Transgenic rice plants produced by electroporation-mediated plasmid uptake into protoplasts

Transgenic rice plants have been regenerated by somatic embryogenesis from cell suspension derived protoplasts electroporated with plasmid carrying the NPTII gene under the control of the 35S promoter from cauliflower mosaic virus. Heat shock of protoplasts prior to electroporation maximised the throughput of kanamycin resistant colonies. Omission of kanamycin from the medium for plant regeneration was essential for the recovery of transgenic rice plants carrying the NPTII gene. This report of the production of kanamycin resistant transgenic rice plants establishes the use of protoplasts for rice genetic engineering.

The epidemiology of childhood burns in Jiamusi, China

The causes and severities of burning injury were analysed in 1006 children admitted to our department over a 11-year period. A substantial number of patients were less than 5 years old. Proportionally more boys and less girls were injured. More of the accidents occurred in summer and winter and less during the spring and autumn; more occurred in the rural and mountain areas than in the cities. In the younger children 88 per cent of the injuries occurred at home while eating and drinking, only a few burns happening in kindergarten and school. This report suggests which methods of prevention should be stressed.

Antiviral effect of lymphokine-activated killer cells: characterization of effector cells mediating prophylaxis

Lymphokine-activated killer (LAK) cells generated by cultivation of C57BL/6 mouse spleen cells in the presence of recombinant interleukin-2 were transferred into natural killer (NK) cell-deficient suckling mouse recipients. These mice were then challenged with either murine cytomegalovirus (MCMV) or lymphocytic choriomeningitis (LCMV) and sacrificed 3 days later. No interleukin 2 infusions were given. Mice receiving as few as 5 x 10(5) LAK cells had several 100-fold decreases in spleen MCMV titers as compared with untreated mice. This treatment had no effect on spleen LCMV titers. The LAK cell cultures contained 10 to 17% NK 1.1+, 50 to 55% Lyt-2+, and 33 to 50% immunoglobulin D+ cells. Double fluorescence labeling and in vitro cytotoxicity assays with fluorescence-activated cell sorting revealed at least two mutually exclusive killer cell populations. NK 1.1+ LAK cells resembled freshly isolated activated NK cells with regard to target cell range (YAC-1 cell killing greater than L-929, P815, and EL-4 cell killing), large granular lymphocyte (LGL) morphology, and decreased ability to lyse interferon (IFN)-treated target cells. Lyt-2+ LAK cells lysed the targets mentioned above but at lower levels and without the differences in susceptibility mentioned above. These Lyt-2+ LAK cells also had a decreased ability to lyse IFN-treated targets, in contrast to classic cytotoxic T lymphocytes, which lyse IFN-treated targets far more efficiently than untreated targets. Purified populations of LAK cells obtained by fluorescence-activated cell sorting were used in the antiviral protection model. The results showed that protection against MCMV could be mediated by NK 1.1+, NK 1.1-, Lyt-2+, Lyt-2-, and IgD- populations but not by IgD+ cells. The five protective populations all had in common the LGL phenotype and cytotoxic activity in vitro. The IgD+ population did not contain LGLs, lyse target cells in vitro, or mediate an antiviral effect in vivo. These results suggest that LAK cells may be therapeutically useful against certain virus infections (MCMV) but not others (LCMV) and that despite their heterogeneity in antigenic phenotype and cytotoxic activity, their pattern of antiviral activity in vivo resembles that of NK cells, which protect against MCMV but not LCMV.

Production of kanamycin resistant rice tissues following DNA uptake into protoplasts

Rice protoplasts (Oryza sativa L. v Taipei 309) have been transformed to kanamycin resistance following uptake of pCaMVNEO induced by electroporation, PEG and PEG combined with electroporation. Protoplast-derived colonies selected on medium containing 100 μg/ml of kanamycin expressed NPTII activity, and contained DNA that hybridised to a 1.0 Kb BamHI fragment of pCaMVNEO carrying the NPTII gene. Expression of the transformation frequency in relative terms (number of kanamycin resistant colonies compared to the number of colonies on kanamycin free medium) gave frequencies of 26.1%, 8.5% and 2.9% following electroporation, PEG and PEG with electroporation respectively. In absolute terms (number of kanamycin resistant colonies compared to the number of protoplasts plated) these represent frequencies of 19.9×10(-5), 9.0×10(-5) and 2.7×10(-5) for the three procedures.

Intracisternal injection of CRF antagonist blocks surgical stress-induced inhibition of gastric secretion in the rat

The effects of intracisternal injection of CRF antagonist, alpha-CRF 9-41, on the inhibition of gastric acid secretion elicited by intracisternal injection of corticotropin-releasing factor (CRF) and stress were investigated in conscious pylorus-ligated rats. Intracisternal injection of the alpha-helical CRF 9-41 (50 micrograms) did not influence basal gastric secretion, but injected concomitantly with intracisternal CRF (5 micrograms), completely blocked CRF (5 micrograms)-induced inhibition of gastric secretory volume, acid concentration and output. Intracisternal injection of alpha-helical CRF 9-41 (3, 10, 50 micrograms) produced a dose-related reversal (0, 52 and 100%) of brain surgery-induced inhibition of gastric acid output. By contrast intravenous injection of CRF antagonist (50 micrograms) did not inhibit gastric hyposecretory response to brain surgery. These data suggest that endogenous CRF in the brain may mediate stress-induced gastric hyposecretion in the rat.

Effects of oestradiol benzoate injections, exposure to the boar and age on the attainment of puberty in the gilt

Thirty large white cross Landrace prepubertal gilts from five litters were allocated at random within litters to one of six treatment. All the gilts were given three daily intramuscular injections of 6 micrograms/kg liveweight of oestradiol benzoate but the first injection was given at either 100 days, 120 days, 140 days, 160 days, 180 days or 200 days old. From the time the first oestrogen injection was given, until the end of the experiment, the gilts were allowed daily contact with a boar for 20 minutes. The gilts were mated with a mature boar at the appearance of the second oestrus and they were slaughtered 20 days later. The numbers of gilts ovulating in the treatment groups were determined from plasma progesterone concentrations measured twice weekly throughout the experiment. The numbers of gilts ovulating within 10 days of the oestradiol benzoate injections were 3 of 5, 1 of 5, 0, 0, 3 of 5 and 1 of 5, respectively, in the groups first treated at 100 days, 120 days, 140 days, 160 days, 180 days and 200 days old. For those gilts which were successfully mated, no significant differences were observed between the treatment groups in the number of viable embryos per gilt.

Natural killer cells are not required for interferon-mediated prophylaxis against vaccinia or murine cytomegalovirus infections

Natural killer (NK) cell-depleted or control mice were treated prophylactically with polyinosinic: polycytidylic acid (polyI: polyC) or purified beta interferon (IFN) and then infected with either vaccinia virus or murine cytomegalovirus. NK cell depletion alone enhanced virus titres in the spleen and peritoneal cavity. However, poly I: polyC and IFN inhibited virus replication equally well in control and NK cell-depleted mice. This suggests that prophylactic IFN treatment mediates antiviral effects independently of NK cells.

Effect of a carbohydrate-restricted, calorie-reduced diet on the growth of young rats and on serum growth hormone, somatomedins, total thyroxine and triiodothyronine, free T4 index, and total corticosterone

We have studied the effect of a carbohydrate-restricted, calorie-reduced diet on the growth of young rats and on serum levels of GH, somatomedins [insulin-like growth factors (IGFs) I and II], total T4 and T3, free T4 index, and total corticosterone. Experimental animals consumed the same quantities of protein and fat as controls, but only 50.3% as much carbohydrate and 76% as many calories. While the experimental group grew at 69.4% of the control rate, their mean (+/- SEM) GH level (175.7 +/- 36.9 ng/mL) was not significantly different from that in the control group (180 +/- 30 ng/mL). In contrast, serum total IGF and IGF-I, while not correlated with serum GH levels, were significantly correlated in all animals with body weight (r = .87 and r = .82, respectively, P less than .01) and tail length (r = .61 and r = .62, respectively, P less than .01). The somatomedin levels of the carbohydrate-restricted rats were significantly lower than those of their age-matched, but not weight-matched, controls by the eighth day of study. Serum T4, T3, and free T4 index were not significantly different in these two groups, while total corticosterone in the experimental group (245 +/- 73 ng/mL) was slightly lower than in controls (292 +/- 80 ng/mL, P less than .05). These data indicate that by restricting carbohydrate intake we have compromised the anabolic use of dietary protein by growing rats, resulting in a retardation of growth and a reduction in serum total IGF and IGF-I levels.

Purification and properties of Escherichia coli 4'-phosphopantothenoylcysteine decarboxylase: presence of covalently bound pyruvate

4'-Phosphopantothenoylcysteine decarboxylase was purified 900-fold from Escherichia coli B with an overall yield of 6%. The enzyme migrates as a single band with a molecular weight of 35,000 +/- 3000 in 10% polyacrylamide gel electrophoresis under denaturing conditions. The native enzyme has an apparent molecular weight of 146,000 +/- 9000 as determined by a gel exclusion column. At pH 7.6 and 25 degrees C, Km = 0.9 mM and Vmax = 600 nmol/(min X mg of protein). The pH optimum for Vmax is between 7.5 and 7.7. Hydroxylamine, phenylhydrazine, potassium cyanide, and sodium borohydride as well as pyridoxal phosphate and pyridoxal inactivated the enzyme. The enzyme contains covalently bound pyruvate as suggested by the isolation of [3H]lactate and pyruvate from [3H]NaBH4-reduced enzyme and native enzyme, respectively. One mole of [3H]lactate was isolated per 39,000 g of [3H]NaBH4-reduced and completely inactivated enzyme, and 1 mol of pyruvate was isolated per 31,000 +/- 4000 g of native enzyme. Mild base treatment released lactate and pyruvate from the reduced and the native enzymes, respectively, suggesting the pyruvate is attached to the enzyme by an ester bond. These findings are in accord with similar results obtained with the horse liver enzyme (R. Scandurra, personal communication). The presence of covalently bound pyruvate in the bacterial and mammalian enzymes suggests that pyruvate plays a major role in the mechanism of action.

Changes in the health situation among the rural population and the challenges to the preventive services in China

China has a population of one billion, of which 80% live in rural areas. Faced with the changing situation in rural health care work subsequent to the economic structural reform in the vast rural areas and their challenges to the prevention services, appropriate measures in Chinese rural health care work were taken. All levels of leaders of health care and other departments were instructed to adhere to the policy of “prevention first”, to expand the functions and tasks of prevention, to reform the current health organisational structure, to strengthen the three-level health care network and to collect funds from various sources to support health care work and the prevention of disease.

Enzymatic transformation of PGH2 to PGF2 alpha catalyzed by glutathione S-transferases

Glutathione S-transferases (GSTs) purified from both rat liver cytosol and microsomes catalyzed the direct reduction of PGH2 to PGF2 alpha. As much as 40% of the substrate was transformed into a prostanoid whose Rf value corresponded to that of PGF2 alpha. The identification of the reaction product as PGF2 alpha was confirmed by TLC and reverse-phase HPLC as well as by mass spectral analysis. In the absence of GSTs, PGH2 was found to be primarily converted to PGE2 and PGD2. Also, PGF2 alpha formation was completely abolished by decylglutathione, a potent inhibitor of both peroxidase and transferase activity associated with GSTs. These results indicate that the direct reduction of endoperoxide moiety of PGH2 to form PGF2 alpha is an enzymatic process. Interestingly, selenium-dependent glutathione peroxidase (Se-GSH-Px) showed very little PGF2 alpha formation from PGH2. However, this enzyme was very active in the reduction of PGG2 to PGH2. In contrast, GSTs were very poor in the conversion of PGG2 to PGH2. Therefore, it is possible that the relative tissue distribution of Se-GSH-Px and GSTs might play an important role in the tissue specific synthesis of PGF2 alpha.

Induction of alloreactive cytotoxic T cells by acute virus infection of mice

Alloreactive cytotoxic T lymphocytes (CTL) distinct from virus-specific CTL and activated natural killer (NK) cells were generated during acute lymphocytic choriomeningitis virus (LCMV) infection of C57BL/6J mice. The alloreactive CTL shared similar antigenic markers (Thy-1.2+, Lyt-2.2+, and asialo GM1-) with the virus-specific CTL that appeared at the same time 7 days postinfection, but had different target specificities. These alloreactive CTL lysed allogeneic but not syngeneic or xenogeneic targets. These were distinct from activated NK cells, which lysed all target cell types, peaked 3 days postinfection, and had a phenotype of asialo GM1+, Thy-1 +/-, Lyt-2.2-. Cold target competition studies indicated that there were several subsets of alloreactive T cells with distinct specificities, and that these alloreactive T cells were not subsets of the virus-specific T cells. Similar types of alloreactive CTL were induced at much lower levels in C3H/St mice. This may indicate that the generation of this "aberrant" T cell activity is under genetic control. Hence, the LCMV infection of C57BL/6J mice induces several cytotoxic effector populations including alloreactive CTL, activated NK cells, and virus-specific CTL. Virus infections therefore have the ability not only to polyclonally stimulate B cells, as previously described, but also to stimulate CTL.