[Applications of bacterial pathogens to the mosquito control]

Both Bacillus thuringiensis subsp. isrealensis (Bti) and Bacillus sphaericus are common bacteria found in a variety of soil and aquatic habitats. Some strains of them can produce a protein crystal, called parasporal body (or crystal) beside the spore in the cell during sporulation, and it is toxic if eaten by mosquito larvae. As the parasporal bodies are ingested into a mosquito digestive tract, they will be digested and activated by certain enzymes in alkaline digestive juice. The activated toxins can destroy midgut epithelium and other tissues, and then the mosquitoes will be intoxicated and killed. There are some factors affecting efficiency of the toxins produced by these two mosquitocidal bacteria. First, the toxicity of the toxins will decrease as larval age and density increase. Second, difference in mosquito species will demonstrate a different tolerance to both toxins. However, larvae of Anopheles are more tolerant to Bti than those of Aedes and Culex; whereas larvae of Aedes are more tolerant to B. sphaericus than Culex and Anopheles. Environmental factors are as important as the mosquito hosts in influencing the efficiency of the toxins. For examples, raising temperature under suitable ranges may increase the toxicity of the toxins. The UV light of sunlight could inhibit activity of the toxins and therefore decrease their efficiency. Quality and depth of the water are also important environmental factors affecting toxicity of the toxins to the mosquito larvae. The precipitation of the crystal and organic materials absorbing the toxins decreases their toxicity to the mosquito larvae as well.

[Expanded forehead flap for reconstruction of the nose]

Eight cases of reconstruction of nose by using skin expander are reported in detail in this article. In which, 6 cases were total nose reconstruction, 2 were upper partial reconstruction. The results were good in all cases. It is considered that the forehead flap is the place of choice in nasal reconstruction. It gives good shape contour and best color match. After application of tissue expander it could provide more skin for reconstruction, and prove more advantages in repairing the donor site. It has been observed that the reconstructed nose contour was satisfactory, with no obvious constriction after more than a year follow up. The methods and advantages of operation and some typical cases are presented.

c-ras-Ha gene expression is regulated by insulin or insulinlike growth factor and by epidermal growth factor in murine fibroblasts

Although much is known about the structure of ras-encoded proteins, little is known about how expression is regulated. In serum-stimulated murine fibroblasts, c-ras-Ha mRNA levels fluctuated with the growth state but not with the position in the cell cycle. Two types of growth factors regulated c-ras-Ha expression: insulin (IN) or insulinlike growth factor I, each apparently acting through its cognate receptor, and epidermal growth factor (EGF). In quiescent cells, IN or insulinlike growth factor I induced c-ras-Ha mRNA three- to fivefold within 4 h, but thereafter the mRNA declined. By contrast, EGF had little effect in 4 h but induced the mRNA after 4 to 6 h. When quiescent cells were given serum or IN and EGF simultaneously, c-ras-Ha mRNA rose steadily, beginning 1 to 2 h after stimulation, and reached a stable five- to sevenfold elevation in 16 h. Thus, c-ras-Ha gene expression was sequentially regulated by two growth factors, one of which (IN) does not induce expression of other growth-regulated protooncogenes. A transformed derivative cell line that does not require IN for G1 progression has lost early IN-dependent but not late serum-dependent regulation. The results support the possibility that c-ras-Ha and IN action are functionally linked.

A three-year clinical comparison of a sodium monofluorophosphate dentifrice with sodium fluoride dentifrices on dental caries in children

This study compared the anticaries effects of these three fluoride-containing dentifrices: 1100 ppm F as NaF (positive control); 2800 ppm F as SMFP; and 2800 ppm F as NaF. The group using the 2800 SMFP dentifrice showed no significant differences in DMFS or DMFT, compared to the positive control, at anytime during the study. This indicated that higher levels of sodium monofluorophosphate in a dentifrice offer no advantage in caries protection over the conventional level of sodium fluoride, 1100 ppm F.

The effect of a fluoride dentifrice containing an anticalculus agent on dental caries in children

In this double-blind caries study, 1160 Taiwanese children (ages 8-15) completed a program using a test dentifrice containing 1.243 percent sodium fluoride and soluble pyrophosphates, or a control dentifrice without these agents. The average reduction of new carious tooth surfaces was 39 percent with the sodium fluoride dentifrice.

A critical evaluation of some problems associated with clinical caries trials by computer simulation

Unbiased examiners' errors have little effect on the outcome of a clinical trial, provided that they are not larger than 10%. Unbiased error greater than 10% would tend to make the variance larger than expected. Demonstration schemes as discussed in this paper may show spurious positive effects, due to attempts by examiners to avoid reversals in diagnosis. Professional intervention is mostly responsible for the SU component - the direct transition from sound surface to DMF. These surfaces are lost for reasons other than caries activities per se. It should not be included in the measure of caries experience in clinical trials. The component UU represents the surfaces that show incipient caries at two consecutive examinations. It represents mostly past history and has little bearing on current caries activities. Since the DMFS = IU + SU + UU, and the contributions of IU as a rule are small, the use of DMFS as a measure of caries experience in clinical trials is unjustified. The NCI = SI + IU deals directly with the stage where the cariostatic agent is supposed to be working. There is a definite advantage to using this index as the caries experience measure in clinical trials.

Effect of cimetidine on serum prolactin in normal women and patients with hyperprolactinaemia

In normal women, intravenous injection of the H2-antihistamine, cimetidine, provoked a 3-4 fold rise in serum prolactin, without changes in serum growth hormone, thyrotrophin, or gonadotrophins. Hyperprolactinaemic patients with pituitary tumours, idiopathic hyperprolactinaemia or hypothalamic lesions demonstrated little or no rise in serum prolactin (expressed as a percentage increment) in response to cimetidine; these responses were significantly more blunted than the prolactin responses to intravenous TRH in the same subjects. Post-partum women also demonstrated blunted percentage prolactin responses to cimetidine, although responses to TRH were, in most patients, normal. Dynamic testing of prolactin secretion with cimetidine is no more useful than TRH in distinguishing tumourous from non-tumourous hyperprolactinaemia.