and 76 very extensive metabolizers. The 0-8 h urinary recoveries of DM and DX were 0.4% +/- s 0.5% and 26% +/- s 13%, respectively. There was no difference in 0-8 h urinary recoveries between male and female subjects. CONCLUSION: DM metabolic phenotyping provides a new information for debrisoquine 4-hydroxylation (CYP2D6) polymorphism in native Chinese.

Adolescent↗

PubMed1997

[ECG changes during [correction of dring] high G centrifuge training].

ECG of 47 healthy subjects, during G-training on the human centrifuge were recorded and analyzed. Training consisted of 4 G profiles and carried out in 6 d. Subjects were divided into 3 groups according to different anti-G equipment used. The results showed that: high incidence of arrhythmia (87%) was observed, and it increased with the increase of G level; subjects with R/S < 1 under +Gz environment, or HR sharply dropped immediately after the +Gz load have lower G-tolerance; incidence of arrhythmia is lower when advanced anti-G equipment was used.

Acceleration↗

PubMed1997

[Effect of different Anti-G suits on lower limb blood flow].

To study effects of different Anti-G suits (AGS) and different inflation pressure on human cardiac system, changes in lower limb arterial blood flow (BF), heart rate and blood pressure in 5 male subjects with three bladder coverage AGS and a capstain AGS were observed and recorded until inflation pressure reached to its maximum. The percent of bladder coverage was about 30%, 65% and 90% of lower body for three bladder AGS. All AGS were inflated to maximum pressure in +1Gz seating position. The results showed that calf BF, could be blocked by bladder AGS, and the relationship between the mean pressure for BF block and the percentage of bladder coverage was y = 29.66 - 16.35x. (P < 0.0001, r = -0.9229). While the thigh and calf BF was not blocked in subjects with the capsule AGS. The results indicate that the effect of "the higher bladder coverage AGS + lower IP" is probably equal to that of "the lower bladder coverage AGS + higher IP" in holding calf BF.

Aerospace Medicine↗

PubMed1997

High performance liquid chromatographic determination of dextromethorphan and its metabolite in human urine.

A reverse-phase high-performance liquid chromatographic method was established for the determination of dextromethorphan (DM) and its metabolite dextrophan (DX) in human urine. The sample was purified by an acid-base extraction followed by HPLC analysis on a phenyl column. The eluate was monitored by fluorescence at 280 nm (excitation) and 310 nm (emission). The limit of detection of DM was 0.023 mg.L-1. The within-day and between-day RSD% of DM and DX were all lower than 5%. The average recovery was 104.78%.

Chromatography, High Pressure Liquid↗