Resistance to trimethoprim in Haemophilus influenzae

The mechanisms of resistance to trimethoprim in eleven U.K. clinical isolates of Haemophilus influenzae were studied. The levels of dihydrofolate reductase (DHFR) activities in crude extracts from four resistant wild-types were similar to those in susceptible controls. However, activities in extracts from the other seven resistant wild-type isolates, and transformants of two of these, were at least triple those in the sensitive strains. Resistance to trimethoprim was also selected for in vitro during prolonged exposure to the drug and was associated with increased levels of DHFR specific activity in the mutants. DHFR enzymes were, however, still very susceptible to inhibition by trimethoprim. Activities in four extracts, including one from a transformant of a resistant mutant, were reduced by at least 45% following incubation with 10(-8) M trimethoprim. The results suggested that overproduction of the chromosomal DHFR enzyme may be the resistance mechanism in some organisms. The much lower DHFR activities measured in extracts from other resistant isolates may reflect synthesis of chromosomal enzymes that have reduced susceptibility to trimethoprim.

Effects of hyperlipidemic sera and lipoproteins on prostacyclin synthesis by rabbit aortic smooth muscle cells

The effects of various hyperlipidemic sera and serum high density lipoproteins (HDL) and low density lipoproteins (LDL) on the synthesis of prostacyclin (PGI2) by rabbit aortic smooth muscle cells in culture were studied. Data show that HDL induces a dose-dependent increase in the synthesis of PGI2 in smooth muscle cells. Although LDL at comparable cholesterol concentrations to HDL also results in an increase of PGI2 synthesis in a dose-dependent pattern, the extent of this increase is much less than that induced by HDL. Smooth muscle cells incubated with hyperlipidemic serum and hyperlipidemic + aspirin-treated sera synthesize less PGI2 as compared to normal serum, but cells incubated with hyperlipidemic + 8501-treated serum generate an amount of PGI2 similar to that seen with normal serum. We suggest that 8501 may directly stimulate PGI2 synthetase in smooth muscle cells.

Clinical and experimental observations on treatment of peptic ulcer with wei yang an (easing peptic-ulcer) capsule

The therapeutic effects of peptic ulcer treated with cimetidine and Wei Yang An were compared clinically and experimentally by the double blind method. Results showed that the effects of the two are similar, but the long-term effect of Wei Yang An was better. Wei Yang An was also good for most cimetidine resistant ulcers, with few side effect. Animal experiment showed that Wei Yang An inhibited the ulcers.

[Differentiation of Magnolia denudata Desr. flower buds]

The article gives the results of an observation on the differentiation of Magnolia denudata buds. In Huaining County, Anhui Province, differentiation of the buds starts at the beginning of May. By the end of June the differentiation of various parts of the flower is completed. The process takes about 50 days. The differentiation of buds goes on at a fairly fast speed and in a fairly uniform way. Based on the results of the observation, the authors advise that application of fertilizer, especially the top application should not be late. The beginning of March is a very important time for the development of buds in length and size, and for the final harvest as well. The proper time to pick the flower buds comes when they are fully developed before the perianth appears.

Amelogenin post-secretory processing during biomineralization in the postnatal mouse molar tooth

The primary structures, molecular genetics and biosynthesis of the amelogenin protein of the developing tooth are established, but knowledge of their subsequent post-secretory processing and its relation to enamel biomineralization is fragmentary. Preparations of tooth matrix proteins were isolated from molars (M1) of mice from birth to 15 days and analysed by SDS-PAGE and immunochemical methods. Amelogenin proteins, isolated and partially purified by HPLC, were characterized by amino acid analysis and SDS-PAGE. At birth a 26 kDa amelogenin was present that during subsequent developmental stages generated a series of 20-25 kDa amelogenins differing in apparent size by approximately 1 kDa. Amino acid analyses showed that all these amelogenins have amino-terminal TRAP sequences; analyses for both glycosylation and phosphorylation were negative. It is suggested that these post-secretory amelogenins are generated by a sequence of specific carboxy-terminal cleavages, and that the observed post-secretory processing of amelogenin is functionally linked to the structure of the enamel matrix and the control of crystallite development.

[Preparation, identification and functional studies on liposome (ApoA-I:PC)]

Liposome (ApoA-1: PC) was prepared by the deoxycholic acid dialysis method and identified by agarose gel electrophoresis, two dimensional thin-layer chromatography and electron microscopy. The purified liposomes manifested one band in Amino black 10B staining and no color in Oil red O staining due to the presence of phospholipid. Only one brown spot appeared in two dimensional TLC, and electron microscopy with 1% sodium phosphotungstate negative staining revealed discoidal shapes stuck together. All of the above indicate that the liposome consisted of ApoA-1 and PC. Liposomes were added to the medium of smooth muscle cell cultures and then LDL receptor expression and cholesterol efflux from the cells were observed. The results suggest that the ApoA-1:PC can enhance the expression of LDL receptors indirectly by stimulating cholesterol efflux from the cells.

[Studies on the toxicity of a new synthetic drug SC1001-aminum]

SC1001A is a new sedative, hypnotic and anti-epileptic drug. Screening for possible mutagenicity of the agent consisted of a battery scheme of short-term mutagenic tests with different hereditary detecting end points. Three assays were with in the scheme: Ames test (for detecting gene mutation in vitro), micronucleus test (for detecting chromosomal aberration in vivo) and CHL (Chinese hamster lung cell line) test (for detecting chromosomal aberration in vitro). In addition, a routine teratogenicity study on SC1001A was carried out in mice. They were given daily at 3-dose levels (exposed to up to 33% of the LD50 by gastric incubation from the 6th through the 15th day of gestation. SC1001A gave uniformly negative results in all three mutagenic assay systems. Results of the teratogenic experiment showed that only the pregnant rate in bred mice in the moderate dose group and the mean maternal body weight gain of the dams during gestation in the low dose group were significantly lower than those in the corresponding control group. A clear dose-response relationship was not demonstrated. All dose levels of SC1001A used caused no adverse effects on the number of survival fetuses per litter, growth or development of the fetal mice. No malformations in the external appearance, of the internal organs and of the skeletal systems in fetal mice were observed. The above-mentioned results indicated that SC1001A induced neither gene mutation nor chromosomal damage both in vitro and in vivo. There was no evidence of teratogenesis. Therefore, it is estimated that SC1001A is probably comparatively safe as a pharmaceutical product for human beings in usual dosage.

Regulation of luteinizing hormone secretion in prepubertal heifers fed an energy-deficient diet

The effects of feeding a diet restricted in energy on the endocrine mechanisms regulating LH secretion in prepubertal heifers were examined. On Day 0, thirty heifers were assigned to be either ovariectomized (OVX; n = 10), ovariectomized and administered an estradiol implant (OVXE; n = 10), or to remain ovary-intact (INT, n = 10). Five heifers each were then assigned to be fed either a control (C) or a two-phase, low-to-high energy (L), dietary treatment. The C diet was formulated to support weight gains of 1.1 kg/day throughout the experiment (Day 0-197). Heifers receiving the L treatment were provided a diet restricted in energy (33% of C diet) from Day 0-127 followed by a diet similar to that fed to heifers receiving the C treatment from Day 128-197. Secretion of LH increased rapidly following ovariectomy in C-OVX and L-OVX heifers. During the period of energy restriction, LH pulse frequency was reduced, and mean LH concentration, pulse amplitude, and pituitary response to LHRH were greater in L-OVX than in C-OVX heifers. In L-OVXE and L-INT heifers, secretion of LH was low and unchanged during the period of dietary energy restriction. In contemporaneous treatment groups fed the C diet (C-OVXE and C-INT), frequency of LH pulses increased gradually during this period and C-INT heifers attained puberty on Day 121 +/- 18. Upon switching heifers in the L-OVX, L-OVXE, and L-INT treatments to the C diet, all characteristics of LH secretion changed markedly within 14 days to levels similar to those detected in the C treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of cloprostenol sodium and clenbuterol HCl on reproductive performance in postparium anestrous cows

Two experiments were conducted to study effects of cloprostenol sodium (cloprostenol) and clenbuterol HCl (clenbuterol) during postpartum anestrus on subsequent reproductive performance in cows. In Experiment I, 96 cows received either 0.5 mg cloprostenol (PGF, n = 25), 364 mg clenbuterol (CLEN, n = 24), 0.5 mg cloprostenol and 364 mg clenbuterol (CLEN+PGF, n = 21) or no treatment (Control, n = 26) on Day 20 post partum. Treatments failed to influence postpartum interval, pregnancy rate or the incidence of short estrous cycles preceding the first normal estrous cycle. In Experiment II, anestrous cows were administered cloprostenol (0.5 mg) on either Day 20 (PGF20, n = 27) or Day 35 post partum (PGF35, n = 25), or served as untreated controls (Control, n = 26). Neither postpartum interval nor pregnancy rate were affected by cloprostenol treatment. In conclusion, treatment of postpartum cows with PGF did not alter the resumption of normal estrous cycles following parturition.

[An epidemiological survey of gallstones with gray-scale ultrasound]

Gray-scale real-time ultrasound has been employed to investigate gallstone with a positive result of 553 cases out of 15,856 healthy subjects in city and countryside, the incidence being 34.88%. The feature of incidence is as follows: 1. The incidence of the simple gallbladder stone is more common than that of the other sites (male is about 81.15%, female is about 87.29%); 2. The incidence of gallstones of city residents is higher than that of the country people with significant difference statistically (P less than 0.01); 3. The incidence of gallstone in female city residents is higher than male, about 2.5:1, which shows significant difference. (P less than 0.01); 4. The incidence of gallstones in female city residents is higher than in countryside (P less than 0.01); 5. There is no significant difference in the incidence of gallstone between male and female in the countryside (P greater than 0.05); 6. There is no significant difference in the incidence of gallstones between city male and the male in the countryside (P greater than 0.05); 7. Either in the city or in the countryside, it has been shown that there is a tendency of increasing incidence of gallstone with age in both sexes (P less than 0.01). The relationship between the gallstone and the clinical symptoms has been discussed in this paper.

Optical characterization of thin films by guided waves

The study of guided waves in a thin layer allows a precise characterization of refractive index and thickness. Optical anisotropy can also be measured. We show how this technique can be applied to the characterization of a multilayer structure.

Surface optical coatings by ion assisted deposition techniques: study of uniformity

Uniformity of layers produced by IAD strongly depends on the characteristics of the ion beam: optical characterization is made by guided wave measurements. The thickness and refractive index including anisotropy must be considered separately to interpret the measured uniformity.