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Biomedical subjects

Q Chen

Publications and source records attributed to Q Chen.

At least 757 records · Page 42Linked to original sources
PubMed1990

Short-term treatment with cell wall degrading enzymes increases the activity of the inositol phospholipid kinases and the vanadate-sensitive ATPase of carrot cells.

Treating carrot (Daucus carota L.) suspension culture cells with a mixture of cell wall degrading enzymes, Driselase, resulted in an increase in the percentage of [(3)H]phosphatidylinositol bisphosphate. Analysis of the lipid kinase activities in the isolated plasma membranes after whole cell treatment indicated that treatment with Driselase (2% weight/volume; the equivalent of 340 units per milliliter of hemicellulase and 400 units per milliliter of cellulase activity) or treatment with hemicellulase (31.7% weight/volume, 20.7 units per milliliter) resulted in an increase in the inositol phospholipid kinase activity. However, treatment with cellulase alone had no effect at 0.5% (weight/volume, 17.2 units per milliliter) or inhibited the kinase activity at 1% (weight/volume, 34.4 units per milliliter). The active stimulus in Driselase was heat sensitive. The plasma membrane vanadate-sensitive ATPase activity also increased when the cells were treated with Driselase. A time course study indicated that both the inositol phospholipid kinases and the plasma membrane vanadate-sensitive ATPase responded to as little as 5 seconds of treatment with 2% Driselase. However, at the lowest concentration of Driselase (0.04%, weight/volume) that resulted in an increase in inositol phospholipid kinase activity, the ATPase activity was not affected. Because inositol phospholipids have been shown to activate the vanadate-sensitive ATPase from plants (AR Memon, Q Chen, WF Boss [1989] Biochem Biophys Res Commun 162: 1295-1301), a stimulus-response pathway involving both the inositol phospholipid kinases and the plasma membrane vanadate-sensitive ATPase activity is discussed.

Journal Article↗
PubMed1990

Arachidonic acid absorption in human jejunum in organ culture: effects of ethanol.

Human jejunal tissue obtained by peroral biopsy was cultured in control medium and in medium containing 100 mmol l-1 ethanol. Subsequently, the incorporation and metabolism of [3H]-arachidonic and [14C]-linoleic acid were evaluated. Of the two fatty acids a significantly higher amount of [3H]-arachidonic acid was incorporated into phospholipids and more [14C]-linoleic acid was incorporated into triacylglycerols. This preferential distribution of the labelled fatty acids was not affected by ethanol, but when ethanol was present in the tissue culture medium, there was a significant decrease in the incorporation of both fatty acids into tissue phospholipids. The study thus shows that ethanol in moderate concentrations can affect human jejunal absorption and metabolism of polyenoic fatty acids, contributing to a decrease in the amount of eicosanoid precursors available in jejunal tissue.

Arachidonic Acid↗
PubMed1990

Chronic metabolic measurements of normal brain tissue response to photodynamic therapy.

The metabolic response of normal rat brain to photodynamic therapy (PDT) was studied over a 1 week interval using in vivo 31P-NMR spectroscopy. Rats injected with 12.5 mg/kg Photofrin II were submitted to brain photoactivation 48 h after drug administration with either 140 or 70 J/cm2 light (630 +/- 1 nm) from an Argon dye laser. Control studies, animals not given drug or light, animals submitted only to brain illumination without drug, and animals given drug but no light, were also performed. The data revealed a transient metabolic degradation; a decrease in the ratio of beta-nucleotriphosphate to inorganic phosphate (P less than 0.001) at 24 h after PDT treatment was followed by a return to pretreatment spectral values. Brain tissue alkalosis was also noted, with significant (P less than 0.05) differences in brain tissue pH detected at 72 h post treatment between 70 J/cm2 PDT vs control studies and at 1 week post treatment between 140 J/cm2 vs 70 J/cm2, 140 J/cm2 vs no light-no drug and 140 J/cm2 vs drug only. The data suggest that there is no difinitive metabolic marker from 31P-NMR spectroscopy that can identify necrotic brain tissue caused by PDT. Phosphorus-31 NMR data are also presented which suggest that PDT damage to brain is not solely the result of microvascular occlusion causing ischemic necrosis.

Animals↗
PubMed1990

[Effect of reserpine on both CL seizures and cAMP levels in seizure mice brain].

Reserpine injection (1 mg/kg i.p.) could not only significantly reduce cAMP levels in both cerebral cortex and hippocampus in naive WC1 mice, but also potentiate the degree of seizures elicited by CL. Reserpine injection could significantly shorten CL-seizures latency and decrease its threshold, too. Reserpine pretreatment could also diminish CL seizure-induced accumulation of cAMP. These results indicated the cAMP level elevated by seizure activity was associated with monoamine neurotransmitter activity, and the seizure-induced accumulation of cAMP might take part in the process which eliminated the spread of seizure discharges and speeded up the termination of seizures.

Animals↗
PubMed1990

[Electron microscopic observation of the effects of Rhodiola kirilowii (Regel.) Maxim. in preventing damage of the rat viscera by a hypoxic high altitude environment].

This paper has shown that the pathologic damages done to rat's viscera due to hypoxic environment of altitude can be reduced significantly by oral administrations of Shengmaiyin, Danshen-Chuanxiong mixture and Rhodiola kirilowii. Shengmaiyin that maintains interior substances in the plate layer bodies proves more effective than Danshen-Chuanxiong mixture, while the latter excels in preventing capillary contraction, thus improving blood circulation. Rhodiola kirilowii has the effects of both Shengmaiyin and Danshen-Chuanxiong mixtures.

Altitude Sickness↗
PubMed1990

[A kindling model of epilepsy induced by intraperitoneal injection of coriaria lactone in rats].

Fifty adult male Sprague-Dawley rats were divided into five groups. Intraperitoneal injections of various doses of coriaria lactone (CL, 0.75, 1.25, 1.75, and 2.0 mg/kg) and normal saline were given respectively per 2 days. The behavior of the rats was observed and the ECoG was recorded by telemetric method. The results of experiments show that a kindling model of epilepsy can be established by intraperitoneal injection of CL in rats. This chronic experimental model is of value for application because it is easily established and the rate of being kindled is relatively high, but the mortality is low, and the kindling effect can last well. The model can avert the pathological change caused by artificial injury to brain, so it is advantageous to the research on neurochemistry and ultrastructure. In our experimental condition, it is optimal to select 1.25 mg/kg or 1.75 mg/kg as the dosage of CL for establishing kindling model.

Animals↗
PubMed1990

[Bioelectric potentials of bone in experimental fracture healing].

A specific electric potential gradient exists on the surface of long bone and the electric gradient changes after fracture. The electric potentials at the fracture site were measured and it was shown to change most actively during the early healing phase, and thereafter reached the normal level gradually. When soft tissue was damaged, certain potential changes occurred. But this change was different from that in the fracture site, indicating that the tissue has "biological window" effect of electrization.

Animals↗
PubMed1990

Indirect inactivation of rat brain cytosolic diacylglycerol kinase by nucleoside-5'-monophosphate.

Cytosolic diacylglycerol kinase was inhibited drastically by nucleoside monophosphate. The inhibition was relatively specific for adenosine-5'-monophosphate (5'-AMP), although uridine-5'-monophosphate was also effective. The effect of 5'-AMP on diacylglycerol kinase appeared to be indirect since the degree of inhibition lessened with the dilution of the cytosol and the more purified enzyme failed to respond to 5'-AMP. A 5'-AMP-dependent mediator is proposed to be involved in the inactivation of diacylglycerol kinase.

Adenosine Monophosphate↗
PubMed1990

[Microsurgery to treat lesions in or near the eyeball wall].

Four sub-retinal cysticerci and 12 cases of nonmagnetic intraocular foreign bodies near the eyeball wall were first localized with indirect ophthalmoscopy and then removed successfully under surgical microscopy. Three layers, ie white sclera, black supra-choroid pigment and light brown choroidal tissue with white vascular pattern were encountered before reaching the sub-retinal larval. The ischemic appearance of the choroid probably was caused by compression of the larval underneath it. Intraocular foreign bodies usually appeared in the wound accompanied by liquified vitreous as soon as the incision was made. If intraocular inflammation exist, foreign body can be found within the pus or dense exudates.

Adult↗
PubMed1990

[Mitochondrial encephalomyopathy. Report of a case].

A typical case of mitochondrial encephalomyopathy with lactic acidemia and stroke-like episodes (MELAS) was reported. The main clinical manifestations consisted of short stature, psychomotor deterioration, sensorineural deafness, and hemiparesis. The laboratory findings disclosed abnormal lactic acid tolerance abnormal EEG, VEP, AEP, SEP, and MCV. The CT scan showed multiple intracerebral infarcts, basal ganglia calcifications, and cerebral atrophy. A muscle biopsy was performed. The frozen sections with modified gomori trichrome stain revealed ragged-red-fiber which reacted strongly positive in NADH-TR stain. The electron microscopy revealed subsarcolemmal aggregation of mitochondria of various sizes with paracrystalline inclusions, abnormally arranged cristae, and osmiophilic dense-bodies in their matrices.

Adult↗
PubMed1990

[Measurement and clinical application of MEFV and PEFV curves in young children].

Previous studies of children's ventilatory functions revealed that a history of pediatric respiratory illness could cause an adult airway to be highly susceptible to the adverse effects of a variety of bronchial stimulants and infectious agents and easy to develop obstructive airway diseases in adult life. Ten indexes of ventilatory function were measured with MEFV and PEFV curves in 333 normal young children aged between 3 and 6, and 15 sick children of bronchopneumonitis in the same age range. Multiple regression equations of different indexes of normal children were set up. The measured values of various indexes of the sick children were much lower than the correspondent predicted values calculated from multiple regression equations, especially VT, VmaxFRC and VmaxFRC/FRC (P less than 0.05). The results suggest that the measurement of PEFV is a convenient and sensitive method to test children's ventilatory function.

Child↗
PubMed1989

Hydrolysis of triacylglycerol arachidonic and linoleic acid ester bonds by human pancreatic lipase and carboxyl ester lipase.

The hydrolysis of polyenoic fatty acid ester bonds with pure human colipase-dependent lipase, with carboxyl ester lipase (CEL) and with these enzymes in combination was studied, using [3H]arachidonic- and [14C]linoleic acid-labelled rat chylomicrons as a model substrate. During the hydrolysis with colipase-dependent lipase, the amount of 3H appearing in 1,2-X-diacylglycerol (DG) markedly exceeded that of 14C. When CEL was added in addition this [3H]DG was efficiently hydrolyzed. CEL alone hydrolyzed the triacylglycerol (TG) at a low rate. The hydrolysis pattern with human duodenal content was similar to that seen with colipase-dependent lipase and CEL in combination. Increasing the concentration of taurodeoxycholate (TDC) and taurocholate (TC) or of TDC alone stimulated the hydrolysis of [3H]- and [14C]TG, but increased the accumulation of labelled DG that could act as substrate for CEL. It is suggested that very-long-chain polyenoic fatty acids of DG formed during the action of the colipase-dependent lipase on TG containing these fatty acids may be a physiological substrate for CEL.

Arachidonic Acid↗
PubMed1989

Quantitative benedict test using bicinchoninic acid.

Cupric ion (Cu2+), in complex form, functions as a selective oxidizing agent for a variety of compounds in the qualitative Benedict test. Cupric ion is reduced to cuprous ion (Cu+) in the reaction. We found that the cuprous ion formed in this type of redox reaction could be detected and quantified using 2,2'-bicinchoninic acid. This reagent produced an intense purple complex with cuprous ion. The color development in this modified Benedict test was dependent on pH, temperature, and time. The reaction is insensitive to ethanol and sodium dodecyl sulfate. This improved method of the Benedict test has enhanced sensitivity and makes the quantitation of compounds possible. This method should be useful for studies of Benedict-positive compounds which are available only in small amounts.

Biochemistry↗
PubMed1989

Characterization of Inositol Phosphates in Carrot (Daucus carota L.) Cells.

We have shown previously that inositol-1,4,5-trisphosphate (IP(3)) stimulates an efflux of (45)Ca(2+) from fusogenic carrot protoplasts (M Rincón, WF Boss [1987] Plant Physiol 83: 395-398). In light of these results, we suggested that IP(3) might serve as a second messenger for the mobilization of intracellular Ca(2+) in higher plant cells. To determine whether or not IP(3) and other inositol phosphates were present in the carrot cells, the cells were labeled with myo-[2-(3)H]inositol for 18 hours and extracted with ice-cold 10% trichloroacetic acid. The inositol metabolites were separated by anion exchange chromatography and by paper electrophoresis. We found that [(3)H]inositol metabolites coeluted with inositol bisphosphate (IP(2)) and IP(3) when separated by anion exchange chromatography. However, we could not detect IP(2) or IP(3) when the inositol metabolites were analyzed by paper electrophoresis even though the polyphosphoinositides, which are the source of IP(2) and IP(3), were present in these cells. Thus, [(3)H] inositol metabolites other than IP(2) and IP(3) had coeluted on the anion exchange columns. The data indicate that either IP(3) is rapidly metabolized or that it is not present at a detectable level in the carrot cells.

Journal Article↗
PubMed1989

Normal brain tissue response to photodynamic therapy: histology, vascular permeability and specific gravity.

The response of photodynamic therapy on normal brain was investigated in 140 Fisher rats. The rats were injected i.p. with Photofrin II (12.5 mg/kg) and 48 h later the dural area over the frontal cortex was photoactivated with red light (630 +/- 1 nm) from an argon dye laser. Treatment was performed with optical energy densities of 140 and 70 J/cm2. Histopathology, vascular permeability and specific gravity measurements were conducted on different populations of rats at 4 h, 24 h, 72 h and 1 week after photodynamic therapy (PDT). Histopathology revealed similar gross and microscopic pathology associated with light energies of 70 and 140 J/cm2 after all time points. A large cerebral infarct approximately the size of the brain surface area treated, evolved 24 h following treatment. Evans blue extravasation indicated a small area of vascular permeability evident as early as 4 h following PDT treatment at both energy levels, with increasing permeability evident at later time points. Specific gravity measurements taken on a representative area of the lesion indicated a significant (P less than 0.01) amount of edema present at 24 h post treatment with a gradual reduction approaching control values over the time period of 1 week. The data indicate a significant amount of damage to normal brain from low PDT treatment doses.

Animals↗
PubMed1989

The major low-molecular-weight heat shock protein in chloroplasts shows antigenic conservation among diverse higher plant species.

Several plant species are known to synthesize low-molecular-weight nucleus-encoded heat shock proteins (HSPs) which localize to chloroplasts. DNA sequence analysis of chloroplast HSP cDNAs from pea (Pisum sativum) and soybean (Glycine max) has shown that the carboxyl-terminal halves of these proteins are homologous to low-molecular-weight HSPs from a wide range of eucaryotes (E. Vierling, R. T. Nagao, A. E. DeRocher, and L. M. Harris, EMBO J. 7:575-581, 1988). We used a pea cDNA to construct fusion proteins containing either the carboxyl-terminal heat shock domain or the amino-terminal domain of the chloroplast HSP. The fusion proteins were overexpressed in Escherichia coli and used to produce choloroplast HSP-specific polyclonal antibodies. The carboxyl-terminal antibodies recognized chloroplast HSP precursor proteins from pea and from three divergent plant species, Arabidopsis thaliana, petunia (Petunia hybrida), and maize (Zea mays). The amino-terminal antibodies recognized effectively only the pea precursor. When intact plants of each species were subjected to a heat stress regime mimicking field growth conditions, significant levels of the mature forms of the chloroplast HSPs accumulated in pea, A. thaliana, and maize. The levels of accumulated HSPs remained unchanged for 12 h following the stress treatment. We conclude that the synthesis of chloroplast-localized HSPs is an important component of the stree response in all higher plants and that chloroplast HSPs from dicotyledonous and monocotyledonous plants have a conserved carboxyl-terminal domain.

Antigens↗