PubMed Health⌕ Search

Biomedical subjects

F Qin

Publications and source records attributed to F Qin.

At least 37 records · Page 2Linked to original sources
PubMed1998

Effect of alpha-tocopherol, taurine and selenium on the attenuation of ischemia/reperfusion injury of splanchnic organs.

BACKGROUND: Splanchnic artery occlusion shock is caused by increased capillary permeability and cellular injury precipitated by oxygen derived free radicals following ischemia and reperfusion of splanchnic organs. The purpose of this study was to assess the role of several well-known oxygen-derived free radical scavengers in ameliorating or preventing this syndrome. STUDY DESIGN: Anesthetized rats were subjected to periods of occlusion of the visceral arteries and reperfusion. Tocopherol, taurine, selenium or a 'cocktail' of these three agents was injected subcutaneously for 4 consecutive days prior to operation. Mean arterial blood pressure was measured throughout the experimental period. Fluorometry and technetium-99m pyrophosphate counting of the visceral organs were performed as well as a histologic grading system for intestinal viability. RESULTS: Final mean arterial blood pressure associated with the 'cocktail' and selenium groups was 79.1 +/- 27.4 mmHg and 83.6 +/- 17.8 mmHg, respectively. These values were significantly higher than the control group, 40.8 +/- 11.4 mmHg (P < 0.05). Similar patterns of the benefit of selenium in contrast with the other groups were obtained with fluorescein perfusion, radioisotopic activity and histologic analysis. CONCLUSION: Pretreatment with selenium of splanchnic ischemia and reperfusion in the rat improves mean arterial blood pressure and microcirculatory visceral perfusion. Further analysis of the precise protective mechanism of selenium for reperfusion injury will enable visceral organs to withstand the consequences of increased capillary leakage and oxidant injury.

Animals↗
PubMed1998

Intermediate myasthenia syndrome following acute organophosphates poisoning--an analysis of 21 cases.

1. Twenty-one cases out of 272 patients of acute organophosphates poisoning were diagnosed as intermediate syndrome (IMS) with a prevalence at 7.7%. The responsible OP insecticides included parathion, omethoate and some OP containing pesticide mixtures. IMS occurred mainly in severe OP poisoning patients who recovered from the acute cholinergic crisis at 7-75 h after the onset of acute poisoning. 2. Muscular weakness appeared in the following three categories of muscles: (1) neck flexors and proximal limb muscles; (2) muscles innervated by motor cranial nerves and/or (3) respiratory muscles. Blood acetylcholinesterase activity was persistently inhibited. Electroneuromyography (ENMG) with repetitive nerve stimulation (RNS) at frequencies of 20 Hz or 30 Hz in seven patients showed decrements of common muscle action potentials during the presence of myasthenia in five patients and became normal when their muscle strength recovered. 3. Mild IMS recovered within 2-7 days and had a favorable prognosis. Severe IMS patients with respiratory paralysis needed immediate endotracheal intubation and mechanical ventilation. Recovery of weakness of the respiratory muscles and proximal limb muscles took longer, the slowest being 30 days. Four of the patients died of respiratory paralysis and the fatality rate was 19%. 4. The mechanism of IMS remains to be further investigated. The RNS/ENMG changes indicate a post-synaptic block at the neuromuscular junctions. 5. In order to promote the recognition of this syndrome, we proposed to name the syndrome as Intermediate Myasthenia Syndrome (IMS).

Adolescent↗
PubMed1998

[Effect of the IL-6 transfected bone marrow stromal cells on the recovery of hematopoietic functions in bone marrow transplanted mice].

OBJECTIVE: To study the effect of the IL-6 transfected bone marrow stromal cell, QXMSC1 IL-6, on the hematopoietic reconstitution in bone marrow transplanted mice. METHODS: Bone marrow transplantation model was established by infusing hematopoietic cells combined with QXMSC1 IL-6 into syngeneic recipient mice through the tail vein. CFU-S, CFU-GM, CFU-E, BFU-E, and peripheral blood pictures were assayed. RESULTS: QXMSC1 IL-6 could increase the CFU-S, CFU-GM, CFU-E and BFU-E yields in BMT mice, and accelerate the recovery of peripheral blood cells. CONCLUSION: QXMSC1 IL-6 can improve the hematopoietic reconstitution in bone marrow transplanted mice.

Animals↗
PubMed1998

[Reconstruction with silicone rubber tube after resection of hypopharyngeal and cervical esophageal cancer].

OBJECTIVE: To treat the benign stenosis and defects caused by resection of cancers of hypopharyngeal and cervical esophagus. METHODS: Silicone rubber tubes made by ourselves were utilized to reconstruct the defect. It was found that in animal models, the granulation surface was covered with epithelial tissues and new lumen formed. RESULTS: Among 30 cases treated with silicone rubber tubes, 6 cases (20.0%) developed hypopharyngeal fistulae after operations. Twenty-five cases with cancer and 5 cases with benign stenoses and hypopharyngeal fistulae were followed-up from 5 months to 4 years. The silicone rubber tubes in 25 cases were decannulated, of them, 23 cases recovered normal swallowing function. Two cases developed severe stenosis again and 2 cases were under observation. In 25 cases with cancer, 2 had local relapse of cancer three to six months after the first operation. Four cases had cervical metastasis. All these 6 cases died within one year after operation. One case died of lung metastasis, two cases died of inflammation of lungs. Among 25 patients with cancers, the three-year survival rate was 50.0% (5/10). CONCLUSION: For defects in hypopharynx and cervical esophagus less than 10 cm, silicone rubber tube reconstruction is satisfactory.

Adult↗
PubMed1998

[Effects of dopexamine on cardiac hemodynamics during myocardial ischemia in rats and in comparison with fenoldopam and procaterol].

The effect of dopexamine hydrochloride(DPX) on cardiac hemodynamics during acute myocardial ischemia (AMI) was studied in rats and compared with those of fenoldopam hydrochloride(FODA) and procaterol hydrochloride (PCT). The results showed that i.v. DPX remarkably attenuated the increases of total peripheral resistance(TPR) and left ventricular end-diastolic pressure and the decreases of + dp/dt max caused by ischemia, while DPX showed no significant effect on mean arterial pressure(MAP). Although FODA was more potent than DPX in attenuating the increase of TPR and the decrease of myocardial contractility caused by ischemia, it significantly decreased MAP. The effects of PCT on all these variables were the smallest among the 3 agents. The results suggest that DPX has a better prospect in the treatment of ischemic heart disease in view of its actions of decreasing TPR, mild increase of myocardial contractility, without MAP decrease and myocardial oxygen consumption increase.

Adrenergic beta-2 Receptor Agonists↗
PubMed1997

Maximum likelihood estimation of aggregated Markov processes.

We present a maximum likelihood method for the modelling of aggregated Markov processes. The method utilizes the joint probability density of the observed dwell time sequence as likelihood. A forward-backward recursive procedure is developed for efficient computation of the likelihood function and its derivatives with respect to the model parameters. Based on the calculated forward and backward vectors, analytical formulae for the derivatives of the likelihood function are derived. The method exploits the variable metric optimizer for search of the likelihood space. It converges rapidly and is numerically stable. Numerical examples are given to show the effectiveness of the method.

Markov Chains↗
PubMed1997

Subconductance states of a mutant NMDA receptor channel kinetics, calcium, and voltage dependence.

The kinetic properties of main and subconductance states of a mutant mouse N-methyl-D-aspartate (NMDA) receptor channel were examined. Recombinant receptors made of zeta-epsilon 2 (NR1-NR2B) subunits having asparagine-to-glutamine mutations in the M2 segment (zeta N598Q/epsilon 2N589Q) were expressed in Xenopus oocytes. Single channel currents recorded from outside-out patches were analyzed using hidden Markov model techniques. In Ca(2+)-free solutions, an open receptor channel occupies a main conductance (93 pS) and a subconductance (62 pS) with about equal probability. There are both brief and long-lived subconductance states, but only a single main level state. At -80 mV, the lifetime of the main and the longer-lived sub level are both approximately 3.3 ms. The gating of the pore and the transition between conductance levels are essentially independent processes. Surprisingly, hyperpolarization speeds both the sub-to-main and main-to-sub transition rate constants (approximately 120 mV/e-fold change), but does not alter the equilibrium occupancies. Extracellular Ca2+ does not influence the transition rate constants. We conclude that the subconductance levels arise from fluctuations in the energetics of ion permeation through a single pore, and that the voltage dependence of these fluctuations reflects the modulation by the membrane potential of the barrier between the main and subconductance conformations of the pore.

Animals↗
PubMed1997

An STS-based radiation hybrid map of the human genome.

We have constructed a physical map of the human genome by using a panel of 83 whole genome radiation hybrids (the Stanford G3 panel) in conjunction with 10,478 sequence-tagged sites (STSs) derived from random genomic DNA sequences, previously mapped genetic markers, and expressed sequences. Of these STSs, 5049 are framework markers that fall into 1766 high-confidence bins. An additional 945 STSs are indistinguishable in their map location from one or more of the framework markers. These 5994 mapped STSs have an average spacing of 500 kb. An additional 4484 STSs are positioned with respect to the framework markers. Comparison of the orders of markers on this map with orders derived from independent meiotic and YAC STS-content maps indicates that the error rate in defining high-confidence bins is < 5%. Analysis of 322 random cDNAs indicates that the map covers the vast majority of the human genome. This STS-based radiation hybrid map of the human genome brings us one step closer to the goal of a physical map containing 30,000 unique ordered landmarks with an average marker spacing of 100 kb.

Animals↗
PubMed1997

[Intermediate syndrome after acute organophosphorus pesticides poisoning: clinical analysis of 10 cases].

Ten patients with intermediate syndrome (IMS) after acute organophosphorus (OP) pesticides poisoning were observed. The occurrence rate of IMS was 5.4% among total inpatients of acute OP poisoning in the same period. The majority of IMS cases were of severe oral OP poisoning. Seven to 68 hours after poisoning there were initial signs including motor weakness of muscles innervated by the 9th and 10th cranial nerves (e.g. dysphagia, hoarse voice). The neck flexor muscles and proximal limb muscles were also involved. Patients with respiratory muscle paralysis usually required urgent tracheal intubation and mechanical ventilation. The IMS in this group persisted for 6-30 days (mean 13 days) with no fatality. The relevant kinds of pesticide, the development and regression of IMS, and the treatment and possible mechanism of IMS were discussed.

Adult↗
PubMed1997

[Levels of serum G-CSF and supplement of GM-CSF in rats sustaining delayed resuscitation after major burn].

UNLABELLED: Delayed fluid resuscitation of burn shock may lead to infection in early period following major burn injury, resulting in multiple organ failure with high mortality. The change in colony stimulation factors (CSFs) may play a role in developing infection. We assessed the levels of serum granulocyte colony stimulation factor (G-CSF), tumor necrosis factor-alpha (TNF-alpha), phagocytosis of neutrophil and counts of peripheral blood cells of rats with 30% TBSA full thickness burn having either immediate or delayed fluid replacement. We also evaluated the efficacy of granulocyte-macrophage colony-stimulating factor (GM-CSF) in improving survival of rats following burn injury with a superimposed burn wound infection. THE RESULTS: 1. A delayed rise in serum G-CSF was found in delayed resuscitation group, and the levels of serum G-CSF and phagocytosis of neutrophil were lower compared with immediate resuscitation group. 2. Nonsurvival group had lower levels of serum G-CSF and higher content of TNF-alpha compared with survival. 3. Supplement of GM-CSF could significantly improve animal survival with burn wound infection following severe burn shock. CONCLUSION: Decrease in G-CSF production plays a role in developing fatal wound infection after severe burn shock; supplement of GM-CSF is beneficial in improving survival.

Animals↗
PubMed1996

A gene map of the human genome.

The human genome is thought to harbor 50,000 to 100,000 genes, of which about half have been sampled to date in the form of expressed sequence tags. An international consortium was organized to develop and map gene-based sequence tagged site markers on a set of two radiation hybrid panels and a yeast artificial chromosome library. More than 16,000 human genes have been mapped relative to a framework map that contains about 1000 polymorphic genetic markers. The gene map unifies the existing genetic and physical maps with the nucleotide and protein sequence databases in a fashion that should speed the discovery of genes underlying inherited human disease. The integrated resource is available through a site on the World Wide Web at http://www.ncbi.nlm.nih.gov/SCIENCE96/.

Amino Acid Sequence↗
PubMed1996

Estimating single-channel kinetic parameters from idealized patch-clamp data containing missed events.

We present here a maximal likelihood algorithm for estimating single-channel kinetic parameters from idealized patch-clamp data. The algorithm takes into account missed events caused by limited time resolution of the recording system. Assuming a fixed dead time, we derive an explicit expression for the corrected transition rate matrix by generalizing the theory of Roux and Sauve (1985, Biophys. J. 48:149-158) to the case of multiple conductance levels. We use a variable metric optimizer with analytical derivatives for rapidly maximizing the likelihood. The algorithm is applicable to data containing substates and multiple identical or nonidentical channels. It allows multiple data sets obtained under different experimental conditions, e.g., concentration, voltage, and force, to be fit simultaneously. It also permits a variety of constraints on rate constants and provides standard errors for all estimates of model parameters. The algorithm has been tested extensively on a variety of kinetic models with both simulated and experimental data. It is very efficient and robust; rate constants for a multistate model can often be extracted in a processing time of approximately 1 min, largely independent of the starting values.

Algorithms↗
PubMed1995

Int-2 influences the development of the nodose ganglion.

The int-2 gene was first described as a common proviral integration site in tumors induced by mouse mammary tumor virus (MMTV). During embryonic development int-2 is produced and released by cells in the rhombencephalon and diffuses to the ectoderm to induce formation of the otocyst from the otic placode. Int-2 also influences the development of the vestibulocochlear ganglion that is derived from the otic placode. During embryogenesis the otic and nodose placodes, primordia of the inner ear and the nodose ganglia, respectively, are located adjacent to each other in the embryonic ectoderm. The nodose ganglia provide sensory innervation to all of the viscera. Using Northern analysis we determined that a high level of int-2 is transcribed in stage 14 chick embryos. This is the time when cells begin to migrate from the nodose placodes to form the nodose ganglia. Using human and mouse sequences to design primers around the translation start site of the transcript, a partial clone containing the translation start site of chick int-2 was obtained by polymerase chain reaction amplification from chick genomic DNA and cloned. An antisense oligodeoxynucleotide was designed to the region of the translation start site, and in vitro and in vivo techniques were used to demonstrate that inhibition of int-2 translation using this antisense oligonucleotide causes delayed and abnormal development of the nodose placodes. For in vitro studies, explants of stage 12 chick embryos containing neural tube, adjacent surface ectoderm, and pharyngeal endoderm were cultured with int-2 antisense oligonucleotide.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Gated, ion-selective channels observed with patch pipettes in the absence of membranes: novel properties of a gigaseal.

Gigaohm seals made between patch pipettes and hydrophobic substrates have a finite conductance which are cation-selective and capable of producing quantized gating indistinguishable from the gating of biological ion channels. The selectivity sequence and streaming potentials of these seals suggests the existence of a pore of similar dimensions to the nicotinic acetylcholine channel. The ionic selectivity of these seals appears similar to the seal selectivity observed with membrane patches (Fischmeister, R., R. K. Ayer, and R. L. DeHann. 1986. Pfluegers Arch. 406:73-82) and the possibility of discrete gating within the seal region suggests caution when interpreting patch clamp data from unfamiliar preparations. The data suggests that the permeation pathway is the narrow space between the hydrophobic substrate and the pipette. Since this space has one hydrophobic wall, a hydrophilic channel lining may not be essential for channel permeation and gating.

Biophysical Phenomena↗
PubMed1992

Quantitative NMR imaging of multiphase flow in porous media.

Quantitative description of multiphase flow in porous media and local saturation distributions at steady states are of fundamental importance for petroleum recovery. The use of MRI provides an unprecedented means for obtaining such information. In this paper, profile imaging techniques for quantitative evaluation of fluid saturations during flow experiments in porous media are developed. The procedures for overcoming problems arising from very short, fluid saturation-dependent and spatial variation of T2, which are common in porous media, were addressed. The general methods developed should also be applicable to similar inhomogeneous biological systems. Experimental NMR imaging measurements of two-phase displacement were conducted in several limestones and sandstones representing various different types of pore structures, including a macroscopically homogeneous structure, a laminated structure, and a sample that exhibits porosity at different scales. The advantages of using each different type of profile imaging sequence to investigate flow in different types of porous structures are demonstrated. Images showing many features of multiphase flow, including nonuniform flow through different bedding structures, are obtained during the flow experiments. The use of profile images for obtaining many important petrophysical properties, such as permeability, porosity, saturation, and pore structural information, is discussed.

Geological Phenomena↗
PubMed1990

Abnormal hemoglobins in the Silk Road region of China.

A review is presented of the occurrence of 24 abnormal hemoglobins (13 alpha-chain variants and 11 beta-chain variants) in populations in the Silk Road area of Northwestern China. Most frequently occurring were Hb D-Punjab [beta 121(GH4)Glu----Gln] in Uygurs, Kazaks, and Khalkhas, Hb G-Taipei [beta 22(B4)Glu----Gly] in persons of the Han nationality, and Hb G-Coushatta [beta 22 (B4)Glu----Ala] in the Uygurs, Kazaks, Hans, and related nationalities. The data suggest that these variants likely originated in Central Asia, in the Han nationality of China, and in the minorities of northern China, respectively. Other variants occurred at considerably lower frequencies and were imported from other countries or arose as independent mutations. Two variants [Hb Tashikuergan or alpha 19(AB1)Ala----Glu; Hb Tianshui or beta 39(C5) Gln----Arg] were observed for the first time. The data from this study of the many variants support the movements of various populations in this area, as reported in numerous historical documents.

China↗