A new iridovirus isolated from soft-shelled turtle

A virus was isolated from soft-shelled turtle (Trionyx sinensis) with 'red neck disease' on a farm in Shenzhen, China, the virus multiplied and caused a cytopathogenic effect (CPE) at 15-30 degrees C in CO, FHM, CK and BF-2 cells. The optimum conditions for replication was in CO cells at 25-30 degrees C. The virus was sensitive to chloroform treatment, acid (pH 3) or alkaline (pH 10) conditions and heating at 56 degrees C for 30 min. Treatment with 5-iodo-2-deoxyuridine (IUDR) inhibited viral replication, indicating the presence of a DNA genome. Electron microscopy of infected CO culture fluid revealed spherical particles measuring 120-160 nm in diameter. Observation of ultra-thin sections showed numerous hexagonal viral particles in the cytoplasm and nucleus of cells typical of an iridovirus. This virus was moderately virulent for turtles in infection tests. We suggest that this virus is named soft-shelled turtle iridovirus (STIV).

A Structural Equation Model of the Effects of Negative Affectivity, Leader-Member Exchange, and Perceived Job Mobility on In-role and Extra-role Performance: A Chinese Case

In this paper, we contrast the effects of leader-member exchange (LMX) with the effects of perceived job mobility on in-role performance and organizational citizenship behavior (OCB). We further model negative affectivity as the antecedent of both LMX and perceived job mobility and suggest that LMX and perceived job mobility mediated the relationship between negative affectivity and performance. We obtained matching data from supervisor and subordinates in a major battery manufacturing company in southern China. Subordinates provided the negative affectivity, perceived job mobility, and LMX assessment, and their immediate supervisors provided the in-role performance and OCB assessment. Results from a structural equation analysis show that both LMX and perceived job mobility predicted OCB. Instead of being a direct antecedent of OCB, the relationship between negative affectivity and OCB is found to be mediated by LMX and perceived job mobility. Theoretical implications of the results are discussed. Copyright 1999 Academic Press.

Review of Pasteuria penetrans: Biology, Ecology, and Biological Control Potential

Pasteuria penetrans is a mycelial, endospore-forming, bacterial parasite that has shown great potential as a biological control agent of root-knot nematodes. Considerable progress has been made during the last 10 years in understanding its biology and importance as an agent capable of effectively suppressing root-knot nematodes in field soil. The objective of this review is to summarize the current knowledge of the biology, ecology, and biological control potential of P. penetrans and other Pasteuria members. Pasteuria spp. are distributed worldwide and have been reported from 323 nematode species belonging to 116 genera of free-living, predatory, plant-parasitic, and entomopathogenic nematodes. Artificial cultivation of P. penetrans has met with limited success; large-scale production of endospores depends on in vivo cultivation. Temperature affects endospore attachment, germination, pathogenesis, and completion of the life cycle in the nematode pseudocoelom. The biological control potential of Pasteuria spp. have been demonstrated on 20 crops; host nematodes include Belonolaimus longicaudatus, Heterodera spp., Meloidogyne spp., and Xiphinema diversicaudatum. Pasteuria penetrans plays an important role in some suppressive soils. The efficacy of the bacterium as a biological control agent has been examined. Approximately 100,000 endospores/g of soil provided immediate control of the peanut root-knot nematode, whereas 1,000 and 5,000 endospores/g of soil each amplified in the host nematode and became suppressive after 3 years.

Potentiation of retinoic acid-induced differentiation of human acute promyelocytic leukemia NB4 cells by butyric acid, tributyrin, and hexamethylene bisacetamide

Cytodifferentiation therapy by all-trans-retinoic acid (RA) for acute promyelocytic leukemia patients is encouraging in spite of several limitations preventing better clinical outcomes. Most patients in complete remission induced by RA experience relapse and resist further treatment with RA. This resistance primarily is due to a systemic self-induced catabolism of RA, which interferes with the maintenance of effective plasma levels of RA. In this report we explored the possibility that treatment with combinations of RA and other differentiation agents may induce differentiation at lower RA concentrations, which in turn may produce diminished levels of resistance. We found that although n-butyric acid (BA), tributyrin (TB) (a prodrug of BA), or hexamethylene bisacetamide (HMBA) were inactive as sole agents they potentiated RA-induced differentiation of human acute promyelocytic NB4 cells. A measure of the effectiveness of these combinations was that the concentrations of RA in combination with BA and HMBA inducing half-maximal differentiation were 20- to 40-fold lower than those needed with RA alone. Furthermore, the concentrations of BA and HMBA in these combinations were at achievable plasma levels. Therefore, these combinations may have clinical utility for treatment of a variety of malignancies that are sensitive to RA alone.

Minimal Growth Temperature of Pasteuria penetrans

Pasteuria penetrans is an obligate, mycelial, and endospore-forming bacterial parasite of Meloidogyne spp. with promise for the management of root-knot nematodes. Our objective was to use regression analysis of developmental time (days) to various temperatures to determine the minimal temperature for growth and development of P. penetrans in Meloidogyne spp. The data set for regression originated from a previously published report. The data fit well to hyperbolic equations. For various developmental stages of P. penetrans, the minimal growth temperature ranged from 16.7 degrees C to 17.8 degrees C and averaged 17.2 degrees C.

Estimating Incidence of Attachment of Pasteuria penetrans Endospores to Meloidogyne spp. with Tally Thresholds

Pasteuria penetrans has .been identified as an important biological control agent of root-knot nematodes. In this study the use of tally thresholds was evaluated for estimating P. penetrans endospore attachment to second-stage juveniles (J2) of Meloidogyne spp. A tally threshold (T) is defined as the maximum number of individuals in a sample unit that may be treated as absent based on binomial sampling. Three different data sets that originated from centrifugal bioassay, incubation bioassay, and field experiments were investigated. The data sets each contained 70, 33, and 111 estimates of the mean number of endospores attached per J2 (m), respectively. Empirical relationships between m and proportions of J2 with </=T endospores attached (P(T)) were developed using parameters from the linear regression of ln(m) on P(T) (0 < P(T) < 1): ln(m) = a + b P(T), T was set to 0, 1, 2, 3, 4, 5, 8, and 10 endospores/J2. The results indicated that the variances of linear equations tended to decrease with increasing T values for all three data sets. T values of 0, 1, 8, and 10 endospores/J2 for centrifugal bioassay and incubation bioassay, and of 0, 1, 2, and 3 endospores/J2 for field experiments were associated with an r(2) of >= 0.8. These T values were robust for estimating m from P(T), reducing the variability as well as the time and effort spent in estimating the mean number of endospores attached per J2.

Ultrastructure, Morphology, and Sporogenesis of Pasteuria penetrans

ABSTRACT Pasteuria penetrans is a bacterial parasite of root-knot nematodes that shows great potential as a biocontrol agent. Scanning and transmission electron microscopy were used to study the ultrastructure, morphology, and sporogenesis of four isolates of P. penetrans. The effects of different Meloidogyne spp. and tobacco cultivars on sporangium size and morphology of endospores attached to the cuticle of second-stage juveniles (J2) of root-knot nematodes also were investigated. The P. penetrans isolates and their origins were P-20 from M. arenaria race 1 in Levy County, FL; P-100 from Meloidogyne sp. in Pasco County, FL; B-4 from Pratylenchus scribneri in Seminole County, FL; and P-120 from Meloidogyne spp. in Alachua County, FL. Sporangia of the four isolates were identical morphologically and similar in their dimensions, ranging from 2.39 to 3.42 mum in diameter and from 1.38 to 2.38 mum in height. Different Meloidogyne spp. and tobacco cultivars had no effect on sporangium size. Endospores attached to J2 were visualized in three forms: endospores retaining the sporangium wall, endospores covered with a thin exosporium, and endospores without covering. Sporogenesis of P. penetrans was similar to that of other gram-positive bacteria and generally matched the seven-stage scheme reported for Bacillus thuringiensis.

Suppression Mechanisms of Meloidogyne arenaria Race 1 by Pasteuria penetrans

The biological control of Meloidogyne arenaria on peanut (Arachis hypogaea) by Pasteuria penetrans was evaluated using a six x six factorial experiment in field microplots over 2 years. The main factors were six inoculum levels of second-stage juveniles (J2) of M. arenaria race 1 (0, 40, 200, 1,000, 5,000, and 25,000 J2/microplot, except that the highest level was 20,000 J2/microplot in 1995) and six infestation levels of P. penetrans as percentages of J2 with endospores attached (0, 20, 40, 60, 80, and 100%). The results were similar in 1994 and 1995. Numbers of eggs per root system, J2 per 100 cm(3) soil at harvest, root galls, and pod galls increased with increasing nematode inoculum levels and decreased with increasing P. penetrans infestation levels (P </= 0.05), except that there was no effect of P. penetrans infestation levels on J2 per 100 cm(3) soil in 1994 (P> 0.05). There were no statistical interaction effects between the inoculum levels of J2 and the infestation levels of P. penetrans (P > 0.05). When the infestation level was increased by 10%, the number of eggs per root system, root galls, and pod galls decreased 7.8% to 9.4%, 7.0% to 8.5%, and 8.0% to 8.7% in 1994 and 1995, respectively, whereas J2 per 100 cm(3) soil decreased 8.8% in 1995 (P </= 0.05). The initial infestation level of P. penetrans contributed 81% to 95% of the total suppression of pod galls, whereas the infection of J2 of the subsequent generations contributed only 5% to 19% suppression of pod galls. The major suppressive mechanism of M. arenaria race 1 by P. penetrans on peanut is the initial endospore infestation of J2 at planting.

Suppression of Meloidogyne arenaria Race 1 by Soil Application of Endospores of Pasteuria penetrans

The potential of Pasteuria penetrans for suppressing Meloidogyne arenaria race 1 on peanut (Arachis hypogaea) was tested over a 2-year period in a field microplot experiment. Endospores of P. penetrans were mass-produced on M. arenaria race 1 infecting tomato plants. Endospores were inoculated in the first year only at rates of 0, 1,000, 3,000, 10,000, and 100,000 endospores/g of soil, respectively, into the top 20 cm of microplots that were previously infested with M. arenaria race 1. One peanut seedling was planted in each microplot. In the first year, root gall indices and pod galls per microplot were significantly reduced by 60% and 95% for 100,000 endospores/g of soil, and 20% and 65% for 10,000 endospores/g of soil, respectively. Final densities of second-stage juveniles (J2) in soil were not significantly different among the treatments. The number of endospores attached to J2 and percentage of J2 with attached endospores significantly increased with increasing endospore inoculation levels. Pasteuria penetrans significantly reduced the densities of J2 that overwintered. In the second year, root and pod gall indices, respectively, were significantly reduced by 81% and 90% for 100,000 endospores/g of soil, and by 61% and 82% of 10,000 endospores/g of soil. Pod yields were significantly increased by 94% for 100,000 and by 57% for 10,000 endospores/g of soil, respectively. The effect of P. penetrans on final densities of J2 in soil was not significant. Regression analyses verified the role of P. penetrans in the suppression of M. arenaria. The minimum number of endospores required for significantly suppressing M. arenaria race 1 on peanut was 10,000 endospores/g of soil.

Quantification of Endospore Concentrations of Pasteuria penetrans in Tomato Root Material

Six methods for quantification of the endospore concentrations of Pasteuria penetrans from tomato roots are described. Mortar disruption and machine disruption methods gave the highest estimations (endospores per gram of root material) of 83.7 and 79.0 million, respectively. These methods were significantly superior to incubation bioassay (47.7 million), enzymatic disruption (32.1 million), and enzymatic disruption + flotation (25.8 million) methods. A centrifugation bioassay method gave the lowest estimation of 12.7 million.

Bassiatin, a new platelet aggregation inhibitor produced by Beauveria bassiana K-717

A new platelet aggregation inhibitor, bassiatin, was isolated from the cultured broth of Beauveria bassiana which had been isolated from a soil sample collected in Yunnan province, China. The structure of bassiatin was determined to be (3S, 6R)-4-methyl-6-(1-methylethyl)-3-phenylmethyl-1, 4-perhydrooxazine-2,5-dione by NMR analysis, X-ray crystallographic analysis and chemical synthesis. Bassiatin inhibited ADP-induced aggregation of rabbit platelets with the IC50 being 1.9 x 10(-4) M.

Specific inhibition of hepatitis b virus gene expression by an antisense oligonucleotide in vitro

It was previously shown that a number of antisense oligonucleotides against hepatitis B virus (HBV) mRNAs were highly effective in inhibition of HBV gene expression (Yao et al., 1995). Here, using radioisotope techniques, we report a specific inhibition of HBV surface antigen (HBsAg) production in vitro by 2.2.15 cells (Hep-G2 cells transfected with HBV genome) by the antisense oligonucleotide 15-S-asON, a 15-mer phosphorothioate analogue complementary to the cap site of the SPII promoter of HBV mRNA, at a concentration of 2-5 mumol/l. After 24 and 48 hrs of incubation of cells with 15-S-asON, the intracellular concentration of the latter rose to 69.4 and 75.8 nmol/l, respectively, and the HBsAg level assayed by ELISA was reduced by 50.0% and 70.6%, respectively. These results were checked by use of the radioimmunoprecipitation method: 2.2.15 cells exposed to 15-S-asON and labelled with [35S]-methionine for 48 hrs showed a decrease of the HBsAg level by 81.26% but almost none of the total proteins. No cytotoxicity of the 15-S-asON was observed with regard to the cell morphology and growth. These results indicate that the tested antisense oligonucleotide specifically inhibits the HBV gene expression.

A novel bioactive delta lactone FD-211. Taxonomy, isolation and characterization

During our screening program for natural product drugs effective against multidrug-resistant mammalian cells, we have discovered a new delta lactone FD-211 from the fermantation broth of Myceliophthora lutea TF-0409. FD-211 had a broad spectrum activity against cultured tumor cell lines, including adriamycin-resistant HL-60 cells.

[Effect of wu lin powder and its ingredients on atrial natriuretic factor level in mice]

Wu Lin powder (WLP) is a prescription that causes urination to remove dampness. In order to elucidate its mechanism of action, the effect of WLP on atrial natriuretic factor (ANF) was observed. The results showed that the level of ANF was significantly higher in the plasma of mice after giving WLP as well as giving Alisma orientalis or Cinnamomum cassia orally, compared with control, P < 0.05, 0.01 and 0.001 respectively. The effect was most evident at 45 minute after giving WLP (P < 0.05). It is suggested that ANF might play an important role in therapeutic action of WLP.

Potential applications of cytodifferentiation therapy in hematologic malignancies

Retinoids, including retinoic acid (RA), are naturally occurring and synthetic analogs of vitamin A that inhibit cell growth and induce cell differentiation in many experimental tumor models. Differentiation of the human myelogenous leukemia cell line HL-60 by RA led to the finding that cells from patients with acute promyelocytic leukemia (APL) are terminally differentiated by RA. One mechanism for the activity of RA in a variety of cell types involves the RA nuclear receptors (RA receptors [RARs] and retinoid X receptors), which have specific high-affinity binding sites for RA and some of its metabolites. Other mechanisms may also be involved in RA-induced differentiation. Recent studies suggest that RA acylation (retinoylation) may be involved in the RA induction of differentiation in leukemia cells. Combinations of RA with cyclic adenosine monophosphate (cAMP)-elevating agents led to synergistically induced differentiation of HL-60 cells. The lower doses of RA needed in combination therapy are unlikely to lead to RA resistance, a major limitation of RA therapy in APL. In vitro studies suggest that combinations of RA with either PGE or the butyric acid (BA) prodrug tributyrin (TB) may be useful in differentiation therapy for APL and other malignancies. This is a US government work. There are no restrictions on its use.

Pathological changes of oxytalan fibers in the human gingiva of chronic periodontitis

The gingiva samples were obtained from 40 patients with chronic periodontitis after flap operation and 20 cases having healthy gingiva after ectopic wisdom tooth extraction. We investigated the oxytalan fibers by light microscopy (LM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The results demonstrated that under normal conditions numerous oxytalan fibers were widely and evenly distributed throughout the periodontal tissues. There was marked degeneration of the oxytalan fibers in chronic peridontitis. The predominant features were disintegration, fragmentation or disappearance of the oxytalan fibers under the basement membrane. Around the blood vessels, the oxytalan fibers decreased in density with fragmentation of the fibers and sometimes they disappeared almost completely. These results indicated that degeneration and destruction of the oxytalan fibers were closely correlated with the chronic periodontitis process, leading to reduced function occlusion of teeth.

Tributyrin: a prodrug of butyric acid for potential clinical application in differentiation therapy

Butyric acid (BA) induces cytodifferentiation in vitro of a wide variety of neoplastic cells. The potential clinical utility of BA is limited by the apparent difficulty of achieving effective concentrations because of its rapid metabolism and short plasma half-life. In this study we addressed two approaches that may achieve effective concentrations of BA in vivo. One strategy is to use BA derivatives as prodrugs that can be metabolized to yield effective BA concentrations in vivo over a sustained period of time. Another strategy is to define agents that are synergistic with BA so that the desired effect can be achieved at lower concentrations of BA. In this study monobutyrin (MB) and tributyrin (TB) were studied in vitro for their effects on inducing differentiation of human myeloid leukemia HL60 cells and murine erythroleukemia cells. On a molar basis TB was about 4-fold more potent than either BA or MB for inducing differentiation of HL60 cells. BA, MB, or TB induced erythroid differentiation of murine erythroleukemia cells. On a molar basis TB was 3- to 4-fold more potent than BA, whereas MB was much less potent than BA. Combinations of all-trans-retinoic acid with either BA, MB, or TB induced myeloid differentiation of HL60 cells synergistically. We saw marked reductions in the doses of each agent that were needed in combination to achieve the same effect as single agents. For example, 130 microM TB, 110 nM all-trans-retinoic acid, and a combination of 13 microM TB plus 13 nM all-trans-retinoic acid all induced half-maximal differentiation of HL60 cells. Our results suggest that the readily available TB may be an effective prodrug of BA and may be useful either as a sole agent or in combination with other agents for cytodifferentiation therapy of human malignancies.

The present status in all-trans retinoic acid (ATRA) treatment for acute promyelocytic leukemia patients: further understanding and comprehensive strategy are required in the future

All-trans retinoic acid (ATRA) has recently been recognized as the first line therapeutic agent in the treatment of patients with acute promyelocytic leukemia (APL). The extraordinary high remission rate achieved by ATRA in comparison with other chemotherapeutic agents suggested that ATRA differentiation induction therapy seemed superior to conventional chemotherapy for APL patients. However, after the great excitement aroused after the initial successes, we have to take stock and examine in detail several problems which have emerged preventing us from improving the clinical outcome in APL. Maintenance in order to prolong remission and prevention of or retreatment for the relapse are the major subjects of concern at present. Efforts should be made either to keep ATRA effective for APL patients or to resensitize the relapsing patients for repeated ATRA therapy. The administration of ATRA should be carefully adapted in accordance with the individual patient's condition. From both conceptual and practical points of view, ATRA differentiation therapy should be combined with chemotherapy, bone marrow transplantation and biomodifier treatment. Thus, a more comprehensive strategy must be planned and developed in the near future. Using molecular biological techniques, the diagnosis of APL can be more precisely made and the course of the disease more closely monitored. The central dogma, still to be revealed, is the relationship between APL pathogenesis, the chromosome translocation present with the relevant molecular alterations and the response to ATRA treatment. Current studies in all these above fields have provided us with a deeper understanding of the pathogenesis of APL and the physiological function and curative action of ATRA.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum-free culture system for L-CFU assay on acute non-lymphocytic leukemia cases

A completely serum-free culture system for L-CFU assay in vitro on 5 cases of acute non-lymphocytic leukemia (ANLL) is reported. Several agents were tested for the requirement of L-CFU assay in order to substitute the animal or human serum in the conventional culture medium. The results showed that fraction V of bovine serum albumin (2 x 10(-4) mol/L), iron saturated human transferrin (400 micrograms/ml), insulin (1 U/ml), and cholesterol (20 micrograms/ml) were indispensible components for the growth of ANLL L-CFU. Colonies of larger size could be obtained by adding 2-mercaptoethanol. HTB9-CM as the source of growth stimulating factor was used in all experiments. This method is useful for the study of L-CFU proliferation regulated by the human hemopoietic growth factors and the standardization of L-CFU assay.

A clinical and experimental study on all-trans retinoic acid-treated acute promyelocytic leukemia patients

Fifty patients with acute promyelocytic leukemia (APL) have been treated with all-trans retinoic acid (RA). In vitro induced differentiation of primarily cultured bone marrow cells from the patients, colony-forming unit granulocyte-macrophage (CFU-GM) and L-CFU colony-forming assays, and karyotype analysis were performed over the treatment course. The very high bone marrow complete remission (CR) rate (94%) suggested that all-trans RA was superior to conventional chemotherapeutic regimens for the treatment of APL. The leukemic clone was reduced by RA-induced terminal differentiation and loss of proliferation capacity of leukemic cells. Relapse after CR in about 40% of patients was the major reason for the failure of the RA treatment. Patients who relapsed after a chemotherapy-maintained CR could be effectively reinduced to second CR by RA. However, if relapse occurred after a CR maintained by both RA and chemotherapy, the sensitivity of newly emerged leukemic clones to RA was greatly reduced. Therefore, it is suggested that RA should be replaced by conventional chemotherapy as soon as CR is achieved. Laboratory studies proved valuable in selecting cases for RA therapy and in predicting therapeutic effects and prognosis.