[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.

[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.

[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.

[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.

[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.

[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.

[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.

[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.

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.