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Biomedical subjects

L C Li

Publications and source records attributed to L C Li.

At least 55 records · Page 3Linked to original sources
PubMed1996

Genetic and immunological findings in patients with newly diagnosed insulin-dependent diabetes mellitus. The Swedish Childhood Diabetes Study Group and The Diabetes Incidence in Sweden Study (DISS) Group.

Two large population-based case-control studies are reviewed. The aim is to determine the effects of HLA, other genetic factors and immune markers (ICA, IAA and GAD65Ab) on the age at onset of insulin-dependent diabetes mellitus (IDDM) in 0-34 year olds. The primary HLA risk gene sequence for IDDM was difficult to identify because of the low recombination frequency within the HLA region. The frequency of the DR3-DQA1*0501-DQB1*0201 haplotype and the DR3-DQA1*0501-DQB1*0201 (DQ2)/DR4-DQA1*0301-DQB1*0302 (DQ8) genotype were higher among patients diagnosed before the age of 10 compared with those diagnosed after the age of 30. The negatively associated haplotype, DR15-DQA1*0102-DQB1*0602 was absent before the age of 10, but the frequency increased with increasing age at onset. The IDDM2 gene representing the variable number of tandem repeat (VNTR) sequences and 5' of the insulin gene on chromosome 11 were associated with IDDM since homozygous short VNTR was positive but not homozygous, and heterozygous long VNTR was negatively associated with the disease. The diagnostic sensitivity and specificity of GAD65 (GA65Ab) and insulin (IAA) autoantibodies varied with the age at onset and gender. GAD65Ab had the highest sensitivity (> 80%) in patients older than 20 years of age with no difference in gender. The lowest sensitivity (54%) was in 0-10 year old boys, while age did not affect the sensitivity in girls. In contrast, the sensitivity of IAA was highest (46%) before the age of 15 but decreased thereafter as did the sensitivity for ICA. Classification of patients who develop IDDM above 20-25 years of age was inadequate since many patients classified with NIDDM either had GAD65Ab or ICA or developed these antibodies after 1-2 years of NIDDM. We conclude that not only age but also gender affect the risk for IDDM associated with HLA, other IDDM genes as well as commonly used immunological markers for IDDM.

Age Factors↗
PubMed1995

[Study on preventing alopecia caused by chemotherapy with cold pillow compresses].

Thirty cancer patients were studied by using cold pillow compress to prevent alopecia resulting from chemotherapy. The result indicated that persistent use of cold pillow compress, which made the patients comfortable, could reduce the hair follicles inhibition or damage which caused by chemotherapeutic agents. So alopecia can be prevented or decreased.

Alopecia↗
PubMed1995

An in-vitro evaluation of silicone elastomer latex for topical drug delivery.

A silicone elastomer latex was evaluated as a topical drug-delivery system. With the addition of a fumed silica and the removal of water, the latex produced elastomeric solid films. The water vapour permeability of the solid film was found to be a function of the film composition. An increase in silica content and the incorporation of a water-soluble component, PEG 3350, rendered the silicone elastomer-free film even more permeable to water vapour. The release of hydrocortisone from the elastomer film can be described by a matrix-diffusion-controlled mechanism. Drug diffusion is thought to occur through the hydrophobic silicone polymer network and the hydrated hydrophilic silica region in the film matrix. Silicone elastomer film with a higher silica content exhibited a faster drug-release rate. The addition of PEG 3350 to the film further enhanced the drug-release rate.

Administration, Topical↗
PubMed1995

[Effects on the growth and development of mandible with different treatment following condylar neck fracture in rat]

The condylar necks of young rats are fractured on this experiment.Fractures are treated with nonfixation and fixation,The growth and development of mandible can be interrupted in two groups,with a relatively small in condylar head,a relatively thick in condylar neck.A coronoid and a mandible length are relatively short.But the growth and development of mandible almost are completed,bilateral mandibles are almost symmetry except for ramus.The difference are not found in between two groups.The results of this study implied that young condylar neck fracture may be treated by conservation.

Journal Article↗
PubMed1995

Experience with repair of hypospadias using bladder mucosa in adolescents and adults.

From July 1984 to January 1994, 113 hypospadias operations were performed using a free bladder mucosa graft. There were 31 primary cases and 82 secondary cases in which prior operations had been done. The meatus was penile in 33 patients, penoscrotal in 72 and perineal in 8. The cosmetic and functional results were satisfactory. Postoperative complications included 8 fistulas that required closure and 6 cases of stenosis treated by dilation. Our results suggest that hypospadias repair with a bladder mucosa graft is feasible and reliable. The technique has been performed successfully in the most complex as well as simple cases in adults and adolescents.

Adolescent↗
PubMed1993

Iontophoresis of hydrocortisone across hairless mouse skin: investigation of skin alteration.

The effects of hydration, sodium dodecyl sulfate (SDS), and electric current on the permeability of hairless mouse skin was examined in vitro with a neutral solute, hydrocortisone, as a permeant. The study was carried out by pretreating the skin with (1) normal saline, (2) 0.06% SDS in 0.3% NaCl, (3) normal saline plus 0.5 mA anodic current, and (4) 0.06% SDS in 0.3% NaCl plus 0.5 mA anodic current for 8 h. The pretreated skin was then immediately used for passive or anodic transport of hydrocortisone. Results show that pretreatment of skin with either normal saline or 0.06% SDS resulted in a slightly increased passive penetration of hydrocortisone with a prolonged lag time, but did not significantly change the anodic transport of hydrocortisone. There was no significant difference between normal saline pretreatment and 0.06% SDS pretreatment, indicating that 0.06% SDS did not irreversibly alter the permeability of skin other than its hydration effect. Pretreatment of skin with current, and especially with current combined with 0.06% SDS, yielded a significant increase in both passive and anodic transport of hydrocortisone with reduced lag time, indicating that alteration of the skin structure had occurred. The reversibility of this alteration depends on the duration of exposure of the skin to the electric field. Short-term exposure (< 2 h) does not appear to change the permeability of skin in any significant way; long-term exposure may lead to slowly reversible or irreversible skin alteration.

Animals↗
PubMed1993

A factorial design study on the physical stability of 3-in-1 admixtures.

The effects of dextrose concentration, the compounding method, and storage conditions, on the physical stability of 3-in-1 admixtures were investigated using a 2n factorial design. The main effect of these three variables on the weight percent of oil globules larger than 5 microns (by HIAC) was found to be statistically significant. However, the effects of interaction amongst these variables, except the two-way interaction between dextrose concentration and storage conditions, were found to be statistically insignificant. A higher dextrose concentration was shown to enhance the physical stability of the admixtures, while low-temperature storage (three days at 5 degrees C) was more favourable for maintaining the physical stability of the admixtures with a low dextrose concentration. Although sequential pumping produced admixtures with a slightly lower final weight percentage of larger oil globules (> 5 microns), the method of compounding has the least impact on the physical stability of the admixtures in comparison with the other two variables evaluated in this study. The storage of the admixtures at room temperature for one day was shown to have a greater adverse effect on admixtures with a low dextrose concentration.

Analysis of Variance↗
PubMed1993

The effect of surfactant on drug-plastic sorption phenomenon in solution.

The sorption of calcitriol into PVC from an injectable formulation containing Tween 20, a nonionic surfactant, was studied. The amount of drug sorbed by the plastic decreased as the concentration of the surfactant increased. The apparent partition parameter of the drug between PVC strips and the solution was experimentally determined at three different concentrations of the surfactant. A physical model was developed to describe mathematically the partition equilibrium of the drug between the plastic solid phase, the micellar phase of the surfactant, and the aqueous phase of the solution. This model also allowed the calculation of the drug/plastic and drug/micelle partition parameters using the experimentally determined apparent partition parameters.

Absorption↗
PubMed1993

[Laser cholelithotripsy through choledochofiberscope: report of 30 cases].

Laser cholelithotripsy was performed in 30 patients. Stones crushed by the laser were completely removed in 29 patients (96.7%) without any complications. Animal experiments and clinical application showed that the procedure caused no damage to the bile duct. But when the duct was flushed by flow water at a speed of not less than 15 ml a minute, with the tip of quartz fiber of Nd-YAG laser attached directly to the stone, the beam was radiated with 50 to 60 watt power for 1 minute each time in an interval of 1-3 minutes. Cholelithotripsy is indicated for patients with large or impacted residual stones after cholelithotomy, which can not be removed by choledochofiberscope and retrieval forceps. It can also be used to incise cycloid bile duct stricture with 50 watt power.

Adult↗
PubMed1992

Diffusion control in blood coagulation. Activation of factor X by factors IXa/VIIIa assembled on human monocyte membranes.

This study examines mechanisms that regulate the activation of blood coagulation proteases on intact cell membranes. The activation of factor X by factors IXa and VIIIa assembled on viable monocytes is presented as a biologically relevant model for membrane-dependent proteolysis of coagulation zymogens. The hypothesis that this reaction is limited by diffusion was tested by comparing predicted with observed concentration dependence, temperature dependence, and effective rate coefficient. Rates of factor X catalysis were measured using a chromogenic substrate specific for the product, factor Xa. The value of KR and of K1/2, i.e. concentrations giving half-maximal rates in reciprocal functional titrations with substrate and enzyme, respectively, were directly correlated with the concentration of the titrated component. Arrhenius plots constructed over temperatures encompassing 10-35 degrees C were biphasic with downward concavity. Apparent activation energies were 6.01 +/- 0.93 and 35.84 +/- 8.9 kcal/mol for the interval above and below the inflection point, respectively. The effective rate coefficient calculated from apparent kinetic parameters was 3.58 +/- 0.1 x 10(12) M-1 s-1. This rate is similar to the maximal rate of collision between factor X molecules and the monocyte, i.e. 2.9 x 10(12) M-1 s-1 estimated from the steady-state von Smoluchowski equation for uniformly reacting spherical particles. The observed agreement between predicted and experimental results indicates that under biologically relevant conditions, the rate of factor X activation by the intrinsic protease is controlled by diffusion of factor X toward the catalytic site.

Blood Coagulation↗
PubMed1992

Functional assembly of intrinsic coagulation proteases on monocytes and platelets. Comparison between cofactor activities induced by thrombin and factor Xa.

Generation of coagulation factor Xa by the intrinsic pathway protease complex is essential for normal activation of the coagulation cascade in vivo. Monocytes and platelets provide membrane sites for assembly of components of this protease complex, factors IXa and VIII. Under biologically relevant conditions, expression of functional activity by this complex is associated with activation of factor VIII to VIIIa. In the present studies, autocatalytic regulatory pathways operating on monocyte and platelet membranes were investigated by comparing the cofactor function of thrombin-activated factor VIII to that of factor Xa-activated factor VIII. Reciprocal functional titrations with purified human factor VIII and factor IXa were performed at fixed concentrations of human monocytes, CaCl2, factor X, and either factor IXa or factor VIII. Factor VIII was preactivated with either thrombin or factor Xa, and reactions were initiated by addition of factor X. Rates of factor X activation were measured using chromogenic substrate specific for factor Xa. The K1/2 values, i.e., concentration of factor VIIIa at which rates were half maximal, were 0.96 nM with thrombin-activated factor VIII and 1.1 nM with factor Xa-activated factor VIII. These values are close to factor VIII concentration in plasma. The Vsat, i.e., rates at saturating concentrations of factor VIII, were 33.3 and 13.6 nM factor Xa/min, respectively. The K1/2 and Vsat values obtained in titrations with factor IXa were not significantly different from those obtained with factor VIII. In titrations with factor X, the values of Michaelis-Menten coefficients (Km) were 31.7 nM with thrombin-activated factor VIII, and 14.2 nM with factor Xa-activated factor VIII. Maximal rates were 23.4 and 4.9 nM factor Xa/min, respectively. The apparent catalytic efficiency was similar with either form of factor VIIIa. Kinetic profiles obtained with platelets as a source of membrane were comparable to those obtained with monocytes. These kinetic profiles are consistent with a 1:1 stoichiometry for the functional interaction between cofactor and enzyme on the surface of monocytes and platelets. Taken together, these results indicate that autocatalytic pathways connecting the extrinsic, intrinsic, and common coagulation pathways can operate efficiently on the monocyte membrane.

Blood Platelets↗
PubMed1992

Iontophoretic permeation of sodium cromoglycate through synthetic membrane and excised hairless mouse skin.

The iontophoretic transport properties of sodium cromoglycate were characterized using a synthetic membrane and excised hairless mouse skin. The permeation rate of sodium cromoglycate through the synthetic membrane was found to be linearly dependent on the density of electrical current applied. Passive diffusion through the excised hairless mouse skin was not demonstrated for sodium cromoglycate; however, under iontophoresis, an appreciable permeation was exhibited by the drug through the animal skin, which was also found to be a function of the electrical current density.

Animals↗
PubMed1992

Stability and sorption of calcitriol in plastic tuberculin syringes.

The stability of commercially formulated calcitriol 1 and 2 micrograms/mL and calcitriol formulation subsequently diluted to 0.5 microgram/mL in 0.9% sodium chloride injection, 5% dextrose injection, or water for injection was evaluated after eight hours' storage in polypropylene syringes. The apparent affinities of calcitriol for polypropylene and polyvinyl chloride were also examined. Three calcitriol 0.5 microgram/mL solutions (diluted in 0.9% sodium chloride injection, 5% dextrose injection, or water for injection) and aqueous calcitriol formulations, 1 and 2 micrograms/mL, were placed in 1-mL polypropylene tuberculin syringes and assayed by high-performance liquid chromatography initially and after two, four, and eight hours' storage under room light at ambient temperature. Samples of calcitriol 2 micrograms/mL were also exposed to polypropylene or polyvinyl chloride at room temperature for 20 days. The remaining calcitriol concentrations were determined and apparent calcitriol polymer/water partition coefficients were calculated. Calcitriol concentrations did not change substantially during the eight-hour stability study. The mean apparent polymer/water partition coefficient for polyvinyl chloride was 66 times that for polypropylene, indicating that calcitriol has a definite affinity for polyvinyl chloride but no similar affinity for polypropylene. Aqueous calcitriol solution 1 or 2 micrograms/mL or 0.5 microgram/mL in 0.9% sodium chloride injection, 5% dextrose injection, or water for injection, when stored in polypropylene syringes exposed to ambient temperature and room light, appears to be stable for eight hours. Calcitriol appears to have greater affinity for polyvinyl chloride than for polypropylene.

Adsorption↗
PubMed1992

Stability of ganciclovir sodium in 5% dextrose injection and in 0.9% sodium chloride injection over 35 days.

The stability of ganciclovir 1 and 5 mg/mL in 5% dextrose injection and in 0.9% sodium chloride injection was studied at 25 degrees C and 5 degrees C over 35 days. Ganciclovir (as the sodium salt) was added to 120 polyvinyl chloride bags containing either 5% dextrose injection or 0.9% sodium chloride injection to attain ganciclovir concentrations of 1 and 5 mg/mL. Thirty bags were prepared for each combination of drug concentration and i.v. solution. Half of the bags in each group were stored at 25 degrees C; the other half were stored at 5 degrees C. Samples withdrawn from all 120 bags immediately after preparation were frozen for later determination of initial concentration. At 7, 14, 21, 28, and 35 days after preparation, approximately 5-mL samples representing each test condition were withdrawn for analysis. The samples were visually examined, tested for pH, and assayed by high-performance liquid chromatography. There was no significant loss of ganciclovir under any of the study conditions over 35 days. All solutions were clear throughout the study period. The pH decreased slightly in both diluents at both ganciclovir concentrations but did not deviate from the manufacturer's range (9-11). Admixtures containing ganciclovir 1 and 5 mg/mL (as the sodium salt) in 5% dextrose injection and 0.9% sodium chloride injection were stable in polyvinyl chloride bags stored at 25 degrees C and 5 degrees C for 35 days.

Chromatography, High Pressure Liquid↗