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Biomedical subjects

C Hu

Publications and source records attributed to C Hu.

At least 145 records · Page 8Linked to original sources
PubMed1994

The chromatographic behaviour of cephalosporins in gel filtration chromatography, a novel method to separate high molecular weight impurities.

The interaction between cephalosporins and the dextran matrix of Sephadex gel in gel filtration chromatography has been thoroughly studied. Twelve cephalosporins with specific structures were examined under different chromatographic conditions, including 12 different mobile phases comprising inorganic or organic compounds of different charge or/and density of electrons on their negative ions, different types of Sephadex gel (Sephadex G-10 and Sephadex G-50) and different flow rates. It was found that the more negative the charge or/and density of electrons on the negative ions of buffer components, the more was the adsorption of cephalosporins on the solid phase; this indicated tht the mobile phase played an important rôle in gel filtration chromatography for cephalosporins. By choice of suitable chromatographic conditions, optimum separation of high molecular weight impurities from cephalosporins could be achieved. The novel method could be used as a routine method for the quality control of cephalosporin preparations.

Cephalosporins↗
PubMed1994

Presence of hepatitis B surface antigen (HBsAg)-specific cytotoxic T cells in asymptomatic HBsAg carriers.

To investigate whether there is any evidence of an immune stimulation against hepatitis B virus surface antigen (HBsAg) in asymptomatic HBsAg carriers, proliferative and cytotoxic responses to HBsAg were measured in their peripheral blood lymphocytes. Although the majority of asymptomatic carriers had no proliferative response to HBsAg, 3 (25%) of 12 carriers showed significant T cell proliferation against HBsAg. In addition, using HBsAg-expressing autologous lymphoblastoid cell line (LCL) as target cells, HBsAg-specific cytotoxic activity was found in 2 of 3 asymptomatic HBsAg carriers who had a proliferative response against HBsAg. Furthermore, 6 cytotoxic T lymphocyte (CTL) clones were isolated from 1 asymptomatic carrier. The epitope recognized by 2 CTL clones was mapped to the major HBsAg residues 158-172. These CTL clones were able to produce interferon-gamma, tumor necrosis factor-alpha, or granulocyte-macrophage colony-stimulating factor. These findings demonstrate the presence of HBsAg-specific, major histocompatibility complex class I-restricted CTL in asymptomatic HBsAg carriers.

Adult↗
PubMed1994

Improved accuracy in direct automated DNA sequencing of small PCR products by optimizing the template concentration.

Data are presented illustrating the optimum concentration range of reverse transcription PCR-generated products under 500 bp for accurate base calling with direct automated DNA sequencing. A 357-bp fragment of the human estrogen receptor, which includes the DNA binding domain of the protein, was used as a representative example of a gene fragment that can be rapidly amplified and sequenced. Using the Taq DNA polymerase dye terminator sequencing protocol and automated sequencing apparatus from Applied BioSystems, 0.1 to 1.0 pmol of PCR product in a 20-microL reaction volume provided > 97% accurate base detection. Concentrations greater or lower than this range increased the number of ambiguous bases due to alterations in the signal-to-noise ratios. This procedure has been successfully utilized with 140-440-bp PCR products within the optimum concentration range. These results show that low amounts of PCR products are necessary and sufficient for direct sequence analysis.

Base Sequence↗
PubMed1994

[Stereoscopic visual evoked potential elicited by static random dot stereogram].

Using 16.56' visual disparity stimulation produced by television random dot stereogram (TVRDS), we recorded visual evoked potentials (VEPs) elicited from 35 normal subjects with and without breaking their stereopsis and 28 stereoblind subjects. The results showed that a constant negative-positive wave complex was observed in 33 of 35 normal subjects; this negative-positive wave-complex disappeared when the stereopsis was artificially inhibited by a prism and in the stereoblind group, and no VEP wave was elicited in all of the stereoblind patients except in one with paralytic strabismus. The results revealed that under this condition the VEPs elicited by TVRDS were specific VEPs related to visual disparity stimulation and were stereoscopic ones. The TVRDS is an effective electro-physiological means to examine the stereopsis objectively and a new way to approach the occurrence and development of stereopsis.

Adolescent↗
PubMed1994

Comparative effects of amifostine (Ethyol) on normal hematopoietic stem cells versus human leukemic cells during ex vivo purging in autologous bone marrow transplants.

The protective action of amifostine (Ethyol, US Bioscience, Inc. West Conshohocken, PA) against the toxic effects of cyclophosphamide derivatives on the normal progenitor/stem cell pool was investigated. Early and late normal progenitor/stem cells were studied in the presence of placenta-conditioned medium (placenta-conditioned medium-granulocyte-macrophage colony-forming units); in the presence of granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, interleukin-3, erythropoietin, stem cell factor (5R-CFU-GM); stimulated granulocyte-macrophage colony-forming and in a long-term culture-initiating cell assay. The preservation of an antileukemic effect was investigated by growing leukemic progenitor cells in the presence of phytohemagglutinin and leukocyte feeder layer with or without 25u interleukin-2. In 10 of 13 cases, a statistically significant (P < .05) protective effect was found on PCM-granulocyte-macrophage colony-forming units, in four of 10 cases on factor-stimulated granulocyte-macrophage colony-forming units, and in two of six cases on long-term culture-initiating cell. In contrast, amifostine exhibited no protective effect (none of nine cases) on leukemic progenitor cells. From the experimental data, it seems that amifostine is able to protect human normal progenitor/stem cells from cyclophosphamide derivative toxicity, while preserving their antileukemic effects. The therapeutic usefulness of such protection in autologous bone marrow transplantation with purged marrow is obvious.

Amifostine↗
PubMed1994

[Establishment of a primary eye care network and creation of a cataract-free zone in Shunyi County of Beijing].

Based on the epidemiological survey of eye diseases in 1985, a primary eye care network was established in Shunyi County of Beijing in 1987. Cataract surgery was the primary measure for the prevention of blindness, with the aim of creating a cataract-free zone in the county. The activities included (1) establishment of a County Guiding Committee for the prevention of blindness; (2) establishment of a 3-levelled primary eye care network and a referral and monitor system; (3) training of 7 ophthalmologists, 449 eye care workers and 6 optometrists; (4) extensive publicity of knowledge for the prevention of blindness; (5) screening of low vision and blindness in which 815 cataract blind patients were identified; and (6) conducting benefit ophthalmic counselling services. Up to December, 1991, 667 cataract operations were performed, representing 81.84% of the total cataract blind, to meet the qualifications of a cataract-free zone. 90.64% of the blind were restored sight and 59.16% of the blind were able to resume work. Operative infection occurred in none and 97.42% of the operations had no complication.

Aged↗
PubMed1993

An open reading frame in the Rhodospirillum rubrum plasmid, pKY1, similar to algA, encoding the bifunctional enzyme phosphomannose isomerase-guanosine diphospho-D-mannose pyrophosphorylase (PMI-GMP).

The nucleotide sequence of a BglII fragment (3188 bp) from the plasmid pKY1 of Rhodospirillum rubrum was determined. A significant similarity was found between the amino acid sequences deduced from the nucleotide sequence of BglII fragment with that of algA, encoding the bifunctional enzyme with both the activities of phosphomannose isomerase and guanosine diphospho-D-mannose pyrophosphorylase of Pseudomonas aeruginosa.

Amino Acid Sequence↗
PubMed1993

Intravitreal pharmacokinetics of liposome-encapsulated amikacin in a rabbit model.

BACKGROUND: Intravitreal injection of antibiotics has become a standard therapy for bacterial endophthalmitis. The duration of effective antimicrobial levels in the vitreous after single injection, however, may not be long enough to get optimal response. The authors prepared liposome-encapsulated amikacin for prolonging the duration of intravitreal therapeutic concentrations and investigated the intravitreal pharmacokinetics of the liposomes and amikacin in phosphate buffer solution (PBS) as control. METHODS: The liposome-encapsulated amikacin was prepared by reverse-phase evaporation method. The intravitreal pharmacokinetics of the liposomes was compared with amikacin in PBS by fluorescence polarization immunoassay. Albino rabbits were randomly distributed into 12 groups. Rabbits in groups 1 to 6 and in groups I to VI (control groups) received an intravitreal injection of the liposome-encapsulated amikacin and amikacin in PBS, respectively. RESULTS: The encapsulation rate of amikacin was 91%. The time of 50% spontaneous degradation (half-life) of the liposomes in PBS (38 degrees C, pH 7.4) was 47.6 days, and the time of 50% release (half-life) of the drug from the liposomes in PBS was 84.8 hours. The vitreous amikacin concentrations in groups 1 to 6 were significantly greater (P < 0.05) than those in control groups I to VI in every time interval, except in groups 1 to 3 at 1 hour after injection. The difference was particularly obvious in the endophthalmitis groups. The clearance of encapsulated amikacin in vitreous appeared to be related to the state of blood-ocular barrier and to the structural integrity of vitreous. The distribution, the absorption, and the elimination of encapsulated amikacin in vitreous showed the first-order kinetics. CONCLUSION: The liposome-encapsulated amikacin prolonged half-life of the drug in vitreous. The results of the pharmacokinetic analysis suggested that in endophthalmitis, especially in severe cases, the liposomes may be preferable to conventional preparation.

Absorption↗
PubMed1993

Gastrointestinal manifestations of neurofibromatosis in childhood.

Von Recklinghausen's neurofibromatosis (VRN) is a familial disorder characterised by a generalized neuroectodermal dysplasia--symptomatic involvement of the gastrointestinal tract is rare. We report on our experience with two children who had proven gastrointestinal neurofibromas and highlight the need for careful assessment in children with VRN who develop abdominal pain.

Child↗
PubMed1993

A simple technique for blood collection in the pig.

A simple technique for blood collection in pigs of body weight 15-40 kg is described. The subcutaneous abdominal vein was used for rapid collection of 5-20 ml of blood samples. The animals were premedicated with 10 mg/kg of ketamine and 600 micrograms of atropine given intramuscularly prior to blood collection.

Animals↗
PubMed1992

Internalization of CD4 molecules in human T-cells demonstrated by immuno-electron microscopy.

Internalization of CD4 molecules on human CD4-enriched T-cells was demonstrated by immunocytochemical electron microscopy. CD4+ T-cell subclones were obtained from normal human peripheral blood, followed by one-way MLC screening and co-culturing with IL-2. Fixed and non-fixed T-cell samples were indirectly immunolabeled with mouse anti-human CD4 monoclonal antibody and goat anti-mouse IgG conjugated with peroxidase. Unfixed T-cells were immunolabeled at 4 degrees C and then re-incubated for 5-45 min at 37 degrees C. The selected CD4+ T-cell subclones showed strong CD4 binding on the cell surface after IL-2 incubation. However, fresh T-cells, monocytes, bone marrow cells and CD8+ T-cells all stained negative for CD4. The distribution of CD4 molecules on the fixed cell surface showed a homogeneous pattern. Capping and internalization of CD4-antibody-peroxidase complexes from the cell surfaces were observed follow a pathway of receptor-mediated endocytosis in unfixed T cells. Endocytotic vesicles, vacuoles of diverse sizes and shapes near the cell membrane or deep in the cell center were found to contain CD4 molecules. Negatively stained Golgi saccules were observed up to 45 min after re-incubation. These results suggest that increased CD4 molecules can be induced on the surface of normal human T-cells in vitro. Internalization and accumulation of CD4 molecules occurred in CD4-enriched T-cells with IL-2 pretreatment.

Adult↗
PubMed1992

Immunopharmacological activity of cefodizime in young and elderly subjects: in vitro and ex vivo studies.

The biological response modifying activities of cefodizime (CDZ), a new third-generation cephalosporin, were investigated in vitro and ex vivo. In vitro investigations using cells isolated from the blood of young healthy donors showed no stimulating activity of CDZ on peripheral blood lymphocytes, natural killer cell activity, IL-1 production by adherent mononuclear cells, PMN chemiluminescence or PMN chemotaxis. A slight but statistically insignificant increase in PMN phagocytosis and phagocytic index was observed in the same population. IL-1 production was increased in three subjects with low resting state values. In a controlled ex vivo study, 20 healthy elderly subjects selected on the basis of depressed phagocytic function were treated with CDZ 1 g i.m. b.i.d. or placebo for eight days. PMN function was determined at baseline and on the day after the last dose. In the CDZ group a significant increase in both phagocytosis and phagocytic index was found, while there were no changes in the placebo group. In conclusion, CDZ restored depressed PMN phagocytic function in a population of elderly subjects. Patients with impaired PMN function who require antibiotic treatment may benefit from this activity of CDZ.

Adult↗
PubMed1992

A study of the detection of sperm antibody in cervical mucus with a modified immunobead method.

OBJECTIVE: To develop a new immunobead binding test (IBT) procedure that will detect sperm antibody in cervical mucus (CM), especially in very small samples of mucus. DESIGN: After the interaction of donor sperm with bromelin-dissolved CM, the motile sperm cells were separated from other cells and debris and then tested with a standard immunobead method. SETTING: The CM and serum samples were obtained from a sequence of referred patients who were sent to this testing laboratory. PATIENTS: There were 60 women who provided 64 samples of CM and 41 samples of blood serum. They were partners in infertile couples. INTERVENTIONS: None. MAIN OUTCOME MEASURE: A useful distinction was made between positive and negative results for the mucus samples by this CM-IBT procedure. The usable samples of mucus could be as little as 0.05 g (wet weight). RESULTS: From the 60 women, seven mucus samples were positive; in the repeated testing, the same results were obtained with five of the six positive samples and seven of seven negative samples. CONCLUSION: This method (CM-IBT) can be clinically useful for detecting sperm antibody in CM, especially because it is effective for tiny samples. In this method, the motile sperm cells are better separated from the debris after the incubation step. When the IBT was applied to the serum samples from the same women, there was no correlation between serum-IBT and CM-IBT, showing that both materials must be tested.

Antibodies↗
PubMed1992

Fentanyl and medetomidine anaesthesia in the rat and its reversal using atipamazole and either nalbuphine or butorphanol.

The intraperitoneal injection of anaesthetic agents is a simple and convenient method of anaesthetizing rats. However, all of the anaesthetic combinations in current use which are administered by intraperitoneal injection produce prolonged sedation, and full recovery of consciousness may take several hours. Fentanyl, a mu agonist opioid, and medetomidine, an alpha 2-adrenoceptor agonist were mixed and administered as a single intraperitoneal injection. Combinations of 300 micrograms/300 micrograms/kg and 300 micrograms/200 micrograms/kg of fentanyl/medetomidine were shown to produce surgical anaesthesia in the rat. This anaesthetic regimen produced significant respiratory depression (P less than 0.01) and animals did not regain their righting reflex until 193 +/- 21 min (mean +/- 1 SD) after injection. Administration by intraperitoneal injection of atipamezole, a specific alpha 2-adrenoceptor antagonist (1 mg/kg) mixed with a mu antagonist/k agonist opioid (nalbuphine, 2 mg/kg or butorphanol 0.4 mg/kg), resulted in a rapid (less than 8 min) reversal of anaesthesia and the associated respiratory depression, and apparent full recovery of consciousness.

Anesthesia↗