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Biomedical subjects

L Qi

Publications and source records attributed to L Qi.

At least 55 records · Page 3Linked to original sources
PubMed1997

Synthesis of Copper Nanoparticles in Nonionic Water-in-Oil Microemulsions

Synthesis of well-dispersed copper nanoparticles was achieved by reduction of aqueous copper chloride solution using NaBH4 in the nonionic water-in-oil (w/o) microemulsions formed by Triton X-100, n-hexanol, cyclohexane, and water. It has been shown that instead of copper oxide produced in aqueous solution, metallic copper particles are formed in w/o microemulsions because of the high local copper concentration in water pools of the microemulsions, indicating the advantage offered by w/o microemulsions over aqueous phases. The absorption spectrum of the colloidal copper particles obtained in microemulsions does not exhibit the plasmon peak characteristic of the Cu surface. It is conceivable that the lack of the plasmon absorption band is attributed to the formation of a CuCl monolayer on the copper particles.

Journal Article↗
PubMed1997

Effect and clinical value of splanchnic nerve block of hemodynamics in ACST.

The condition of acute cholangitis of severe type (ACST) develops very rapidly and the prognosis is poor. The main clinical feature is that there is an obvious dynamic variation, which is the principal factor for the early occurrence of shock and death. In this study the Japanese long ear rabbits were used and biliary tract pressure increasing and splanchnic nervous plexus blocking experiments were conducted. Our results indicate that 0.6% of lidocaine can be used to block the right celiac plexus. It can avoid the decrease of blood pressure due to the pressure increase of the biliary tract, and the decrease of blood pressure due to the pressure increase of the biliary tract can be corrected by local anesthesia. 8 cases in conformity with the ACST diagnostic standards received the right renal capsule block injection for the purpose of stopping the celiac plexus, 6 cases of whom had a return of blood pressure to various extent, suggesting that the splanchnic nervous activity in the occurrence of ACST is of great significance. The technique may provide a new approach for the clinical treatment of ACST.

Acute Disease↗
PubMed1997

[Choice of time and mode of operation in severe acute pancreatitis].

We report the treatment of 75 patients of severe acute pancreatitis. Operations were performed on patients with pancreatic infection and organ failure according to the principle of "individualization". Operation was also indicated for the patients aged 60 who had had no improvement after a short period of non-operative treatment because of the susceptibility to develop MOF, Non-operative treatment was administered to other patients. This therapeutic mode can increase the cure rate while complications can be decreased. Early operation is necessary for patients with single organ failure in case sequential MOF might happen. The main components of operation were elimination of necrostic lesion, lysis of the pancreas, multiple drainage, and adequate postoperative peritoneal lavage. This operation can not only eliminate necrostic tissue, but also prevent progressive pancreatic necrosis. It introduces free drainage, and can bring satisfactory therapeutic result and reduce the possibility of reoperation.

Adult↗
PubMed1995

An active site phenylalanine of 3-oxo-delta 5-steroid isomerase is catalytically important for proton transfer.

3-oxo-delta 5-steroid isomerase (KSI) from Pseudomonas testosteroni catalyzes the isomerization of a variety of 3-oxo-delta 5-steroids to their conjugated delta 4-isomers through the intermediate formation of a dienolate ion. This dienolate is formed by proton transfer from C-4 of the substrate to Asp-38, which then protonates the dienolate at C-6. Catalysis is enhanced by electrophilic assistance (hydrogen bonding) to the 3-oxygen by Tyr-14. We have investigated the effect of modifying phenylalanine-101 (F101), a hydrophobic residue that is located in the binding pocket of KSI. Two mutant enzymes (F101L and F101A) of KSI were prepared, and their kinetic properties were examined with 5-androstene-3, 17-dione (1) as the substrate. Both of the mutants show reduced values of kcat compared to the wild type (WT), by about 30-fold (F101L) and by 270-fold (F101A), with only a small difference in Km values. There is little change in the Ki's ( < or = 4-fold) for the product 4-androstene-3,17-dione (3), although both enzymes bind the intermediate analog d-equilenin (4) about 25-fold less tightly than does the WT. Fluorescence spectra of 4 bound to each of these enzymes suggest that 4 is ionized at the active site of WT, un-ionized at the active site of F101A and a mixture of these ionization states at the active site of F101L. Free energy profiles are constructed for each of the mutant enzymes, and these are compared to the free energy profile for the WT.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological Transport↗
PubMed1995

Repeated radial keratotomy.

38 cases 59 eyes received repeated radial keratotomy in which the secondary incisions were performed along the scars of old incisions. The average follow-up after the reoperation was 13 months. Before reoperation, the mean spherical equivalent of the refraction was -3.78D and the mean keratometry was 40.15D. 13 months after the reoperation, the mean spherical equivalent of the refraction decreased by 2.30D, and the mean keratometry decreased by 2.04D. After the reoperation, the mean uncorrected visual acuity increased by 5 lines. There was no relationship between the therapeutic effect of the reoperation and the degree of initial myopia or pre-reoperative keratometry. The repeated radial keratotomy can decrease the degree of astigmatism and its complications are few.

Adult↗
PubMed1994

Cytotoxic saponins from New Zealand Myrsine species.

The observed biological activity in two New Zealand Myrsine species has been shown to be due to the presence of triterpene saponins. From Myrsine australis a series of eight oleanane-type saponins was obtained, with compounds 1-4 and 7 and 8 being novel. Also isolated were ardisiacrispin A [5] and ardisiacrispin B [6]. The structures of the new compounds were determined by chemical and spectroscopic techniques. Extracts of Myrsine salicina yielded only one saponin, 5. Saponins 1-8 were shown to be combinations of four oleanane triterpenes bonded to beta-D-xylp(1-->2)-beta-D-glcp(1-->4)-[beta-D-glcp(1-->2)]-alpha-L -arap (compounds 1, 3, 5, 7) and this same tetrasaccharide with alpha-L-rhap replacing the beta-D-xylp unit (compounds 2, 4, 6, 8).

Animals↗
PubMed1994

Cardiac responses activated by nicotine in canine ganglial plexus between aorta and pulmonary artery.

In order to study the location and function of nicotine-sensitive neurons of cardiac ganglial plexuses, microdissections of collections of fat pads were carried out, and nicotine (100 micrograms) was injected into the ganglial plexus between aorta and pulmonary artery (A-PGP) in 30 anesthetized open-chest dogs. There were numerous ganglia or neurons in A-PGP. Either positive or negative inotropic and chronotropic responses were elicited following injections of nicotine into A-PGP. Control injections of 0.1 ml saline into A-PGP and injections of nicotine (100 or 200 micrograms) into right marginal ganglial plexus did not elicit any cardiac responses. After acute decentralization, nicotine (100 micrograms) was again injected into the same locus of A-PGP. Some positive and negative responses could still be induced, but their frequencies were reduced. These suggest that nicotine can directly activate the efferent parasympathetic and sympathetic neurons and indirectly activate them by stimulating the afferent neurons existing on the surface of dog heart.

Animals↗
PubMed1993

Mechanisms of endotoxin-induced intestinal injury in a hyperdynamic model of sepsis.

The goal of this study was to test the hypothesis that endotoxin-induced bacterial translocation is the result of a selective decrease in intestinal blood flow that causes an oxidant-mediated intestinal mucosal injury. To accomplish this goal, 116 instrumented rats receiving a nonlethal dose of endotoxin (5 mg/kg IP) or saline were studied. Organ blood flow and cardiac output were measured using the microsphere technique and intestinal permeability was measured both by the blood to luminal clearance of 51Cr-EDTA and by horseradish peroxidase. Cardiac output was higher in the endotoxin-treated group than in the saline group (76 +/- 12 versus 95 +/- 17 mL/min; p < 0.05). Although endotoxin induced a hyperdynamic state, blood flow to the distal ileum and cecum was selectively decreased by 35%-50% (p < 0.01), whereas blood flow to the rest of the intestine, spleen, pancreas, and liver was normal. Furthermore, blood flow to the ileal mucosa was decreased to a greater extent than to the remainder of the gut wall (p < 0.05). Small bowel permeability to 51Cr-EDTA was increased at sites of decreased blood flow (ileum) but not at sites of normal (jejunum) blood flow. Allopurinol, a competitive inhibitor of xanthine oxidase, ameliorated the endotoxin-induced decrease in ileal blood flow as well as the increase in ileal permeability. Thus these studies support the hypothesis that endotoxin-induced mucosal injury is the result of an ischemia reperfusion-mediated injury of the distal small intestine and cecum.

Allopurinol↗
PubMed1993

Elemental diet-induced bacterial translocation and immunosuppression is not reversed by glutamine.

Previously, we documented that bacterial translocation occurs in rats fed an elemental liquid diet (4.25% amino acids plus 28% glucose) for 7 days. Since controversy exists over the protective effect of glutamine on diet-induced bacterial translocation, we compared the effect of two elemental diets, one containing 0% and the other 30% of amino acids as glutamine. After 7 days on the test diets or chow (307 kcal/kg/day), the rats were killed and half the animals had their organs cultured for translocating bacteria; immune function was quantitated in the other half by measuring the blood, splenic, and mesenteric lymph node (MLN) blastogenic responses to the T-cell mitogens phytohemagglutinin (PHA) and concanavalin A (ConA). The incidence of bacterial translocation was higher in the rats fed the glutamine (88%) or nonglutamine (75%) elemental diets than in the chow-fed rats (13%) (p < 0.05). Both elemental diets equally reduced the blastogenic response of lymphocytes harvested from all three lymphoid compartments (blood, spleen, MLN) (p < 0.01 vs. chow). The percentage of reduction averaged 30% to 40% when PHA was used as the test mitogen and 50% to 70% when ConA was used. These results indicate that glutamine does not prevent elemental diet-induced bacterial translocation or immune suppression.

Animals↗
PubMed1992

[Protective action of phenytoin on cerebral ischemia in rats].

In order to study and modify the ischemic brain lesions, protecting the reversible damage of neurons, and limiting the ischemic damage both models of cerebral ischemia--focal cerebral ischemia induced by photochemically, and brain reperfusion after ligation of common carotid arteries bilateral in Wistar rats were used to investigate the protective effect of diphenylhydantoin (DPH) on cerebral ischemia. Two groups of rats received DPH 10 mg/kg and 30 mg/kg respectively were compared with those having received normal saline immediately after cerebral ischemia. The effects of DPH on the changes of EEG, biochemical marker and pathologic lesion in focal cerebral ischemia in rats were evaluated. The results showed that the degree of restoration of EEG in the group treated with DPH was better than in the group with normal saline, the content of water in ischemic cerebral tissue was decreased significantly (P < 0.05), the activity of Na-K-ATPase and antioxidant was increased significantly (P < 0.01, P < 0.05, respectively), and the percentage of necrotic neurons in periischemic area was decreased markedly (P < 0.001) in groups treated by DPH. The results suggest that there is a definite protective effect of DPH on cerebral ischemia.

Animals↗
PubMed1992

[Effects of artificial cultured Panax notoginseng cell on cardiovascular system].

Alcoholic extract from artificial cultured Panax notoginseng cell (SCC) ip has been found conducive to increasing the resistance of mice to anoxia. In vitro it helps to increase the outflow of coronary vessels, decrease the heart rate, inhibit the constriction of aortic strip stimulated by nor-epinephrine and relax spasmodic constriction of ileum smooth muscles markedly. SCC powder suspension on po administration can contract bleeding and coagulation time. The pharmacologic activities of SCC are similar to those of crude Panax notoginseng.

Animals↗
PubMed1991

Bacterial translocation from the gut impairs systemic immunity.

The goal of this study was to determine the influence of bacterial translocation on systemic immunity, since bacteria and their products play a major role in the development and maintenance of the host's immune system. To test this hypothesis, we measured the blastogenic response of mononuclear cells harvested from the blood, spleen, Peyer's patches, and mesenteric lymph nodes of control and Escherichia coli C25 monoassociated mice to a battery of mitogens. The E. coli C25 monoassociation model was used because this bacterial translocation model is not associated with experimental manipulations that are likely to affect the systemic immune system. The mitogenic response of lymphocytes isolated from the E. coli C25 monoassociated mice was significantly depressed compared to the control groups (p less than 0.01). Since the biologic significance of depressed in vitro mitogen responsiveness is difficult to determine, we assessed the ability of the mice to control a bacterial challenge using an in vivo Staphylococcus aureus abscess model. It appears that the observed changes in mitogen responsiveness may be of biologic significance, since the ability of the E. coli C25 monoassociated mice to control the injected S. aureus was impaired (p less than 0.01). These results suggest that an association exists between bacterial translocation and decreased systemic immune responsiveness.

Animals↗
PubMed1990

Different lymphocyte compartments respond differently to mitogenic stimulation after thermal injury.

Because of the association between the development of an immunocompromised state and an increased risk of infection, increasing attention has been focused on describing and characterizing the immune consequences of thermal injury. Results of human studies are largely based on the in vitro responsiveness of peripheral blood leukocytes, while splenocytes are generally used in the animal studies. Because the response of lymphocytes from different lymphocyte compartments may vary, we compared the responses of murine peripheral blood, splenic, Peyer's patch, and mesenteric lymph node lymphocytes to a battery of mitogens after thermal injury. Burn-induced immunosuppression was maximal in the splenic lymphocyte compartment, where the responses to all three test mitogens were depressed throughout the 28-day postburn study period. Although the PHA-induced mitogen response of lymphocytes from the other three lymphoid compartments remained suppressed throughout the study period, the response to the mitogens Con-A and PWM generally returned to normal or supranormal levels by the seventh postburn day, Therefore it appears that the effect of a thermal injury on lymphocyte function varies according to the lymphocyte compartment examined and the mitogen tested. These results raise the question of whether animal studies using splenic lymphocytes can be correlated with human studies performed on circulating blood lymphocytes.

Animals↗
PubMed1988

In vitro cell-mediated immunity after thermal injury is not impaired. Density gradient purification of mononuclear cells is associated with spurious (artifactual) immunosuppression.

Mononuclear cells isolated by density gradient centrifugation from the peripheral blood of burn patients, but not healthy volunteers, are contaminated with large numbers of nonmononuclear cells. These contaminating leukocytes could cause artifactual alterations in standard in vitro tests of lymphocyte function. Thus, we compared the in vitro blastogenic response of density gradient purified leukocytes and T-cell purified lymphocytes from 13 burn patients to mitogenic (PHA) and antigenic stimuli. The mitogenic and antigenic response of the patients' density gradient purified leukocytes were impaired compared to healthy volunteers (p less than 0.01). However, when the contaminating nonlymphocytes were removed, the patients' cells responded normally to both stimuli. Thus, density gradient purified mononuclear cells from burn patients are contaminated by leukocytes that are not phenotypically or functionally lymphocytes. Since the lymphocytes from burn patients respond normally to PHA and alloantigens after the contaminating nonlymphocyte cell population has been removed, it appears that in vitro assays of lymphocyte function using density gradient purified leukocytes may give spurious results.

Adult↗
PubMedDate not supplied

Separation of reducing monosaccharides by capillary zone electrophoresis.

The separation of reducing monosaccharides derived from glycosidoproteins and glycolipids by capillary zone electrophoresis (CZE) is dependent on the pH and concentration of the borate buffer. Five saccharides were completely separated in a fused silica capillary tube (50 microns i.d., 65 cm) containing 50 mM borate buffer (pH 10.5) as carrier, with high resolution, at an applied potential of 20 kV after the reducing saccharides were derivatized with 1-naphthylamine. On-column UV (254 nm) monitoring allowed quantitation of these saccharides at least in the concentration range of 10-100 mM in reaction solution. This method was applied to the determination of the monosaccharides composition of various carbohydrate materials to demonstrate its usefulness.

Electrophoresis↗
PubMedDate not supplied

The Caco-2 cell monolayer system as an in vitro model for studying bacterial-enterocyte interactions and bacterial translocation.

Partly because of inherent limitations of in vivo models, the cellular mechanisms underlying the process of bacterial translocation across the intestinal epithelial barrier are incompletely understood. We therefore used the Caco-2 intestinal cell line as an in vitro model to examine the bacterial translocation process under controlled conditions. Caco-2 cells were grown on porous membranes in the upper compartment of a two-compartment system. Caco-2 cells were cultured for 7, 14, 21, or 28 days. Cellular confluence and tight junction integrity were verified by measurements of dextran permeability and transepithelial electrical resistance. Bacterial translocation was measured by culturing the bacteria (E. coli C25) that were able to cross the Caco-2 cell monolayer. The passage of E. coli C-25 and dextran across the Caco-2 monolayer was higher and the transepithelial electrical resistance lower after 7 days of culture than after 14 or 21 days of culture. The Caco-2 cells became impermeable to dextran blue after 14 days of culture with an average transepithelial electrical resistance of 173.1 +/- 9.24 ohms.cm2. When increasing doses of (10(2)-10(9) colony-forming units) of E. coli were tested in 14-day-old Caco-2 monolayers, bacterial translocation occurred in a time- and dose-dependent fashion. Once cellular confluence and tight junction integrity have been established, bacterial translocation across Caco-2 cells appears to be a time- and dose-dependent process.

Cell Movement↗
PubMedDate not supplied

Protein malnutrition alone and in combination with endotoxin impairs systemic and gut-associated immunity.

Because protein-malnourished or endotoxemic patients are at an increased risk of developing nosocomial infections, this study was performed to investigate the effects of protein malnutrition and endotoxemia, alone and in combination, on systemic and intestinal immunity. Protein malnutrition was created by feeding the animals a solid diet containing 0.03% protein. Subgroups of these protein-malnourished mice were killed after being challenged with saline or endotoxin on days 0, 7, 14, or 21. At death, the animals were weighed, tissues were harvested for histologic analysis (ileum, mesenteric lymph node [MLN], liver, and spleen), mitogen responsiveness (MLN, Peyer's patches, and spleen), and xanthine oxidase measurements (ileum and cecum). Separate groups were evaluated for survival. Both the saline and endotoxin-challenged mice had lost about 30% of their body weight after 21 days on the low-protein diet. The protein-malnourished mice were more susceptible to endotoxin-induced mortality (70% at 21 days) than the normally nourished mice (0%) (p less than .001). The mitogen responsiveness of the protein-malnourished mice to the T-cell mitogens (PHA and Con-A) progressively decreased the longer the mice were protein malnourished, and this decreased in blastogenic responsiveness was associated with histologic evidence of lymphoid atrophy. In contrast, the blastogenic response to the primarily B-cell mitogen, PWM, was largely preserved. The endotoxin challenge further depressed the immune state of mice tested after 0, 7, or 14 (but not 21) days of protein malnutrition. Thus, both protein malnutrition and endotoxin impaired systemic and gut-associated immune responsiveness to mitogens. However, in the protein-malnourished mice, the degree of immune suppression did not correlate with endotoxin-induced mortality.

Animals↗