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Biomedical subjects

L Chen

Publications and source records attributed to L Chen.

At least 595 records · Page 33Linked to original sources
PubMed1999

[Relationship between brain edema induced by freezing injury and concentration of Evan blues and cytosolic free calcium in brain tissues].

The authors studied the changes of Evan blues(EB) of brain tissues and concentration of cytosolic free calcium ([Ca2+]i), and relationship between them and water content of brain tissues following freezing brain edema in rats, to elucidate mechanism and type of brain edema induced by freezing injury. The results indicated that there were close positive relationship between water content and EB of brain tissues, and between [Ca2+]i and water content. We found that not only cytotoxic brain edema(intracellular edema) occurred but also occurred vasogenic brain edema(extracellular edema) followed by blood brain barrier breakdown after brain edema. Freezing brain edema is mixed brain edema.

Animals↗
PubMed1999

[Axial aponeurotic flap combined with skin graft in the treatment of lower lid ectropion and severe infra-orbital soft tissue depression].

OBJECTIVE: The correction of ectropion of lower lid and severe infra-orbital soft tissue depression is very difficult. Former methods included simple skin graft, tubed graft, transfer of local skin flap and so on. These methods had some disadvantages, such as not enough tissue to fill the depression, too much damage done to the donor area and operation in stages required. METHODS: After investigation on the anatomy of temporal region, designed the following method. Combined transfer of the galea aponeurotica and temporal fascia was used to repair severe infra-orbital soft tissue depression and ectropion of lower lid in 6 cases. RESULTS: It was discovered that the combined transfer of the galea aponeurotica and temporal fascia was rich in blood circulation because they received blood supply from parietal branch of superficial temporal artery and could be transferred to a distance as far as 15-18 cm. The skin graft used to cover the fascia usually resulted in good survival. This technique was used in 6 cases with good success. CONCLUSION: This method had some merits such as the tissue flap had good blood supply, little damage done to the donor area, good correction of the severe depression, good appearance following correction, operation done under local anesthesia and completed in one-stage operation.

Adolescent↗
PubMed1999

[Pharmacological comparison between volatile oil and water extract].

OBJECTIVE: To compare the pharmacological differences between volatile oil and water extract in eight aromatic drugs for resolving dampness. METHOD: Volatile oil and water extract of eight commonly used aromatic drugs for resolving dampness were ig administered to rats respectively, and the effects of volatile oil and water extract on the secretion of gastric juice, volume of gastric mucous blood flow and activity of SOD in gastric mucous membrane were studied. RESULT: It was shown that the effects of aromatic volatile oil in eight drugs on the indexes mentioned above were generally equal or similar to those of water extract, and it was obvious that the volatile oil in some high oil content drugs such as Amonum cardamomum L(Baidoukou), Alpinia katsumadai Hagata (Caodoukou), Amomum villosum Lour (Saren), and Amomum tsao-ko Crevost et Lem (Caogou) had better effects on the secretion of gastric juice and volume of gastric mucous blood flow that those of water extract. CONCLUSION: It has been pharmacologically proved that in using aromatic drugs for resolving dampness, the loss of aromatic (volatile) components should be avoided.

Animals↗
PubMed1999

[Studies on tannin and hydrolysate in three species of Chinese Caesalpinia plants].

OBJECTIVE: To get Chinese Caesalpinia plants that can replace the imported Tara to produce tannin and gallic acid. METHOD: Extract tannin with water, condense and hydrolyze the extracts with alkali, the hydrolysates were identified. Furthermore, an enlarged scale experiment was conducted. RESULT: Tannin contents of the plants were 32.2%, 46.6% and 58.5% respectively, the converted ratios of raw material to hydrolysate were 154:1, 11.8:1, 3.09-2.79:1 respectively. CONCLUSION: We got the Tara-replacing plants in Chinese Caesalpinia plants for the first time.

Caesalpinia↗
PubMed1999

[Species and distribution of Chinese medicinal plant Caesalpinia].

OBJECTIVE: To gain a clear idea on the resources of medicinal plant Caesalpinia in China. METHOD: Conducting field investigation and consulting related specimens and data. RESULT: The distribution, growing environment and medicinal parts of 14 species of Caesalpinia have been clarified, and a key for their identification is given. CONCLUSION: A scientific basis for further study of the medicinal plant Caesalpinia in China has been provided.

Caesalpinia↗
PubMed1999

[Forensic medical examination of "5.8" Shenzhen air crash].

The air crash of B-2928 on May 8 1997 in Shenzhen was reported, which caused 35 dead and 37 wounded. The interval and cause of death, degree of injuries, cause of the accident and individual identification were investigated. Forensic measures to deal with such tragedies were suggested and discussed.

Accidents, Aviation↗
PubMed1999

[Forensic medical identification of death due to poisoning of tetrodotoxin in puffer fish].

One case died of poisoning of tetrodotoxin in dry fugu fillet was reported. Through the detailed forensic examination for this lethal case, many questions about forensic medical identification of death due to poisoning of tetrodotoxin was discussed and its medico-legal significance was also discussed. In particular, emphasis was placed on the details of a case, extraction of TTX in specimen, quantitative detection of TTX, purplish mouth and nails, dilatation of stomach and intestines, excluding other causes and combining animal experiment in order to get definite forensic medical identification.

Adult↗
PubMed1999

[Expression of CDK4 protein in oral carcinogenesis].

OBJECTIVE: To study the expression of cyclin dependent kinase 4(CDK4) protein in oral carcinogenesis. METHODS: An LSAB immunohistochemistry method was applied to 80 cases of paraffine-fixed tissues to study the expression and distribution of CDK4 in normal oral mucosa, oral premalignant lesion (OPL) and oral squamous cell carcinoma. RESULTS: The overexpression of CDK4 protein was observed in the progression of OPL. Meanwhile, a correlation analysis was applied to investigate the relationship between P16 and CDK4 expression, and the result showed that the coefficient of correlation was 0.813, which was statistically significant. CONCLUSION: The overexpression of CDK4 is involved in the progression of OPL, and there is a positive feedback loop between CDK4 and P16.

Cyclin-Dependent Kinase 4↗
PubMed1999

[Bilateral large vestibular aqueduct syndrome (7 cases reported)].

OBJECTIVE: To explore the CT features and the auditory threshold in patients with bilateral large vestibular aqueduct syndrome. METHOD: The diameter of vestibular aqueduct in CT and the auditory threshold in each ears of seven patients were measured. RESULT: Asymmetry of the enlarged vestibular aqueduct was found in all patients of whom the side the vestibular aqueduct enlarged was found having a greater hearing loss than the other side in the same patient (paried t-test; P < 0.05). CONCLUSION: The measurement of vestibular aqueduct may be useful in determining the prognosis of patients with large vestibular aqueduct syndrome.

Adolescent↗
PubMed1999

[Distribution of luteinizing hormone (LH) and human chorionic gonadotropin (hCG) in the nervous system, Hatschek's pit and gonads of protochordata].

Immunocytochemical localization of the nervous system, Hatschek's pit and gonads in protochordata was carried out using two specific antibodies against human LH and hCG. The results indicate that there are two different kinds of LH- and hCG-like immunopositive cells in the brain vesicle and nerve tuber of amphioxus, and nerve ganglion in Styela plicata showed immuno-negative reaction to LH and hCG antibodies. At the same time, we found for the first time that LH- and hCG-like immuno-positive cells existed in the early gonads (ovaries and testis) in protochordata. Positive substance distributed in the cytoplasm, nucleoplasm and nucleolar membrane of oogonia as well as early spermatogenic cells in testis. Afterwards, this positive substance was still distributed in the cytoplasmic membrane, cytoplasm, nuclear membrane and nucleoplasm of oocyte during the development and maturation of ovary, and spermatid and spermatozoa showed immuno-negative reaction in testis. These results will provide a new mophological proof that LH and hCG may be directly involved in regulation of the gonadal development and maturation of protochordata.

Animals↗
PubMed1999

[Determination of dicarboxylic acids in a new compound liquid fertilizer by gas chromatography].

A method for determination of succinic acid, glutaric acid and adipic acid in a new compound liquid fertilizer by gas chromatography is described. The sample after dried at 80 degrees C was extracted by ethyl alcohol, and then esterified in the presence of BF3. The esterified derivatives were injected into a gas chromatograph with a 5% SE-30 packed column, programmed from 140 degrees C (held for 1 min) to 160 degrees C (held for 6 min) at a rate of 6 degrees C/min. Internal standard was diethyl malonate. Calibration curves of the three diethyl esters were linear in the ranges of 2.3-9.3 micrograms, 10.8-43.2 micrograms and 2.8-11.0 micrograms respectively.

English Abstract↗
PubMed1999

[Preparation and application of a new chloromethylstyrene encapsulated silica single anion column].

The silanized silica was firstly encapsulated with chloromethylstyrene and then quaternized by N, N-dimethylbenzylamine. Thus a new kind of strong anion stationary phase was prepared. This strong anion silica column has superior separation ability for the anions by using indirect ultraviolet detection with wavelength at 254 nm and the mobile phase of V(methanol):V(0.125 mol/L NaH2PO4) = 60:40. Moreover, separation of mono- and di-petroleum sulfonates in Yumen sample could also be good with gradient elution. The sample was first eluted with 100% A [V(methanol):V(water) = 60:40] for 1 min, then the eluent was changed linearly to 100% B [V(0.125 mol/L sodium phosphate monobasic):V(methanol) = 60:40] within 1 min, then the sample was continuously eluted with 100% B for 6 min.

Chromatography, High Pressure Liquid↗
PubMed1999

[Chiral separation of thio-glycidyl ether on amylose-chiral stationary phase by high performance liquid chromatography].

In the present study, we synthesized amylose-tris(phenylcarbamate), and used it as chiral stationary phase based on silica gel. This stationary phase offered a practically useful chiral separation medium. Amylose was allowed to react with an excess of phenylisocyanate in pyridine for 48 h. The obtained carbamate was dissolved in DMF and adsorbed on silica gel previously treated with 3-aminopropyltriethoxysilane. The mass ratio of the carbamate to the silica gel was 0.45/2.55. The four thio-glycidyl ethers were resolved on the amylose tris(phenylcarbamate) chiral stationary phase. Separation was carried out with a hexane/2-propanol mixture as mobile phase at a flow rate of 1.0 mL/min at room temperature. The effects of 2-propanol concentration on the retention and resolution have been investigated.

Amylose↗
PubMed1999

[Chiral separation of thioglycidyl ether and glycidylselenide on cyclodextrin bonded stationary phase via high performance liquid chromatography].

beta- Cyclodextrin bonded chiral stationary phases (CD-CSP) were prepared after the method of Armstrong (CD-CSP I) and of Huang Tianbao (CD-CSP II). With the separation of o-, m- p-nitroaniline, it was found that the chromatographic properties of CD-CSP II was superior to that of CD-CSP I. Three racemes of thioglycidyl ethers and two racemes of glycidylselenides were resolved on CD-CSP II via high performance liquid chromatography. The mobile phase consisted of different volume ratios of methanol/0.3% triethylammonium acetate buffer solution(pH 5), and the eluate was detected with a UV-visible detector at a wavelength of 254 nm. With the increase of methanol volume ratio in the mobile phase, the retention time decreased rapidly, but within the range of methanol valume ratio 40/100 to 50/100, the separation factor only decreased slightly. The racemes examined contained aromatic groups and hydroxy groups which can form inclusion complexes and hydrogen bonding interactions with beta-cyclodextrin. The chiral separation of the racemes is successful with the mobile phase of V(methanol):V(buffer) = 40:60.

Aniline Compounds↗
PubMed1999

[The effect of cAMP on the transcription and regulation of angiotensin II type 1 receptor gene in cardiomyocytes of neonatal rats].

OBJECTIVE: To clarify the effect of cAMP on the transcription of angiotensin II type 1 (AT1) receptor mRNA in cardiomyocytes. METHODS: Cardiomyocytes from SD neonatal rats were cultured in DMEM containing 10% fetal bovine serum (FBS) with 0.1 mmol/L 5-bromodeoxyuridine (Brdu). At day 5-7, primary cultured cells were used. FBS and Brdu were deprived 24 h before the stimulation. The levels of AT1 mRNA in primary cultured cardiomyocytes were examined by RT-PCR. RESULTS: Stimulation of forskolin (30 mumol/L) plus 3-isobutyl-1-methyl-xanthine (IBMX, 30 mumol/L) which induced the accumulation of cellular cAMP decreased the expression of AT1 receptor mRNA to (64.4 +/- 20.3)% of control at 6 h treatment; while it increased the expression of AT1 receptor mRNA to (209.6 +/- 24.0)% of control at 48 h treatment. CONCLUSIONS: cAMP regulated the transcription of AT1 receptor gene.

Animals↗
PubMed1999

[Angiotensin II regulates the expression of collagens in rat heart].

OBJECTIVE: To testify the effect of angiotensin (Agn) II on the regulation and expression of collagen I, III genes in rat heart as well as the influence of DMP811 (a novel nonpeptide selective angiotension type 1 antagonist) on the effect of Ang II. METHODS: Six-week-old male SD rats with osmotic minipump subcutaneously containing either Ang II or saline were used. (1) Saline-infused(control) group (n = 6), (2) Ang II-infused group (n = 6). (3) Ang II-infused and DMP811-treated (3 mg.kg-1.d-1, by gavage) group (n = 6). Ang II (200 ng.kg-1.min-1) or saline was continuously infused for 1 week. After extraction of cardiac total RNA, the levels of collagen I, III mRNA and proteins were measured with RT-PCR and Sirius red staining respectively. RESULTS: Cardiac weight, cardiac weight/body weight radio, the mRNA levels of collagen I, III were increased by (4.7 +/- 0.4)%, (4.9 +/- 0.9)%, (22.0 +/- 4.7)% and (20.6 +/- 4.9)% respectively, in group 2 compared with those in group 1. The analysis of collagen on Sirius red-stained sections showed that Ang II increased the deposits of both collagen I and III. The above changes caused by Ang II could be inhibited fully by DMP811. CONCLUSIONS: Ang II up-regulated the expressions of collagen I, III via angiotension type 1 receptor.

Angiotensin II↗
PubMed1999

[The improvement on related condition of corneal cryopreservation and roles of cryopreserved corneas in emergent keratoplasty].

PURPOSE: To study the cryopreserved corneal endothelium viability on the condition that a series of related factors on long-term corneal cryopreservation were modified. The frozen corneas were used for emergent penetrating keratoplasty on poor condition patients. To evaluate the role of cryopreserved corneas on clinical application, especially on emergent keratoplasty. METHODS: Residual peripheral corneas were stained with Trypan blue and Alizarin red in order to assess endothelium survival rate after central grafts were punched. Specular microscope was used to measure corneal thickness and count endothelium density. The transparent rate of grafts, infective control rate, retinal restorative rate and the recovery degree of visual acurity were emphasized respectively. RESULTS: Endothelium survival rate of grafts was 82.1% averagely. Postoperative endothelium density was 1,642 cells/mm2 and graft thickness was 0.59 mm averagely. The epithelial defects healed after 2-5 days of the operation and edematous grafts were reclear after 2-4 weeks of the operation in all grafts, except for chemical burn and thermal burn. The transparent rate was 87.5%. Infective controll rate was 90.63%. Retinal restorative rate was 55.56%. Some useful visual acurity can be obtained when the infection was under controlled and the retinal was reattached. CONCLUSION: Modified long-term corneal cryopreservation is effective in maintaining endothelium viability and integrity. Furthermore, it could provide donors anytime because of it's unlimited preservative duration. Our study emphasizes especially the role of cryopreserved corneas in emergent keratoplasty.

Adolescent↗