Search PubMed⌕ Search

Biomedical subjects

L Huang

Publications and source records attributed to L Huang.

At least 577 records · Page 32Linked to original sources
PubMed1993

Truncation of the carboxy-terminal 28 amino acids of glycoprotein B specified by herpes simplex virus type 1 mutant amb1511-7 causes extensive cell fusion.

Three amber mutations were introduced proximal to the syn3 locus of the herpes simplex virus type 1 glycoprotein B (gB) gene specifying gB derivatives lacking the carboxy-terminal 28, 49, or 64 amino acids. A complementation system that utilized gBs expressed in COS cells to complement gB-null virus K delta T was established. The 49- or 64-amino-acid-truncated gBs failed to complement gB-null virus K delta T, while the 28-amino-acid-truncated gB complemented K delta T efficiently. Mutant herpes simplex virus type 1 KOS (amb1511-7) specifying the 28-amino-acid-truncated gB fused Vero cells extensively.

Amino Acid Sequence↗
PubMed1993

Glucose use in neonatal rabbit hearts reperfused after global ischemia.

In this study, we measured both glycolysis and glucose oxidation during reperfusion of previously ischemic hearts obtained from 7-day and 6-wk-old rabbits. Isolated working hearts perfused with 11 mM [3H/14C]glucose, 0.4 mM palmitate, 0.5 mM lactate, and 100 microU/ml insulin were subjected to either 30 or 40 min of global ischemia followed by a 60-min period of reperfusion. Recovery of mechanical function was 58% in 7-day-old hearts subjected to 40 min of ischemia. In 6-wk-old rabbits, a 45% recovery of function was seen after only 30 min of ischemia. Addition of 1 mM dichloroacetate (DCA) to the perfusate at reperfusion increased glucose oxidation rates during reperfusion in both 7-day and 6-wk-old hearts (from 102 +/- 22 to 262 +/- 27 and from 280 +/- 63 to 523 +/- 97 nmol.min-1.g dry wt-1, respectively). Addition of DCA, however, resulted in a significant improvement in recovery of mechanical function only in 6-wk-old hearts (from 45 to 67% of preischemic function). These results demonstrate that fatty acid-perfused neonatal rabbit hearts are more able to tolerate ischemia than the matured rabbit hearts. However, our data suggest that there may be less potential to improve mechanical recovery in neonatal hearts during the actual reperfusion period by stimulating glucose oxidation.

Aging↗
PubMed1993

Distribution within the organs of a reticuloendothelial system of liposomes containing lipid A.

Lipid A was incorporated into egg phosphatidylcholine (PC)/cholesterol liposomes which were then tested in mice in order to investigate the effect of lipid A on in vivo biodistribution of liposomes. Addition of lipid A up to 3.2 mol% decreased hepatic uptake and slightly increased splenic uptake of liposomes. When more than 3.2 mol% lipid A incorporated into liposomes, hepatic uptake increased with lipid A concentration. Liposomes containing 25 mol% lipid A were rapidly cleared from circulation and taken up mainly by the liver. Ganglioside GM1 or N-monomethoxypoly(ethyleneglycol)-phosphatidylethanolamine (PGE-PE), which is known to prolong the half life of circulating liposomes, was included in liposomes along with lipid A. Lipid A antagonized the effect of GM1 more effectively than that of PEG-PE. This may be due to the different mechanisms of action exerted by GM1 and PEG-PE in liposome circulation. Hepatic uptake of liposomes containing lipid A increased with vesicle size. However, the unique splenic accumulation of large PEG-PE liposomes was only slightly affected by inclusion of a small amount of lipid A (< 7 mol%). These liposomes might be useful for intravenous delivery of antigen to the spleen for increased immune response.

Animals↗
PubMed1993

[A study on the effect of dynorphin A- (1-13) ICV injection on water, sodium and potassium excretion of rats].

The effect of Kappa-agonist dynorphin A-(1-13) on the urine flow was studied in ethanol-anesthetized rats. Intracerebroventricular injection of dynorphin A- (1-13) (5 micrograms, 10 micrograms) induced a potent diuretic response with insignificant action on mean arterial pressure and heart rate. The diuretic response began to show at about 20 min after injection and lasted 120 min. This diuretic effect could be almost completely blocked by pretreatment with naloxone (20 micrograms) or atropine (10 micrograms).

Animals↗
PubMed1993

[Effect of yin and qi tonifying herbs on hyperthyroid model of yin-deficient rats].

The article reports the effect of Yin and Qi tonifying herbs (Radix Rehmanniae, Radix Ophiopogonis and Pseudostellaria Heterophylla) on hyperthyroid model of Yin-deficient rats. The model rats were made Yin-deficient by injecting thyroxine. Observation showed that after injection, indexes such as anus temperature, oxygen consumption, weight, diet, activity, general conditions, triiodothyronine (T3) and thyroxine (T4) in serum were markedly changed. It is thus suggested that the Yin and Qi tonifying mixture of the above three herbs can regulate and correct Yin-deficiency in hyperthyroid model of Yin-deficient rats.

Animals↗
PubMed1993

Percutaneous transseptal balloon valvuloplasty for dilating mitral valve stenosis (report of 200 cases).

Two hundred cases with mitral valve stenosis were treated by percutaneous single balloon (Inoue balloon) valvuloplasty at our institute from May 1988 to July 1992. The subjects included 137 females and 63 males with a mean age of 36.5 +/- 8.8 years (15-58 years). Hemodynamic and left ventriculographic findings were evaluated immediately before and after the procedure, and the results showed that the mean left atrial pressure was reduced from 25.08 +/- 9.13 mmHg to 10.64 +/- 4.10 mmHg (P < 0.001), the pressure gradient across the mitral valve was reduced from 25.49 +/- 10.22 mmHg to 6.71 +/- 4.87 mmHg (P < 0.001), and systolic pulmonary pressure was reduced from 52.78 +/- 21.42 mmHg to 38.56 +/- 16.47 mmHg (P < 0.001). At the same time, cardiac output and mitral orifice area were increased from 3.84 +/- 0.11 L/min to 4.66 +/- 0.28 L/min (P < 0.001) and from 1.08 +/- 0.28 cm2 to 2.20 +/- 0.47 cm2 (P < 0.001) respectively. Follow-up of 6-48 months (median 24 months) in 50 nonselective patients showed a symptomatic improvement rate of 100%. Percutaneous transseptal balloon mitral valvuloplasty (PBMV) proved to be a highly effective and safe nonsurgical method that can yield very good results in relieving symptomatic rheumatic mitral stenosis, with minimal morbidity and no mortality in this group. PBMV works by splitting the adhered mitral commissures toward the mitral annulus.

Adolescent↗
PubMed1993

Captopril reduces graft coronary artery disease in a rat heterotopic transplant model.

BACKGROUND: Transplant coronary artery disease (CAD) is characterized by severe myointimal proliferation causing vascular stenosis. Nontransplant vascular injury models have shown that angiotensin converting enzyme (ACE) inhibitors reduce myointimal proliferation and preserve lumen integrity. We examined the effect of the ACE inhibitor captopril on graft CAD in a Lewis to F344 rat heterotopic cardiac transplantation model. METHODS AND RESULTS: Twenty-five control rats (group 1) were observed without captopril administration after heterotopic cardiac transplantation, and the other 19 rats (group 2) were administered captopril (50 mg/kg per day in drinking water) after heart transplantation. Graft survival 3 months after transplantation was significantly (P < .02) higher in group 2 (18 of 19, 95%) than that in group 1 (16 of 25, 64%). Cellular rejection grades of the heart allografts were significantly higher in group 1 than those in group 2 both at 3 months (grades, 2.5 +/- 0.4 vs 1.3 +/- 0.7; P < .01) and 6 months (grades, 2.4 +/- 0.9 vs 0.8 +/- 0.5; P < .05) after transplantation. The grades of graft CAD (vascular rejection) were also significantly higher in group 1 than those in group 2 both at 3 months (grades, 2.3 +/- 0.7 vs 0.9 +/- 0.9; P < .05) and 6 months (grades, 3.0 +/- 0.9 vs 0.9 +/- 0.3; P < .01) after transplantation. The cardiac allographs in group 2 showed minimal intimal proliferation, intact elastic laminae, and reduced smooth muscle cell proliferation. CONCLUSIONS: These results suggest that the ACE inhibitor captopril may be effective in prevention of accelerated graft CAD.

Animals↗
PubMed1993

[Computer analysis of evoked field potentials in hippocampal slice].

A microcomputer system for the processing of evoked field potentials of brain slices was developed on the IBM PC-AT microcomputer. In the system, a 385-point finite impulse response (FIR) filter was designed and fast Fourier convolution algorithm was adopted to attain both high quality of filtering and high efficiency of calculation. Also a method for wave peak recognition by analysing waveform slope was established and an interface circuit was designed for the automatic control of the FM tape recorder by the computer. As a result, automated parameter measurement of epileptiform activity recorded from hippocampal slices was successfully realized with high accuracy.

Animals↗
PubMed1993

[Antipyretic and anti-inflammatory effects of Artemisia annua L].

The antipyretic, heat-resisting anti-inflammatory analgesic and bacteriostasis effects of water extracts ethyl-acetate and n-butyl alcohol extracts of Artemisia annua are reported. Animal experiment has demonstrated that qinghao acid is one of the actively bacteriostatic constituents. Scopoletin is one of the anti-inflammatory constituents of Artemisia annua.

Animals↗
PubMed1992

Interaction of synthetic glycophospholipids with phospholipid bilayer membranes.

A series of glycophospholipids synthesized by coupling mono-, di-, or tri-saccharides to dioleoylphosphatidylethanolamine (DOPE) by reductive amination was used to investigate the interaction of glycophospholipids with phospholipid bilayer membranes. These synthetic glycophospholipids functioned as a stabilizer for the formation of DOPE bilayer vesicles. The minimal mol% of glycophospholipid needed to stabilize the DOPE vesicles were as follows: 8% N-neuraminlactosyl-DOPE (NANL-DOPE), 20% N-maltotriosyl-DOPE (MAT-DOPE), 30% N-lactosyl-DOPE (Lac-DOPE), and 42% N-galactosyl-DOPE (Gal-DOPE). The estimated hydration number of glycophospholipid in reverse micelles was 87, 73, 46, and 14 for NANL-DOPE, MAT-DOPE, Lac-DOPE, and Gal-DOPE, respectively. Thus, the hydration intensity of the glycophospholipid was directly related to the ability to stabilize the DOPE bilayer phase for vesicle formation. Glycophospholipids also reduced the transition temperature from gel to liquid-crystalline phase (Tm) of dipalmitoylphosphatidylcholine (DPPC) bilayers. Interestingly, incorporation of NANL-DOPE induced a decrease of membrane fluidity of DPPC bilayers in the gel phase while other glycophospholipids had no effect. Also, low level of NANL-DOPE but not other glycophospholipids increased the transition temperature (TH) from liquid-crystalline to hexagonal phase of dielaidoylphosphatidylethanolamine bilayers. These results showed that NANL-DOPE with a highly hydratable headgroup which provides a strong stabilization activity for the L alpha phase of phospholipid membranes, may also be involved in specific interactions with neighboring phospholipids via its saccharide moiety.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1992

Prolonged survival of thymoma-bearing mice after vaccination with a soluble protein antigen entrapped in liposomes: a model study.

EG7-OVA cells are mouse thymoma EL4 cells stably transfected with the complementary DNA of chicken ovalbumin (OVA) and thus express OVA epitopes as a unique antigen. Cytotoxic T lymphocytes specific to OVA can be elicited by immunization of mice with OVA osmotically loaded into syngeneic splenocytes or entrapped in liposomes. Cytotoxic T lymphocytes thus induced can specifically cytolyse the EG7-OVA cells in vitro in an antigen-specific and major histocompatibility complex-restricted manner. In the present study, we have examined in this model system whether immunization with liposomal OVA can protect mice against tumors induced by EG7-OVA cells. Vaccination with OVA either entrapped in liposomes or osmotically loaded in the syngeneic splenocytes prolonged the survival of mice which had been challenged with EG7-OVA cells, but not those mice challenged with the parent EL4 cells. The antitumor effect was attributed to the induced OVA-specific cytotoxic T lymphocyte activity, since other forms of acquired immunity such as interaction of tumor cells with specific antibody could not be detected. Our results demonstrate that immunization with antigen incorporated in liposomes could be a useful means of inducing a protective antitumor response.

Animals↗
PubMed1992

Effect of cationic cholesterol derivatives on gene transfer and protein kinase C activity.

Four different cationic derivatives of cholesterol were synthesized which contain either a tertiary or a quaternary amino head group, with and without a succinyl spacer-arm. Their ability to inhibit protein kinase C (PKC) activity was measured in a detergent mixed micellar solution. Derivatives containing a quaternary amino head group were effective inhibitors (Ki approx. 12 and 59 microM) of PKC and derivatives containing a tertiary amino head group were approx. 4-20-fold less inhibitory. Liposomes containing an equimolar mixture of dioleoylphosphatidylethanolamine (DOPE) and a cationic cholesterol derivative were tested for the DNA-mediated transfection activity in mouse L929 cells. Highest activity was found with the derivative with low PKC inhibitory activity and with a succinyl spacer-arm. The transfection activity of this tertiary amine derivative, N,N-dimethylethylenediaminyl succinyl cholesterol was dependent on DOPE as a helper lipid; liposomes containing dioleoylphosphatidylcholine and this derivative had little activity. The transfection protocol of this new cationic liposome reagent was optimized with respect to the ratio of liposome/DNA, dose of the complex and time of incubation with cells. Several adherent cell lines could be efficiently transfected with this liposome reagent without any apparent cytotoxicity. However, the transfection activity was strongly inhibited by the presence of serum components.

Animals↗
PubMed1992

Retinoic acid is enriched in Hensen's node and is developmentally regulated in the early chicken embryo.

Retinoic acid (RA) has been considered as a potential morphogen in the chicken limb and has also been suggested to be involved in early embryonic development. On the basis of biological activity, previous reports suggest that Hensen's node, the anatomical equivalent in the chicken of the Spemann's organizer, may contain RA. Here, by using a molecular assay system, we demonstrate that Hensen's node contains retinoids in a concentration approximately 20 times more than that in the neighboring tissues. Furthermore, stage 6 Hensen's node contains approximately 3 times more retinoid than that of stage 4 embryos. These endogenous retinoids may establish a concentration gradient from Hensen's node to adjacent tissues and play a role in establishing the primary embryonic axis in the vertebrate. The results also suggest that the retinoid concentration in Hensen's node is developmentally regulated.

Animals↗
PubMed1992

Distinctive selection mechanisms govern the T cell receptor repertoire of peripheral CD4-CD8- alpha/beta T cells.

The T cell receptor (TCR) repertoire of CD4+ and CD8+ alpha/beta T cells is heavily influenced by positive and negative selection events that occur during T cell development in the thymus. The coreceptors CD4 and CD8 appear to be essential for this selection to occur. To gain insight into whether T cells that express TCR alpha/beta but lack either coreceptor (CD4- CD8- TCR alpha/beta or alpha/beta double-negative [DN] cells) are also subject to positive and negative selection, and whether selection can occur in the absence of coreceptors, we have performed an extensive immunogenetic analysis of the TCR V beta repertoire of alpha/beta DN cells in lymph nodes of normal mice. Our results show that alpha/beta DN cells appear to be unaffected by clonal deletion of V beta 5 and V beta 11 in I-E-expressing mice, and do not undergo deletion of V beta 6- and V beta 8.1-expressing T cells in Mls-1a-positive mice. They are also unaffected by positive selection of V beta 17a+ T cells in the context of I-Aq. The results suggest that most selection events require the participation of CD4 and CD8, while alpha/beta DN cells are unselected. This argues that most alpha/beta DN cells probably have never expressed CD4 or CD8. However, a unique form of repertoire selection occurs: enrichment of V beta 17a+ alpha/beta DN cells in I-E+ mice. This could be an instance of coreceptor-independent selection.

Animals↗
PubMed1992

Induction of cytotoxic T lymphocytes in vivo with protein antigen entrapped in membranous vehicles.

Intravenous administration of APC such as splenocytes loaded with a soluble protein Ag has been shown to prime for an Ag-specific CTL response. It is thought that the APC directly presents loaded Ag in a MHC-restricted manner. However, it is demonstrated in this study that allogeneic splenocytes, MHC-free RBC, and even synthetic lipid vesicles (liposomes) after loading with OVA can elicit an OVA-specific and MHC-restricted CTL response. Biodistribution studies of these Ag-associated vehicles showed that the liver, spleen, and lung were the major organs responsible to scavenge these carriers, suggesting that the monocyte-macrophage system was involved in the Ag presentation for CTL. Depletion of macrophages by a specific macrophage killer, Cl2MDP, containing liposomes, abolished the CTL induction by immunization with OVA Ag carried by these vehicles except the induction by syngeneic splenocytes. Thus, the syngeneic splenocytes present Ag directly to the T cells, but other membranous vehicles carry the Ag to the host APC including macrophages, which then present it to the T cells. These results indicate that formulation of an Ag in membranous/colloidal vehicles may be a way to prime for a CTL response.

Animals↗
PubMed1992

Amphipathic poly(ethylene glycol) 5000-stabilized dioleoylphosphatidylethanolamine liposomes accumulate in spleen.

Relatively small liposomes (d less than 200 nm) composed of dioleoylphosphatidylethanolamine (DOPE) and cholesterol (Chol) and containing dioleoyl-N-(monomethoxypoly(ethylene glycol)succinyl)phosphatidylethanolamine (PEG-PE), with PEG of M(r) 5000 (PEG5000-PE), accumulate in the spleen (approximately 40% i.v. injected dose), unlike dioleoylphosphatidylcholine (DOPC)/Chol/PEG5000-PE liposomes of similar size, which show prolonged circulation in the blood. Spleen accumulation was dependent on the injection dose, PEG-PE concentration, and the PEG chain length. The DOPE/Chol/PEG5000-PE liposomes are plasma stable and morphologically indistinguishable from DOPC/Chol/PEG5000-PE liposomes. These results reveal the significance of the matrix lipid in determining the circulation time of PEG-PE-containing liposomes, and are relevant to the design of liposomes which avoid or accumulate in the spleen.

Animals↗
PubMed1992

Class I restricted CTL recognition of a soluble protein delivered by liposomes containing lipophilic polylysines.

CD8+ cytotoxic lymphocytes recognize peptides derived from endogenous antigens complexed with class I major histocompatibility complex while CD4+ helper cells recognize peptides from exogenous antigens bound to class II MHC molecules. A soluble protein can be introduced into the class I pathway of antigen processing and presentation using an appropriate vehicle to deliver the antigen into the cytosol. Cationic liposomes containing lipophilic polylysine readily form complexes with an anionic, soluble protein ovalbumin. Mouse thymoma EL4 cells incubated with such complexes can be sensitized for killing by OVA-specific CTL effector cells. This method of target sensitization by a soluble antigen is more sensitive than the osmotic loading method previously reported.

Animals↗