The first biosimilar approved for the treatment of osteoporosis: results of a comparative pharmacokinetic/pharmacodynamic study

To demonstrate the clinical comparability between RGB-10 (a biosimilar teriparatide) and the originator, a comparative pharmacokinetic trial was conducted. The study was successful in establishing bioequivalence. Marketing authorisation for RGB-10 (Terrosa®) was granted by the European Medicines Agency in 2017.

INTRODUCTION

Teriparatide, the first bone anabolic agent, is the biologically active fragment of human parathyroid hormone. The imminent patent expiry of the originator will open the door for biosimilars to enter the osteology market, thereby improving access to a highly effective, yet prohibitively expensive therapy.

METHODS

Subsequent to establishing comparability on the quality and non-clinical levels between RGB-10, a biosimilar teriparatide, and its reference product (Forsteo®), a randomised, double-blind, 2-way cross-over comparative study (duration: four days) was conducted in 54 healthy women (ages: 18 to 55 years) to demonstrate the pharmacokinetic/pharmacodynamic (PK/PD) equivalence and comparable safety of these products. Extents of exposure (AUC_0-tlast) and peak exposure (C_max), as measured by means of ELISA, were evaluated as co-primary PK endpoints, and serum calcium levels, as measured using standard automated techniques, were assessed for PD effects. Safety was monitored throughout the study.

RESULTS

The 94.12% CIs for the ratio of the test to the reference treatments, used due to the two-stage design (85.20-98.60% and 85.51-99.52% for AUC_0-tlast and C_max, respectively), fell within the 80.00-125.00% acceptance range. The calcium PD parameters were essentially identical with geometric mean ratios (GMRs) of 99.93% and 99.87% for AUC and C_max, respectively. Analysis of the safety data did not reveal any differences between RGB-10 and its reference.

CONCLUSION

Based on the high level of similarity in the preclinical data and the results of this clinical study, marketing authorisation for RGB-10 (Terrosa®) was granted by the European Medicines Agency (EMA) in 2017.

Experimental Assessment of the Degradation of "Unbiodegradable" Organic Solids in Activated Sludge

In current process models activated sludge consists of biodegradable and unbiodegradable organic fractions. Recent evidence suggests that this approach may not be accurate because some of this "unbiodegradable" material may indeed be degradable. To improve sludge production predictions, it is important to know to what extent the "unbiodegradable" organic fraction is degradable. Assuming that volatile suspended solids (VSS) is a measure of the sum of biodegradable and unbiodegradable organic solids and the integral of the oxygen uptake rate (OUR) is representative of the biodegradable organics, the combination of these measurements can be used to predict the change of unbiodegradable organic solids within an aerobic digestion batch experiment. This procedure was used to estimate degradation rates of "unbiodegradable" VSS between 0.006 to 0.029 d(-1). The advantage of the proposed method is that the degradation rate can be determined directly based on measurements and relies on a limited number of assumptions.

Physiological adaptation of growth kinetics in activated sludge

Physiological adaptation as it occurs in bacterial cells at variable environmental conditions influences characteristic properties of growth kinetics significantly. However, physiological adaptation to growth related parameters in activated sludge modelling is not yet recognised. Consequently these parameters are regarded to be constant. To investigate physiological adaptation in activated sludge the endogenous respiration in an aerobic degradation batch experiment and simultaneous to that the maximum possible respiration in an aerobic growth batch experiment was measured. The activated sludge samples were taken from full scale wastewater treatment plants with different sludge retention times (SRTs). It could be shown that the low SRT sludge adapts by growth optimisation (high maximum growth rate and high decay rate) to its particular environment where a high SRT sludge adapts by survival optimization (low maximum growth rate and low decay rate). Thereby, both the maximum specific growth rate and the decay rate vary in the same pattern and are strongly correlated to each other. To describe the physiological state of mixed cultures like activated sludge quantitatively a physiological state factor (PSF) is proposed as the ratio of the maximum specific growth rate and the decay rate. The PSF can be expressed as an exponential function with respect to the SRT.

A dynamic physicochemical model for chemical phosphorus removal

A dynamic physico-chemical model for chemical phosphorus removal in wastewater is presented as a tool to optimize chemical dosing simultaneously while ensuring compliant effluent phosphorus concentration. This new model predicts the kinetic and stoichiometric variable processes of precipitation of hydrous ferric oxides (HFO), phosphates adsorption and co-precipitation. It is combined with chemical equilibrium and physical precipitation reactions in order to model observed bulk dynamics in terms of pH. The model is calibrated and validated based on previous studies and experimental data from Smith et al. (2008) and Szabo et al. (2008) as a first step for full-plant implementation. The simulation results show that the structure of the model describes adequately the mechanisms of adsorption and co-precipitation of phosphate species onto HFO and that the model is robust under various experimental conditions.

Vitamin D-neutralizing CYP24A1 expression, oncogenic mutation states and histological findings of human papillary thyroid cancer

OBJECTIVE

The aims of the present study were to examine gene and protein expression of the vitamin D-inactivating 24-hyroxylase (CYP24A1) and the activating 1-alpha-hydroxylase (CYP27B1) enzyme in human papillary thyroid cancer (PTC), furthermore, to investigate the association between CYP24A1 expression and numerous clinical, histological parameters and somatic oncogene mutation status of thyroid tumor tissues.

MATERIALS AND METHODS

Gene expression analysis was carried out in 100 Hungarian thyroid samples, both normal and papillary tumor tissue sections of the same patient. The specific mRNA to the selected genes was analyzed by TaqMan probe-based quantitative real-time RT-PCR. The somatic oncogene mutation states of BRAF, NRAS, HRAS and KRAS were also tested.

RESULTS

CYP24A1 mRNA expression was markedly increased in 52 cases (52%) of the examined papillary cancers compared with that of normal thyroid tissue. There was a tendency toward difference in the distribution of high-level CYP24A1 in the PTC accompanied with somatic oncogene mutation. Positive correlation was seen between increased CYP24A1 expression rate and a group of variables reflecting tumor malignity (mainly vascular invasion, lymph node metastasis, tumor size, hypothyreosis) by principal components analysis. No significant alteration was seen in CYP27B1 gene expression between neoplastic and normal tissues.

CONCLUSIONS

A definite alteration was seen in vitamin D3-inactivating CYP24A1 gene activity in PTC compared to their normal tissues on a relatively large patient population. Our findings raise the possibility that CYP24A1 may also directly be involved in thyroid carcinogenesis.

Comparative statistical analysis of osteoporosis treatment based on Hungarian claims data and interpretation of the results in respect to cost-effectiveness

The efficacy of interventions used in real life for the treatment of osteoporosis has not been evaluated on a national basis. We analysed the database of the single Hungarian health care provider between 2004 and 2010. A marked reduction in fracture incidence and hospitalization was seen, which also proved to be cost-effective.

INTRODUCTION

Osteoporosis and its consequences place a significant burden on the health care systems of developed countries. Present therapeutic modalities are effective in reducing the risk of fractures caused by osteoporosis. However, we do not know whether the interventions introduced in the past 15 years have significantly reduced the number of osteoporotic fractures in real life, and if yes, how cost-effectively.

METHODS

The database of the National Health Insurance Fund Administration in Hungary was analysed for the period between 2004 and 2010. Two specific patient groups were identified within the population. Patients, who were under osteoporosis treatment in more than 80% of the potential treatment days in three consecutive years (patients with high compliance), were compared with patients where this ratio was under 20% (patients with low compliance). Several statistical comparative models were implemented in order to capture a complete picture on the differences. Because of natural data heterogeneity of administration databases, propensity matching was applied as well.

RESULTS

Comparing treated vs. control subjects, patients with high compliance showed a significant decrease in fracture risk and hospitalization, which was more robust after propensity adjustment. On the basis of the observed statistically significant differences, cost-effectiveness analysis was implemented. Utility loss due the observed fractures was compared with the total cost differences of the two arms based on modelling. Our calculations proved the cost-effectiveness of the long-term high compliance in real world settings.

CONCLUSION

Our findings infer that the standardized and uniform health care of osteoporotic patients in a country may reduce general fracture incidence and hospitalization in a cost-effective way.

Report on a case of fibrogenesis imperfecta ossium and a possible new treatment option

Fibrogenesis imperfecta is an extremely rare acquired progressive bone disorder of unknown etiology. In its course, normal bone architecture is replaced at sites by structurally unsound collagen-deficient tissue resulting in a disorganized bone structure and a skeleton that is radically susceptible to deformity and fracture. Herein, we report the case of a patient who had experienced constant bone pain and several spontaneous fractures since 1997. In 10 years' time with the sole exception of his skull, the disease affected the entire skeleton causing a significant decrease in height and progressive disablement. Laboratory findings included elevation of serum alkaline phosphatase and C-terminal telopeptide of type 1 collagen, with normal serum calcium, phosphate, 25-hydroxy-vitamin-D, and parathyroid hormone concentrations. Monoclonal gammopathy was present with no pathological plasma cells in bone marrow. Radiological and histological results were inconclusive suggesting either osteoporosis, osteomalacia, or Paget's disease and later on osteosclerosis. Treatment administered for the abovementioned conditions has proven to be of no effect. The findings eventually raised the possibility of fibrogenesis imperfecta ossium, which was confirmed by polarized light microscopy as well as transmission electron microscopy. The suggested therapy for the disease is melphalan that could not be initiated due to legal restrictions. Steroid monotherapy also reported to be moderately successful in one case resulted in no improvement. Paraproteinemia had been suggested not only to be a characteristic feature but also a possible etiological factor in this condition. In 2012, plasmapheresis was initiated monthly at the beginning, later on biweekly. In response, the patient's symptoms improved dramatically supporting the abovementioned theory.

Instrumentation, control and automation in wastewater--from London 1973 to Narbonne 2013

Key developments of instrumentation, control and automation (ICA) applications in wastewater systems during the past 40 years are highlighted in this paper. From the first ICA conference in 1973 through to today there has been a tremendous increase in the understanding of the processes, instrumentation, computer systems and control theory. However, many developments have not been addressed here, such as sewer control, drinking water treatment and water distribution control. It is hoped that this review can stimulate new attempts to more effectively apply control and automation in water systems in the coming years.

Anaerobic model for high-solids or high-temperature digestion - additional pathway of acetate oxidation

Current anaerobic digestion models cannot properly simulate processes that are operated under high solids concentrations or high temperatures. A modification to existing models has been implemented by adding important missing degradation pathways, to accommodate these systems without artificially recalibrating the model parameters. Specifically, we implemented the alternate acetate oxidizing mechanism that is more tolerant to ammonia than the standard aceticlastic pathway. Inhibition values were estimated and an empirical function has been used to apply ammonia inhibition. The model also relates metabolic activity to un-ionised species such as undissociated acetic acid as substrate (although not obligatory for all organisms) and unionised ammonia as inhibitor. The model relies on an equilibrium chemistry module (e.g. including the phosphate buffer), resulting in more accurate pH predictions, which is crucial for proper modeling of CO2 and NH3 stripping. Calibration results from three case-studies modeling thermal hydrolysis and subsequent digestion of sludge are presented.

A new approach to assess the dependency of extant half-saturation coefficients on maximum process rates and estimate intrinsic coefficients

The Monod equation is often used to describe biological treatment processes and is the foundation for many activated sludge models. The Monod equation includes a "half-saturation coefficient" to describe the effect of substrate limitations on the process rate and it is customary to consider this parameter to be a constant for a given system. The purpose of this study was to develop a methodology, and its use to show that the half-saturation coefficient for denitrification is not constant but is in fact a function of the maximum denitrification rate. A 4-step procedure is developed to investigate the dependency of half-saturation coefficients on the maximum rate and two different models are used to describe this dependency: (a) an empirical linear model and (b) a deterministic model based on Fick's law of diffusion. Both models are proved better for describing denitrification kinetics than assuming a fixed K(NO3) at low nitrate concentrations. The empirical model is more utilitarian whereas the model based on Fick's law has a fundamental basis that enables the intrinsic K(NO3) to be estimated. In this study data was analyzed from 56 denitrification rate tests and it was found that the extant K(NO3) varied between 0.07 mgN/L and 1.47 mgN/L (5th and 95th percentile respectively) with an average of 0.47 mgN/L. In contrast to this, the intrinsic K(NO3) estimated for the diffusion model was 0.01 mgN/L which indicates that the extant K(NO3) is greatly influenced by, and mostly describes, diffusion limitations.

A new interpretation of endogenous respiration profiles for the evaluation of the endogenous decay rate of heterotrophic biomass in activated sludge

In current activated sludge models aerobic degradation, resulting in loss of activity and mass of activated sludge is expressed with only one process called decay. The kinetics of this process is regarded to be first order and constant with respect to the loading conditions. In this work twelve aerobic digestion batch experiments were conducted for the activated sludge of seven different water resource recovery facilities (WRRFs). An analysis of the obtained respirograms shows three clearly distinguishable phases. The first phase is assumed to be due to the degradation of stored material (X(STOR)) and active biomass simultaneously. The second phase is exclusively due to the degradation of active biomass that is regarded to consist mainly of ordinary heterotrophic biomass (X(OHO)). The first order decay rate is slower than the degradation rate in phase 1 and varies between samples. The decay rate correlates with the activity of the activated sludge expressed as the ratio of initial heterotrophic OUR and the initial organic fraction X(ORG) of the activated sludge. This second phase was detectable until day 5 of most of the experiments. After that time within phase 3 the OUR decrease slows down and the OUR even increased for short intervals. This behaviour is thought to be due to the activity of higher organisms and the adaptation of microorganisms to starvation.

Going for mainstream deammonification from bench to full scale for maximized resource efficiency

A three-pronged coordinated research effort was undertaken by cooperating utilities at three different experimental scales investigating bioaugmentation, enrichment and performance of anammox organisms in mainstream treatment. Two major technological components were applied: density-based sludge wasting by a selective cyclone to retain anammox granules and intermittent aeration to repress nitrite oxidizers. This paper evaluates process conditions and operation modes to direct more nitrogen to the resource-saving metabolic route of deammonification.

Models for nitrification process design: one or two AOB populations?

Models for engineering design of nitrifying systems use one ammonia oxidizer biomass (AOB) state variable. A simple extension using two AOB populations allows a more accurate prediction of nitrification systems at switching process environments. These two AOB subpopulations are characterized by two different sets of kinetic parameters. Selection pressure and competition between the two functional AOB populations are determined by process conditions as demonstrated by three case studies: Case study I describes dynamics of two AOB populations showing different temperature sensitivities (modified Arrhenius term on growth and decay) when bioaugmented from the warm sidestream treatment environment to the cold mainstream and vice-versa. Case study II investigates competition between fast growing micro-strategists and k-strategists adjusted to low ammonia levels depending on the internal mixed liquor recycle rate (IMLR). Case study III shows that AOB transferred from the waste activated sludge of an SBR to the parallel continuous flow system with different decay kinetics can overgrow or coexist with the original population.

Activated sludge modelling: development and potential use of a practical applications database

This study aims at synthesizing experiences in the practical application of ASM type models. The information is made easily accessible to model users by creating a database of modelling projects. This database includes answers to a questionnaire that was sent out to model users in 2008 to provide inputs for a Scientific and Technical Report of the IWA Task Group on Good Modelling Practice - Guidelines for use of activated sludge models, and a literature review on published modelling projects. The database is analysed to determine which biokinetic model parameters are usually changed by modellers, in which ranges, and what values are typically used for seven selected activated sludge models. These results should help model users in the calibration step, by providing typical parameter values as a starting point and ranges as a guide. However, the proposed values should be used with great care since they are the result of averaging practical experience and not taking into account specific parameter correlations.

Preconditioning is a method that may reduce the negative side-effect of pneumoperitoneum

Increased intra-abdominal pressure during laparoscopy leads to hypoxia due to reduced blood flow. Aim of our study was to investigate whether preconditioning can reduce this negative effect of the pneumoperitoneum. Fifty female Wistar rats were used, divided into 5 groups. I: Sham operation (Sham), II: conventional pneumoperitoneum (PP), III: transvaginal pneumoperitoneum (TV), IV: preconditioning for 2.5 minutes in two cycles (Pre 2.5), V: preconditioning for 5 minutes (Pre 5). Malondialdehyde (MDA), reduced glutathione (GSH), sulfhydrylgroup (SH-) concentrations, superoxide-dismutase (SOD) and mieloperoxidase (MPO) activity, and anti-apoptotic pathway marker p-AKT level and inflammatory cytokine TNF-α were measured. SOD activity and GSH concentration were decreased in PP and TV groups comparing to Sham and preconditioning groups. MPO activity was decreased also in PP and TV groups comparing to the Sham group but in the preconditioning groups it has remained high. MDA concentration in plasma was increased in PP and TV groups comparing to Sham and preconditioning groups. There was no difference in the case of blood MDA and SH-concentrations between groups. Anti-apoptotic pathway marker p-AKT level was decreased in the TV group comparing to the sham and preconditioning groups. TNF-α level was increased in TV and preconditioning groups compared to the sham group. According to the results preconditioning can reduce negative effects of pneumoperitoneum.

Transgastric small bowel resection by using hybrid technique — Experimental study

Introduction:The Natural Orifice Transluminal Endoscopic Surgery (NOTES) is an abdominal operation carried out with flexible endoscopic instruments and their advanced versions via natural orifices. The NOTES causes theoretically less pain, operative stress, shorter hospitalization, quicker recovery and it is scarless. The aim of this investigation was to evaluate the feasibility and safety of transgastric small bowel resection. Materials and methods: Seven domestic pigs were investigated and entered the study; body weight 25 kg in average. General anesthesia was performed. One trocar was used for laparoscopic observations during gastrotomy and transgastric penetration with the gastroscope, later for assistance with a grasper for manipulation of the bowel loops and for the application of the linear stapling device. Then the needle knife was used to complete a 1.5 cm long incision in the gastric wall. The gastroscope was advanced into the peritoneal cavity and a small bowel loop was identified and elevated with a flexible grasper. Through the second channel of the scope a coag grasper was used to dissect the mesentery. Then a linear stapler was inserted through the assisting trocar and the resection was performed. Afterwards the bowel ends were opened with the needle knife and the stapler was reinserted for a side-to-side anastomosis. The specimen was removed via the stomach. Gastric closure was completed by laparoscopic mini-instruments through the stapler-port. All special events and all problems were prospectively documented. Follow-up was performed over 2 weeks and body weight was recorded. Then a laparoscopy was performed to document adhesions or abscess formation. Finally the animals were sacrificed to evaluate further evidence of infection or adhesions. Results: The operations were carried without complications, there was no case of letal outcome. On the 12th day the abdominal laparoscopic revision was carried out, after the revision in one case adhesion could be detected, no other kinds of complications were noticed. Conclusion: According to our results, the transgastric small bowel resection is a safe procedure, but further special instruments are needed. These experimental procedures should be evaluated carefully and critically in clinical practice.

Effect of vitamin E on reperfusion injuries during reconstructive vascular operations on lower limbs

INTRODUCTION

The challenge against reperfusion injury and tissue oxidative stress, especially in vascular surgical interventions has an essential importance to reach the optimal clinical result. Numerous experimental attempts have proved the positive antioxidant effect of vitamin E in both chronic and acute phase models. In our study we monitored the effect of continuous preoperative treatment with vitamin E, on oxidative stress and tissue inflammation reactions developed after reconstructive operations.

PATIENTS AND METHODS

32 patients have been involved in a randomized, prospective study, all suffering from AFS occlusion proved by angiography, and all undergone supragenual reconstruction. Duration of ischemia and amount of tissues under vascular clamping were almost the same in all patients. In the group treated with E-vitamin, we administered 1 x 200 mg of vitamin E p/o from the preoperative day till the 7th post operative day. Patients of the second group did not receive vitamin E.

MATERIALS AND METHODS

Peripheral blood samples were collected immediately before operation and at the end of the second reperfusion hour (early reperfusion period). Late reperfusion period has been monitored by analyzing blood samples taken at 24th hour and 7th day next to the operative ischemia. Among oxidative stress parameters, direct measurement of reactive oxygen intermediator (ROI) and determination of antioxidant state (GSH, Total-SH group, SOD) have been performed. Malondialdehyde was chosen as marker for lipidperoxidation. Inflammation reactions were monitored up on expression of adhesion molecules (CD11a and CD18). We also controlled the oscillation of myeloperoxidase (MPO) activity.

RESULTS

Our study has proved that preoperative (from the preoperative day till the 7th post operative day) administration of 200 mg vitamin E could reduce the level of oxidative stress developed after ischemic-reperfusion insult (lipidproxidation, antioxidant enzymes). According to our results, the prooxidant-antioxidant imbalance also diminished in the group with E-vitamin treatment. We proved that elective administration of vitamin E could decrease the WBC activity (MPO activity, free radicals production, expression of adhesion molecules) and its consequential local inflammation process, during early reperfusion.

New framework for standardized notation in wastewater treatment modelling

Many unit process models are available in the field of wastewater treatment. All of these models use their own notation, causing problems for documentation, implementation and connection of different models (using different sets of state variables). The main goal of this paper is to propose a new notational framework which allows unique and systematic naming of state variables and parameters of biokinetic models in the wastewater treatment field. The symbols are based on one main letter that gives a general description of the state variable or parameter and several subscript levels that provide greater specification. Only those levels that make the name unique within the model context are needed in creating the symbol. The paper describes specific problems encountered with the currently used notation, presents the proposed framework and provides additional practical examples. The overall result is a framework that can be used in whole plant modelling, which consists of different fields such as activated sludge, anaerobic digestion, sidestream treatment, membrane bioreactors, metabolic approaches, fate of micropollutants and biofilm processes. The main objective of this consensus building paper is to establish a consistent set of rules that can be applied to existing and most importantly, future models. Applying the proposed notation should make it easier for everyone active in the wastewater treatment field to read, write and review documents describing modelling projects.

A systematic approach for model verification: application on seven published activated sludge models

The quality of simulation results can be significantly affected by errors in the published model (typing, inconsistencies, gaps or conceptual errors) and/or in the underlying numerical model description. Seven of the most commonly used activated sludge models have been investigated to point out the typing errors, inconsistencies and gaps in the model publications: ASM1; ASM2d; ASM3; ASM3 + Bio-P; ASM2d + TUD; New General; UCTPHO+. A systematic approach to verify models by tracking typing errors and inconsistencies in model development and software implementation is proposed. Then, stoichiometry and kinetic rate expressions are checked for each model and the errors found are reported in detail. An attached spreadsheet (see http://www.iwaponline.com/wst/06104/0898.pdf) provides corrected matrices with the calculations of all stoichiometric coefficients for the discussed biokinetic models and gives an example of proper continuity checks.

LCT 13910 C/T polymorphism, serum calcium, and bone mineral density in postmenopausal women

SUMMARY

LCT 13910 CC genotype is associated with lactose intolerance, a condition often resulting in reduced milk intake. Women with the CC genotype were found to have decreased serum calcium and reduced bone mineral density.

INTRODUCTION

The CC genotype of the 13910 C/T polymorphism of the LCT gene is linked to lactose intolerance and low calcium intake.

METHODS

We studied 595 postmenopausal women, including 267 osteoporotic, 200 osteopenic, and 128 healthy subjects. Genotyping, osteodensitometry, and laboratory measurements were carried out.

RESULTS

Frequency of aversion to milk consumption was 20% for CC genotype and 10% for TT + TC genotypes (p = 0.03). The albumin-adjusted serum calcium was 2.325 +/- 0.09 mmol/L for CC genotype and 2.360 +/- 0.16 mmol/L for TT + TC genotypes (p = 0.031). Bone mineral density (BMD; Z score) was lower in the CC than TT + TC genotypes, respectively, at the radius (0.105 +/- 1.42 vs 0.406 +/- 1.32; p = 0.038), at the total hip (-0.471 +/- 1.08 vs -0.170 +/- 1.09; p = 0.041), and at the Ward's triangle (-0.334 +/- 0.87 vs -0.123 +/- 0.82; p = 0.044).

CONCLUSION

LCT 13910 C/T polymorphism is associated with decreased serum calcium level and lower BMD in postmenopausal women.

A comparative analysis of different approaches for integrated WWTP modelling

In this paper a comparative analysis of the most important approaches for integrated WWTP modelling is presented. After an introductory presentation of the most important drawbacks and challenges for plant wide modelling, the fundamentals of three different approaches to construct integrated models are presented: "Interfaces" "Standard Supermodel" and "Tailored Supermodel". Afterwards, a comparative analysis of these approaches from different points of view (difficulties for the model end user, characterization of the process in the plant, flexibility or adaptability for each case of study, simulation platform requirements and computational costs) is carried out. From this comparison, some important conclusions about the suitability of each alternative depending on the simulation case study are extracted.

Activated sludge modelling in practice: an international survey

The Good Modelling Practice Task Group (GMP-TG) of the International Water Association (IWA) is developing guidelines for the use of Activated Sludge Models (ASM). As part of this work the group created and sent out a questionnaire to current and potential activated sludge model users in 2007. The objectives of the questionnaire were (i) to better define the profile of ASM users, (ii) to identify the tools and procedures that are actually used and (iii) to highlight the main limitations while building and using ASM-type models. Ninety-six answers were received from all over the world, from several types of organisation. The results were analysed to identify the modellers' perceptions of models depending on their profile. The results also highlighted the main topics of interest for improving modelling procedures which are standardisation of the available modelling guidelines and better experience and knowledge transfer.

Denitrification with carbon addition--kinetic considerations

The Blue Plains Advanced Wastewater Treatment Plant (Washington, D.C.) uses methanol as an external carbon source in a postdenitrification process, to achieve low effluent total nitrogen concentrations. This becomes more difficult in winter, at lower mixed liquor temperatures and higher flows, as a consequence of the kinetic behavior of the methanol-utilizing heterotrophs. The paper reports on an experimental batch test study conducted on Blue Plains postdenitrification sludge to investigate (1) the maximum specific growth rate of methanol-utilizing heterotrophs (Mu(METH)); (2) the temperature dependency of the growth rate; and (3) the efficacy of alternate substrates (ethanol, acetate, and sugar). A limited number of tests were conducted on sludge from two other treatment plants with methanol addition.

Significance of design and operational variables in chemical phosphorus removal

Batch and continuous experiments using model and real wastewaters were conducted to investigate the effect of metal salt (ferric and alum) addition in wastewater treatment and the corresponding phosphate removal from a design and operational perspective. Key factors expected to influence the phosphorus removal efficiency, such as pH, alkalinity, metal dose, metal type, initial and residual phosphate concentration, mixing, reaction time, age of flocs, and organic content of wastewater, were investigated. The lowest achievable concentration of orthophosphate under optimal conditions (0.01 to 0.05 mg/L) was similar for both aluminum and iron salts, with a broad optimum pH range of 5.0 to 7.0. Thus, in the typical operating range of wastewater treatment plants, pH is not a sensitive indicator of phosphorus removal efficiency. The most significant effect for engineering practice, apart from the metal dose, is that of mixing intensity and slow kinetic removal of phosphorus in contact with the chemical sludge formed. Experiments show that significant savings in chemical cost could be achieved by vigorously mixing the added chemical at the point of dosage and, if conditions allow, providing a longer contact time between the metal hydroxide flocs and the phosphate content of the wastewater. These conditions promoted the achievement of less than 0.1 mg/L residual orthophosphate content, even at lower metal-to-phosphorus molar ratios. These observations are consistent with the surface complexation model presented in a companion paper (Smith et al., 2008).

Phosphate complexation model and its implications for chemical phosphorus removal

A phosphate complexation model is developed, in an attempt to understand the mechanistic basis of chemically mediated phosphate removal. The model presented here is based on geochemical reaction modeling techniques and uses known surface reactions possible on hydrous ferric oxide (HFO). The types of surface reactions and their reaction stoichiometry and binding energies (logK values) are taken from literature models of phosphate interactions with iron oxides. The most important modeling parameter is the proportionality of converting moles of precipitated HFO to reactive site density. For well-mixed systems and phosphate exposed to ferric chloride during HFO precipitation, there is a phosphate capacity of 1.18 phosphate ions per iron atom. In poorly mixed systems with phosphate exposed to iron after HFO formation, the capacity decreased to 25% of the well-mixed value. The same surface complexation model can describe multiple data sets, by varying only a single parameter proportional to the availability of reactive oxygen functional groups. This reflects the unavailability of reactive oxygen groups to bind phosphate. Electron microscope images and dye adsorption experiments demonstrate changes in reactive surface area with aging of HFO particles. Engineering implications of the model/mechanism are highlighted.

Use of three lumen catheter facilitates bowel movement after pancreato-duodenectomy

BACKGROUND/AIMS

The advantages of jejunal nutrition in postoperative bowel paralysis following pancreato-duodenectomy were analyzed.

METHODOLOGY

Patients resected for pancreatic cancer received 25 kcal/kg/day and were followed up for 10 days postoperatively. Nasojejunal tube ensured enteral feeding in 16 patients (Gr. I), 6 patients (Gr. II) were nourished parenterally. Laboratory parameters, outcome were compared. Bowel movements were registered. Patients of Gr.1 received 25 kcal/kg parenterally. Jejunal nutriment (1.5 cal/mL) followed gradually up to 1500mL. Parenteral nutriment decreased reflecting enteral intake. Patients of Gr. II were nourished parenterally only for 8 days. Laboratory data were measured preoperatively, on the 1st, 4th, 10th days.

RESULTS

The first stool appeared on the 4th day in Gr. I In Gr. II the bowel movement was delayed by 8 days. Laboratory data from the 1st, and 10th days were compared. In Gr. I serum total protein increased from 48.06 to 58.7g/L (p<0.001), serum albumin from 27.5 to 32.2g/L (p<0.02), CRP decreased from 117.8 to 74.1mg/L (p<0.035). No changes were significant in Gr. II. Length of hospitalization, weight loss did not differ between the 2 groups.

CONCLUSIONS

Immediately postoperative use of a three-luminal tube ensured early enteral nutrition, improved serum total protein, albumin values and facilitated bowel movements.

Elemental balance based methodology to establish reaction stoichiometry in environmental modeling

Kinetic models in activated sludge, anaerobic digestion and other environmental modeling fields rely on the proper formulation of stoichiometric coefficients. Elemental balancing provides a simple and rigorous way to establish the stoichiometric coefficients of reactions represented in the Gujer matrix. The deduction of these coefficients is frequently trivial, from basic mass balancing considerations. In more complex cases, such as the Anammox growth reaction, rigorous elemental balancing is required to establish the proper formulation. This paper demonstrates the methodology based on a simple aerobic heterotrophic growth reaction where stoichiometry coefficients (such as the (1-Y(H))/Y(H) term for oxygen) are well known. In the second step the methodology is applied for the Anammox growth reaction. The fraction of N(2) gas in current models originates from the NH(4)+ and the NO(2)- electron donor/acceptor pair in equal proportion. This paper demonstrates that this stoichiometry is a simplification leading to elemental balance errors. The proper stoichiometric coefficients are derived.

Mesohepatectomy without hilar dissection in the treatment of malignant focal liver diseases

BACKGROUND/AIMS

Mesohepatectomy is a method of surgical treatments for the centrally-located liver diseases. These operations were performed without hilar dissection by our modification and the results were evaluated.

METHODOLOGY

Between 2000 and 2002 we performed eight modified mesohepatectomy in cases of central malignant tumors of the liver. Preoperative examinations were done by strict protocol. We performed the operation with CUSA US scalpel. On postoperative days 1, 3, 5 and 7, we monitored the patients' liver enzymes, bilirubin level and hemostasis factors. After recovering the patients received chemotherapy. Follow-up was done 3 and 6 months later.

RESULTS

The time of operation and the blood consumption were significantly less with this modified technique comparing data found in the literature. The average tumor-free interval is 6.5 months, in five patients.

CONCLUSIONS

On reflection of these data, we consider mesohepatectomy performed without hilar dissection to be a suitable method for the treatment of centrally-located tumors. Postoperative morbidity rate is of a similar degree to that of operations using prior dissection, and the advantageous effects of parenchyma sparing mesohepatectomy are retained.

A biofilm model for engineering design

A biofilm model is presented for process engineering purposes--wastewater treatment plant design, upgrade and optimisation. The model belongs in the 1D dynamic layered biofilm model category, with modifications that allow it to be used with one parameter set for a large range of process situations. The biofilm model is integrated with a general activated sludge/anaerobic digestion model combined with a chemical equilibrium, precipitation and pH module. This allows the model to simulate the complex interactions that occur in the aerobic, anoxic and anaerobic layers of the biofilm. The model has been tested and is shown to match a variety of design guidelines, as well as experimental results from batch testing and full-scale plant operation. Both moving bed bioreactors (MBBR) and integrated fixed film activated sludge (IFAS) systems were simulated using the same model and parameter set. A new steady-state solver generates fast solutions and allows interactive design work with the complex model.

Hindered and compression settling: parameter measurement and modelling

The Vesilind settling velocity function forms the basis of flux theory used both in state point analysis (for design and capacity rating) and one-dimensional dynamic models (for dynamic process modelling). This paper proposes new methods to address known shortcomings of these methods, based on an extensive set of batch settling tests conducted at different scales. The experimental method to determine the Vesilind parameters from a series of bench scale settling tests is reviewed. It is confirmed that settling cylinders must be slowly stirred in order to represent settling performance of full scale plants for the whole range of solids concentrations. Two new methods to extract the Vesilind parameters from settling test series are proposed and tested against the traditional manual method. Finally, the same data set is used to propose an extension to one-dimensional (1-D) dynamic settler models to account for compression settling. Using the modified empirical function, the model is able to describe the batch settling interface independently of the number of layers.

Laparoscopic treatment of nonparasitic hepatic cysts

BACKGROUND

We present our experience with laparoscopic deroofing of nonparasitic hepatic cysts.

METHODS

Laparoscopic deroofing was performed due to a solitary hepatic cyst in 21 patients and polycystic liver in four patients. Laparoscopy was indicated when a cyst was larger than 5 cm (the general size of cysts was 6.9 cm) and caused complaints and was in a superficial position. In eight patients in whom the cyst was larger than 10 cm, omentoplasty was performed.

RESULTS

Intraoperative complications were not detected. Two conversions were performed because of the deep position of the cyst. Postoperative bile leakage was detected in one case that was treated conservatively. The average hospital stay was 4.7 days. Relapse occurred in two patients (8%), but only one of them required a second operation.

CONCLUSIONS

We recommend laparoscopic deroofing for treatment of nonparasitic liver cysts. This operation causes only slight discomfort for the patients, the intra- and postoperative morbidity is low, and relapses are rare.