Identification of a U2/U6 helix la mutant that influences 3' splice site selection during nuclear pre-mRNA splicing

Base substitutions in U2/U6 helix I, a conserved base-pairing interaction between the U6 and U2 snRNAs, have previously been found to specifically block the second catalytic step of nuclear pre-mRNA splicing. To further assess the role of U2/U6 helix I in the second catalytic step, we have screened mutations in U2/U6 helix I to identify those that influence 3' splice site selection using a derivative of the yeast actin pre-mRNA. In these derivatives, the spacing between the branch site adenosine and 3' splice site has been reduced from 43 to 12 nt and this results in enhanced splicing of mutants in the conserved 3' terminal intron residue. In this context, mutation of the conserved 3' intron terminal G to a C also results in the partial activation of a nearby cryptic 3' splice site with U as the 3' terminal intron nucleotide. Using this highly sensitive mutant substrate, we have identified a mutation in the U6 snRNA (U57A) that significantly increases the selection of the cryptic 3' splice site over the normal 3' splice site and augments its utilization relative to that observed with the wild-type U2 or U6 snRNAs. In a previous study, we found that the same U6 mutation suppressed the effects of an A-to-G branch site mutation in an allele-specific fashion. The ability of U6-U57 mutants to influence the fidelity of both branch site and 3' splice site recognition suggests that this nucleotide may participate in the formation of the active site(s) of the spliceosome.

Direct interaction of SOS1 Ras exchange protein with the SH3 domain of phospholipase C-gamma1

A recent report that microinjection of the SH3 domain of PLC-gamma1 could induce DNA synthesis raised the functional importance of the SH3 domain of PLC-gamma1 in mitogenic signaling. In this report, we provide evidence that SOS1, a p21Ras-specific guanine nucleotide exchange factor, directly binds to the SH3 domain of PLC-gamma1, and that the SH3 domain of PLC-gamma1 is involved in SOS1-mediated p21Ras activation. SOS1 was coprecipitated with the GST-fused SH3 domain of PLC-gamma1 in vitro. The interaction between SOS1 and the PLC-gamma1 SH3 domain is mediated by direct physical interaction. The carboxyl-terminal proline-rich domain of SOS1 is involved in the interaction with the PLC-gamma1 SH3 domain. Moreover, PLC-gamma1 could be co-immunoprecipitated with SOS1 antibody in cell lysates. From transient expression studies, we could demonstrate that the SH3 domain of PLC-gamma1 is necessary for the association with SOS1 in vivo. Intriguingly, overexpression of the SH3 domain of PLC-gamma1, lipase-inactive PLC-gamma1, or wild-type PLC-gamma1 elevated p21Ras activity and ERK activity when compared with vector transfected cells. The PLC-gamma1 mutant lacking the SH3 domain could not activate p21Ras. p21Ras activities in cell lines overexpressing either PLC-gamma1 or the SH2-SH2-SH3 domain of PLC-gamma1 were elevated about 2-fold compared to vector transfected cells. This study is the first to demonstrate that the PLC-gamma1 SH3 domain enhances p21Ras activity, and that the SH3 domain of PLC-gamma1 may be involved in the SOS1-mediated signaling pathway.

Transplant of cultured autologous pure melanocytes after laser-abrasion for the treatment of segmental vitiligo

Segmental vitiligo is a special type of vitiligo with unilateral distribution of lesions and has a stable course. Clinically, many patients with segmental vitiligo have unsatisfactory responses to topical corticosteroid or UV phototherapy. We have developed a technique for the isolation of melanocytes from a small specimen of normally pigmented skin obtained via a suction blister. The melanocytes can be proliferated in culture and then replanted onto laser-abrased vitiliginous areas. We used this procedure to treat 25 patients with segmental vitiligo that were refractory to medical therapy. The repigmented portion of the total treated area amounted to 95-100% in 21 patients and 65 to 94% in 4 patients. The response rate to treatment was 100% in this study. No scarring or other side-effects developed. The results of this study demonstrate that this method is a valuable tool for the treatment of patients with segmental vitiligo.

Linear free energy relationships implicate three modes of binding for fluoroaromatic inhibitors to a mutant of carbonic anhydrase II

[figure: see text] Linear free energy relationships between binding affinity and hydrophobicity for a library of fluoroaromatic inhibitors of F131V carbonic anhydrase II (CA) implicate three modes of interaction. X-ray crystal structures suggest that F131 interacts with fluoroaromatic inhibitors, while P202, on the opposite side of the active site cleft, serves as the site of the hydrophobic contact in the case of the F131V mutant. 2-Fluorinated compounds bind more tightly, perhaps due to the field effect of the nearby fluorine on the acidity of the amide proton.

History of the Korean GLPs and the activities and perspectives of the Korean Society of GLP

The Korean Society of Good Laboratory Practice (KSGLP) was established Dec. 10, 1998. The objectives of the KSGLP are to enhance the quality of domestic studies and the level of GLP compliance, in safety testing, and to promote information exchange among its members. The activities of KSGLP include: offering workshops and symposiums, linking with related governmental organizations, collecting GLP related information and providing the information to the related organizations, building international networks to collect information and to establish relationship, developing training materials and publishing periodicals, and other business necessary to achieve the objectives of the KSGLP. The KSGLP achieved its goals within a short period of time by offering workshops and symposia, and by providing important GLP related information in newspapers or via the KSGLP's internet homepage (www.ksglp.or.kr). The main role of the KSGLP will be to disseminate GLP technology nationwide. The KSGLP would like to help many labs that are preparing their facilities for GLP compliance. Further, the KSGLP is hoping to share GLP experiences with other members.

The SH2-SH2-SH3 domain of phospholipase C-gamma1 directly binds to translational elongation factor-1alpha

Phospholipase C-gamma1 (PLC-gamma1) is a lipase that hydrolyzes PIP2 to generate two second messengers, IP3 and DAG. By using the yeast two-hybrid system, we identified the translational elongation factor-1alpha (EF-1alpha) as a binding protein of PLC-gamma1 from the human B-lymphocyte library. Direct interaction between EF-1alpha and PLC-gamma1 was confirmed by the in vitro binding experiment using purified PLC-gamma1. Furthermore, from the in vitro binding experiment, we could demonstrate that the carboxyl terminal region of EF-1alpha is involved in the interaction with PLC-gamma1, and that both SH2 and SH3 domains of PLC-gamma1 are required for the interaction with EF-1alpha. In vivo interaction between EF-1alpha and PLC-gamma1 was confirmed by the immunoprecipitation experiment using anti-EF-1alpha antibody. The interaction between EF-1alpha and PLC-gamma1 was enhanced by EGF-treatment. Taken together, we suggest that EF-1alpha might play a role in PLC-gamma1-mediated signal transduction.

The Drosophila CPEB homolog, orb, is required for oskar protein expression in oocytes

The establishment of polarity axes in the Drosophila egg and embryo depends upon the localization and on-site expression of maternal mRNAs. The critical step in the targeting of posterior determinants is the localization of oskar (osk) mRNA to the pole and its on-site translation. Osk protein then recruits other posterior group gene products involved in the formation of pole plasm and in the localization and regulation of the posterior determinant, nanos. Here we have investigated the role of the Drosophila CPEB homolog, the orb gene, in the osk mRNA localization pathway. We demonstrate that the expression of Osk protein is dependent upon the orb gene. In strong orb mutants, Osk protein expression is undetectable, while in the hypomorphic mutant, orb(mel), little or no on-site expression of Osk protein at the posterior pole is observed. The defects in Osk protein accumulation in orb mutant ovaries are correlated with a reduction in the length of the osk poly(A) tails. We show that osk mRNA is in immunoprecipitable complexes with Orb protein in ovaries and that the osk 3' UTR can be UV cross-linked to Orb protein in ovarian extracts. These data suggest that Orb is required to activate the translation of osk mRNA and at that this may be accomplished by a mechanism similar to that used by the Xenopus CPEB protein to control translation of "masked" mRNAs.

Transformation of rat fibroblasts by phospholipase C-gamma1 overexpression is accompanied by tyrosine dephosphorylation of paxillin

We previously have shown that the overexpression of phospholipase C-gamma1 (PLC-gamma1) in rat 3Y1 fibroblasts results in malignant transformation (Chang, J.-S., Noh, D.Y., Park, I.A., Kim, M;.J., Song, H., Ryu, S.H. and Suh, P.-G. (1997) Cancer Res. 57, 5465-5468). The transformed cells, which initially are in an elongated and flat form after seeding in plastic dishes, become rounded during continued culture. We found that tyrosine dephosphorylation of paxillin accompanies this morphological change of the transformed cells and that PLC-gamma1 co-immunoprecipitates together with paxillin and vice versa, but not after the cells have become round. Transformed cells growing on fibronectin-pre-coated dishes regain their flat morphology and this is accompanied by paxillin tyrosine phosphorylation. Furthermore, immunoprecipitation analysis showed that paxillin forms a heteromeric complex with PLC-gamma1 in cells grown on fibronectin. These results suggest that a complex formation between paxillin and PLC-gamma1 may play a role in cell-substrate adhesion.

The anesthetic management of a preterm infant weighing 500 grams undergoing ligation of patent ductus arteriosus--a case report

PDA (patent ductus arteriosus) is a common congenital heart disease. Usually surgical intervention through left thoracotomy or recently through video assisted thoracoscopy will be recommended if the preceding or intent medical treatment fails or is contraindicated. However, once surgical intervention is decided, various complications are still a real fear in the mind of the surgeon and the anesthesiologist, particularly if the infant is premature or very sick. Here we report an anesthetic management in a female preterm infant weighing 500 grams, who underwent PDA ligation. She was born at gestation age of 28 weeks at our hospital, and since her birth she was noted to have infant respiratory distress syndrome associated with renal dysfunction. She was admitted to the neonatal intensive care unit (NICU) straightaway. After thorough examination, a severe PDA was disclosed. The possibility of pulmonary hemorrhage and heart failure could be predicted in view of the large left to right shunt. Worst of all was that her poor renal function contradicted a medical treatment. So we decided to carry out the ligation procedure at once although she was premature and only 5 days old. The NICU was chosen as the operation theater for transferring concerns. General anesthesia was induced and maintained by atropine 0.01 mg, pancuronium 0.1 mg, fentanyl 2 micrograms, and ketamine 0.15 mg intravenously. Supplemental oxygen was given throughout the operation. The PDA was ligated through left thoracotomy and blood loss was minimal. The peri-operative course was uneventful. The patient recovered well following surgery and anesthesia.

Immunogenicity of synthetic HIV-1 V3 loop peptides by MPL adjuvanted pH-sensitive liposomes

A successful HIV-1 vaccine should be capable of generating humoral and cellular immune responses at the same time. The only response shown to be effective in this regard is virus-neutralization antibodies and virus-specific cytotoxic T-lymphocytes (CTL) directed against the viral antigens. In the present study, it is shown that V3 peptides encapsulated pH-sensitive liposomes elicit the virus neutralization antibodies and virus specific CTL response at the same time in Balb/c mice. None of the immunization protocols elicited an antibody response and CTL response when R15K and T26K was used as immunogen without liposomes. In contrast, antibodies and CTL response were detectable in the mice which were immunized with peptide encapsulated pH-sensitive liposomes. Antibody production was confirmed by virus neutralizing assay. CD4+ T-cells are involved in target cell lysis to some degree but CTL activity is mainly due to the CD8 + T-cells. The consistency of the antibody and CTL response was related to the V3 loop peptides size. The T26K (26mer) peptide induced a stronger antibody and CTL response than R15K (15mer) in vivo. Based on the results of this study, T26K was used as a potentially effective HIV-1 vaccine component and T26K encapsulated pH-sensitive liposomes composed of phosphatidylethanolamine-beta-oleoyl-gamma-palmitoyl (POPE)/cholesterol hemisuccinate (CHOH)/monophosphoryl lipid A (MPL) (7:3:0.1, mole ratio) may be used as a potentially immunomodulating adjuvant system for the development of HIV and other viral vaccines.

Adult type anomalous origin of the left coronary artery from the main pulmonary artery: report of one case

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA syndrome) is a rare disease. Most of the cases suffer from myocardial infarction, congestive heart failure or even death during the early infantile period, and thus are called "infantile type". We present one five-year-old girl with ALCAPA syndrome, adult type, who was initially suspected to be a case of atypical Kawasaki disease (KD) complicated with coronary arterial aneurysms. Due to persistent dilatation of the coronary artery after medical treatment for one year and a turbulent flow noticed between the left coronary artery (LCA) and the main pulmonary artery (MPA), cardiac catheterization was arranged. The diagnosis was established from the coronary cineangiography in spite of a direct connection between the aorta and LCA revealed from the echocardiogram. Thereafter open heart surgery was undertaken. Diagnosis of ALCAPA syndrome can be made by echocardiogram, but this is not fully satisfactory. Selective coronary cineangiography remains the definitive diagnosis. Although the patients of adult type are more asymptomatic, surgical correction should be undertaken as soon as the diagnosis is established since a substantial risk is still present.

Fermentation extract effects on the morphology and metabolism of the rumen fungus Neocallimastix frontalis EB188

The effects of Aspergillus oryzae fermentation extract, Amaferm, on the rumen fungus Neocallimastix frontalis EB188 were studied. The secretion of cellulase was increased by 67% and rhyzoid development was increased 3.8-fold in the presence of extract. Strength of fungal response increased in a dose-dependent manner and demonstrated a positive correlation between cell surface area and enzyme secretion. Above certain concentrations of extract, however, the development of the fungus and enzyme secretions remained at control values or slightly diminished. Supernatant fluid appearance of the intracellular enzyme, malate dehydrogenase, paralleled the secretion of cellulase both in the presence and absence of extract. Ether solubilization of extract demonstrated that the active component(s) possessed a moderately polar value between 2.7 and 2.8. Thin layer chromatography separated extract into inert, inhibitory and intensely stimulating fractions. These results support the idea that by accelerating fungal growth and metabolism, Amaferm increases the rate (or extent) of fibre degradation caused by rumen fungi and that this, in turn, may contribute to enhanced animal performance.

The significance of early subtle coronary arterial lesions on echocardiogram in Kawasaki disease

Intensive echocardiographic studies were undertaken in 37 patients with Kawasaki disease (KD) and 12 febrile controls during the acute stages. Video-tape recordings were read doubly-blinded by 3 pediatric cardiologists at 2 hospitals. Three characteristics of subtle coronary arterial lesions, including contour of lumen, smoothness of endothelium and sono-homogeneity of the surrounding tissue were particularly described. Seven of the 37 KD patients (19%) were found to have coronary arterial aneurysms (CAA) at the end of the convalescent stage. The 3 cardiologists agreed in the diagnosis of the subtle lesions by 72%. More patients with Kawasaki disease were found to have an irregular endothelium than the controls (P < 0.001). KD patients later complicated with CAA were more likely to have had the three characteristics of subtle coronary lesions during the acute stage than the KD patients without aneurysms (P < 0.001). Also, the coronary arterial size measured during the acute stage were found to be positively correlated with their largest dilatation at the convalescent stage (P = 0.0001, r = 0.61). We conclude that early subtle coronary arterial lesions can herald the development of coronary arterial aneurysms.

Kawasaki disease complicated by peripheral gangrene

An 8.5-month-old male infant with Kawasaki disease (KD) received high-dose intravenous immunoglobulin (IVIG) therapy on the fifth day after fever onset. However, multiple peripheral limb ischemias occurred 2 days later. Accordingly, heparin followed by dipyridamole was administered. Aside from a small amputation at the tip of the right middle finger, all other digital ischemias resolved. This presentation demonstrates that early recognition and management of peripheral gangrene in KD may keep its sequela to a minimum.

Repeated fed-batch operations for microbial detoxification of mercury using wild-type and recombinant mercury-resistant bacteria

A wild-type mercury-resistant strain Pseudomonas aeruginosa PU21 (Rip64), and an Escherichia coli PWS1 strain genetically engineered to harbor mercury resistance were examined for their capacity to detoxify soluble mercuric ions with repeated fed-batch operations. The specific mercury detoxification activity for the two strains at different initial mercury concentrations was determined by resting-cell experiments. The fed-batch operations were conducted with different initial culture volumes (Vo), inoculum sizes (Xo), and different mercury feeding rates (FHg) to investigate the effects of those operation parameters on the performance of mercury detoxification. The results showed that the wild-type and the recombinant strains had an optimal specific activity of 5 x 10(-7) and 8 x 10(-8) micrograms cell-1 h-1, respectively. In fed-batch operation for P. aeruginosa PU21, under the conditions of Vo = 400 ml and Xo = 4.5-4.8 x 10(9) cells ml-1 the overall mercury detoxification efficiency (eta) for FHg = 16.9 mg Hg h-1 was 5.26 mg Hg l-1 h-1, nearly 35% higher than that for a lower FHg (11.7 mg Hg h-1). Among the three initial culture volumes examined in this study, the highest eta (5.60 mg Hg l-1 h-1) was obtained when Vo = 1200 ml and FHg = 16.9 mg Hg h-1. It was also found that an inoculum size higher than 4.0 x 10(9) cells ml-1 enabled a stable fed-batch operation, while as the inoculum was reduced to around 1.6 x 10(9) cells ml-1, the mercury feeding caused severe cell death, leading to an unsuccessful fed-batch operation. In the fed-batch operation for E. coli PWS1 strain with Vo = 1200 ml and FHg = 16.9 mg Hg h-1, the mercury detoxification efficiency was 3.07 mg Hg l-1 h-1, only 54% of that for the wild-type P. aeruginosa PU21 strain under the same operating conditions. It was also noticed that the operation with E. coli PWS1 became less efficient at the second fed-batch cycle due to plasmid instability of the recombinant strain.

Selective adsorption/recovery of Pb, Cu, and Cd with multiple fixed beds containing immobilized bacterial biomass

Fixed-bed columns packed with calcium alginate (CA)-immobilized biomass of Pseudomonas aeruginosa PU21 were utilized to remove lead (Pb), copper (Cu), and cadmium (Cd) from the contaminated water. In the absence of competing metals, saturation capacity of CA-immobilized cells in batch operations was 1.60, 2.42, and 1.06 mmol/g, for Pb, Cu, and Cd, respectively. The Langmuir constants (K) obtained from the Langmuir isotherm were 157.6, 4.2, and 3.7 mM-1 for Pb, Cu, and Cd, respectively. Results from single-metal biosorption with 10-cm immobilized-cell columns show that, for an influent metal concentration of 193 microM, the total capacities for Pb, Cu, and Cd, respectively, were 5.12, 4.03, and 3.48 mmol, which is nearly 25-30% higher than those obtained from columns containing only cell-free CA matrix. With the influent containing ternary mixtures of Pb, Cu, and Cd, columns with immobilized cells exhibited predominant selectivity to Pb, whereas in the cell-free columns, the dominance of Pb adsorption reduced, along with an appreciable increase in the adsorption of Cu. The metal-laden columns were regenerated by elution with HCl solution (pH 2.0). The metal recovery ratios were 80:1, 60:1, and 27:1 for Cu, Cd, and Pb, respectively. Moreover, with a pH gradient elution, the column-trapped metals can be optimally recovered at distinct pH values. Continuous biosorption of Pb, Cu, and Cu with four columns in series was also conducted. Results from the multibed operation demonstrate that Pb ions strongly inhibited the adsorption of Cu and Cd, which only occurred initially, and subsequently, an essential portion of the adsorbed Cu and Cd ions was replaced by Pb ions due to the ion exchange effect. However, since Pb ions were rapidly removed from the bulk at the onset of metal loading, Pb adsorption in columns 2-4 was negligible for the first 10-30 h, leading to an elevation in the breakthrough time (tb) and the capacity for Cu and Cd in columns 2-4. A back-propagation neural network model was shown to be able to predict the breakthrough curves of the three metals in the multicolumn processes with a ternary-metal feed.

Src homology domains of phospholipase C gamma1 inhibit nerve growth factor-induced differentiation of PC12 cells

Phospholipase C gamma1 (PLC-gamma1) is phosphorylated on treatment of cells with nerve growth factor (NGF). To assess the role of PLC-gamma1 in mediating the neuronal differentiation induced by NGF treatment, we established PC12 cells that overexpress whole PLC-gamma (PLC-gamma1PC12), the SH2-SH2-SH3 domain (PLC-gamma1SH223PC12), SH2-SH2-deleted mutants (PLC-gamma1deltaSH22PC12), and SH3-deleted mutants (PLC-gamma1deltaSH3PC12). Overexpressed whole PLC-gamma1 or the SH2-SH2-SH3 domain of PLC-gamma1 stimulated cell growth and inhibited NGF-induced neurite outgrowth of PC12 cells. However, cells expressing PLC-gamma1 lacking the SH2-SH2 domain or the SH3 domain had no effect on NGF-induced neuronal differentiation. Overexpression of intact PLC-gamma1 resulted in a threefold increase in total inositol phosphate accumulation on treatment with NGF. However, overexpression of the SH2-SH2-SH3 domain of PLC-gamma1 did not alter total inositol phosphate accumulation. To investigate whether the SH2-SH2-SH3 domain of PLC-gamma1 can mediate the NGF-induced signal, tyrosine phosphorylation of the SH2-SH2-SH3 domain of PLC-gamma1 on NGF treatment was examined. The SH2-SH2-SH3 domain of PLC-gamma1 as well as intact PLC-gamma1 could be tyrosine-phosphorylated on NGF treatment. These results indicate that the overexpressed SH2-SH2-SH3 domain of PLC-gamma1 can block the differentiation of PC12 cells induced by NGF and that the inhibition appears not to be related to the lipase activity of PLC-gamma1 but to the SH2-SH2-SH3 domain of PLC-gamma1.

[Seroepidemiology of Toxoplasma gondii infection among dogs in Taipei, Taiwan]

Seroprevalence of toxoplasmosis in dogs was investigated in Taipei from July 1995 to June 1996 by the latex agglutination assay. A total of 289 serum samples were taken from stray and domestic dogs as well as from dogs in randomly selected animal hospitals and pet stores. The overall seroprevalence among all dogs was 24.6% (71/289). With regard to the source of the dogs, the seropositivity was 15.4% (10/65) for dogs in animal hospitals, 16.3% (7/43) for dogs in pet stores, 15.5% (11/71) for domestic dogs and 39.1% (43/110) for stray dogs. The seropositivity of stray dogs was significantly higher than that of the domestic dogs (P < 0.05). However, there was no significant difference among the randomly selected places or dog strains (P > 0.05).

Development of microbial mercury detoxification processes using mercury-hyperresistant strain of Pseudomonas aeruginosa PU21

A mercury-hyperresistant strain of Pseudomonas aeruginosa PU21 harboring plasmid Rip64 was utilized to develop bioprocesses able to detoxify and recover soluble mercuric ions in aquatic systems. The kinetics of mercury detoxification was investigated to determine the parameters needed for the design of the bioprocesses. Batch, fed-batch, and continuous bioreactors were utilized to evaluate the efficiency and feasibility of each mode of operation. The results showed that the specific mercury detoxification rate was dependent on cell growth phases, as well as the initial mercury concentrations. Cells at the lag growth phase exhibited the best specific detoxification rate of approximately 1.1 x 10(-6) microg Hg/cell/h, and the rate was optimal at an initial mercury concentration of 8 mg/L. In batch operations with initial mercuric ions ranging from 2 to 10 mg/L, the mercuric ions added were rapidly volatilized from the media in less than 2-3 h. With periodic feeding of 3 or 5 mg Hg/L at fixed time intervals, the fed-batch processes had mercury removal efficiencies of 2.9 and 3.3 mg Hg/h/L, respectively. For continuous operations, the effluent cell concentration (Xe) was essentially invariant at 527 and 523 mg/L with the dilution rates (D) of 0.18 and 0.325 h-1, respectively. The increase in mercury feeding concentrations (Hgf) from 1.0 to 6.15 mg Hg2+/L did not affect the steady-state cell concentration (Xe) but forced the effluent mercury concentration (Hge) to increase. The decrease in the dilution rate, however, resulted in lower Hge values. It was also found that sequential mercury vapor absorption columns recovered over 80% of the Hg degrees released from the bioreactor while the residual mercury vapor was subsequently immobilized by an activated carbon trap in the down stream of the absorption column.

Induction of V3-specific cytotoxic T lymphocyte responses by HIV gag particles carrying multiple immunodominant V3 epitopes of gp120

Effort to develop a vaccine to prevent infection of human immunodeficiency virus (HIV) have focused on the induction of neutralizing antibodies. In our previous study, we reported that chimeric gag-env virus-like particles (VLPs) induce neutralizing antibodies which block HIV infection. In addition to the neutralizing antibodies, the cytotoxic T-lymphocyte (CTL) response is considered to be another major immune defense mechanism required for recovery from many different viral infections. In the present study, we have constructed chimeric fusion proteins using HIV-2 gag precursor protein with (1) four neutralizing epitopes from HIV-1 gp160; (2) three tandem copies of consensus V3 domain, which have been derived from 245 different isolates of HIV-1 and carries both the principal neutralizing determinant (PND) and CTL epitopes; and (3) V3 domains from HIV-1IIIB, HIV-1MN, HIV-1RF, and HIV-1SF2. These chimeric fusion proteins were expressed in a large quantity within insect cells, and released as VLPs into the cell culture medium. The purified gag-env VLPs from all three constructs appear to be spherical particles similar to immature HIV but slightly larger than the gag VLPs. Immunoprecipitation analysis showed that the chimeric proteins were recognized not only by HIV-1 positive patient sera, but also by monoclonal and polyclonal antisera raised against V3 peptides of HIV-1IIIB, HIV-1MN, HIV-1RF, and the gp120 antiserum against HIV-1SF2. Balb/C mice immunized with these chimeric VLPs successfully induced CTL activity against V3 peptide-stimulated target cells. In addition, a high degree of cross-reactivity was observed among the four different strains of HIV-1 V3 domain, indicating that the tandem multiple consensus V3 peptide sequence carried by HIV-2 gag can be used as a potential HIV vaccine against various HIVs.

Overexpression of phospholipase C-gamma1 in rat 3Y1 fibroblast cells leads to malignant transformation

Phospholipase C-gamma1 (PLC-gamma1) mediates signals from various extracellular origins to evoke cellular events such as mitogenesis. Previously, we reported that PLC-gamma1 was highly expressed in colorectal cancer and familial adenomatous polyposis, suggesting that PLC-gamma1 might be oncogenic. In this study, we have established rat 3Y1 fibroblasts that overexpress whole PLC-gamma1 and src homology 2 (SH2)-SH2-SH3 domain of PLC-gamma1. These cells showed a transformed phenotype and were tumorigenic when transplanted into nude mice. These results indicate that overexpression of PLC-gamma1 could transform rat fibroblasts, and the transformation is mediated by SH2-SH2-SH3 domain of PLC-gamma1.

Observation of Q-spoiling ef fects on the resonance modes from a noncircularly deformed liquid jet

Spectral changes in fluorescence and lasing spectra were observed from a noncircularly deformed ink-doped ethanol jet, which was induced by a lateral gas flow. The distortion parameter was determined from the analysis of diffraction patterns to be as much as ~10%. Q -spoiling effects were clearly observed in the appearance of high- Q (~10(7)) modes in fluorescence and their disappearance in lasing. From the behavior of resonance modes, we concluded that the effective Q does not decrease so rapidly as predicted by the relation obtained from the ray-optics model. We also found that the signals leak out, with a wide angular spreading, mainly from near the boundary of the major axis, even for a large distortion parameter.

Optical vortices produced with a nonspiral phase plate

We present simple methods to produce optical vortices on the axis of beam propagation with nonspiral phase plates. We show that a phase plate that provides linear phase retardation on one half of a laser beam produces optical vortices, which is demonstrated experimentally by use of a thickness-varying glass platelet. We also demonstrate and explain that mixed dislocations of a bent edge dislocation transform into a pair of vortices with opposing topological charges.

Single-particle scattering effects on the resonance modes of microdroplets

Scattering patterns captured at two different directions from ink-doped ethanol droplets containing submicrometer-sized particles, which had been pumped by nanosecond pulses, were obtained simultaneously. By use of ray optics we interpreted the various scattering patterns of the lasing in droplets. The scattering image of one side and the spectral image of the opposite side were also detected simultaneously. We observed that particles scatter with similar output couplings among modes of the same order. We also found that a single particle could react to modes of different orders with different output couplings.