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Biomedical subjects

J-Y Wang

Publications and source records attributed to J-Y Wang.

At least 19 recordsLinked to original sources

Laparoscopic Witzel gastrostomy--a reappraised technique.

BACKGROUND: Laparoscopic gastrostomy is the best alternative for long-term enteral feeding when percutaneous endoscopic gastrostomy is not possible. The aim of the present study was to determine the feasibility, complications, adequacy of feeding support, and tolerability of laparoscopic Witzel gastrostomy (LWG) in head and neck cancer patients. The initial results and the results of extended follow-up were evaluated. METHODS: A consecutive series of 48 patients with stenotic head and neck or esophageal cancer were referred for laparoscopic gastrostomy. The patients consisted of 42 men and 6 women aged 36 to 82 years (mean, 54 years). After laparoscopic placement of a Foley catheter of 16 F into the stomach, a seromuscular tunnel 4 cm in length is created, embedding the catheter by interrupted sutures. Three stay sutures for gastropexy are fixed and tied on the abdominal skin at the end of the procedure. The mean duration of the procedure was 62.4 +/- 11 min (52-124 min). RESULTS: Laparoscopic Witzel gastrostomy could be performed successfully in all patients with aerodigestive cancer. None of the laparoscopic gastrostomy tube placement procedures was converted to an open surgery, and none of the 48 patients in this series died as a result of the laparoscopic procedure. All LWG complications (11%) were minor, consisting of superficial wound infections, balloon rupture, and chronic granulation. No major complications were encountered. The mean usage time of gastrostomy was 6.3 +/- 5.3 months. CONCLUSIONS: Current techniques of LWG could be an alternative to percutaneous endoscopic gastrostomy (PEG) for long-term enteral access, because it has proved to be safe and reproducible with relatively few complications.

Adult↗

Empirical treatment with a fluoroquinolone delays the treatment for tuberculosis and is associated with a poor prognosis in endemic areas.

BACKGROUND: A study was conducted to evaluate the effect of the empirical use of fluoroquinolones on the timing of antituberculous treatment and the outcome of patients with tuberculosis in an endemic area. METHODS: All patients with culture confirmed tuberculosis aged > or =14 years diagnosed between July 2002 and December 2003 were included and their medical records were reviewed. RESULTS: Seventy nine (14.4%) of the 548 tuberculosis patients identified received a fluoroquinolone (FQ group), 218 received a non-fluoroquinolone antibiotic (AB group), and 251 received no antibiotics before antituberculous treatment. Fifty two (65.8%) experienced clinical improvement after fluoroquinolone use. In the FQ group the median interval from the initial visit to starting antituberculous treatment was longer than in the AB group and in those who received no antibiotics (41 v 16 v 7 days), and the prognosis was worse (hazard ratio 6.88 (95% CI 1.84 to 25.72)). More patients in the FQ and AB groups were aged >65 years (53.2% and 61.0% v 31.5%), had underlying disease (53.2% and 46.8% v 34.3%), and were hypoalbuminaemic (67.2% and 64.9% v 35.1%). Of the nine mycobacterial isolates obtained after fluoroquinolone use from nine patients whose initial isolates were susceptible to ofloxacin, one (11.1%) was resistant to ofloxacin (after fluoroquinolone use for 7 days). Independent factors for a poor prognosis included empirical fluoroquinolone use, age >65, underlying disease, hypoalbuminaemia, and lack of early antituberculous treatment. CONCLUSIONS: 14.4% of our patients with tuberculosis received a fluoroquinolone before the diagnosis. With a 34 day delay in antituberculous treatment and more frequent coexistence of underlying disease and hypoalbuminaemia, empirical fluoroquinolone treatment was associated with a poor outcome. Mycobacterium tuberculosis isolates could obtain ofloxacin resistance within 1 week.

Adolescent↗

Quantification of methanogens by fluorescence in situ hybridization with oligonucleotide probe.

To monitor anaerobic environmental engineering system, new method of quantification for methanogens was tested. It is based on the measurement of specific binding (hybridization) of 16S rRNA-targeted oligonucleotide probe Arc915, performed by fluorescence in situ hybridization (FISH) and quantified by fluorescence spectrometry. Average specific binding of Arc915 probe was 13.4+/-0.5 amol/cell of autofluorescent methanogens. It was 14.3, 13.3, and 12.9 amol/cell at the log phase, at stationary phase and at the period of cell lysis of batch culture, respectively. Specific binding of Arc915 probe per 1 ml of microbial sludge suspension from anaerobic digester linearly correlated with concentration of autofluorescent cells of methanogens. Coefficient of correlation was 0.95. Specific binding of oligonucleotide probe Arc915 can be used for the comparative estimation of methanogens during anaerobic digestion of organic waste. Specific binding of Arc915 probe was linear function of anaerobic sludge concentration when it was between 1.4 and 14.0 mg/ml. Accuracy of the measurements in this region was from 5 to 12%.

Anaerobiosis↗

Bacteraemia due to ciprofloxacin-resistant Salmonella enterica serotype Choleraesuis in adult patients at a university hospital in Taiwan, 1996-2004.

Eighty-one adult patients with Salmonella enterica serotype Choleraesuis (S. Choleraesuis) bacteraemia treated at a university hospital from 1996 to 2004 were evaluated. Multivariate analysis with a logistic regression model was used to characterize risk factors for primary bacteraemia and mycotic aneurysm and to determine the association of clinical characteristics of patients based on ciprofloxacin susceptibility of the causative organism. The incidence per 100,000 discharges was 0.76 in 1996 and 3.9 in 2004. The overall rate of ciprofloxacin resistance among these isolates was 59% (87 isolates) and the annual rate increased with time from 0% prior to 2000 to 80% in 2004. Among these patients, 48 (59%) had primary bacteraemia and 13 (16%) had secondary bacteraemia with mycotic aneurysm. Seventy (86%) patients had fever at presentation, 22 (27%) developed shock during hospitalization, and eight (10%) died of S. Choleraesuis bacteraemia. Patients with immunocompromised conditions had a higher risk of developing primary bacteraemia (OR 18.442, P < 0.001). Hypertension (OR 15.434, P = 0.002) and male gender (OR 7.422, P = 0.039) were associated with mycotic aneurysm. Patients with mycotic aneurysm were more frequently infected with ciprofloxacin-susceptible isolates (P = 0.028) and ciprofloxacin-susceptible isolates were also more frequently associated with recurrent infection than ciprofloxacin-resistant isolates (P = 0.038). The incidence of S. Choleraesuis bacteraemia has increased in the past 8 years, and this increase is associated with the upsurge of ciprofloxacin-resistant isolates.

Adolescent↗

Epimedium brevicornum Maxim extract relaxes rabbit corpus cavernosum through multitargets on nitric oxide/cyclic guanosine monophosphate signaling pathway.

Epimedium brevicornum Maxim (EbM) has been reputed to have sexual stimulation effects on males. The study is aimed to test the hypothesis that EbM extracts relaxed the corpus cavernosum (CC) smooth muscle through activation of multitargets on nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling pathway. Water extract of EbM and its subfraction (EP-20) were prepared and standardized by high-performance liquid chromatography. Isolated rabbit CC strips were mounted in organ baths and isometric tension was recorded in the presence or absence of specific inhibitors related to NO/cGMP signaling such as L-N(G)-nitro-arginine methyl ester (L-NAME), 1H-[1,2,4]oxadiazolo-[4,3-a] quinoxalin-1-one (ODQ, a guanylyl cyclase inhibitor) or phosphodiesterase 5 (PDE 5) inhibitors. cGMP level was determined in EP-20-treated CC strips. The results showed that EP-20 enriched the content of L-arginine in the process of purification and relaxed the CC smooth muscle precontracted with phenylephrine (PE, 1 microM) in a concentration-dependent manner. Besides, EP-20 increased the amount of cGMP production in rabbit CC tissues. Coincubation with EP-20 and L-NAME or ODQ significantly decreased EP-20-induced relaxation whereas EP-20 increased sodium nitroprusside-induced relaxation in PE-precontracted CC strips. Besides, EP-20 increased the potency and the duration of the relaxation effects caused by electrical field stimulation. Finally, EP-20 could potentiate PDE 5 inhibitors in relaxation of PE-precontracted CC strips. We concluded that extract of EbM relax the CC smooth muscle through multitargets in NO/cGMP/PDE 5 pathway and might bring into perspective the treatment strategy for those patients with erectile dysfunction.

3',5'-Cyclic-GMP Phosphodiesterases↗

Changes in pulmonary arteriole protein kinase calpha expression associated with supplemental L-arginine in broilers during cool temperature exposure.

The present study was conducted to examine the effect of supplemental L-arginine on pulmonary arteriole protein kinase Calpha (PKCalpha) expression in broilers exposed to cool temperature, to investigate further the molecular mechanisms of supplemental L-arginine on modulating pulmonary vascular functions in hypertensive broilers. Broilers were subjected to sub-thermoneutral (cool) temperature to induce pulmonary hypertension syndrome (PHS), and an additional 10 g/kg L-arginine was added to the basal diet to evaluate the effects of supplemental L-arginine on PHS mortality, plasma nitric oxide (NO) production and pulmonary arterioles PKCalpha expression. Supplemental L-arginine reduced PHS mortality but did not affect right/total ventricle (RV/TV) ratios in clinically healthy birds. Birds fed additional L-arginine had increased plasma NO and decreased PKCalpha protein expression in pulmonary arterioles; NO production was negatively correlated with PKCalpha expression. These results demonstrated that supplemental L-arginine diminished PKCalpha expression in birds exposed to cool temperature. It is suggested that NO-induced loss of PKCalpha expression might be partially responsible for its effects on dilating pulmonary vasculature and inhibiting pulmonary vascular remodelling in vivo.

Animals↗

Clinical features and predictors for mortality in patients with infective endocarditis at a university hospital in Taiwan from 1995 to 2003.

The clinical features and microbiological characteristics of 315 patients with definite or possible infective endocarditis (IE) from January 1995 to December 2003 were evaluated. There were 187 males and 128 females with a mean age of 51 years (range, 1 month to 92 years). Ninety-three patients (30%) had a diagnosis of valvular heart disease and 24 (8%) had received prosthetic valve replacement. Blood culture was negative in 62 patients (20%). Staphylococci (91 patients, 32%), including methicillin-susceptible Staphylococcus aureus (15%), methicillin-resistant S. aureus (11%), and coagulase-negative staphylococci (6%), were the most commonly encountered pathogens followed by viridans group streptococci (77 patients, 24%). Eight patients (25%) had various neurological, renal, embolic, and cardiac complications. Patients with neurological complications [odds ratio (OR) 8.175, P<0.001], nosocomial IE (OR 6.661, P<0.001), underlying malignancy (OR 4.993, P<0.001), elevated serum creatinine level (OR 3.132, P=0.001), or elevated WBC count (>15000/mm3) (OR 2.537, P=0.007) were at significantly increased risk of mortality. This study found mortality from IE was associated with several factors, among which neurological complications were the most hazardous. Patients with more than one risk factor had poorer prognosis. These results suggest the need for more aggressive management in patients with IE when multiple risk factors for mortality are identified.

Adult↗

Silk gland specific secretory expression of egfp gene in silkworm Bombyx mori with rAcMNPV system.

To evaluate the possibility of establishing an in vivo baculovirus expression system in a silk gland specific secretory way, the recombinant Autographa californica nucleopolyhedrovirus (AcserpegfpDeltaEGT) carrying the reporter gene egfp downstream of silkworm ser1 promoter and signal peptide coding sequence was generated. The purified recombinant baculovirus AcserpegfpDeltaEGT was injected into the haemocoel of newly ecdysed 5thHendekl) instar silkworm larvae at the amount of 10(6) pfu per larva. At 5 days post injection, green fluorescence derived from EGFP could be observed with fluorescent microscope in only the silk gland but not other tissues after dissection of the silkworm. By making an opening on the silk gland wall, green fluorescence could be observed in the outflow of silk gland indicating the secretion of EGFP and the effectiveness of ser1 signal peptide. Western blotting assay confirmed that EGFP exists in the water-soluble part of cocoon silk too. We also established a simple protocol to purify EGFP from the secreted silk proteins.

Animals↗

Detection of circulating cancer cells with K-ras oncogene using membrane array.

K-ras oncogene is frequently found in human cancers and thus may serve as a potential diagnostic marker for cancer cells in circulation. So far, there is no reliable method for detecting cancer cells with K-ras oncogene in peripheral blood. The objective of this study was to develop a diagnostic membrane array using activated K-ras oncogene-associated molecules as detection targets. In our previous study, cDNA microarray analysis showed that there were 94 genes differentially expressed in K-ras mutant stably transfected adrenocortical cells. In the present study, we obtained 22 up-regulated genes in the closest relation to K-ras oncogene through bioinformatic analysis. At first, we carried out membrane array analysis by using in vitro culture cells. We demonstrated that this diagnostic technique was feasible and highly sensitive. A number as low as 5 cancer cells bearing K-ras oncogene in 1 ml of blood could be distinctively detected. Then, we collected blood specimens from 76 cancer patients. Direct sequencing analysis of these 76 samples showed that K-ras mutation was present in 43 patients with mutation sites mainly at codons 13, 15 and 61, which have been commonly established to be activated sites. We subsequently analyzed these 76 specimens with our diagnostic membrane array. Thirty-nine specimens were detected as positive for activated K-ras oncogene. Eighty percent (12/15) of mutations occurred at codon 13, 72.7% (8/11) at codon 61, and 88.9% (8/9) at codon 15 were accurately detected by our diagnostic membrane. Finally, through a series of biostatistical analyses, the sensitivity, specificity and accuracy of the diagnostic membrane array were 83.7, 90.9 and 86.8%, respectively. These findings suggest that the K-ras oncogene membrane array has a great potential for further investigation and clinical application.

Computational Biology↗

Therapeutic effect of surfactant protein D in allergic inflammation of mite-sensitized mice.

BACKGROUND: Surfactant protein D (SP-D) is involved in the innate immunity within the lung and may have important roles in modulating the inflammatory process of asthma. OBJECTIVE: To examine the potential immunomodulating role of SP-D on the allergic response in mice, and its interaction with the alveolar macrophages (AMs) during allergic inflammation. METHODS: A recombinant 60 kDa fragment of human SP-D (rfh SP-D), Survanta, and budesonide were administrated, respectively, to Der p-sensitive BALB/c mice before or after allergen challenge (AC). Total and differential cell counts, levels of cytokines in bronchoalveolar lavage fluids(BALFs), and levels of Der p-specific IgE and IgG1 antibodies in sera, were assayed. The production of nitric oxide (NO), and inducible NO synthase (iNOS) expression, in AMs, were determined by ELISA and RT-PCR, respectively. RESULTS: Instillation of rfh SP-D to sensitized mice 6 h after AC (therapeutic), but not 24 h before AC (preventive), markedly reduced infiltration of eosinophils, and also reduced levels of IL-4, IL-5, eotaxin, and TNF-alpha but elevated levels of IFN-gamma in the BALF. These effects were comparable with those obtained with budesonide treatment, whereas Survanta did not have a suppressive effect, either before or after AC. There was significant inhibition of NO production in the rfh SP-D pre-treated AMs of allergen-sensitized mice, but not in naive mice. CONCLUSIONS: These results indicate that rfh SP-D has a therapeutic effect on allergen-induced bronchial inflammation, and that this might be because of its inhibitory effect on NO and TNF-alpha production by AMs, and it thus prevents the development of T-helper type 2 cytokine response.

Allergens↗

ABO/secretor genetic complex is associated with the susceptibility of childhood asthma in Taiwan.

BACKGROUND: Histo-blood groups, ABO, Lewis (Le) and secretor (Se) were found to be associated with lower lung function and wheezing in coal miners as well as in asthmatic children in some studies but not others, possibly reflecting the genetic heterogeneity among different ethnicities and local environmental exposure. OBJECTIVE: The present study was conducted to determine the association between ABO, Lewis and secretor genetic complex with susceptibility of childhood asthma in Taiwan. METHODS: We randomly selected 136 asthmatic children and 161 age-matched controls from a childhood asthma survey conducted in primary schools. ABO and Lewis blood groups were determined by red blood cell agglutination methods. Analysis of Se genotype was performed by PCR with sequence-specific primers. RESULTS: There was a higher prevalence rate in secretor subjects (Se/Se) (odds ratio (OR)=1.7, confidence interval (CI)=1.022-2.938) in asthma as compared with controls. The combined effect of these three blood systems revealed that blood group O/secretor phenotype (Se/Se) (OR=2.7, CI=1.126-6.033), and blood group O/Le(a-b-) (OR=3.6, CI=1.080-11.963, P<0.03) individuals were significantly associated with asthma. The Lewis Le(a-b-) recessive genotype (OR=3.3, CI=1.267-8.482), or the joint blood group O/Le(a-b-) phenotype (OR=5.2, CI=1.259-21.429, P<0.02), was significantly associated with high serum IgE (>500 IU), respectively. There was no association of these three blood systems with the sensitivity of dust mite, Dermatophagoide pteronyssinus, in our study population. CONCLUSIONS: We concluded that blood group O/secretors (Se/Se) and O/Le(a-b-) were associated with childhood asthma, and may act as one of the predominant factors for environmental triggers of allergy for asthmatic children in Taiwan.

ABO Blood-Group System↗

Mite allergen induces nitric oxide production in alveolar macrophage cell lines via CD14/toll-like receptor 4, and is inhibited by surfactant protein D.

BACKGROUND: Previously, we have found that dust mite allergens can directly activate alveolar macrophages (AMs), induce inflammatory cytokines, and enhance T-helper type 2 cytokine production. A molecule of innate immunity in the lung, surfactant protein D (SP-D), is able to bind mite allergens and alleviates allergen-induced airway inflammation. OBJECTIVES: This study was aimed at investigating the activation pathway of mite allergen (Dermatophagoides pteronyassinus, Der p)-induced nitric oxide (NO) production by AMs, and the role of SP-D in the modulation of activated AMs by mite allergens. METHODS: Porcine SP-D was purified from bronchoalveolar lavage fluids of Lan-Yu mini-pigs, by affinity chromatography on maltose-sepharose. NO production, inducible expression of lipopolysaccharides (LPS)-related binding and responding surface receptors complex, CD14 and toll-like receptor 4 (TLR4), as well as inducible NO synthase (iNOs) and nuclear factor-kappaB activation were studied in two AMs cell lines, MH-S (BALB/c strain),and AMJ2-C11 (C57BL/6 strain), and one peritoneal macrophage cell line (RAW264.7), after stimulation with LPS, or Der p. RESULTS: LPS and Der p elicited different responses of NO production in the different cell lines, and the response might depend upon the expression of the cell surface CD14/TLR4 complex in different genetic backgrounds of macrophage cell lines. Pretreatment of macrophages with SP-D could inhibit NO production from Der p or LPS-stimulated alveolar macrophages. CONCLUSION: Mite allergen-induced alveolar macrophage activation is mediated by CD14/TLR4 receptors and can be inhibited by SP-D; it further supports the concept that SP-D may be an important modulator of allergen-induced pulmonary inflammation.

Animals↗

The use of sewage sludge and horticultural waste to develop artificial soil for plant cultivation in Singapore.

Greenhouse pot experiments were performed with Ipomoea aquatica (Kang Kong) to evaluate artificial soil produced from poor fertility subsoil, horticultural compost, and sewage sludge. The addition of horticultural compost and sewage sludge to subsoil substantially improved plant growth, improved the physical properties of subsoil and enriched subsoil by essential nutrients for plants. The effect was enhanced when the two ingredients were added to subsoil together. The highest yield of biomass of I. aquatica was observed in artificial soil prepared by mixing subsoil with 4% (wet weight/wet weight) of horticultural compost and 2% (dry weight/wet weight) of sewage sludge. The contents of heavy metals in plants, grown in the artificial soil, were significantly lower than toxic levels. The artificial soil could be recommended for urban landscaping and gardening in Singapore.

Conservation of Natural Resources↗

Modified devascularization surgery for isolated gastric varices assessed by endoscopic ultrasonography.

BACKGROUND: This study aimed to assess the role of endoscopic ultrasonography (EUS) in the surgical management of isolated gastric varices (IGV), and to report the authors' experience in the treatment of IGV with modified devascularization surgery. METHODS: In this study, 26 cirrhotic patients with IGV were treated with devascularization surgery for variceal hemorrhage. Preoperatively, percutaneous transhepatic portography (PTP) and EUS were used to determine the mode of therapy for IGV. Fundectomy was performed for 14 patients with fundic IGV, whereas 12 patients with cardiac IGV underwent proximal gastrectomy. RESULTS: A significantly higher proportion of patients with cardiac varices showed grade 3 IGV on preoperative EUS than those who had fundic varices (p < 0.05). No major complications were observed during or after the operation, and only one patient died of prolonged shock and massive transfusion. Postoperatively, gastric varices had been eradicated completely in 25 of 26 patients, as determined by EUS study. During a mean follow-up period of 50 months, two patients had recurrent varices without bleeding, as demonstrated by EUS. The overall 5-year survival rate for the fundic IGV group was 67.9%, whereas that for the cardiac IGV group was 64.3% (p > 0.05). CONCLUSIONS: This study showed that devascularization surgery is highly effective for the prevention of recurrent bleeding from IGV and provides an alternative treatment method. Preoperatively, EUS is very helpful in detailed devascularization of patients with specific IGV, and may be used also for postoperative follow-up evaluation.

Adult↗

Taurodeoxycholate increases intestinal epithelial cell proliferation through c-myc expression.

BACKGROUND: Bile salts have been shown to modulate gastrointestinal epithelial restitution, differentiation, and other functions. Prior studies have shown that the bile salt taurodeoxycholate increases cell migration after injury. The purpose of this experiment was to determine the effect that taurodeoxycholate has on intestinal epithelial cell growth, c-myc expression and function. METHODS: IEC-6 or Caco-2 cells were treated with varying concentrations of taurodeoxycholate (.05 to 1 mmol/L) and proliferation determined. Apoptosis was measured by use of DNA fragmentation assay and nuclear staining. Cell phase was determined with propidium iodide flow cytometry. C-myc expression was determined by Northern and Western blot analysis, and c-myc function was inhibited by specific c-myc antisense. RESULTS: There was no change in cell structure. Apoptosis was not induced. Six days after exposure to taurodeoxycholate, IEC-6 cell proliferation was significantly increased. Flow cytometry showed a significant increase in S-phase concentration and a significant decrease in G1-phase concentration of the cell cycle. Taurodeoxycholate also increased c-myc protein and mRNA expression, and inhibition of c-myc function prevented taurodeoxycholate-induced cell proliferation. CONCLUSIONS: Exposure to physiological concentrations of the bile salt taurodeoxycholate increases intestinal epithelial cell proliferation. This effect is at least partially mediated through a c-myc-dependent mechanism. Bile salts can have a beneficial effect on the intestinal mucosa.

Animals↗

Glutathione S-transferase P1 gene polymorphism and air pollution as interactive risk factors for childhood asthma.

BACKGROUND: Polymorphisms at the glutathione S-transferase (GST) P1 locus were associated with asthma-related phenotypes and bronchial hyper-responsiveness. OBJECTIVE: This study investigated whether GSTP1 genotypes and outdoor air pollution were interactive risk factors on childhood asthma. METHODS: Four hundred and thirty-six subjects were recruited for oral mucosa samplings from 2853 fourth- to ninth-grade schoolchildren from three districts with different air pollution levels in southern Taiwan. PCR-based assays were performed by oral mucosa DNA to determine GSTP1 genotypes. We also conducted a nested case-control study comprising 61 asthmatic children and 95 controls confirmed by International Study of Asthma and Allergies in Childhood questionnaire results and methacholine challenge test. Multiple logistic regression was used to adjust for potential confounding factors. RESULTS: All participants were homozygous at the Ala-114 locus. Although only a marginally significant association existed between the frequency of homozygosity at the Ile-105 locus and asthma when air pollution was not considered, we found a significant gene-environmental interaction between GSTP1-105 alleles and air pollution after adjusting for confounders (P=0.035). Specifically, we found that compared with participants carrying any Val-105 allele in low air pollution, those who are Ile-105 homozygotes in high air pollution district had a significantly increased risk of asthma (adjusted odds ratio (AOR)=5.52, 95% confidence interval (CI)=1.64-21.25). Compared with participants carrying any Val-105 allele, in high air pollution district, children with Ile-105 homozygotes had a significantly increased risk of asthma (AOR=3.79, 95% CI=1.01-17.08), but those who carried two Ile-105 alleles in low or moderate air pollution districts did not show similar tendencies. The risk of asthma also revealed a clear dose-response relationship with outdoor air pollution in children with Ile-105 homozygotes. CONCLUSION: Our result suggests a gene-environmental interaction between GSTP1-105 genotypes and outdoor air pollution on childhood asthma.

Adolescent↗

Microbiological monitoring in the biodegradation of sewage sludge and food waste.

AIM: To study the microbiology of intensive, in-vessel biodegradation of a mixture of sewage sludge and vegetable food waste. METHODS AND RESULTS: The biodegradation was performed in a closed reactor with the addition of a starter culture of Bacillus thermoamylovorans SW25 under conditions of controlled aeration, stirring, pH and temperature (60 degrees C). The content of viable bacterial cells, determined by flow cytometry, increased from 5 x 108 g-1 of dry matter to 61 x 108 g-1 for 6 days of the process and then dropped to the initial value at the end of the process. The reductions of organic matter, 16S rRNA of methanogens and coenzyme F420 fluorescence during 10 days of the treatment were 67, 54 and 87% of the initial values, respectively. The biodegradability of the organic matter decreased during the 10 days of the treatment from 3.8 to 1.3 mg CO2 g-1 of organic matter per day. The treatment of sewage sludge and food waste at 60 degrees C did not remove enterobacteria, which are the agents of intestinal infections, from the material. The percentage of viable enterobacterial cells, determined by fluorescent in situ hybridization (FISH) with Enterobacteriaceae-specific oligonucleotide probe and flow cytometry, varied from 1 to 14% of the viable bacterial cells. CONCLUSIONS: The mixture of sewage sludge and food waste can be degraded by the aerobic thermophilic bacteria; the starter culture of Bacillus thermoamylovorans SW25 can be used to perform this process; and enterobacteria can survive under treatment of sewage sludge and food waste at 60 degrees C for 13 days. SIGNIFICANCE AND IMPACT OF THE STUDY: The results show that FISH with an oligonucleotide probe can be used to study not only the growth but also the degradation of biomass. Obtained results could be used to design the bioconversion of sewage sludge and food waste into organic fertilizer.

Bacillus↗