Search PubMed⌕ Search

Biomedical subjects

V Ivanov

Publications and source records attributed to V Ivanov.

At least 19 recordsLinked to original sources
PubMed2006

A phase II trial of rituximab as adjuvant to intensive sequential chemotherapy in patients under 60 years with untreated poor-prognosis diffuse large B-cell lymphoma.

The potential benefit of rituximab as adjuvant to high-dose therapy (HDT) has been investigated in patients under 60 years with poor-risk (age-adjusted international prognostic index at 2-3) CD20+ diffuse large B-cell lymphoma (DLBCL). The treatment consisted of four cycles of high-dose CEOP (cyclophosphamide, epirubicin, vincristine, prednisone), plus etoposide and cisplatin during the two last cycles. Peripheral blood stem cells were collected after cycle 1, and reinfused after cycles 3 and 4. Four weekly rituximab infusions were subsequently delivered. Among the 36 patients included, 30 could complete chemotherapy schedule, and 24/36 received rituximab. A complete response occured in 26/36 patients (72%). With a median follow-up of 30 months, the estimated 5-year overall survival (OS) and event-free survival (EFS) rates (mean +/- s.d.) were 65 +/- 16 and 63 +/- 15%, respectively. For the 24 patients who received both chemotherapy and rituximab, the estimated 5-year OS and EFS rates were 86 +/- 14 and 82 +/- 15%. These data suggest that rituximab after HDT is feasible. Both complete remission rate and survival curves compare favorably with the poor outcome usually observed in high-risk DLBCL patients managed with HDT without rituximab.

Adult↗
PubMed2006

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↗
PubMed2005

Early administration of recombinant erythropoietin improves hemoglobin recovery after reduced intensity conditioned allogeneic stem cell transplantation.

The use of recombinant human erythropoietin (rHuEPO) has been controversial after myeloablative allogeneic Stem cell transplantation (allo-SCT). Reduced intensity conditioning regimens (RIC) offer a novel approach that might translate into a different profile of erythropoietic recovery. We treated 20 consecutive patients with rHuEPO early after matched sibling RIC allo-SCT. Conditioning included fludarabine, busulfan and antithymocyte globulin. EPO treatment was analyzed in terms of toxicity, impact on the frequency of Red blood cell transfusions (RBCT) and kinetics of Hemoglobin recovery within the 60 days post-allo-SCT. Results were compared with 27 matched patients who did not receive rHuEPO. In the first 2 months after allo-SCT all patients receiving rHuEPO (100%) achieved an Hb level > 11 g/dl at a median of 30 (15-35) days post-allo-SCT, as compared to only 63% of the patients not receiving rHuEPO (P = 0.007) at a median of 35 (20-55) days (P = 0.03). A total of 70% (95% CI, 50-90) of rHuEPO patients maintained an Hb over 11 g/dl in the second month as compared to only 19% (95% CI, 4-34) in the other group (P = 0.0004). For patients receiving RBCT, the use of rHuEPO was associated with a trend towards reduced RBCT requirements. This pilot study suggests a potential benefit of early administration of rHuEPO after RIC allo-SCT on early erythropoietic recovery.

Adult↗
PubMed2005

Startup of pilot-scale aerobic granular sludge reactor by stored granules.

The startup of a pilot-scale aerobic granular sludge reactor was investigated by seeding with 4-month stored aerobic granules. Two liters of granules were inoculated into the reactor (5.9% of reactor volume), which gave a biomass concentration of 1.03 g l(-1). Experimental results showed that seeding granules could be successfully maintained in the reactor. The microbial activity of seeding granules could be fully recovered to that of fresh granules after 2 days of operation, and new granules started to grow after day 5. Newly developed aerobic granules at stable period had similar size and morphology as seeding granules, and a biomass concentration of 6.0 g l(-1) was achieved in the reactor. The experiment demonstrated for the first time that stored aerobic granules could be used for easy and quick startup of aerobic granular sludge reactor.

Aerobiosis↗
PubMed2005

Bioflavonoids effectively inhibit smooth muscle cell-mediated contraction of collagen matrix induced by angiotensin II.

Plant-derived bioflavonoids have been recognized to support arterial wall structural integrity and interfere with a variety of proatherosclerotic stimuli. In this study we tested the effects of bioflavonoids on the contractile activity of cultured human aortic smooth muscle cells (SMC) embedded in a 3-dimensional type I collagen matrix. Collagen I solution mixed with human aortic SMC in 24-well plates were allowed to form gels. Tested compounds were added to the wells, and the gels were set afloat by gentle tapping. Digital photographs of the gels were taken after 24 hours of incubation at 37 degrees C. The area of contracted gel was measured and expressed as a percentage of the control gel area from 3 or more replicates. Expression of matrix metalloproteinase (MMP-2) in conditioned media was assessed by gel zymography. Different classes of bioflavanoids showed variable efficiency in inhibiting angiotensin II (ATII)-dependent collagen gel contraction by SMCs. An increase in the number of gallate groups per catechin molecule was associated with increased inhibition of angiotensin II-dependent collagen gel contraction by SMC. Antioxidants (N-acetyl cysteine and ascorbic acid) did not inhibit collagen gel contraction. Bioflavonoid inhibition of collagen gel contraction by SMC correlated with inhibition of matrix metalloproteinase-2 expression. Bioflavonoids participate in the regulation of SMC-mediated contraction and have a strong potential in counteracting pathophysiological effects of ATII. Bioflavonoid activity depends on structural characteristics and can be related to extracellular matrix integrity.

Angiotensin II↗
PubMed2005

Phosphate removal from the returned liquor of municipal wastewater treatment plant using iron-reducing bacteria.

AIM: The application of iron-reducing bacteria (IRB) to phosphate removal from returned liquor (liquid fraction after activated sludge digestion and anaerobic sludge dewatering) of municipal wastewater treatment plant (WWTP) was studied. METHODS AND RESULTS: An enrichment culture and two pure cultures of IRB, Stenotrophomonas maltophilia BK and Brachymonas denitrificans MK identified by 16S rRNA gene sequencing, were produced using returned liquor from a municipal WWTP as carbon and energy source, and iron hydroxide as oxidant. The final concentration of phosphate increased from 70 to 90 mg l(-1) in the control and decreased from 70 to 1 mg l(-1) in the experiment. The mass ratio of removed P to produced Fe(II) was 0.17 g P g(-1) Fe(II). The strain S. maltophilia BK showed the ability to reduce Fe(III) using such xenobiotics as diphenylamine, m-cresol, 2,4-dichlorphenol and p-phenylphenol as sole sources of carbon under anaerobic conditions. CONCLUSIONS: Bacterial reduction of ferric hydroxide enhanced the phosphate removal from the returned liquor. SIGNIFICANCE AND IMPACT OF THE STUDY: The ability of the facultative anaerobes S. maltophilia BK and B. denitrificans MK to reduce Fe(III) was shown. These micro-organisms can be used for anaerobic removal of phosphate and xenobiotics by bacterial reduction of ferric ions.

Bacteria, Anaerobic↗
PubMed2004

Bacteriological examination of ballast water in Singapore Harbour by flow cytometry with FISH.

In this study the concentrations of total bacteria, enterobacteria, Vibrio spp., and E. coli have been compared for ballast water samples taken from ships in Singapore Harbour. The cell concentrations were enumerated using FISH and flow cytometry. The data were highly variable, reflecting the many influences upon ballast water as it is utilized in the shipping industry. The concentration of bacterial species was determined as a proportion of the total concentration of cells for the ballast water sampled. For the ballast water sampled these concentrations were 0.67-39.55% for eubacteria, 0-2.46% for enterobacteria, 0.18-35.82% for Vibrio spp., and 0-2.46% for E. coli. Using FISH and flow cytometry, an informative determination of the bacterial hazards of ship ballast water can be made.

Bacteria↗
PubMed2004

Decreased RBCTs after reduced intensity conditioning allogeneic stem cell transplantation: predictive value of prior Hb level.

BACKGROUND: RBCT (RBCT) requirements of stem cell transplant (SCT) recipients are often substantial and may be related to transplant type. STUDY DESIGN AND METHODS: An analysis was done of RBCT requirements and Hb recovery kinetic in the first 60 days after HLA-identical sibling allogeneic SCT in a series of 110 consecutive patients treated for various malignant diagnoses. Patients were prepared with either an antithymocyte globulin (ATG) and reduced intensity chemotherapy-based conditioning (RIC) (n=64) or a myeloablative conditioning regimens (MAC; n=46). Patients received marrow (n=64) or PBPCs (n=46). RESULTS: Overall, intensity of conditioning regimen (RIC vs. MAC; p=0.0005) and graft source (PBPC vs. marrow; p<0.0001) independently predicted RBCT requirements. Hb recovery was accelerated after RIC when compared to MAC allo-SCT (p=0.02). In RIC patients, RBCTs were inversely correlated to Hb level before conditioning (p<0.0001) and the dose of ATG (p=0.009). Moreover, Hb level before allo-SCT significantly influenced Hb recovery kinetic after RIC but had no impact on RBCT requirements and Hb recovery after MAC. CONCLUSION: Thus, RIC conditioning creates a different pattern of erythropoiesis recovery as compared to a MAC regimen and suggest a need for studies aimed at further reducing RBCT and accelerating Hb recovery.

Adolescent↗
PubMed2004

Iron-mediated removal of ammonium from strong nitrogenous wastewater from food processing.

The combination of microbial reduction and further microbial oxidation of iron was applied to the treatment of food-processing wastewater and recovery of ammonium. Fe2+ ions were formed by iron-reducing bacteria under anaerobic conditions. Ammonium was recovered by co-precipitation with negatively charged iron hydroxides produced during oxidation of Fe2+ by iron-oxidizing bacteria under microaerophilic conditions. The value-added by-product of this process can be used as a slowly released ammonium fertilizer.

Bacteria↗
PubMed2004

Biotechnology of intensive aerobic conversion of sewage sludge and food waste into fertilizer.

Biotechnology for intensive aerobic bioconversion of sewage sludge and food waste into fertilizer was developed. The wastes were treated in a closed reactor under controlled aeration, stirring, pH, and temperature at 60 degrees C, after addition of starter bacterial culture Bacillus thermoamylovorans. The biodegradation of sewage sludge was studied by decrease of volatile solids (VS), content of organic carbon and autofluorescence of coenzyme F420. The degradation of anaerobic biomass was faster than biodegradation of total organic matter. The best fertilizer was obtained when sewage sludge was thermally pre-treated, mixed with food waste, chalk, and artificial bulking agent. The content of volatile solid and the content of organic carbon decreased at 24.8% and 13.5% of total solids, respectively, during ten days of bioconversion. The fertilizer was a powder with moisture content of 5%. It was stable, and not toxic for the germination of plant seeds. Addition of 1.0 to 1.5% of this fertilizer to the subsoil increased the growth of different plants tested by 113 to 164%. The biotechnology can be applied in larger scale for the recycling of sewage sludge and food wastes in Singapore.

Bacteria, Aerobic↗
PubMed2004

Removal of micro-particles by microbial granules used for aerobic wastewater treatment.

Microbial granules with a diameter from 0.4 mm to 3.0 mm have been produced by fast sedimentation and retention of microbial aggregates in sequencing batch airlift reactors used for model wastewater treatment. The wastewater was with or without addition of calcium salt. The granules were able not only to degrade organic matter but to remove nano- and micro-particles from wastewater due to microchannels and pores in the matrix of the granules. To detect the removal of 0.1 microm, 0.6 pm, 4.2 microm fluorescent microspheres, and cells of Escherichia coli, stained by permeable nucleic acid stain SYTO9, the granules were incubated with these particles. The rate of particle removal and their accumulation in the granules was measured by a Fluoview300 confocal laser scanning microscope (CLSM) (Olympus, Japan); a FACSCalibur flow cytometer (Becton Dickinson, CA, USA), and a fluorescence spectrometer LS-50B (Perkin-Elmer, UK). The release or removal of biological and non-biological particles was analyzed by a flow cytometer after DNA staining. Total number of the particles bigger than 0.1 microm in the reactors was approximately 4 x 10(7) per ml, and 23% of these particles were bacterial cells. The 0.1 microm and 4.2. microm microbeads were accumulated within 250 microm in the upper layer of the microbial granule but externally added cells of Escherichia coli penetrated to the depth of approximately 800 microm in the granules without calcium addition. Microbial granules contained also attached ciliates but accumulation of the particles in protozoan cells was smaller than in the granule matrix. Kinetics of particle sorption was revealed by flow cytometry and fluorescence spectrometry. Almost half of the stained cells of E. coli can be removed by the granules for one hour. The ability of the microbial granules to remove the particles can enhance their function in aerobic treatment of wastewater.

Aerobiosis↗
PubMed2003

Rapid improvement of disseminated aspergillosis with caspofungin/voriconazole combination in an adult leukemic patient.

A 57-year-old man with acute myeloid leukemia (AML) French-American-British (FAB) 4 developed disseminated invasive cerebral and pulmonary aspergillosis during postinduction aplasia. According to international consensus, infection was categorized as probable (two host factors: deep neutropenia for >10 days and refractory fever for >96 h; major clinical criteria of lower respiratory tract and CNS invasive fungal infection; positive results for galactomannan antigen in three blood samples). After the failure of standard amphotericin-based therapy, the spectacular regression of multifocal brain and lung lesions was rapidly achieved under a caspofungin acetate/voriconazole combination. Further permanent caspofungin maintenance with voriconazole added during aplasia periods permitted two consolidation courses and autograft-based intensification without any delay.

Antifungal Agents↗
PubMed2003

Biomass and porosity profiles in microbial granules used for aerobic wastewater treatment.

AIMS: To obtain biomass and porosity profiles for aerobically grown granules of different diameters and to determine a suitable range of granule diameters for application in wastewater treatment. METHODS AND RESULTS: Microbial granules were cultivated in an aerobic granulated sludge reactor with model wastewaters containing acetate, or ethanol plus acetate, or glucose as the main carbon source. Granules were formed by retaining microbial aggregates using a settling time of 2 min. Sampled granules had diameters ranging from 0.45 to 3 mm. Microbial biomass in the granules was detected with the nucleic acid stain SYTO 9 and confocal laser scanning microscopy. The thickness of the microbial biomass layer was proportional to the granule diameter, and had a maximum value of 0.8 mm. The thickness of the microbial biomass layer correlated with the penetration depth of 0.1 microm fluorescent beads into the granule. CONCLUSIONS: The microbial biomass and porosity studies suggest that aerobically grown microbial granules should have diameters less than a critical diameter of 0.5 mm, if deployed for wastewater treatment applications. This critical diameter is based on the assumption that whole granules should have a porous biomass-filled matrix. SIGNIFICANCE AND IMPACT OF THE STUDY: This work could contribute to the development of aerobic granulation technology for effective biological wastewater treatment.

Aerobiosis↗
PubMed2003

Monitoring of microbial diversity by fluorescence in situ hybridization and fluorescence spectrometry.

The goal of the research was the development of a simple method to quantify microbial groups in environmental samples. Fluorescence intensity was measured in the sample before and after whole cell fluorescence in situ hybridization with rRNA-targeted, fluorochrome-labeled oligonucleotide probes. To determine specific and non-specific binding of different oligonucleotide probes the following approaches have been used: (1) incubation of the sample with probes at two different temperatures; (2) hybridization of labeled probe in the presence of unlabeled probe; (3) incubation of the sample with labeled specific probe or labeled nonsense probe. Specific binding (hybridization) of the probe was calculated as the difference between total binding and non-specific binding of the probe. Specific binding was 40-50% of total binding in the environmental samples tested. The ratio of the specific binding of different probes may be used to quantify the ratio of different microbial groups in the environmental samples. This quantification is suitable for the microbiological monitoring of microbial aggregates because it is a simple technique and the results can be measured by a portable fluorometer.

Bacteria↗
PubMed2003

The effect of organic loading rate on the aerobic granulation: the development of shear force theory.

The effect of organic loading rate (OLR) on aerobic granulation was studied by adopting three column-shaped, sequential aerobic sludge blanket reactors (SASBR). The reactors had been fed with laboratory prepared, synthetic dextrose-nutrient broth substrate. Experimental results showed clearly that the formation, characteristics and stability of aerobic granules had a close relationship with the strength of OLR applied. Aerobic granules appeared firstly under the OLR of 4 kg COD x (m3 x day)(-1). The system stabilization was demonstrated by its little-changed amount and morphology of granules. The characteristics of the stabilized granules were: 5.4 mm in mean diameter, 1.29 in roundness, 118 mg O2 x (mg VSS x hr)(-1) in SPOUR. The respective biomass SVI was 50 mL x (g MLVSS)(-1) and the averaged COD removal rate was 95%. Under the OLR of 8 kg COD x (m3 x day)(-1), granules appeared two days later than those for 4 kg COD x (m3 x day)(-1) and they always coexisted with flocs. The formed granule bed was not as compact as that under 4 kg COD x (m3 x day)(-1). There were no granules formed under the OLR of 1 kg COD x (m3 x day)(-1). Instead, flocs with rather loose structure dominated reactor mixed-liquor. The respective SVI's were 65 and 138 mL x (g MLVSS)(-1) under OLR of 8 and 1 kg COD x (m3 x day)(-1). It was proposed that the growth and maintenance of aerobic granules follow the shear force balance theory. Under the OLR of 4 kg COD x (m3 x day)(-1), a balance was reached between the aeration shear force and organic loading rate. Under this favored condition aerobic granules formed quickly and, became stabilized with the experimental parameters remained unchanged.

Bacteria, Aerobic↗
PubMed2002

Size-effect on the physical characteristics of the aerobic granule in a SBR.

Owing to a fast growth rate, aerobic granules display a wide range of sizes, approximately 0.3-5.0 mm in diameter. As the diameter increases, the aerobic granule undergoes serial morphological and physical changes that could cause problems to the reactor operation, a phenomenon which, however, has not been fully studied hitherto. In this study, aerobic granules from a sequencing batch reactor were mechanically separated into various size-categories in order to investigate their physical properties, including sludge volumetric index (SVI), settling velocity (sv), specific surface hydrophobicity, granule strength, total solids, percentage volatile solids and other structural properties. Also, the live and dead biomass distribution was examined under a confocal laser scanning microscope after treatment with nucleic acid viability stains. Regardless of size, the biomass (both live and dead) was densest in the outer layer of the granule, which was about 600+/-50 microm thick. The live cells appeared only in the peripheral zone, while dead biomass spread into the inner zone. The biomass distribution pattern justified the changing physical properties of the granules as they grew bigger. As size increased, the sv, granule total density and biomass density increased but not in parallel with the size increment, while the granule strength, specific surface hydrophobicity and SVI decreased. Nonetheless, beyond a threshold size (4.0 mm diameter), the granules presented peculiar values in those properties, deviating from the initial trends. This was due to both inner and outer structural changes. The physical properties associated significantly with the size factor, for which the correlation coefficients were above 0.67. In view of biological viability and physical properties, the operational size-range suggested for optimal performance and economically effective aerobic SBR granular sludge is a diameter of 1.0-3.0 mm.

Aerobiosis↗
PubMed2002

Presence of anaerobic bacteroides in aerobically grown microbial granules.

Microbial granules were grown in a column-type sequential aerobic sludge blanket reactor inoculated with activated sludge flocs taken from a wastewater treatment plant and containing a medium with glucose as the main carbon source. The reactor selected for granules that could settle rapidly by employing a short settling time of 2 min. Matured granules with diameters between 2 and 3 micro m were examined for anaerobic bacteria as their presence can signal the onset of diffusion limitation problems that can potentially diminish granule stability due to the bacterial production of fermentation gases and organic acids under anaerobic conditions. To detect the anaerobes in the granules, clones were constructed from 16S rRNA PCR amplicons. Two sequence types associated with a strict anaerobe Bacteroides spp. were identified from these clones. Fluorescence in situ hybridization (FISH) followed by confocal laser scanning microscopy (CLSM) demonstrated that cells of Bacteroides spp. were concentrated at a depth of approximately 800 micro m below the surface of the granule. Cell enumeration using flow cytometry showed that the percentage of labeled cells of Bacteroides spp. compared to total bacterial cells in the granules was 0.56%. This is the first study to use a suite of culture-independent techniques to report the presence of a defined species of anaerobic bacteria in aerobically grown microbial granules.

Aerobiosis↗