First Inventory of Fungi in Symptomless and Symptomatic Chinese Mesona Indicates Phytopathological Threat

Chinese mesona (Platostoma palustre) plays an important role as special crop in Southeast Asia and Taiwan for the production of herbal tea, grass jelly, and further processed food. In order to assess the potential threat of fungi to Chinese mesona, we surveyed isolates from symptomless plants in the area of mesona production, as well as from leaf spots of potted plants in a garden shop and a plantation in a botanical garden in Taiwan. From leaves, stems, and roots of 15 symptomless plants sampled at five collection events over two years, 154 isolates from 810 surface-sterilized plant fragments were obtained and identified based on DNA sequence data of the internal transcribed spacer region, and partially of the β-tubulin and histone H3 genes. The most common species belonged to the genera Cercospora, Colletotrichum, and Fusarium and were considered to be potential plant pathogens. Latent pathogenicity was confirmed by an infection experiment with an endophytic strain of Corynespora cassiicola. Observation of leaf spot disease associated with Cercospora kikuchii suggested pathogenicity of this fungus, which was also isolated as an endophyte from symptomless leaves. We hypothesize that the most common endophytic fungi are latent pathogens in the host and may cause plant disease when the host becomes weakened by senescence or changed cultivation condition. Leaf spots of plants in the botanical garden were associated with a species of Pseudocercospora, which was not found among the endophytic isolates and is newly described based on morphology and analysis of translation elongation factor 1 alpha gene sequences.

Ouabain promotes immune responses in WEHI-3 cells to generate leukemia mice through enhancing phagocytosis and natural killer cell activities in vivo

Ouabain, a cardiotonic steroid, was used for the treatment of heart failure and atrial fibrillation and induces cancer cell apoptosis in many human cancer cells including human leukemia cells. However, there are no reports to show the effects on immune responses in a leukemia mouse model. In this study, WEHI-3 cell generated leukemia mice were developed and treated by oral ouabain at 0, 0.75, 1.5, and 3 mg/kg for 15 days. Results indicated that ouabain did not affect body appearance, but decreased liver and spleen weights, B- and T-cell proliferation at all three doses treatment and increased CD19 cells at 3.0 mg/kg treatment, decreased CD3, CD11b, and Mac-3 cells levels compared with positive control. Furthermore, ouabain increased the macrophage phagocytosis from peripheral blood mononuclear cell and peritoneal cavity at all three doses treatment and increased NK cell activities. Ouabain restored GOT, GPT and LDH levels in WEHI-3 leukemia mice in vivo.

Laminarin Promotes Immune Responses and Reduces Lactate Dehydrogenase But Increases Glutamic Pyruvic Transaminase in Normal Mice In Vivo

BACKGROUND/AIM

Laminarin, a typical component of fungal cell walls, has been shown to induce immune responses in both adult and larval locusts. We investigated the effects of laminarin on immune response and glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT) and lactate dehydrogenase (LDH) levels in normal mice.

MATERIALS AND METHODS

Thirty-six normal BALB/c mice were randomly divided into four groups and treatments were provided by gavage. Group I mice acted as normal control; mice of groups II-IV received laminarin at different doses (100 μl at 1, 2.5 and 5.0 mg/mouse in double-distilled water, respectively). All animals were treated for 14 days and were weighed, blood was collected for determination of cell markers, liver and spleen samples were weighed. Spleens were used for phagocytosis and determination of natural killer (NK) cell activity and cell proliferation by flow cytometric assay.

RESULTS

Laminarin reduced the body weights and weights of liver and spleen. Laminarin increased CD3, CD19 and Mac-3 cell populations at 2.5 and 5 mg/mouse, however, these did not affect CD11b marker levels. Laminarin (1 and 5 mg/mouse) reduced macrophage phagocytosis from peripheral blood mononuclear cells, but did not affect phagocytosis by macrophages from the peritoneal cavity. At an effector:target ratio of 50:1, laminarin reduced NK cell cytotoxic activity at all levels, but at a ratio of 25:1, only at 1 mg treatment. Laminarin did not affect T-cell and B-cell proliferation. Laminarin increased the level of GPT and reduced that of LDH at all doses, indicating laminarin can protect against liver injury. Laminarin is worthy of investigation in future experiments on improving immune responses.

Ouabain Induces Apoptotic Cell Death Through Caspase- and Mitochondria-dependent Pathways in Human Osteosarcoma U-2 OS Cells

BACKGROUND/AIM

Ouabain, a plant-derived product/substance with Na⁺/K⁺-ATPase inhibiting properties, has been shown to exert anti-cancer activity on human cancer cells. This is the first study to investigate the effect of ouabain on apoptotic cell death of human osteosarcoma-derived U-2 OS cells.

MATERIALS AND METHODS

Flow cytometry was used to examine cell viability, cell cycle, and reactive oxygen species (ROS), Ca²⁺, mitochondrial membrane potential (MMP) and caspase activity. Morphological changes were examined by contrast-phase microscopy, while apoptosis-associated protein levels were analyzed by western blot.

RESULTS

Ouabain, at concentrations of 5-60 μM, significantly decreased the total viable cells and induced cell morphological changes in a time-dependent manner. It also time-dependently decreased G₀/G₁ phase and increased S and G₂/M phase in U-2 OS cells. The production of ROS and the levels of MMPs (ΔΨ_m) were inhibited, while Ca²⁺ production in U-2 OS cells was increased. Regarding cell apoptosis, flow cytometry assay revealed increased caspase-3, -8, and -9 activities in U-2 OS cells. Moreover, western blot results showed that ouabain increased the expression of pro-apoptotic protein Bax and decreased the expression of anti-apoptotic protein Bcl-2 in U-2 OS cells. Furthermore, results also showed that ouabain increased cytochrome c release, apoptosis-inducing factor (AIF) and endonuclease (Endo) G that is associated with apoptosis through caspase-dependent and -independent pathway in U-2 OS cells.

CONCLUSION

Our findings provide important insight into the cytotoxic effects of ouabain on U-2 OS cells, in vitro, which are mediated at least partly via cell apoptosis induction.

Characteristic dermoscopic features of primary cutaneous amyloidosis: a study of 35 cases

BACKGROUND

Primary cutaneous amyloidosis (PCA) is a relatively common skin disorder among Asians and South Americans. It is usually diagnosed clinically. However, for cases with atypical presentations, the diagnosis can be a challenge and skin biopsy may be necessary. Dermoscopy has been proved to be a valuable, noninvasive tool in the diagnosis of cutaneous pigmented diseases. Most lesions of PCA show hyperpigmentation and the major histopathological abnormalities of PCA occur in the epidermis and dermal papillae. Dermoscopy might be a powerful tool to provide valuable information for the diagnosis of PCA.

OBJECTIVES

We aimed to find characteristic dermoscopic features of PCA.

MATERIALS AND METHODS

Cases with typical clinical presentations of PCA, either macular or lichen subtypes, were included in this study. All were evaluated using a hand-held, polarized and nonpolarized dermoscope.

RESULTS

A total of 35 patients with clinically diagnosed PCA were enrolled. Eighteen patients had lesions consistent with macular amyloidosis and 17 with lichen amyloidosus. We found two major dermoscopic patterns characteristic of PCA. The most common dermoscopic finding of PCA was a central hub, which could be either white or brown, surrounded by various configurations of pigmentation. For cases of lichen amyloidosus with prominent hyperkeratosis, the central hub was replaced by a scar-like morphology.

CONCLUSIONS

This is the first study to report the characteristic dermoscopic features of PCA. We demonstrate that the use of a dermoscope may assist in achieving an accurate diagnosis of PCA.

Butylated hydroxyanisole affects immunomodulation and promotes macrophage phagocytosis in normal BALB/c mice

Butylated hydroxyanisole (BHA), a synthetic antioxidant, has been used in fat and fatty foods to prevent oxidative deterioration. However, the functions of BHA on immune responses in normal mice remain elusive. The aim of the present study was to investigate the effects of oral treatment of BHA on immune responses in normal mice in vivo. BALB/c mice received various treatments. Blood samples were collected and analyzed. Flow cytometry was used to determine the levels of the cell markers. Results showed that BHA did not significantly affect the weight of the animal body and spleen in normal mice. BHA promoted macrophage phagocytosis from peripheral blood mononuclear cells, but did not alter this process in the peritoneal cavity. Furthermore, BHA did not influence natural-killer cell cytotoxicity in normal mice. Notably, BHA promoted the levels of CD3 (T cells) and decreased the level of CD19 (B cells), but did not significantly affect the levels of CD11b (monocytes) and macrophages (Mac-3) in normal mice. Based on these observations it can be concluded that BHA promotes immune responses by increasing T cells and activating phagocytosis by macrophages in normal mice. However, the molecular mechanisms require further investigation.

Methicillin-resistant Staphylococcus aureus bacteraemia in neonatal intensive care units: an analysis of 90 episodes

AIM

To delineate the clinical features of methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia in infants hospitalized at the neonatal intensive care unit.

METHODS

Episodes of MRSA bacteraemia in Chang Gung Children's Hospital neonatal intensive care unit from 1997 to 1999 were reviewed for incidence, predisposing factors, clinical presentations, treatment and outcome.

RESULTS

Ninety episodes of MRSA bacteraemia were identified. The overall rate of MRSA bacteraemia was 1.05 per 1000 patient days during the 3-y period. Most of the patients were premature infants (76%), with prior operation or invasive procedures (39%), had an indwelling intravascular catheter (79%) and exposure to antibiotic therapy (96%). A localized cutaneous infection was found in 53.3% of the episodes. The most common clinical diagnoses were catheter-related infections (54.4%), skin and soft tissue infections (21.1%), bacteraemia without a focus (20%) and pneumonia (16.7%). Metastatic infection occurred in 18% of these infants. Among the patients treated with vancomycin for < or = 14 d, 88.7% did not develop any complications, and 11.3% developed a recurrence.

CONCLUSIONS

MRSA is an established pathogen in our NICU. MRSA bacteraemia in the neonates predominantly presented as catheter-related infections, and metastatic infections were not infrequently seen. In uncomplicated MRSA bacteraemia, treatment with vancomycin for < or = 14 d seems to be adequate.

The small GTPase Rac suppresses apoptosis caused by serum deprivation in fibroblasts

BACKGROUND

The small GTPase Rac1 is a key signaling protein that mediates a number of important physiologic functions including the organization of the actin cytoskeleton, lipid metabolism, and gene transcription. Rac1 has also been implicated in oncogenic transformation. Expression of constitutively active Rac1 in Rat1 fibroblasts elicits serum- and anchorage-independent growth and causes tumorigenicity in nude mice. The signaling pathways that mediate the role of Rac in cell transformation remain to be identified. Here, we study the role of Rac in cell survival in the absence of serum.

MATERIALS AND METHODS

The cell lines used in this study are Ratl fibroblasts that express constitutively active or dominant negative mutants of Rac1. We used long-term video time-lapse microscopy to analyze the effects of these Rac1 mutants on mitogenicity and apoptosis.

RESULTS

We show that the increase in viability, which is stimulated by Rac1 in the absence of serum, is predominantly caused by an inhibition of apoptosis, with a minor increase in cell division. We also show that Rac1-stimulated cell viability in serum-starved cells is inhibited by chemical inhibition of phosphatidylinositol 3-kinase.

CONCLUSIONS

Our observations indicate a role for Rac1 in survival signaling, possibly via activation of phosphatidylinositol 3-kinase. We propose that Rac1-stimulated cell survival may contribute to the role of Rac1 in serum-independent growth and cell transformation.

Distribution and seasonal occurrence of Forcipomyia taiwana (Diptera: Ceratopogonidae) in the Nantou area in Taiwan

We studied the distribution of Forcipomyia taiwana (Shiraki) in Taiwan, and found this species almost island-wide. Midge seasonality was studied for 4 yr at 3 sites in Nantou, central Taiwan, to identify the extent and causes of midge population outbreaks. The midge population in 1995 was significantly lower than in 3 other years because several typhoons inundated breeding sites. Maximum populations of F. taiwana occurred in June, July, and August. There was a highly significant correlation between the monthly abundance of F. taiwana and temperature and rainfall. A step-up multiple regression indicated that temperature was the most important factor leading to the outbreaks of F. taiwana. Temperature increases from 15 degrees C to near 30 degrees C will increase the midge abundance.

Radiation-induced mutations at the autosomal thymidine kinase locus are not elevated in p53-null cells

To explore further the possibility that some forms of mutated p53 may increase mutagenesis in a positive manner, a double p53 knockout cell line was created, using a promoterless gene targeting approach. The identity of these p53-null cells was confirmed by Southern blot and Western blot analyses. Radiation-induced toxicity and mutagenicity was then compared among p53-null cells, TK6 cells with wild-type p53, and WTK1 cells with a p53 point mutation in codon 237. At the autosomal, heterozygous thymidine kinase locus, p53-null cells had equivalent background mutation frequencies and were approximately equally mutable as TK6, whereas WTK1 was much more sensitive to spontaneously arising and X-ray-induced mutation. Thus, these results indicate that the lack of wild-type p53 did not lead to increased mutagenesis.

A specific shifting deficit in Parkinson's disease: a reversal shift of consistent stimulus-response mappings

Two experiments were designed to investigate effects of cueing upon aptitude for shifting by patients with Parkinson's disease. Subjects executed in alternation two different components of a task set over successive items in a list. We compared the costs of shifting when the stimulus ensemble remained constant from trial to trial ("uniform" lists), with the case in which a change of stimulus ensemble cued each shift of task ("mixed" lists). Shift costs with mixed lists were significantly smaller than those with uniform lists (Exp. 1, ns = 12). This suggests that patients with Parkinson's disease can benefit from cues about the stimulus ensemble in performing tasks. Patients' shifting performance was different from that of controls only in a reversal-shift condition of the previously consistent stimulus-response mappings (Exp. 2, ns = 12). This result suggests that patients with Parkinson's disease suffer from a specific but not a general deficit in ability to shift.

Effects of cell cycle position on ionizing radiation mutagenesis. I. Quantitative assays of two genetic loci in a human lymphoblastoid cell line

Relatively little work has been done on the influence of the position of the cell in the cell cycle on ionizing radiation-induced mutagenesis. We synchronized WTK1 human lymphoblastoid cells with 200 microM lovastatin for 48 h; under these conditions more than 80% of the cells were arrested in G1 phase. Upon release, there was a 12-15-h lag followed by movement of a large fraction into S phase. We irradiated cells with either 1.5 Gy X rays at 1, 15, 18, 21 or 24 h or 1.5 Gy gamma rays at 1, 5, 10, 15 or 24 h after release from lovastatin. We showed that WTK1 cells were most sensitive to ionizing radiation-induced toxicity in G1 and into S phase, and more resistant in mid to late S and G2/M phase. Somewhat surprisingly, we found that the two different gene loci had different sensitivities to radiation-induced mutation through the cell cycle. Cells in late G1 through mid-S phase were most sensitive to radiation-induced mutations at the autosomal thymidine kinase (TK) locus, whereas G1 phase was the most sensitive phase at the X-linked hypoxanthine guanine phosphoribosyl transferase (HPRT) locus.

Colonization and bionomics of Forcipomyia taiwana (Diptera:Ceratopogonidae) in the laboratory

An improvement in colonizing the biting midge Forcipomyia taiwana (Shiraki) was achieved by a new technique that facilitated the rearing of the midges and induced them to mate in the laboratory. At temperature of 15, 20, 25, and 30 degrees C, the development duration of the egg, 4 larval instars, and pupa decreased as temperature increased. Among 7 different diets, the blue green algae, Anabaena sp.Ch3, was the best food for rearing the midges. When the larvae were fed on the blue green algae at 25 degrees C, they needed 12 d to pupate, the pupation rate was 71.4%, the emergence rate was 80.2%, and the average longevity of the male and the female 38.3 and 22.6 d, respectively. When 120 paris were kept in a plastic cage (60 by 60 by 60 cm), swarming and copulation occurred during 0700-0900 and 1700-1800 hours. Swarm occurred throughout the cage and consisted of 10 males. The copulation was performed on the wall and the bottom of the cage, and the average duration was 290 s.

Selection and characterization of alpha-amylase-overproducing recombinant Escherichia coli containing the bacterial hemoglobin gene

We previously reported that the presence of the bacterial (Vitreoscilla) hemoglobin gene enhances alpha-amylase production in recombinant Escherichia coli strain MK79. Using the growth of MK79 on starch as a selective method we have produced a mutant strain (BSC9) that produces up to four times as much alpha-amylase as MK79. Both MK79 and BSC9 produce the most alpha-amylase (per cell and per milliliter) in the stationary phase; almost all of the enzyme is intracellular in both strains. Modification of the standard alpha-amylase assay increases the amount of amylase detected about sixfold. BSC9 has about five to nine times as many copies per cell as MK79 of the recombinant plasmid, which carries both the amylase and hemoglobin genes, but both strains produce about the same amount of hemoglobin. While MK79 respiration decreases upon going from log to stationary phase, BSC9 respiration increases during the same period. The two latter results may be of particular importance in determining the way in which hemoglobin enhances the production of cloned protein products in recombinant bacteria.