FPF1 promotes flowering in Arabidopsis

We have characterized the gene flowering promoting factor1 (FPF1), which is expressed in apical meristems immediately after the photoperiodic induction of flowering in the long-day plants mustard and Arabidopsis. In early transition stages, expression is only detectable in the peripheral zone of apical meristems; however, later on, it can also be found in floral meristems and in axillary meristems that form secondary inflorescences. The FPF1 gene encodes a 12.6-kD protein that has no homology to any previously identified protein of known function. Constitutive expression of the gene in Arabidopsis under control of the cauliflower mosaic virus 35S promoter resulted in a dominant heritable trait of early flowering under both short- and long-day conditions. Treatments with gibberellin (GA) and paclobutrazol, a GA biosynthesis inhibitor, as well as crosses with GA-deficient mutants indicate that FPF1 is involved in a GA-dependent signaling pathway and modulates a GA response in apical meristems during the transition to flowering.

Prospective, open-label, add-on study of lamotrigine in 56 children with intractable generalized epilepsy

The role of lamotrigine (LTG) in childhood epilepsy is emerging. We evaluated the efficacy and adverse effects of LTG in an open, prospective study of 56 children with generalized epilepsies. Six (11%) children became seizure-free, and 24 (43%) had greater than 50% reduction in seizure frequency. LTG was effective against a broad range of generalized seizure types. Three of 15 patients with Lennox-Gastaut syndrome achieved complete seizure control and eight demonstrated 50 to 99% improvement in seizure control. Increase in seizures (7) and rash (5) were the most common side effects. After valproate was discontinued, LTG therapy was resumed, with no recurrence of rash in any patient. This study suggests that LTG may be a useful drug in the treatment of generalized epilepsies in children.

[Effects of preoperative transcatheter hepatic arterial chemoembolization (TAE) on the prognosis of patients with hepatic carcinoma undergoing tumor resection]

This study consists of 77 hepatocellular carcinoma patients. Twenty-six (Group A) received preoperative TAE and 51 did not (Group B). Group A and B were further divided into two subgroups according to their tumor size i.e. Group A1 and B1 (tumor size 3-8 cm); Group A2 and B2 (tumor size > 8 cm). The 1-, 2-, 3-year disease free survival rates were 50.0%, 33.3%, 16.6% for Group A1 and 72.7%, 54.2%, 39.7% for Group B1; 75.0%, 56.2%, 45.0% for Group A2 and 38.9%, 32.4%, 10.8% for Group B2 respectively. The 1-, 3-, 5-years survival rates were 85.7%, 31.2%, 0 for Group A1 and 84.8%, 58.7%, 27.9% for Group B1; 91.6%, 82.5%, 53.0% for Group A2 and 77.8%, 30.1%, 0 for Group B2 respectively. There were significant differences between Group A2 and B2 both in disease free survival rate and 5-year survival rate (P < 0.05). The results also demonstrated that the preoperative TAE did worsen the prognosis of patients with tumor size between 3-8 cm (Group A1) with disease free survival rate and 5-year survival rate shorter than that of Group A2.

Engineering stabilized ion channels: covalent dimers of alamethicin

The peptide alamethicin forms channels with a variety of conductance states. Selective stabilization of a particular state should simplify the task of understanding conductance in terms of channel structure. We synthesized two different covalent dimers of alamethicin in which peptides were linked at their C-terminal ends by flexible tethers. Both dimeric peptides formed channels with conductances that matched those of alamethicin channels. Particular conductance states were selectively stabilized, however, with lifetimes up to 170-fold longer than the same states observed with monomers. In addition, tethering appeared to limit the size of the structures formed so that, even at higher peptide concentrations, a single predominant conductance state was obtained. We suggest this state corresponds to a channel made from six alamethicin molecules (three dimers).

[A genetic epidemiological study on lung cancer]

Segregation ratio, heritability and relative risk of genetic susceptibility were estimated for 355 families of lung cancer in matched pair with genetic epidemiological methods. Results showed that segregation ratio for lung cancer was 0.09-0.12 (95% confidence interval, CI) and heritability of lung cancer was (40.58 +/- 4.01)% and (27.58 +/- 4.76)% for smokers and non-smokers, respectively. Relative risks of genetic susceptibility to lung cancer were 4.73 (95% CI 3.90-5.74) and 2.61 (95% CI 2.18-3.13) in their first and second degree relatives, respectively, after adjustment of smoking with a logistic regression model. It was also found that there was an interaction between smoking habit and genetic background of lung cancer. Thus, it is believed that genetic background is one of the multifactorial causes in lung cancer.

[Studies on relationship between toxicity of trichothecene toxin T-2 and its structure]

Toxic action of mycotoxin T-2 and its metabolite T-2 tetraol and deepoxy T-2; tetraol was studied by cytotoxicity and animal toxicity tests to explore the relationship between toxin T-2 and its structure. Restults showed that proliferation of LLC-PK1 cells and synthesis of DNA could be inhibited by both toxin T-2 and T-2 tetraol. Toxicity of toxin T-2 was 100 times greater than that of T-2 tetraol. There was no obvious toxicity to the proliferation of LLC-PK1 cells and synthesis of DNA in a dose of 10 mg/L deepoxy T-2 tetraol. But, toxin T-2 caused obvious damage in heart muscle and articular cartilage of chicken embryos, and T-2 tetraol and deepoxy T-2 tetraol in heart muscle, but not in articular cartilage. T-2 tetraol produced by hydrolysis of toxin T-2 had toxicity to certain extent, but its strength was significantly less than that of the latter. It suggests that the epoxide group in toxin T-2 played a determinant role for its toxicity. If epoxy cycle of the basic nucleus of the molecule is open, its toxicity will change significantly.

Experimental demonstration of resonant anomalies in diffraction from two-dimensional gratings

Resonant effects in diffraction from two-dimensional dielectric gratings is demonstrated experimentally. A two-layer structure, which consists of a uniform guiding layer and a grating layer, yielded symmetric, low-sideband resonance that is suitable for narrow-band filter applications. Excellent agreement between measured and calculated spectral and angular dependence is obtained.

Hemorrhage in intracranial epidermoid cyst

A case of intracranial epidermoid cyst with intracystic hemorrhage is reported. A 63-year-old woman sustained a head injury after a fall; obtundation and ataxia were noted later. Computed tomography revealed a heterogeneous hyperdense lesion in the posterior and middle cranial fossas. Magnetic resonance imaging showed a lesion with increased signal intensity both on T1 and T2 weighted images. Two craniotomies revealed an intracranial epidermoid cyst with about 6 mL of clotted blood. Pathologic study showed hemosiderin-laden macrophages and neovascularity in the cystic wall granulation tissue, which indicated rupture of the cystic wall with intracystic hemorrhage, which later correlated with the diagnostic image findings. The patient tolerated the two operations well and her postoperative course was smooth. She was discharged in good health without obvious neurologic deficits.

Identification of 2-[125I] iodomelatonin binding sites in the thymus of mice and its significance

The melatonin binding sites in membrane preparations of the mouse thymus were demonstrated using 2-[125I] iodomelatonin as a radioligand. The binding sites were stable, saturable, reversible and of high affinity. Studies on specificity of 2-[125I] iodomelatonin binding suggested that the 2-[125I] iodomelatonin binding sites are highly specific for melatonin. These binding sites fulfilled the standard criteria for receptors. Our work suggested that melatonin should have direct regulatory action on immune system mediated through the melatonin binding sites. Studies on the circadian rhythm showed that there existed the circadian rhythm in the binding capacity for 2-[125I] iodomelatonin in the mouse thymus with the peak values at 12:00-16:00 and the trough values between 00:00 and 4:00. The subcellular distribution of 2-[125I] iodomelatonin binding sites in the mouse thymus was in the following descending order: nuclear > mitochondrial > microsomal > cytosolic fraction. There was also an age-related decrease in 2-[125I] iodomelatonin binding in the mouse thymus. This is correlated with the involution of the thymus.

Cloning, expression and purification of the ligand-binding region of human IL-6R in E. coli and its preliminary functional identification

The ligand-binding region of human IL-6R is taken as the target gene fragment to be cloned and expressed. With pET-3b as expressing vector, two recombinants pET-6R(B) and pET-6R(B)4 have been constructed encoding the ligand-binding region (28 kD) of hIL-6R and its dimmer (53 kD), respectively. After induction with IPTG, they produced two proteins rIL6R-28 of 28 kD and rIL6R-53 of 53 kD amounting to 50% and 30% of total bacteria proteins, respectively. The expressed products were mainly recovered as inclusion bodies. After purification and renaturation, both of them were capable of augmenting the growth-stimulating effect of IL-6 on 7TD1 cells, an IL-6 dependent cell line. The result of ELISA also revealed that both rIL6R-28 and rIL6R-53 had the obvious ligand-binding activity.

[Surgical treatment for iatrogenic damage at the confluence of hepatic duct]

Since 1989, 4 patients with iatrogenic bile duct injuries at the level of bifurcation were treated. Among them, the bifurcation together with both right and left hepatic duct had had wrongly been resected in 2 cases. The bifurcation was partially resected in the other 2 cases. The establishment of a permanent hepaticoentertostomy is essential. Abnormal bile flow would impede surgical effect, hence in the author's opinion, peripheral hepaticoenterostomy such as Longmire's procedure is unsuitable for iatrogenic bile duct injuries. The author's special technique for adequate exposure and accurate dissection of intrahepatic bile ducts is described. Four cases have been followed up for 7 months to 5 years with good result.

[Morphological transformation of BHK-21 cells by nickel titanium shape memory alloy particles encapsulated by titanium oxide]

The special treatment process formed a compact titanium oxide thin film on the surface of medical nickel titanium shape memory alloy (NiTiSMA) particles (< or = 5 microns). The BHK-21 cells were cultivated in 10% infant calf serum containing NiTiSMA particles and NiTiSMA particles encapsulated by titanium oxide respectively, and morphological transformation clones were observed. The results showed that NiTiSMA particles induced obviously morphological transformation clones, and that NiTiSMA particles induced obviously morphorogical transformation of BHK-21 cells (the rate of morphological transformation clones was 13.46%), especially in TPA medium. The rate of morphological transformation in the group containing NiTiSMA particles was not more significantly different than that in the positive control group. The rate of morphological transformation in the group containing NiTiSMA particles encapsulated by titanium oxide was not more significantly different than that in the negative control group, but significantly different than that in the NiTiSMA particles group. Therefore, it is possible that NiTiSMA particles are directly carcinogenic and that NiTiSMA particles encapsulated by titanium oxide are not potentially carcinogenic.

Expression of human interleukin-11 cDNA in E. coli

A 551-bp hIL-11 gene fragment that includes no nucleotide sequences encoding signal polypeptide and the initial 8 amino acids of the mature protein was cloned into a high-level expression vector pEx31B of E. coli. The authors identified the recombinant plasmid, designated pEx31-IL11, by restriction endonucleases digestion and DNA sequencing. The resulting recombinant plasmids were then used to transform E. coli strain HB101, and expression in the PL promoter system, which is temperature-regulated, was achieved. The expressed fusion protein amounts to 50% of total bacterial proteins. The hIL-11 protein expressed in E. coli was fused to the N-terminal 99 amino acids of the MS2 polymerase to form the inclusion body. These recombinant proteins can be purified to about 80% by extracting inclusion body with urea. One IL-6-dependent cell line 7 TD1 was used for bioassay. The recombinant hIL-11 protein was preliminarily purified and renatured to a specific activity of 10(5)U/mg, even in the presence of an excess of a neutralizing anti-IL-6 antibody.

Cationic lipids for reporter gene and CFTR transfer to rat pulmonary epithelium

Increasing evidence indicates that cationic liposomes are capable of safely transferring foreign genes to pulmonary epithelium in vitro and in vivo. To transfer reporter genes and the cystic fibrosis transmembrane conductance regulator (CFTR) to mammalian respiratory epithelium we used two cationic lipid formulations: N-[1-(2,3-dioleoyloxy)propyl] N,N,N-triethylammonium chloride (DOTMA), and 1,2-dimyristyloxy-propyl-3-dimethylhydroxyethylammonium bromide (DMRIE) at a 1:1 molar ratio with dioleoyl phosphatidylethanolamine (DOPE). Lipid-DNA conjugates containing either CFTR or LacZ were instilled directly into the airways of Sprague-Dawley rats. Rats treated with LacZ cDNA in vivo demonstrated expression in 30-50% of the large and medium-sized airways, with some airways showing high efficiency gene transfer and expression (in the most proximal airways, 70-80% of surface epithelial cells were positive for expression of a nuclear targeted LacZ). While control and LacZ treated tracheas mounted in Ussing chambers showed minimal stimulation of transepithelial chloride (Cl)-currents by cAMP (suggesting low levels of endogenous rat CFTR activity), tracheas taken from animals receiving CFTR exhibited significant forskolin-stimulated currents at 72 h after gene transfer. Human CFTR gene expression was also detected by polymerase chain reaction (PCR) analysis of reverse transcribed lung RNA. These results, together with previous studies using lipid-mediated gene transfer in mice, help confirm the potential for cationic lipid-mediated gene transfer in the gene therapy of cystic fibrosis in humans.

Tumor cell bystander killing in colonic carcinoma utilizing the Escherichia coli DeoD gene to generate toxic purines

Inefficiency of gene delivery, together with inadequate bystander killing, represent two major hurdles in the development of a toxin-mediated gene therapy for human malignancy. The product of the Escherischia coli DeoD gene (purine nucleoside phosphorylase, PNP) differs from the mammalian enzyme in its substrate specificity and is capable of catalyzing the conversion of several non-toxic deoxyadenosine analogs to highly toxic adenine analogs. We have found that expression of E. coli PNP in < 1% of a human colonic carcinoma cell line leads to the death of virtually all bystander cells after treatment with 6-methyl-purine-2'-deoxyribonucleoside, a deoxyadenosine analog that is a substrate for E. coli PNP but not human PNP. Minimal toxicity was observed in non-transfected or E. coli LacZ transfected cells that were treated with this compound. These results establish a rational approach to achieve significant bystander killing, even after gene transfer to only a small fraction of tumor cells.

Nanometric design of extraordinary hydrophobic-induced pKa shifts for aspartic acid: relevance to protein mechanisms

Commonly a key element enabling proteins to function is an amino acid residue or residues with functional side chains having shifted pKa values. This article reports the results on a set of protein-based polymers (model proteins) that exhibit hydrophobic folding and assembly transitions, and that have been designed for the purpose of achieving large hydrophobic-induced pKa shifts by selectively replacing Val residues by Phe residues. The high molecular weight polypentapeptides, actually poly(tricosapeptides) with six varied pentamers in fixed sequence, were designed and synthesized to have the same amino acid compositions but different proximities between a single aspartic acid residue and 5 Phe residues per 30 residues. With the 5 Phe residues distal from the Asp residue, the observed pKa shift was 2.9 when compared to the Val-containing reference. With the 5 Phe residues within 1 nm of the Asp residue, the pKa shift was 6.2. This represents a free energy of interaction of 8 kcal/mole. To our knowledge, this is the largest pKa shift documented for an Asp residue in a polypeptide- or protein-water system. Data are reviewed that do not support the usual electrostatic arguments for pKa shifts of charge-charge repulsion and/or unfavorable ion self-energies arising from displacement of water by hydrophobic moieties, but rather the data are interpreted to indicate the presence of an apolar-polar repulsive free energy of hydration, which results from a potentially highly cooperative competition between apolar and polar species for hydration.

One-step affinity isolation of recombinant protein using the baculovirus/insect cell expression system

We have developed two baculovirus transfer vectors which allow single-step affinity isolation of recombinant proteins after expression in insect cells. Using these vectors, recombinant proteins are synthesized as fusions with glutathione-S-transferase and are amenable to enrichment from a crude insect cell lysate using glutathione affinity agarose. After affinity isolation, glutathione-S-transferase can be cleaved from the recombinant polypeptides of interest at an engineered thrombin cleavage site. We used this approach to successfully isolate glutathione-S-transferase, the human low density lipoprotein receptor, two large polypeptides containing cytoplasmic domains of the cystic fibrosis transmembrane conductance regulator (CFTR), and the full-length CFTR. The approach has potential advantages over prokaryotic overexpression of foreign polypeptides, including: (i) eukaryotic post-translational modification of expressed protein, (ii) increased solubility of recombinant fusion proteins synthesized in insect cells leading to increased affinity yield under mild conditions, and (iii) production of large and/or complex polypeptides which might be difficult to purify from prokaryotic cells. The method also allows enrichment of recombinant protein representing a small fraction (less than 5%) of total insect cell protein produced and provides a general method for eukaryotic protein synthesis and isolation which is independent of the particular protein being expressed.

Growth Depression in Mycorrhizal Citrus at High-Phosphorus Supply (Analysis of Carbon Costs)

Mycorrhizal-induced growth depression of plants in high-P soil has been reported in many species. The carbon costs of factors contributing to this growth depression were analyzed in Volkamer lemon (Citrus volkameriana Tan. & Pasq.) colonized by the mycorrhizal (M) fungus Glomus intraradices Schenck and Smith. M and nonmycorrhizal (NM) plants were each grown at two P-supply rates. Carbon budgets of M and NM plants were determined by measuring whole-plant carbon assimilation and respiration rates using gas-exchange techniques. Biomass, M colonization, tissue-P concentration, and total fatty acid concentration in the fibrous roots were determined. Construction costs of the fibrous roots were estimated from heat of combustion, N, and ash content. Root-growth respiration was derived from daily root growth and root-construction cost. M and NM plants grown in high-P soil were similar in P concentration, daily shoot carbon assimilation, and daily shoot dark respiration. At 52 d after transplanting (DAT), however, combined daily root plus soil respiration was 37% higher for M than for NM plants, resulting in a 20% higher daily specific carbon gain (mmol CO2 [mmol carbon]-1 d-1) in NM than M plants. Estimates of specific carbon gain from specific growth rates indicated about a 10% difference between M and NM plants. Absolute values of specific carbon gain estimated by whole-plant gas exchange and by growth analysis were in general agreement. At 52 DAT, M and NM plants at high P had nearly identical whole-plant growth rates, but M plants had 19% higher root dry weight with 10% higher daily rates of root growth. These allocation differences at high P accounted for about 51% of the differences in root/soil respiration between M and NM plants. Significantly higher fatty acid concentrations in M than NM fibrous roots were correlated with differences in construction costs of the fibrous roots. Of the 37% difference in daily total root/soil respiration observed between high-P M and NM plants at 52 DAT, estimated daily growth respiration accounted for only about 16%, two-thirds of which was associated with construction of lipid-rich roots, and the remaining one-third with greater M root growth rates. Thus, of the 37% more root/soil respiration associated with M colonization of high-P plants, 10% was directly attributable to building lipid-rich roots, 51% to greater M root biomass allocation, and the remaining 39% could have been used for maintenance of the fungal tissue in the root and growth and maintenance of the extramatrical hyphae.

Rapid purification of recombinant baculovirus using fluorescence-activated cell sorting

Expression of foreign proteins in the baculovirus-insect cell expression system has been limited by difficulties in rapid identification and purification of recombinant virus. Although the process of identifying recombinant virus has been greatly facilitated by the introduction of vectors that lead to insect cell co-expression of beta-galactosidase with foreign genes of interest, isolation of pure recombinant virus using plaque purification may still take several weeks to months to accomplish. Using a fluorescent beta-galactosidase substrate, we have established that insect cells harboring recombinant virus can be rapidly isolated using fluorescence-activated cell sorting. Pure recombinant virus can then be readily obtained using this cellular fraction, with a pure viral culture generally obtained within 2-3 weeks of insect cell transfection.