[Study of enamel caries-lesion produced by artificial plaque]

The authors used the cariogenic bacteria isolated from human dental plaque to produce an artificial plaque which can produce carious lesion in vitro. Lesions on human enamel slabs produced by artificial plaque and single bacterium were observed under polarized light microscope and scanning electron microscope. The results showed that the characters of artificial carious lesions are very similar to natural enamel caries. It is very difficult to differentiate them under the microscopes. Compared with the lesions produced by single strain, the destructive fashion observed in lesions produced by artificial plaque is more similar to the changes produced by natural dental plaque.

[Analysis of follow-up data in 83 cases of primary liver cancer]

Eighty-three patients with primary liver cancer (PLC) having survived over 5 years were investigated. 50.6% (42/83) of them were in Stage I and 49.4% (41/83) were in Stage II. Resection was performed in 94.0% (78/83), and hepatic artery ligation and/or cannulation was done in 6.0% (5/83). By the end of March 1990, 66.3% (55/83), were cancer-free, 4.8% (4/83) were living with the cancer, 20.5% (17/83) died from recurrence or metastasis of cancer, 7.2% (6/83) died from liver failure, and 1.2% (1/83) lost followup. 29 cases survived over 10 years after resection of PLC. A comparison with 811 patients having less than 5 years during the same period demonstrates that early discovery, lower gamma glutamyl transpeptidase (gamma-GT) and alanine aminotransferase (ALT), tumor less than or equal to 5 cm, single nodule, well-encapsulated tumor, radical resection, and alpha fetoprotein (AFP) normalization after resection may contribute to prolonged survival. It is concluded that early detection and early radical resection are essential to improve the therapeutic effects.

[Diagnosis, treatment and prognosis of single-nodular minute hepatocellular carcinoma]

This article presents 14 patients of single-nodular minute hepatocellular carcinoma (HCC less than or equal to 2 cm) with coexisting cirrhosis. Of these nine patients were discovered by alpha-fetoprotein (AFP) mass screening or health check-up; and five by follow-up observations of chronic liver disease. All the 14 patients received radical resection with no operative mortality. The 1-5 year survival rates after resection were 100% (14/14), 100% (12/12), 100% (11/11), 100% (9/9), and 100% (7/7), respectively. This study demonstrates that the key point of further improvement in the detection of minute HCC lies in the establishment of diagnosis at a relatively low AFP level (less than 200 ng/ml). Realtime ultrasonography is the diagnostic modality of first choice in screening and monitoring. Surgery is strongly indicated for minute HCC with compensated liver function; Limited resection is the main type of resection for minute HCC with liver cirrhosis. The present data also indicate that HCC is not always multicentric in origin, even in patients with liver cirrhosis Intrahepatic spreading rather than multicentric origin may play a more important role in the multinodular pattern of HCC.

[Electron microscopic observation of the effects of Rhodiola kirilowii (Regel.) Maxim. in preventing damage of the rat viscera by a hypoxic high altitude environment]

This paper has shown that the pathologic damages done to rat's viscera due to hypoxic environment of altitude can be reduced significantly by oral administrations of Shengmaiyin, Danshen-Chuanxiong mixture and Rhodiola kirilowii. Shengmaiyin that maintains interior substances in the plate layer bodies proves more effective than Danshen-Chuanxiong mixture, while the latter excels in preventing capillary contraction, thus improving blood circulation. Rhodiola kirilowii has the effects of both Shengmaiyin and Danshen-Chuanxiong mixtures.

[Hemodynamic effects of nifedipine on pulmonary hypertension secondary to congenital heart disease with shunts]

Ten patients (pts) with pulmonary hypertension (PAH) secondary to congenital heart diseases (CHD) with left to right and bidirectional shunts were studied by right heart catheterization. After getting the control hemodynamic data, pts were given nifedipine (NIF) capsule 10-20 mg sublingually and their pulmonary artery pressure (PAP), systemic blood pressure (SBP), heart rate (HR) were monitored for 60 minutes and the hemodynamic data were redetermined. The results showed that the PAP as well as SBP was decreased and the quantity index of left to right shunt (L-R QI) was also reduced by NIF in L-R shunt group (3/10). In bidirectional shunts group (7/10), 4/7 cases showed total pulmonary artery resistance index (TPRI), pulmonary artery resistance index (PARI) were decreased by 29% (P less than 0.01) and 30% (P less than 0.05) respectively without seriously increased R-L shunts. The other 3/7 pts' TPRI, PARI were increased while systemic vascular resistance index (SVRI) was lowered by 41% (P less than 0.05). The quantity index of pulmonary blood flow (Qlp) was decreased by 30 (P less than 0.05) quantity index of right to left shunt R-L QI was increased sharply by 138% (P less than 0.05) while L-R QI decreased by 76% (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

[Matched investigation of risk factors in coronary heart patients with gallstones]

Seventy-five cases of coronary heart disease with gallstones and another 75 cases without gallstones as controls were studied. The positive rates of previous cholecystitis and chronic intestinal diseases, and familial history of gallstone in the first group were obviously higher than those in the control group (P less than 0.05 & 0.11). The odd ratio (OR) was 4.22, 9.00 and 6.00, respectively. There was no difference in high serous lipid level, obesity, high cholesterol and fat intake (P greater than 0.05) neither group took clofirrate. It demonstrated that susceptible factors for coronary heart disease patients to develop gallstones are probably the same as in general population. The imbalance of lipoid metabolism had no direct associate with gallstones. The synergistic action of the imbalance of lipid metabolism and administration of some kinds of medicine might be a susceptible factor for coronary heart disease patients to develop gallstones.

Isolation and nucleotide sequence determination of a gene encoding a heat-stable enterotoxin of Escherichia coli

An enterotoxin-producing strain of E. coli has been isolated from an infant patient in Shanghai Children Hospital and the gene of its heat-stable enterotoxin has been cloned and sequenced. The pre-pro-STI was composed of 72 amino acid residues corresponding to the encoding of 216 base pairs. There was only one nucleotide difference in the pro-part between this STI gene and the STIb gene reported in the literature. A guanosine base in our STI gene was substituted for a cytosine base in STIb gene resulting in a replacement of proline by alanine. Hence, the STI genes from different human sources are highly conserved though mutagenesis still occurs.

Site-specific degradation of Streptomyces lividans DNA during electrophoresis in buffers contaminated with ferrous iron

Streptomyces lividans DNA contains a modification which makes it susceptible to double-strand cleavage during electrophoresis in buffers contaminated with ferrous iron (which may be present in some batches of EDTA). The cleavage of the DNA is site-specific and the average fragment size resulting from limit digestion of total S. lividans DNA is about 6kb. DNA from Streptomyces coelicolor A3(2) and several other Streptomyces strains, and from E. coli, is not cleaved under the same conditions. A S. lividans mutant has been isolated which lacks the DNA modification. We suspect that many reports of "poor" preparations of S. lividans plasmids may be due to the above effect.

Folic acid and chromosome breakage. I. Implications for genotoxicity studies

Chromosome breakage is significantly lower in culture medium containing folic acid than in medium that does not. This effect is similar to that observed in studies of chromosome fragile sites and suggests that fragile sites and some types of chromosome breakage may share a common mechanism. It also suggests that high non-physiological levels of folic acid in many commonly used culture media may artifactually decrease chromosome breakage.

Comparative studies on spontaneous and mitomycin-C-induced sister-chromatid exchanges in smokers and non-smokers

Both spontaneous and mitomycin-C-induced sister-chromatid exchanges were analyzed in 6 smokers and 6 non-smokers. The average number of spontaneous SCE in smokers' cells was 8.33 +/- 1.08. The frequency in the non-smoking controls was 4.41 +/- 0.72. This difference is highly significant (P less than 0.001). Smokers also had more SCE at all levels of mitomycin C testes. Analysis of variance showed these differences to be highly significant (P less than 0.001).