Biomedical subjects

Y Yan

Publications and source records attributed to Y Yan.

At least 361 records · Page 20Linked to original sources

PubMed1990

[Dissolution of metronidazole stilus].

Metronidazole stilus is a new preparation to be inserted into periodontal pockets for treatment of periodontitis. The certificate and file number of approval given to this new product were issued by the Ministry of Public Health in August, 1989. Its shape looks like a toothpick and the width, thickness and length are 1.5mm, 0.7mm and 3 cm, respectively. The content of metronidazole in each cm of the stilus is 2.2 mg. We have studied the dissolution of the new preparation by rotation basket method. The kinetic process of dissolution approximates first order kinetics. The K, t0.5 and t0.9 are 0.0624 min-1, 12.8 and 38.6 minutes, respectively. The requirement is that the dissolved percentage should not be lower than 60% of the added amount in 30 minutes. In order to have a dissolution test similar to that of the stilus in dental pockets, we examined the dissolution in static condition. The results showed that a very high dissolution rate appeared in the beginning, but it decreased quickly, and 71.76% of metronidazole was not dissolved until 48 hours. So one insertion per two days for clinical use is suggested.

Metronidazole↗

PubMed1990

[Relationship between the precruciate cortex and the ventral lateral posterior nucleus of the thalamus in acupuncture analgesia].

The present study was designed to investigate the relationship between the precruciate cortex (PreCtx) and the ventral lateral posterior nucleus (VPL) of the thalamus in the mechanisms of acupuncture analgesia. Neuronal responses in the nucleus VPL to electrical noxious stimulation of the superficial peroneal nerve were extracellularly recorded. Lidocaine was topically applied at PreCtx. Twenty minutes after the application electroacupuncture (EA) was employed at "Zusanli" and "Huantiao" points for 5 minutes. The nociceptive responses were recorded immediately after cessation of EA and consecutively recorded at the interval of 2 minutes. Similar procedures were made in the control group, in which 0.9% Nacl was topically applied at PreCtx. It was found that topical application of lidocaine at PreCtx did not influence the nociceptive responses of VPL neurons. Following topical application of lidocaine at PreCtx, the nociceptive responses were obviously inhibited 0', 4', 6', 10', and 12' after cessation of EA. In the saline control group the remarkable inhibitory effect of EA was observed 0'-8' after ceasing EA, The results showed that the inhibitory effect of EA in the test group was weaker than that in the control group. However, the difference was not statistically significant. It is suggested that PreCtx participates in the corticofugal modulation of EA effects in the nucleus VPL only to small extent.

Acupuncture Analgesia↗

PubMed1990

[Comparative study on the inhibitory elastase capacity of fructus Forsythiae, radix Salviae Miltiorrhizae, radix Angelicae Sinensis and Ligustrazini].

In this paper elastase capacity was measured with agar radial diffusion using elastin-agar plate. There was a linear correlation between elatase capacity and diameter of agar radial diffusion. Significant inhibitory effects of Fructus Forsythiae, Radix Salviae Miltiorrhizae, Radix Angelicae Sinensis and Ligustrazini Hydrochloridum on elastase were observed and Fructus Forsythiae proved the most effective.

Drugs, Chinese Herbal↗

PubMed1990

[Age-related microvascular changes in human skin].

Microvascular changes in 32 biopsies of normal human skin were observed using electronic computer image analysis. Statistical analysis showed a decrease in microvasculature with increase of age, with significant decreases appearing at ages greater than or equal to 20, suggesting that the changes are closely related to aging of human skin.

Adolescent↗

PubMed1990

[Microvascular injury effects and possibility of early anastomosis in the maxillofacial region following high velocity missile wound: an experimental study in dogs].

In order to provide the basis of microvascular anastomosis for reconstruction of maxillofacial defects from firearm injury by using vascularized free tissue transplantation, we studied the mechanism and pathology of microvascular injuries and the possibility of their early anastomosis. The dogs' face were wounded by 0.7 g or 1.03 g steel spheres whose muzzle velocity were 1300 m/s or 1500 m/s. The injury effects of microvascular angiograms were recorded through high speed X-ray camera at the impacting moment the specimens of small vessel were collected for light and electron microscopy at different times after wound. Some dogs were used for performing microvascular anastomosis in the wound region at different times after wound. We found that there were temporary cavity effects in maxillofacial firearm wounds, in and around which small vessel blunt injuries were found, which spread 3 cm from the wound edge. Microvascular anastomosis 3 days after the wound could get higher shortterm patency rate. These results support the conclusion that if we use microsurgical methods to repair defects in maxillofacial firearm wound region, the pedicles of the flap should be laid beyond 3 cm from the wound edge, and the reconstructive operation should be done 3 days after the wound.

Anastomosis, Surgical↗

PubMed1990

Cloning and identification of a rabbit sperm membrane protein gene.

Antibodies raised against rabbit sperm membrane protein (rSMP-B) interacted with a rat testis cytosolic protein with an estimated molecular weight of 70 kD. The clone expressing rSMP-B was isolated by epitope selection from a rat testis lambda gt11 vector cDNA library. An Eco R1-cut 2.0 kb cDNA fragment encoding rSMP-B was identified. The cDNA fragment (RSD-1) was isolated, subcloned and restriction mapped. Dot hybridization analysis of mRNA prepared from human, rabbit and rat testes showed that the gene encoding rSMP-B is expressed in the testes of all three mammals.

Animals↗

PubMed1990

Nucleic acid sequence of cDNA (RSD-1) encoding a rabbit sperm membrane protein and structural properties of the encoded protein.

The nucleotide sequence of a 2.0 kb cDNA encoding a rabbit sperm tail membrane protein was determined using the chain termination method. Analysis was performed using Sequenase and Klenow enzymes on the target sequence in an M13mp18/19 cloning system. The open reading frame consisted of 438 bp encoding 146 amino acids of the protein, with a calculated Mr of 15507. The hydrophobic amino acid content was 34.9%, and pI was in the vicinity of 5.8.

Amino Acid Sequence↗

PubMed1990

Inhibition of zygote formation and embryo development in mice immunized with monoclonal antisperm antibodies.

Passive immunization of female mice by the intraperitoneal administration of ascitic fluids containing monoclonal antisperm antibodies blocked the development of mouse zygotes to morulae and blastocysts when cultured in vitro. Radioiodinated YWK-I monoclonal antibodies were prepared and administered intraperitoneally to female mice. Significant radioactivity was found in washes of the oviductal lumens. The results suggest that antisperm antibodies block fertilization and may have a deleterious effect on early developing embryos.

Animals↗

PubMed1990

[Study on the risk factors of low birth weight].

To detect the risk factors of low birth weight in the newborns, a case-control study was conducted in 5 Health Stations of Donge-heng District of Beijing from Sept 1985 to June 1986. The subjects of study consisted of 84 infants of low birth weight and their parents with 301 controls. A 2 x 2 table analysis was used in screening important factors and multiple logistic regression was employed to estimate the relative role played by these factors. The results revealed that factors, such as height of parents, maternal nutritional status, prematurity, parents' exposure to the chemicals, fathers' smoking habit were risk factors of importance ranked in order.

Case-Control Studies↗

PubMed1989

Bleomycin hypersensitivity in dyskeratosis congenita fibroblasts, lymphocytes, and transformed lymphoblasts.

We studied the responses of several dyskeratosis congenita (DC) cell lines to the DNA strand-cleaving and base-damaging agent bleomycin. Fibroblasts, peripheral blood lymphocytes, and transformed lymphoblasts of six DC patients and an obligate DC heterozygote showed more chromatid breaks than did respective controls exposed to various concentrations of bleomycin during the G2 phase of the cell cycle (P less than 0.0001). Unsynchronized DC fibroblasts in culture also showed decreased survival, compared to normals, following bleomycin treatment. DC lymphocytes treated with bleomycin for the final 24 h of culture showed more chromatid- and chromosome-type damage than did normals (P less than 0.0001) or G0-treated DC lymphocytes. Spontaneous chromosome breakage was normal in all six DC cell lines. The ability to distinguish affected and heterozygous DC cells without spontaneous chromosome instability from normals on the basis of their bleomycin hypersensitivity provides a marker for future studies of the pathogenesis of this disorder.

Bleomycin↗

PubMed1989

[Molecular cloning, gene structure and subcellular distribution of 7s RNA of rat liver cells].

The cDNA copy of in vitro polyadenylated 7s RNA from rat liver cells have been cloned and sequenced. One clone (p 24) contains a 7 s cDNA fragment with 180 bp from 3'end. Sequence analysis indicated that 7s RNA in rat liver cells showed at least one nucleotide substitution compared with that in rat Novikoff hepatoma cells. Southern blot of rat liver and hepatoma genomic DNA shows that 7s RNA gene is a multigene family (10-20 copies per haploid genome) and these loci seems not to be clustered, but have a dispersed array in the genome. We have determined the subcellular distribution of 7 s RNA in rat liver cell by means of RNA-excess hybridization. The result indicated that 42% 7s RNA exists in cell nuclei. Dot hybridization to RNA from liver cells and hepatoma cells proved that the normal liver cells contain relatively more 7 s RNA than that in hepatoma cells.

Animals↗

PubMed1989

[Clinical, immunophenotypic and cell cyclic analysis in chronic lymphocytic leukemia].

15 cases of chronic lymphocytic leukemia (CLL) were immunophenotyped with a panel of monoclonal antibodies. 13 cases were B-CLL, which was characterized by CD20+, HLA-Dr+, SmIg+ and CD5+/Em+. 2 cases were T-CLL, one with Ts phenotype and HLA-Dr+ T-Cll in the other. The ratio of G0 + G1 cells in bone marrow of CLL was 91.1 +/- 2.3% (76.0 +/- 5.1% in controls), while S + G2M cells was 8.9 +/- 2.3% (23.9 +/- 5.1% in controls). The ratios of various cyclic cells were similar in bone marrow and in peripheral blood. Prolymphocytoid transformation developed in the late stage in 3 CLL patients. The clinical course, cytochemistry and immunologic changes in CLL were also analysed.

Aged↗

PubMed1989

[Tracheo-bronchoplasty: a report of 99 cases].

This paper reported 99 patients (10 with benign lesions and 89 malignant tumors) treated by tracheo-bronchoplasty. Postoperative complications occurred in 11 patients. Of whom 5 died of bronchovascular fistulas, respiratory failure, empyema, or spontaneous pneumothorax. On follow-up, among 13 patients with tracheal carcinoma treated by tracheal and/or carinal reconstructions, 4 lived for more than 5 years, 2 more than 3 years, 1 less than 1 year, and 6 died within 2 years. The survival rates of patients with bronchoplasty for lung cancer were 64.5% and 42.9% at 3 and 5 years, respectively.

Adolescent↗

PubMed1989

[Experimental study of antigastroesophageal reflux by preservation of the lower esophageal sphincter].

Gastroesophageal reflux and its resultant esophagitis are common complications following removal of the middle and lower part of the esophagus as well as the gastric cardia with reconstruction by simple esophagogastrostomy. Twenty-one dogs were randomly divided into 3 groups: (1) LES preserving group; (2) Nissen's fundoplication group; (3) Sweet's esophagogastrostomy group. Results by esophageal manometry, X-ray video tape recorder, and pathological examination respectively, 3 months postoperatively were compared. Esophageal manometry showed that the pressure of the preserved LES was still present. X-ray video tape recorder revealed that antireflex function was present in the preserved LES. Pathological examination confirmed no signs of reflux esophagitis in the mucosal specimen of the preserved LES group. We concluded that LES is the main barrier of gastroesophageal reflux. The intrathoracic LES could still have the function of anti-reflux.

Animals↗

PubMed1988