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Biomedical subjects

R Sun

Publications and source records attributed to R Sun.

At least 73 records · Page 4Linked to original sources
PubMed2000

Effects of growth hormone and prolactin on hematopoiesis.

The use of the neuroendocrine hormones growth hormone (GH) and prolactin (PRL) in preclinical models, demonstrating promotion of hematopoietic recovery and immune function, offers promise for several clinical situations. These hormones do not appear to produce the same extent of immune/hematopoietic effects when compared to conventional hematopoietic and immune stimulating cytokines (i.e. G-CSF or interleukin-2). However, their pleiotropic effects and limited toxicity after systemic administration makes them attractive to test in myeloablative situations. More work needs to be performed to understand the mechanism(s) of GH and PRL action, particularly with regard to hematopoietic progenitor cell expansion and differentiation both in normal and pathologic situations.

Animals↗
PubMed2000

Experience with PCR screening.

The COBAS AmpliScreen Hepatitis C (HCV) Test, Version 2.0, which is designed for screening pools composed of samples from individual units of blood or plasma, employs a MultiPrep sample processing procedure that simultaneously extracts and concentrates HCV, HIV-1 and Hepatitis B virus particles from plasma. An HCV Internal Control (IC) RNA serves as an extraction and amplification control for each independently processed sample. Processed samples are amplified by RT-PCR using HCV-specific complementary primers and detected by hybridization of the amplified products to HCV- and IC-specific oligonucleotide probes. The analytical sensitivity of the test is 25 International Units (IU) of HCV per mL of pooled plasma; all HCV genotypes are detected with similar efficiency. The test detected HCV RNA 23 to 32 days prior to anti-HCV antibody seroconversion for four of the five seroconversion panels tested. The test had sufficient sensitivity to reproducibly detect a single infected unit containing 2.4 x 10(3) copies of HCV per mL in a pool with 23 uninfected units. COBAS AmpliScreen tests for HIV-1 and HBV now being validated by Roche Molecular Systems also incorporate the MultiPrep specimen processing method, thereby making it possible to use a single processed specimen to screen for all three viruses.

Genotype↗
PubMed2000

[Vascular anastomoses in free jejunal reconstruction to the neck vessels: an experience of consecutive 20 cases without using surgical microscope].

Twenty consecutive cases of pharyngoesophageal cancer who underwent free jejunal reconstruction were reported. The common carotid or external carotid artery was used for a feeder of the free graft. The internal jugular vein were served as a drainage vein. All anastomoses were performed in an end-to-side fashion without using surgical microscopes. Mean carotid artery clamping time was 16 minutes and no neurological complications were noticed postoperatively. Graft failure was occurred in 1 patient. The presenting technique, showing 95% success rate, is recommended as a simple option for vascular anastomosis in free jejunal reconstructive surgery.

Anastomosis, Surgical↗
PubMed2000

[Preparation and identification of monoclonal antibodies against human apoptosis-related protein TFAR19].

OBJECTIVE: To obtain mouse anti-human TFAR19 monoclonal antibodies for further study of the structure and function of the apoptosis-related protein TFAR19. METHODS: BALB/c mice were immunized with recombinant human TFAR19, hybridoma cells were screened by cell fusion and subcloning approach. The monoclonal antibodies were identified by ELISA and Western blotting. RESULTS: Three hybridoma cells (C1, C10, 2C12) stable in secreting anti-TFAR19 monoclonal antibodies were obtained. The monoclonal antibodies showed high specificity and high titer to TFAR19 with various affinity. All of them belong to IgG1 subclass. CONCLUSIONS: These monoclonal antibodies could bind specifically to TFAR19 protein.

Animals↗
PubMed2000

[The preparations and spectroscopic studies of infrared radiating materials].

ZrO2 and ZrO2-Al2O3 samples have been prepared by precipitation method, and characterized by FTIR, NIR FT-Raman, XRD and IR emission spectra, respectively. The result showed that these samples are the better infrared radiating materials, which have high efficiency and excellent properties. When compared with pure ointment, ZrO2-Al2O3 prepared has more strong infrared emission peaks. The application of infrared radiating materials in ointment may have a good effect on thermal infrared absorption vibration and absorption of medicine by sick part of body.

Aluminum Oxide↗
PubMed2000

[The Raman spectra study on crystal-octadecyl hydrogen maleate (OHM)].

Raman spectra of crystal-octadecyl hydrogen maleate (OHM), whose geometric disposition of the experiment has y (zx) y y(zz)y, and y(xz)y, y(xx)y respectively, have been recorded and analyzed with the purpose of understanding the structure of OHM crystal. It shows that some of the Raman-active modes of alkyl chain appear polarization. The analysis for crystal structure indicates that the molecular of OHM arrange in layers along [100] and [001] by the mode of dimers, and the molecular layers of chain pile up along [010]. The other groups of OHM corresponding Raman vibration peaks have been analysed as well.

English Abstract↗
PubMed2000

[The synthesis and spectral study of multicomponent heteropoly compounds with Keggin structure].

The Multicomponent heteropoly compounds [Me4N]3 + x[PVxMoyW12-x-yO40]. n(H2O) with Keggin structure have been synthesized, and have been characterized by FTIR and NIR FT-Raman. The vibrational regularity of oxygen-containing bonds (P-Oa, M = Od, M-Ob-M and M-Oc-M) in these heteropoly compounds have been studied. The vibrational frequencies nu as (M = Od) and nu as (M-Ob-M) was shown to prove the reason why the acidity of the heteropoly compounds descended and the oxidization increased by the substitution of V atoms.

English Abstract↗
PubMed1999

Performance characteristics of the AmpliScreen HIV-1 test, an assay designed for screening plasma mini-pools.

This study evaluated the performance characteristics of the AmpliScreen(TM)Human Immunodeficiency Virus-Type 1 (HIV-1) Test, Version 1.5, a test designed for screening pools composed of samples from individual units of blood or plasma. HIV-1, hepatitis C (HCV) and hepatitis B (HBV) virus particles were simultaneously extracted and concentrated from plasma by a multi-prep sample processing procedure. An HIV-1 Internal Control (IC) RNA was added to each sample to serve as an extraction and amplification control. Processed samples were amplified by RT-PCR using HIV-1-specific complementary primers and detected by hybridization of the amplified products to HIV-1- and IC-specific oligonucleotide probes. The analytical sensitivity of the test (concentration that yields >/=95% positive results in a set of replicate tests) was 25 copies of HIV-1 RNA per mL of pooled plasma. Representative strains from all HIV-1 group M subtypes were reproducibly detected (>95% positive results among 22 replicate tests) at concentrations of 30 to 75 viral particles per ml. The test exhibited excellent specificity; it did not cross-react with a set of 30 viral and five bacterial isolates and yielded negative results on a panel of 500 blood samples from HIV-1 seronegative donors. Samples containing abnormally high levels of haemoglobin, albumin, triglycerides or bilirubin in plasma samples did not interfere with the detection of HIV-1 RNA at a concentration of 100 copies of per ml. The test detected HIV-1 RNA 7-17 days prior to anti-HIV-1 antibody seroconversion for all 10 seroconversion panels tested. A fully automated COBAS AmpliScreen(TM)version of this test is being validated. COBAS AmpliScreen tests for HCV and HBV also incorporate the multi-prep specimen processing method, thereby making it possible to use a single processed specimen to screen for all three viruses.

Evaluation Studies as Topic↗
PubMed1999

Accounting for the computational basis of consciousness: a connectionist approach.

This paper argues for an explanation of the mechanistic (computational) basis of consciousness that is based on the distinction between localist (symbolic) representation and distributed representation, the ideas of which have been put forth in the connectionist literature. A model is developed to substantiate and test this approach. The paper also explores the issue of the functional roles of consciousness, in relation to the proposed mechanistic explanation of consciousness. The model, embodying the representational difference, is able to account for the functional role of consciousness, in the form of the synergy between the conscious and the unconscious. The fit between the model and various cognitive phenomena and data (documented in the psychological literatures) is discussed to accentuate the plausibility of the model and its explanation of consciousness. Comparisons with existing models of consciousness are made in the end.

Cognition↗
PubMed1999

Effects of temperature and photoperiod on thermogenesis in plateau pikas (Ochotona curzoniae) and root voles (Microtus oeconomus).

We examined the effects of temperature and photoperiod on metabolic thermogenesis and the thermogenic characteristics of brown adipose tissue in plateau pikas (Ochotona curzoniae) and root voles (Microtus oeconomus), the dominant species of small mammals in the alpine meadow ecosystems on the Qinghai-Tibetan Plateau. Pikas and voles were acclimated in the following groups: (1) Long day-warm temperature (16L:8D, 23 degrees C) (2) Long day-cold temperature (16L:8D, 5 degrees C), (3) short day-warm temperature (8L:16D, 23 degrees C), and (4) short day-cold temperature (8L:16D, 5 degrees C). Both temperature and photoperiod were important environmental cues for changes in thermogenesis for both species. Low temperature and short photoperiod induced increases in metabolic rate, nonshivering thermogenesis (NST), mitochondrial protein contents of brown adipose tissue, and cytochrome C oxidase activity of brown adipose tissue mitochondria in both species. Plateau pikas were more sensitive to cold (79% of the total NST response) than to short photoperiod (21%), while root voles were more sensitive to short photoperiod (60% of the total NST response) than to cold (40%), although cold clearly enhanced thermogenesis. Their thermogenic characteristics correlated with their preferred habitats: plateau pikas are found mainly in more exposed microhabitats in open sunny meadow, while root voles live in more sheltered microhabitats in relatively closed shrub. Our results also showed that temperature and photoperiod combined induce thermogenic adjustments in both species in seasonal acclimatization in their alpine meadow macrohabitat.

Acclimatization↗
PubMed1999

Prolactin exerts hematopoietic growth-promoting effects in vivo and partially counteracts myelosuppression by azidothymidine.

Prolactin (PRL) is a neuroendocrine hormone that influences immune and hematopoietic development. The mechanism of action of this hormone in vivo remains unclear; therefore, we assessed the effects of PRL on hematopoiesis in vivo and in vitro. Normal resting mice were treated with 0, 1, 10, or 100 microg of recombinant human prolactin (rhPRL) for 4 consecutive days and euthanized on the fifth day for analysis of myeloid and erythroid progenitors in the bone marrow and spleen. Both frequencies and absolute numbers of splenic colony-forming unit granulocyte-macrophage (CFU-GM) and burst-forming unit-erythroid (BFU-e) were significantly increased in mice receiving rhPRL compared to the controls that had received saline only. Bone marrow cellularities were not significantly affected by any dose of rhPRL, but the absolute numbers and frequencies of bone marrow CFU-GM and BFU-e were augmented by rhPRL. These results suggest that rhPRL can promote hematopoiesis in vivo. Because rhPRL augments myeloid development in vivo, we examined the potential of the hormone to reverse the anemia and myelosuppression induced by azidothymidine (AZT). Mice were given rhPRL injections concurrent with 2.5 mg/mL AZT in drinking water. rhPRL partially restored hematocrits in the animals after 2 weeks of treatment and increased CFU-GM and BFU-e in both spleens and bone marrow. The experiments with AZT and rhPRL support the conclusion that the hormone increases myeloid and erythroid progenitor numbers in vivo, and they suggest that the hormone is clinically useful in reversing myelosuppression induced by AZT or other myeloablative therapies.

Animals↗
PubMed1999

Comparison of 4 topical anesthetic agents for effect and corneal toxicity in rabbits.

PURPOSE: To compare the onset time, duration of action, corneal toxicity, and corneal epithelial healing time of 4 topical anesthetic agents in rabbits. SETTING: Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada. METHOD: Fifty-six rabbits were treated with 4 topical anesthetics (bupivacaine, lidocaine, procaine, and benzocaine) at different concentrations and different pH of solutions. Corneal sensation, corneal toxicity, and corneal epithelial healing time were measured. RESULTS: The onset time of all 4 anesthetic agents was within 1 minute; however, bupivacaine and lidocaine produced significantly longer action than procaine or benzocaine (P < .05). Buffered bupivacaine and lidocaine had a significantly longer anesthetic effect than that of the nonbuffered solutions (P < .05). No significant effect on corneal epithelial healing time or corneal toxicity was observed. CONCLUSION: Topical bupivacaine and lidocaine had a longer anesthetic effect, particularly in buffered solutions. No significant corneal toxicity was observed.

Anesthetics, Local↗
PubMed1999

Photorefractive keratectomy in keratoconus suspects.

PURPOSE: To compare the refractive outcome after photorefractive keratectomy (PRK) in keratoconus-suspect patients with that in patients with normal corneal topography. SETTING: Gimbel Eye Centre, Calgary, Alberta, Canada. METHOD: In a retrospective study, 3 patients (5 eyes) with unusually shaped corneal topography before surgery were selected as keratoconus suspects. Corneal topography (inferior-superior [I-S] value, central corneal power, and central power difference between both eyes), preoperative and 1 year postoperative refraction, and visual acuity in the keratoconus suspects were compared with those in a control group. RESULTS: The mean preoperative I-S value was 1.79 diopters (D) in the keratoconus-suspect eyes and 0.35 D in the control group eyes (P = .0001). The I-S value of individual corneas in the keratoconus suspects was more than 2 standard deviations above the mean in the control group except in 1 eye in which the steepened area was located in the central cornea. The central power difference between the eyes of this patient was 3.60 D, which was significantly higher than that in the control group. The refractive outcomes in the keratoconus suspects were comparable to those in the control group. CONCLUSION: In this study, the refractive outcomes after PRK in the keratoconus suspects and controls were comparable. However, further investigation with a larger sample and longer follow-up is needed.

Adult↗