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Biomedical subjects

H M Huang

Publications and source records attributed to H M Huang.

At least 55 records · Page 3Linked to original sources
PubMed1999

Optimal proliferation of a hematopoietic progenitor cell line requires either costimulation with stem cell factor or increase of receptor expression that can be replaced by overexpression of Bcl-2.

In vitro proliferation of hematopoietic stem cells requires costimulation by multiple regulatory factors whereas expansion of lineage-committed progenitor cells generated by stem cells usually requires only a single factor. The distinct requirement of factors for proliferation coincides with the differential temporal expression of the subunits of cytokine receptors during early stem cell differentiation. In this study, we explored the underlying mechanism of the requirement of costimulation in a hematopoietic progenitor cell line TF-1. We found that granulocyte-macrophage colony-stimulating factor (GM-CSF) optimally activated proliferation of TF-1 cells regardless of the presence or absence of stem cell factor (SCF). However, interleukin-5 (IL-5) alone sustained survival of TF-1 cells and required costimulation of SCF for optimal proliferation. The synergistic effect of SCF was partly due to its anti-apoptosis activity. Overexpression of the IL-5 receptor alpha subunit (IL5Ralpha) in TF-1 cells by genetic selection or retroviral infection also resumed optimal proliferation due to correction of the defect in apoptosis suppression. Exogenous expression of an oncogenic anti-apoptosis protein, Bcl-2, conferred on TF-1 cells an IL-5-dependent phenotype. In summary, our data suggested SCF costimulation is only necessary when the expression level of IL5Ralpha is low and apoptosis suppression is defective in the signal transduction of IL-5. Expression of Bcl-2 proteins released the growth restriction of the progenitor cells and may be implicated in leukemia formation.

Cell Differentiation↗
PubMed1999

Hair and serum calcium, iron, copper, and zinc levels during normal pregnancy at three trimesters.

The hair and serum levels of calcium, iron, copper, and zinc levels were measured in a group of 70 healthy pregnant women and in 66 age-matched healthy controls living in the Tianjin city of the People's Republic of China. The study subjects were classified into three subgroups according to gestational age. The hair concentrations were measured by X-ray fluorescence spectrometry, whereas those in sera were established by atomic absorption spectrometry. The hair concentrations of Ca, Fe, Cu, and Zn in the three groups of gravida were lower or significantly lower than those in controls. In sera, the differences did not show statistical significance in most cases. A deficiency of calcium was observed in subjects in the last trimester of gestation. This reinforces the importance of supplementation with calcium during pregnancy.

Calcium↗
PubMed1999

Hair concentrations of calcium, iron, and zinc in pregnant women and effects of supplementation.

In this investigation, the concentration levels of hair elements of calcium, iron, and zinc were measured in pregnant women from Tianjin metropolis, China. The subjects were 93 cases of pregnant women who had been suffering from calcium, iron, or zinc deficiency judged by blood tests at the mid-term of the second trimester or early in the third trimester. Of these 93 cases, 82 subjects had their hair element levels measured when the blood tests were conducted. Then, they were supplied with mineral element nutrients of gluconic acidic zinc (noted as Zn-nutrient), gluconic acidic calcium (Ca-nutrient), or/and ferrous sulfate (Fe-nutrient) which were correspondent to the deficient element(s) for more than 2 mo before 84 subjects returned to hospital for further diagnoses and had their hair element levels measured for the second time. Finally, in the third trimester or near-parturient phase, 13 subjects had their hair element levels measured again. Except for the deficiencies of calcium, iron, or/and zinc, these subjects were all healthy without symptoms of any diseases. The concentrations of hair Ca, Fe, and Zn were measured by X-ray fluorescence (XRF) spectrometry. These concentrations of the three hair elements measured at three different times were statistically analyzed. From the analyses, it was clear that hair concentrations of Ca, Fe, and Zn could reflect the effects of supplementation. Also, the mutual resistant effects among Ca-, Fe-, and Zn-nutrients were revealed. However, by appropriate combination, the mutual resistant effects could be depressed and mutual promotional effects might be enhanced. Finally, it could be concluded that mineral element deficiencies might be convalesced by adequate compensations of mineral element nutrients.

Calcium↗
PubMed1999

Simultaneous high-performance liquid chromatographic analysis for famotidine, ranitidine HCl, cimetidine, and nizatidine in commercial products.

A high-performance liquid chromatographic (HPLC) procedure for the simultaneous determination of famotidine (FMT), ranitidine HCl (RNT), cimetidine (CMT), and nizatidine (NZT) was developed using a two-level, full-factorial design with three variables (volume of methanol, percentage of triethylamine, and concentration of phosphate buffer) to select an acceptable mobile phase. A column (15 cm x 4.6 mm ID) of Inertsil ODS-2 (5 microns) was used, and 0.04 M aqueous sodium dihydrogen phosphate/acetonitrile/methanol/TEA at a proportion of 345/20/35/0.7 (v/v/v/v) was the selected mobile phase (1 ml/min). The detection wavelength was set at 230 nm, and procaine HCl was used as the internal standard. Precision and linearity of the method were assessed. None of the commercial samples was found to be outside the compendial limits of 90.0% to 110.0% of the claim amount.

Algorithms↗
PubMed1999

Three-dimensional finite element analysis of subdural hematoma.

BACKGROUND: Head motion, an important factor in acute subdural hematoma (ASDH), can be broken down into translational and rotational elements. We used three-dimensional finite element analysis to examine the thresholds of angular and tangential acceleration required to tear bridging veins in humans during head impact. METHODS: The lengths of midsagittal and parasagittal bridging veins were calculated first. To assess the effect of translational and rotational acceleration, the strain of each vein was then computed under three different motions. The threshold of ASDH was expressed in terms of tangential and rotational acceleration. RESULTS: Deformation-angle histories of the midsagittal and parasagittal bridging veins showed that veins that drain forward into the superior sinus at a 130-degree angle incurred the greatest stretch strain during occipital impact. In the midsagittal plane, pure rotation induced greater stretch strain on these veins (14.4%) than pure translation (2.5%) or combined translation and rotation motion (10.4%). A tangential acceleration of 3,912.9 G or an angular acceleration of 71.2 krad/s2 seemed to approximate the threshold for ASDH in the human midsagittal plane, whereas 5,010.9 G and 97.4 krad/s2 approximated the threshold in the parasagittal plane. CONCLUSION: Impact direction and orientation of bridging veins are both important factors in ASDH. Threshold criteria for ASDH can be expressed in terms of tangential and rotational acceleration.

Acceleration↗
PubMed1999

Cytokine receptor common beta chain as a potential activator of cytokine withdrawal-induced apoptosis.

Growth factors and cytokines play an important role in supporting cellular viability of various tissues during development due to their ability to suppress the default cell death program in each cell type. To date, neither the triggering molecule nor the transduction pathway of these default apoptosis programs is understood. In this study, we explored the possibility that cytokine receptors are involved in modulating cytokine withdrawal-induced apoptosis (CWIA) in hematopoietic cells. Expression of the exogenous cytokine receptor common beta chain (betac), but not the alpha chains, accelerated CWIA in multiple cytokine-dependent cell lines. Reduction of the expression level of endogenous betac by antisense transcripts resulted in prolonged survival during cytokine deprivation, suggesting a critical role of betac in modulating CWIA. Fine mapping of the betac subunit revealed that a membrane-proximal cytoplasmic sequence, designated the death enhancement region (DER), was critical to the death acceleration effect of betac. Furthermore, DER accelerated cell death either as a chimeric membrane protein or as a cytosolic protein, suggesting that DER functions independently of the cytokine receptor and membrane anchorage. Cross-linking of the chimeric membrane-bound DER molecules by antibody or of the FK506-binding protein-DER fusion protein by a synthetic dimerizing agent, AP1510, did not abrogate the death acceleration effect. Transient transfection assays further indicated that DER promoted cell death in the absence of serum in the nonhematopoietic 293 cell line. In summary, our data suggest that betac plays an important role in modulating CWIA via an anchorage-independent and aggregation-insensitive mechanism. These findings may facilitate further studies on the signaling pathways of CWIA.

Antisense Elements (Genetics)↗
PubMed1999

Telescopic video microlaryngeal surgery.

Although traditional microscopic laryngeal surgery has been well developed, we still may encounter some clinical problems, including exposure difficulty, blind areas during examination, and inadvertent cutting through lesions. These problems may lead to an increased risk of complications or protracted or even repeated operations. We have partially overcome these problems since October 1992 with a new telescopic endolaryngeal surgery technique. This technique was developed by combining and modifying the principles of bronchoscopic surgery and endoscopic sinus surgery. With this technique, it is not necessary to use a very slim laryngoscope or apply overpressure on the larynx when introducing and suspending the laryngoscope. Difficult-to-examine regions can be accessed more easily. We can also get a 3-dimensional impression of lesions and related structures, so it is easier to determine a proper cutting line to avoid cutting through lesions. We consider this telescopic method to be a useful alternative to conventional microscopic laryngeal surgery.

Adult↗
PubMed1999

[Construction of expressing vector for phage display scFv and a mouse unspecified antibody library].

The display of antibody gene library on the surface of E. coli filamentous phage offers a new method of obtaining antibodies against specific antigens. In the paper, it is reported that a phagemid for phage display antibody, named after pFUW80, characterized expressing scFv either secretly or stickily. With a series of designed PCR primers, heavy-chain and light-chain variable region genes of mice antibodies were amplified and a mouse unspecified single-chain antibody library with the size of 1.2 x 10(6) clones was constructed. From this library, phage was selected out against antigen human IgG and detected by ELISA and partial sequence analysis. These primary results established the foundation for future research using this system.

Animals↗
PubMed1999

Effects of ear type, sex, age, body weight, and climate on temperatures in the external acoustic meatus of dogs.

OBJECTIVE: To investigate effects of ear type, sex, age, body weight, and ambient climatic conditions on external acoustic meatus (external ear canal) temperatures in dogs. ANIMALS: 650 dogs without clinical signs of ear disease. PROCEDURE: Dogs were assigned to 5 groups on the basis of auricular conformation and amount of hair in the external ear canal and 4 groups on the basis of body weight or age. External ear canal temperatures (EECT) were measured, using an infrared thermometer. Mean EECT determined for each group were compared to evaluate effects of ear type, age, weight, and sex, and EECT measured at different ambient temperatures and humidities were compared to determine climatic effects. RESULTS: Dogs with hirsute ear canals had significantly lower EECT than dogs with hairless ear canals, whereas significant differences were not detected between dogs with erect and pendulous auricles. Dogs < 6 years old had higher EECT than older dogs, and dogs that weighed < 6 kg had lower EECT than larger dogs. External ear canal temperatures measured when ambient temperatures were < 25 C were less than those measured at warmer temperatures. Sex and relative humidity did not affect EECT CONCLUSIONS AND CLINICAL RELEVANCE: EECT of dogs without ear disease were affected by weight and age, amount of hair in the external ear canal, and ambient temperature. However, hirsute ears had lower, not higher, EECT than hairless ears, suggesting that EECT may play less of a role in the development of otitis externa than believed.

Age Factors↗
PubMed1998

Magnolol protects cortical neuronal cells from chemical hypoxia in rats.

The protective effect of magnolol, a component of Magnolia officinalis, against hypoxia-induced cell injury in cortical neuron-astrocyte mixed cultures was examined. Exposure of the cells to chemical hypoxia (0.5 mM KCN) produced morphological changes in neurons but not in astrocytes. KCN induced dose- and time-dependent increases in release of LDH and decreases in viable cell number. Treatment with magnolol (10 and 100 microM) significantly reduced the KCN-induced LDH release in a concentration-dependent manner. A higher concentration (750 microM) magnolol was toxic. Nuclear condensation was not observed in KCN-treated cells, suggesting that chemical hypoxia-induced cell death was via necrosis, rather than via apoptosis. This is the first report demonstrating that magnolol protects neurons against chemical hypoxic damage or necrotic cell death in cortical neuron-astrocyte mixed cultures.

Animals↗
PubMed1998

Following the recovery of naso-pharyngeal cancer patients by trace elements in hair using statistical pattern recognition methods.

This article describes a study where the recovery of nasopharyngeal cancer (NPC) patients was traced by trace elements (TEs) in hair of these patients. These patients whose concentrations of TEs in hair were studied are volunteers who were divided into three groups B, C, and D. Group B was made up of volunteers who had just been diagnosed as having NPC, group C and group D were made up of volunteers who had been diagnosed as having NPC after 3 and 6 mo, respectively, of treatment. For comparison, a control group, namely group A, which was made up of volunteers from healthy persons was added to this study. By implementation of statistic pattern recognition methods, it has been found that the concentrations of TEs in hair can remarkably reflect different recovery phases of NPC patients.

Bayes Theorem↗
PubMed1998

Amyloid beta peptide enhanced bradykinin-mediated inositol (1,4,5)trisphosphate formation and cytosolic free calcium.

Deposition of amyloid beta protein (A beta) and alteration in signal transduction systems may have pathophysiological significance in Alzheimer's disease (AD). This study tested the hypothesis that bradykinin (BK) receptor-mediated signal transduction systems in PC12 cells are altered after treatment with A beta at a concentration not toxic to cells. Exposure to varying doses of A beta 25-35 (1-10 microM) for 18 hrs significantly reduced the number of viable cells, while lower concentrations (0.01-0.1 microM) and control peptide in scramble sequence had no effect. In addition, prolonged exposure of PC12 cells to a sublethal dose of A beta 25-35 (0.1 microM) affected the receptor-mediated signal transduction pathways. BK induced both accumulation of Ins(1,4,5)P3 and elevation in cytosolic free calcium concentration ([Ca2+]i) in the control cells. These responses were further enhanced in the cells treated with A beta. Under similar conditions, A beta-treated cells also demonstrated alterations in the number and affinity of BK receptors. Alternatively, extracellular addition of A beta elevated [Ca2+]i rapidly, without detectable alterations in Ins(1,4,5)P3. This rapid elevation was dependent on extracellular calcium, suggesting that A beta induced calcium influx. Taken together, the results demonstrated that treatment with a sublethal dose of A beta peptide for 18 hrs enhanced BK receptor mediated Ins(1,4,5)P3 formation and mobilization of intracellular calcium, associated with a modification in BK receptors. Changes in the balance of these receptor-mediated signals prior to cell injury could be an important underlying mechanism for A beta peptide-induced degenerative alteration in AD.

Amyloid beta-Peptides↗
PubMed1998

Differential effects of heavy metals on the binding of Xenopus upstream binding factor(xUBF) to DNA.

Xenopus upstream binding factor (xUBF) is a transcription factor for RNA polymerase I which contains multiple DNA-binding motifs. Among these DNA-binding motifs, HMG box I is essential for promoting RNA polymerase I-dependent rRNA gene transcription. Gel shift assay indicated that the binding of recombinant HMG box I to a 136-bp linear DNA probe was significantly inhibited by Cd2+ at 1 microM. The formation of larger protein-DNA complexes was particularly sensitive to Cd2+. The interaction between HMG box I and DNA was completely inhibited by 10 microM of Cd2+, yet this interaction was not inhibited by the same concentration of Ca2+. Hg2+ at 0.1 microM began to cause abnormal band shifting, and protein-DNA bands disappeared to the wells of a polyacrylamide gel in the presence of 10 microM of Hg2+, reflecting that a drastic change in the conformation of HMG box I-DNA had occurred. The binding of HMG box I to DNA was slightly disturbed by As3+ at 1 microM and was significantly affected at 10 microM. Our results suggest that inhibition of the normal binding of UBF to its target DNA may be one of the mechanisms of heavy metal-induced inhibition of RNA synthesis.

Animals↗
PubMed1998

Leached components from dental composites in oral simulating fluids and the resultant composite strengths.

The aim of this study was to analyse the leached moieties of dental composites after storage in ethanol and organic acids of plaque and further evaluate the resultant effect on the diametral tensile strength (DTS) of the composites. Three commercial composites were used: Bis-GMA-based Z100, Bis-GMA/UDMA-based Heliomolar, and Bis-MPEPP-based Marathon One. The solutions used were: 99.9% acetic acid, 99% propionic acid and 75% ethanol. Specimens (4 mm diam. x 2 mm thick) were stored at 37 degrees C in 3 mL of solution for up to 30 days. Gas chromatography/mass spectrometry was used to characterize the leached moieties and DTS of the specimens after immersion was evaluated. Data were analysed using ANOVA and Tukey LSD test. The eluted substances were not all the same in different solutions and composites but mostly increased with immersion time, and included diluents (TEGDMA and decamethacrylate) and some additives, such as an ultra-violet stabilizer (TINUVINP), plasticizers (dicyclohexyl phthalate and bis(2-ethylhexyl) phthalate), initiator (triphenyl stibine), coupling agent (gamma-methacryloxypropyl trimethoxysilane), and phenyl benzoate. The chief polymerizing monomers were not found. More kinds of components were found in the acetic acid and ethanol groups studied. The fewest kinds and quantities of leached moieties were found for Bis-GMA specimens and then Bis-GMA/UDMA ones, most of which are diluent agents. Bis-MPEPP specimens leached the most substances, which were composed mostly of a short phenyl group chain structure. The BisGMA composite showed the highest DTS (54.8 +/- 5.7 MPa), which was not greatly affected by the length of storage. Bis-GMA/UDMA (36.2 +/- 6.8 MPa) and Bis-MPEPP (26.1 +/- 4.5 MPa) composites were significantly reduced (P < 0.05) after 30 days storage in the ethanol (35-50%), in the propionic acid (25-30%), and in the acetic acid (40-60%). Irreversible processes such as the leaching of components occur in fluids simulating an oral environment, which may contribute to irreversible material degradation, especially for non-Bis-GMA-based composites.

Acetates↗
PubMed1998

mcl-1 is an immediate-early gene activated by the granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling pathway and is one component of the GM-CSF viability response.

mcl-1, a bcl-2 family member, was originally identified as an early gene induced during differentiation of ML-1 myeloid leukemia cells. In the present study, we demonstrate that Mcl-1 is tightly regulated by the granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling pathway. Upon deprivation of survival factor from TF-1 myeloid progenitor cells, Mcl-1 levels quickly dropped prior to visible detection of apoptosis of these cells. Upon restimulation of these deprived cells with GM-CSF, the mcl-1 mRNA was immediately induced and its protein product was accordingly resynthesized. Analysis with Ba/F3 cells expressing various truncation mutants of the GM-CSF receptor revealed that the membrane distal region between amino acids 573 and 755 of the receptor beta chain was required for mcl-1 induction. Transient-transfection assays with luciferase reporter genes driven by various regions of the mcl-1 promoter demonstrated that the upstream sequence between -197 and -69 is responsible for cytokine activation of the mcl-1 gene. Overexpression of mcl-1 delayed but did not completely prevent apoptosis of cells triggered by cytokine withdrawal. Its down regulation by antisense constructs overcame, at least partially, the survival activity of GM-CSF and induced the apoptosis of TF-1 cells. Taken together, these results suggest that mcl-1 is an immediate-early gene activated by the cytokine receptor signaling pathway and is one component of the GM-CSF viability response.

Amino Acid Sequence↗
PubMed1998

Modified ultrafiltration in paediatric cardiopulmonary bypass.

Cardiopulmonary bypass (CPB), a nonphysiological procedure, is associated with haemodilution and the inflammatory response, causing the accumulation of body water and organ dysfunction. The purpose of this study was to evaluate the efficacy of modified ultrafiltration. Forty paediatric patients undergoing cardiac operations were randomized into a control group and a modified ultrafiltration group. Blood cells, protein and cytokine concentrations were recorded for 24 h postoperatively. As the fluid was removed at 50 ml/min, both blood cells and protein were concentrated by modified ultrafiltration (p < 0.001). The tumour necrosis factor (TNF)-alpha concentration was increased and interleukin-8 (IL-8) and endothelin (ET) concentrations were unaltered after ultrafiltration. After correction for albumin, TNF-alpha concentration changed little, and IL-8 and ET concentrations (36.75 +/- 12.35, 42.89 +/- 15.54) were decreased significantly (21.47 +/- 13.87, 26.06 +/- 12.54) after ultrafiltration. Modified ultrafiltration is an effective method for removing excess tissue fluid and concentrating blood after CPB. This technique can also filter out some cytokines.

Blood Cell Count↗
PubMed1997

Analysis of trace elements in the hair of volunteers suffering from naso-pharyngeal cancer.

This article describes a study where the trace elements (TEs) of four groups of volunteers were analyzed. The volunteers were divided into four groups A, B, C, and D. Group A was made up of healthy subjects, group B was made up of volunteers who had just been diagnosed as having naso-pharyngeal cancer (NPC), group C was made up of volunteers who had been diagnosed as having NPC after 3 mo of treatment, and group D was made up of volunteers who had been diagnosed as having NPC after 6 mo of treatment. In all groups, 11 trace elements in hair were analyzed. Our study shows that the concentrations of zinc (Zn), copper (Cu), manganese (Mn), and cobalt (Co) in group B are less than that of group A, whereas the concentration of titanium (Ti) in group B is higher. Our results also show that the difference in the level of TEs between group A and the other groups is dramatically decreased as the time of the treatment is increased. This may be a reflection of successful treatment.

Absorption↗