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Biomedical subjects

R Huang

Publications and source records attributed to R Huang.

At least 109 records · Page 6Linked to original sources
PubMed1997

Development of decompensated dilated cardiomyopathy is associated with decreased gene expression and activity of the milrinone-sensitive cAMP phosphodiesterase PDE3A.

BACKGROUND: Phosphodiesterase III (PDE3) inhibitors are inotropic agents used to treat congestive heart failure (CHF) and are less effective in patients with severe CHF. Little is known about relative changes in PDE3 activity or gene expression during the evolution of cardiomyopathy. METHODS AND RESULTS: In the present study, we evaluated temporal changes in PDE3A gene expression before and after pacing-induced CHF in nine mongrel dogs. Three weeks of left ventricular (LV) pacing produced LV end-diastolic pressures of 15+/-1.7 mm Hg, whereas overt CHF at 4 to 5 weeks was associated with LV end-diastolic pressures of 24+/-1.7 mm Hg; prepacing values were 6.6+/-0.6 mm Hg. Total RNA isolated from LV tissues was analyzed on Northern blots; 10 unpaced normal hearts served as tissue controls. Signals for PDE3A mRNAs (7, 8, and 10 kb) or PDE4D (7.6 kb) were normalized against glyceraldehyde-3-phosphate dehydrogenase (GAPDH) or ribosomal 18S RNA. Before the onset of CHF, PDE3A/GAPDH ratios were not different between the control and 3-week paced groups. In contrast, all PDE3A/GAPDH ratios were selectively reduced by 52%, and PDE3A/18S was reduced by 70% (P<.05) in CHF; PDE4D/GAPDH (or 18S) was unchanged. LV tissues from four control and four CHF dogs were also processed to isolate cytosolic and microsomal membrane protein for cAMP PDE3 activity assays. CHF was associated with a significant 54% reduction (P<.05) in microsomal but not cytosolic PDE3 activity. CONCLUSIONS: Selective downregulation of PDE3A may account in part for the ineffectiveness of milrinone in the treatment of severe CHF.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1997

Novel components and enzymatic activities of the human erythrocyte plasma membrane calcium pump.

The plasma membrane Ca2+ pump is essential for the maintenance of cystolic calcium ion concentration levels in eukaryotes. Here we show that the Ca2+-ATPase, purified from human erythrocytes, contains two homopolymers, poly(3-hydroxybutyrate) (PHB) and inorganic polyphosphate (polyP), which form voltage-activated calcium channels in the plasma membranes of Escherichia coli and other bacteria. Furthermore, we demonstrate that the plasma membrane Ca2+-ATPase may function as a polyphosphate kinase, i.e. it exhibits ATP-polyphosphate transferase and polyphosphate-ADP transferase activities. These findings suggest a novel supramolecular structure for the functional Ca2+-ATPase, and a new mechanism of uphill Ca2+ extrusion coupled to ATP hydrolysis.

Adenosine Triphosphate↗
PubMed1997

Effects of hypertonia on voltage-gated ion currents in freshly isolated hippocampal neurons, and on synaptic currents in neurons in hippocampal slices.

We studied the effects of hypertonia on voltage-gated currents of freshly isolated hippocampal CA1 neurons, using open pipette whole-cell as well as gramicidin-perforated patch-clamp recording. Extracellular osmolarity (pi(o)) was raised by adding mannitol (50 or 100 mmol/l) to the bathing solution. Hypertonia depressed voltage-gated sodium, potassium and calcium currents in all trials. The threshold activation voltage of the currents did not change during hypertonic depression, but maximal activation of Ca2+ current shifted to a more negative potential, suggesting stronger depression of high- compared to low-voltage activated currents. During 30 min high pi(o) treatment (recorded with open pipette), the depression reached maximum in 10-15 min of exposure. The depression of the computed transient component of the K+ current recorded by open pipette was statistically not significant. Following hypertonic treatment recovery of the I(Na), the sustained I(K) and sustained I(Ca) were incomplete compared to control cells maintained in normal solution for an equal length of time. In hippocampal tissue slices hypertonia (+25, +50 and +100 mmol/l fructose) reversibly depressed excitatory postsynaptic currents (EPSCs). We conclude that the shutdown of membrane ion currents by elevated pi(o) is not selective, but the degree of the suppression varies among current types. Raising pi(o) in human patients, possibly combined with mild artificial acidosis, may be useful in the prevention and treatment of acute crises associated with excessive excitation or depolarization of neurons.

Animals↗
PubMed1997

Effects of a low-voltage static electric field on energy metabolism in astrocytes.

Mouse astrocytes (glial cells) in primary cultures were exposed to a low-voltage static DC electric field with no current flow and thus with no generation of magnetic fields. The electric field altered the rate of glycolysis, measured by 2-deoxyglucose accumulation. The magnitude and direction of this effect depended on the polarization of the field and the applied voltage. The maximum effect was an increase of approximately 30%, which occurred with field across the cells at an intensity that can be calculated to be 0.3 mV/cm or less. Reversal of the polarization converted the stimulation to a small but statistically significant inhibition.

Animals↗
PubMed1997

The fate of the first avian somite.

We have studied the derivatives of the first somite using the quail-chick marking technique. After transplantation of the somite, the chick embryos were reincubated for periods ranging from 4 h to 11 days. Coronal and sagittal sections of the embryos were prepared for parallel staining with Feulgen-reaction, anti-quail antibody, anti-desmin antibody and QH-1 antibody. The first somite consists of an epithelial envelope surrounding somitocoele cells. Like other somites, it forms sclerotome, dermatome and myotome. Cells contribute to the occipital and parasphenoid bone, the meninges, the dermis in the occipital region and the pharyngeal connective tissue. The contribution of the first somite to bones, meninges, dermis and pharyngeal connective tissue is characterised by sharp anterior and posterior boundaries. In contrast, other derivatives such as connective tissue surrounding the vagus nerve, the carotid artery, and jugular vein exceed 10 to 18 segments. This is also true for myogenic cells participating in the formation of the cucullaris capitis muscle that extends from the temporal bone to the shoulder. In one third of the embryos, myocytes of the intrinsic laryngeal muscles are derived from the grafted first somite. Moreover, endothelial cells originate from this somite and migrate into the head (hind-brain, meninges, dermis), neck (pharynx, connective tissue surrounding the vagus nerve, carotid artery and jugular vein) and thorax. With respect to differentiation and derivatives the first somite is similar to other somites.

Animals↗
PubMed1997

Cell culture studies of the role of elevated extracellular glutamate and K+ in neuronal cell death during and after anoxia/ischemia.

During vascular insults in the brain (stroke) the extracellular concentrations of glutamate and K+ increase. It is well acknowledged that the increase in glutamate contributes to the death of neuronal cells at an earlier time than they would have succumbed to energy deprivation as such, but the origin of the released glutamate is not known and cannot easily be studied in the brain in vivo. We have therefore resorted to cell culture studies which have shown that the neuronal rate of formation of glutamate from glutamine is substantially increased during anoxia, especially in glutamatergic neurons. This increase is further enhanced in the presence of excess K+. Phenylsuccinate, a compound that decreases formation of glutamate from glutamine in glutamatergic neurons, counteracts the increase in glutamate formation and, by doing so, improves cell survival. Astrocytes (glial cells) in neuronal-astrocytic co-cultures to some extent protect against anoxic neuronal damage by accumulating glutamate and thus keeping the extracellular glutamate concentration lower than in isolated neuronal cultures.

Animals↗
PubMed1997

Molecular evolution of the tet(M) gene in Gardnerella vaginalis.

Five clinical isolates of Gardnerella vaginalis known to carry the tetracycline resistance determinant Tet M were examined by hybridization and nucleotide sequencing. Four of the strains carried tet(M) genes with identical sequences. The two versions of the tet(M) gene found in G. vaginalis did not show complete identity with other published tet(M) sequences, but showed mosaic structures with regions of homology to tet(M) gene sequences from Tn916, Tn1545 and the American type plasmid found in Neisseria gonorrhoeae. Hybridization studies showed that all isolates carried the tet(M) gene on a single HindII restriction fragment of variable length. No evidence was found for the presence of sequences homologous to the transposition functions of Tn916.

Base Sequence↗
PubMed1997

Enhancement of whole cell synaptic currents by low osmolarity and by low [NaCl] in rat hippocampal slices.

We recorded whole cell currents of patch-clamped neurons in stratum pyramidale of CA1 region of rat hippocampal tissue slices. Synaptic currents were evoked by orthodromic stimulation while holding potential of the neuron was varied from hyperpolarized to depolarized levels. Extracellular osmolarity (pi(o)) was lowered by superfusion with artificial cerebrospinal fluid in which NaCl concentration ([NaCl]) was reduced. The effect of low extracellular NaCl was tested in additional trials in which NaCl was substituted by isosmolar fructose. Both lowering of pi(o) and isosmotic lowering of extracellular [NaCl] ([NaCl]o) caused reversible increase of excitatory postsynaptic currents. The effect of lowering pi(o) was concentration dependent, and it was significantly stronger than the effect of equivalent isosmotic lowering of [NaCl]o. Inhibitory postsynaptic currents also increased in many but not in all cases. Lowering of pi(o) caused a prolongation of the time constant of relaxation of the capacitive charging current induced by small hyperpolarizing voltage steps. A virtual input capacitance, calculated by dividing this time constant by the input resistance, increased during hypotonic exposure. Isosmotic lowering of [NaCl]o had no effect on time constant or input capacitance. Depolarizing voltage commands evoked spikelike inward currents presumably representing Na+-dependent action potentials generated outside the voltage-clamped region of the cell. These current spikes became smaller in low pi(o) and in low [NaCl]o. Broader, voltage-dependent, presumably Ca2+-mediated inward currents became more prominent during hypotonic exposure. We conclude that lowering of [NaCl]o causes enhancement of excitatory synaptic transmission. Transmission may be facilitated by the uptake of Ca2+ into presynaptic terminals as well as into postsynaptic target neurons, induced by the low [NaCl]o. Lowering of pi(o) enhances synaptic transmission more than does a corresponding isosmotic lowering of [NaCl]. The excess increase recorded from the cell soma in low pi(o) may in part be due to changing electrotonic length caused by the swelling of dendrites.

Animals↗
PubMed1997

[The expression of tumor suppressor gene p53 and Rb gene in nasopharyngeal carcinoma].

In order to observe the relation of tumor supperssor gene p53 and Rb gene to nasopharyngeal carcinoma, we investigated p53 gene mutations in exon 7-8 in 33 cases of nasopharygeal carcinoma (NPC), using single-strand conformation ploymorphism analysis of PCR (PCR-SSCP). The data showed p53 mutations in 7 of 33 specimens at exon 8 (21.2%). No mutation in exon 7 was detected. Analysis of Rb gene in NPC tissues by southern blot revealed the deletion and loss of activity of Rb gene in 11 of 13 cases (86.6%). Our results suggest that Rb gene and p53 gene are closely associated with the tumorigenesis of NPC.

Carcinoma, Squamous Cell↗
PubMed1997

[Detection of occult tumor cells in resected lymph nodes of patients with stage I carcinoma and its clinico-pathological significance].

OBJECTIVE: Detection of tumor micrometastases in resected lymph nodes of cancer patients to obtain more reliable information concerning nodal status and its clinicopathological importance. METHODS: Paraffin blocks of 3,715 resected lymph nodes from 350 Stage I cancer patients, suffering from NSCLC (n = 94), breast cancer (n = 112), esophageal cancer (n = 115), and vulvar cancer (n = 29), were re-examined by immunohisto-chemical staining, using monoclonal anti-cyokeratins (AE1/AE3), anti-EMA, and polyclonal anti-keratins antibodies. RESULTS: Occult nodal metastases was observed in 113 of 350 cancer patients (32.5%), and in 203 of 3,715 lymph nodes examined. The positive rates both in patients and in lymph nodes were higher in NSCLC than in others. Occult nodal metastasis was seen in 58% of pulmonary squamous-cell carcinomas and 53.8% of adenocarcinomas, while it was seen in 22.5% of esophageal and 10.3% of vulval squamous-cell carcinomas, and in 27.7% of breast adenocarcinomas (P < 0.05). Follow up of a fraction of breast cancer patients showed that the prognosis of patients with positive nodes was worse than that in patients with negative nodes (P < 0.05). CONCLUSION: The data suggested that the immunohistochemical technique can significantly facilitate the detection of micrometastatic tumor cells in lymph nodes. The frequency of occult lymph node metastasis may have significant impact on the prognosis of cancer patients.

Adenocarcinoma↗
PubMed1997

[Determination of arbutin in the herbs of Vaccinium vitis-idaea L. by RP-HPLC].

Determination of arbutin in the herbs of Vaccinium vitis-idaea has been carried out by RP-HPLC, using Inertsil-ODS column (4.6 mm x 250 mm) and mobile phase of methanol and water (15:85), and detecting at 280 nm wavelength. The average content of arbutin is 4.44%, RSD = 2.93%; the recovery rate is 100.7%, RSD = 2.85%.

Arbutin↗
PubMed1997

[Cultivated technique of high yield for Polygonatum officinale].

By studying cultivated materials, hided crops, cultivated way, applied fertilizer about the cultivation of Polygonatum officinale, put forward following the methods of cultivation of P. officinale. Choose rhizome segments with top buds as plant materials, adopt level rectangular pieces of land in a field width 100 cm, cultivate late-maturing corn as hiding shady, adopt density of 1.5-2.0 ten thousand plants/mu, apply N and P fertilizers in the growth.

Fertilizers↗
PubMed1997

[Analysis of the stereoisomers of 14 pyrethroids by capillary gas chromatography].

The separation of stereoisomers of 14 pyrethroids has been studied by capillary gas chromatography. The pyrethroids are cypermethrin (P1), phenothrin (P2), allethrin (P3), prallethrin (P4), tetramethrin (P5), permethrin (P6), cyfluthrin (P7), fenvalerate (P8), flucythrinate (P9), bromofenvalerate (P10), fluvalinate (P11), methothrin (P12), resmethrin (P13) and py115 (P14). The gas chromatographic conditions were as follows. Column 1: fused silica, 10m x 0.53mm x 1.0microm film (QF-1); columntemperature: 180 degrees C-260 degrees C depending on the pyrethroids analysed; the temperature of injector and detector: 280 degrees C; carrier gas: H2 4.6mL/min; detector: FID; spilt ratio: 5:1, sample size 1.0 L. The stereoisomers of P2, P3, P4, P5, P6, P8, P9, P10, P12 and P10 can be completely separated by QF-1 column. However the stereoisomers of P11 can not be separated and the three peaks of P1 and P7 have been only separated by column 1. In comparing with packed column of QF-1, there are advantages in superior resolution, lower oven temperature and shorter analysis time for capillary column of QF-1. Column 2: fused silica HP-5 (crosslinked 5% phenyl methyl silicone) 25m x 0.32mm x 1.0microm film; column temperature: P1 and P7 250 degrees C, P11 260 degrees C, and P14 200 degrees C; carrier gas: H2 2.6mL/min. Other conditions were the same as the column 1 described. The stereoisomers of P1, P7, P11 and P14 can be separated, but the separation of stereoisomers was not sufficient. The stereoisomers of P2, P5, P6, P8, P9, P10, P12 and P13 can be completely separated by HP-5 capillary column. However separation on the HP-5 capillary column is not sufficient for diastereoisomers of P3 and P4.

Chromatography, Gas↗
PubMed1997

[Early diagnosis of ectopic pregnancy by uterine curettage with serum hCG assay].

OBJECTIVE: To explore the value of uterine curettage combined with serum hCG assay in the diagnosis of early ectopic pregnancy (EP). METHODS: Judgement was done by uterine curettage pathologic examination of uterine content and determination of serum hCG in 61 patients with suspected EP with clinical symptoms, signs and auxillary examinations. RESULTS: Intrauterine pregnancy was confirmed in 17 patients by the presence of chorionic villi in the uterine contents. 26 patients were diagnosed as having EP by the absence of chorionic villi and elevated levels of hCG 24 hours after curettage. 18 patients who had no chorionic villi and the level of hCG fall down spontaneously after curettage were diagnosed having either intrauterine pregnancy or EP, mostly no further intervention. CONCLUSION: Diagnostic curettage with serum hCG determination can be used for differentiating intrauterine pregnancy from EP and it can also provide a reference for further arrangement.

Adult↗
PubMed1996

Poly(3-hydroxybutyrate) is associated with specific proteins in the cytoplasm and membranes of Escherichia coli.

Poly(3-hydroxybutyrate) (PHB) is well-known as a high molecular weight homopolymer of R-3-hydroxybutyrate which accumulates in storage granules within the cytosols of certain bacteria. Escherichia coli does not amass these granules; however, small amounts of low molecular weight PHB (<0.02% of dry weight) have been found in the plasma membranes in complexes with calcium polyphosphate; the complexes serve as voltage-activated calcium channels. Here we report that polyphosphate-complexed PHB is only a minor fraction of the polyester in E. coli. PHB comprises 0.36 to 0. 55% of the dry weight of log-phase cells, depending on culture medium, and this amount increases by 15 to 20% when the cells are made genetically competent. The PHB is widely distributed throughout the cell, wherein it is primarily associated with proteins. The identity of protein-associated PHB was established by antibody reaction, chemical assay, and 1H NMR spectroscopy. As expected, the physical and chemical properties of protein-associated PHB were found to be considerably different from those of the bulk polymer or granule PHB, e.g. protein-PHB complexes are normally insoluble in chloroform, soluble in water and alkaline hypochlorite, and are converted to crotonic acid more slowly on heating in concentrated sulfuric acid. Our studies indicate that the majority of cellular PHB (over 80%) is located in cytoplasmic proteins, especially proteins of the ribosomal fraction. Western immunoblots, probed with polyclonal anti-PHB IgG, revealed a number of PHB-polypeptides having a wide range of molecular weights in all cell fractions. These results suggest that PHB is a fundamental constituent of cells that may have physiological functions in addition to facilitating ion transmembrane transport or serving as a carbon reserve.

Bacterial Proteins↗
PubMed1996

Pituitary adenylate cyclase activating polypeptide-immunoreactive sensory neurons innervate rat adrenal medulla.

Rat adrenal chromaffin cells were invested by a dense network of nerve fibers immunoreactive to pituitary adenylate cyclase activating polypeptide-38 (PACAP-IR). Immunohistochemical studies demonstrated the presence of PACAP-IR in nodose and dorsal root ganglion cells, but not in neurons of the intermediolateral cell column and other autonomic nuclei of the thoracic and upper lumbar spinal cord. Somata of the T7 to T12 paravertebral ganglia were PACAP-negative. A few lightly labeled neurons were occasionally noted in the dorsal motor nucleus of the vagus. Injection of the retrograde tracer Fluorogold into the left adrenal medulla 3 days prior to sacrifice resulted in the labeling of a population of neurons in the ipsilateral spinal cord intermediolateral cell column (T1 to L1), ipsilateral and contralateral nodose ganglia and ipsilateral dorsal root ganglia from T7 to T10 inclusive. A small number of lightly labeled somata was occasionally noted in the dorsal motor nucleus of the vagus. Combined retrograde tracing and PACAP immunohistochemistry showed that a population of Fluorogold-containing nodose and dorsal root ganglion cells were also PACAP-positive. Pre-treatment of the rats with capsaicin caused a marked reduction of the PACAP-IR in the adrenal gland as well as in the superficial layers of the dorsal horn and caudal spinal trigeminal nucleus. These findings, in conjunction with the apparent absence of PACAP-IR in spinal sympathetic preganglionic neurons, sympathetic postganglionic neurons, and dorsal motor nucleus of the vagus, raise the possibility that PACAP-IR fibers observed in the adrenal medulla are primarily sensory in origin. As a corollary, catecholamine secretion from chromaffin cells may be modulated by the peptidergic sensory afferents in addition to the cholinergic sympathetic preganglionic nerve fibers.

Adrenal Medulla↗
PubMed1996

Thrombin stimulates wortmannin-inhibitable phosphoinositide 3-kinase and membrane blebbing in CHRF-288 cells.

We have investigated thrombin-stimulated morphological changes and the activation of phosphoinositide 3-kinase (PI 3-K), as manifested by the accumulation of PtdIns(3,4)P2 and PtdIns(3,4,5)P3 (labelled with 32P or myo-[3H]inositol), in CHRF-288 cells, a leukaemic cell line derived from a platelet progenitor cell. We report that these cells, when exposed to thrombin or SFLLRN (the peptide Ser-Phe-Leu-Leu-Arg-Asn, a thrombin-receptor ligand) rapidly change shape, forming membrane 'blebs', detectable by differential interference contrast or confocal microscopy, as well as labelled 3-phosphorylated phosphoinositides. The 'blebs' are distinguishable from 'ruffles' or lamellae, since they do not contain phalloidin-detectable actin. Studies with permeabilized cells indicate that PI 3-K is activated synergistically by thrombin+guanosine 5'[gamma-thio]triphosphate. Two forms of PI 3-K, i.e. PI 3-K(gamma) and p85/PI 3-K, regulated by G beta gamma subunits of heterotrimeric G-protein and the small G-protein Rho, respectively, are present in these cells, as is true for platelets. Wortmannin, a known potent and specific inhibitor of PI 3-K activities, inhibits thrombin-stiumlated accumulation of 3-phosphorylated phosphoinositides in a dose-dependent manner (IC50 approximately 10nM), without affecting phospholipase C activation. Pretreatment of CHRF-288 cells with either wortmannin (100 nM) or an unrelated synthetic PI 3-K inhibitor, LY294002 (50 microM), abolishes thrombin-receptor-stimulated blebbing. These results suggest that thrombin-stimulated accumulation of 3-phosphorylated phosphoinositide(s) is required for the shape-change response in CHRF-288 cells.

Androstadienes↗