Soft-sensors application for automated feeding control in high-throughput mammalian cell cultures

The ever-increasing demand for biopharmaceuticals has created the need for improving the overall productivity of culture processes. One such operational concept that is considered is fed-batch operations as opposed to batch operations. However, optimal fed-batch operations require complete knowledge of the cell culture to optimize the culture conditions and the nutrients feeding. For example, when using high-throughput small-scale bioreactors to test multiple clones that do not behave the same, depletion or overfeeding of some key components can occur if the feeding strategy is not individually optimized. Over the recent years, various solutions for real-time measuring of the main cell culture metabolites have been proposed. Still, the complexity in the implementation of these techniques has limited their use. Soft-sensors present an opportunity to overcome these limitations by indirectly estimate these variables in real-time. This manuscript details the development of a new soft-sensor based fed-batch strategy to maintain substrate concentration (glucose and glutamine) at optimal levels in small-scale multi parallel CHO cultures. Two alternatives to the standard feeding strategy were tested: an OUR soft-sensor-based strategy for glucose and glutamine (Strategy 1) and a dual OUR for glutamine and CO₂ /alkali addition for glucose soft-sensor strategy (Strategy 2). The results demonstrated the applicability of the OUR soft-sensor based strategy to optimize glucose and glutamine feedings, which yielded a 21% increase in final viable cell density (VCD) and a 31% in erythropoietin (EPO) titer compared with the reference one. However, CO2/alkali addition soft-sensor suffered from insufficient data to relate alkali addition with glucose consumption. As a result, the culture was overfed with glucose resulting in a 4% increase on final VCD, but a 9% decrease in final titer compared to the Reference Strategy. This article is protected by copyright. All rights reserved.

Retrospective evaluation of the incidence and prognostic significance of spontaneous echocardiographic contrast in relation to cardiac disease and congestive heart failure in cats: 725 cases (2006-2011)

OBJECTIVE

To determine whether the presence of spontaneous echocardiographic contrast (SEC) in cats with cardiomyopathy is associated with increased mortality. To establish whether specific types of cardiomyopathy are more often associated with SEC in an attempt to provide a risk-stratification scheme for cats with increased risk of thromboembolic events.

DESIGN

Retrospective study 2006-2011.

SETTING

Tertiary referral and teaching hospital.

ANIMALS

Seven hundred twenty-five client-owned cats undergoing echocardiographic evaluation.

MEASUREMENTS AND MAIN RESULTS

Patient characteristics, including age, breed, clinical signs, type of cardiovascular disease, presence of SEC, and survival time were recorded. Thyroxine, HCT, and blood pressure were recorded when available. Among cats diagnosed with cardiac abnormalities based on echocardiographic findings, those with SEC were at significantly increased risk of death as compared to those without SEC. Cats with dilated cardiomyopathy, unclassified cardiomyopathy, and hypertrophic cardiomyopathy were significantly more likely to have SEC compared to cats with other types of cardiac disease.

CONCLUSIONS

Cats with cardiomyopathy and SEC have an increased risk of death compared to cats without SEC, although other previously identified factors such as the presence of congestive heart failure and increased left atrium to aorta ratio remain important determinants of mortality. Cats with hypertrophic cardiomyopathy, unclassified cardiomyopathy, and dilated cardiomyopathy may benefit from anticoagulant therapy due to the increased risk of SEC in these subpopulations.

A liquid chromatography-tandem mass spectrometry-based investigation of the lamellar interstitial metabolome in healthy horses and during experimental laminitis induction

Lamellar bioenergetic failure is thought to contribute to laminitis pathogenesis but current knowledge of lamellar bioenergetic physiology is limited. Metabolomic analysis (MA) can systematically profile multiple metabolites. Applied to lamellar microdialysis samples (dialysate), lamellar bioenergetic changes during laminitis (the laminitis metabolome) can be characterised. The objectives of this study were to develop a technique for targeted MA of lamellar and skin dialysates in normal horses, and to compare the lamellar and plasma metabolomic profiles of normal horses with those from horses developing experimentally induced laminitis. Archived lamellar and skin dialysates (n = 7) and tissues (n = 6) from normal horses, and lamellar dialysate and plasma from horses given either 10 g/kg oligofructose (treatment group, OFT; n = 4) or sham (control group, CON; n = 4) were analysed. The concentrations of 44 intermediates of central carbon metabolism (CCM) were determined using liquid chromatography-tandem mass spectrometry. Data were analysed using multivariate (MVA) and univariate (UVA) analysis methods. The plasma metabolome appeared to be more variable than the lamellar metabolome by MVA, driven by malate, pyruvate, aconitate and glycolate. In lamellar dialysate, these metabolites decreased in OFT horses at the later time points. Plasma malate was markedly increased after 6 h in OFT horses. Plasma malate concentrations between OFT and CON at this time point were significantly different by UVA. MA of lamellar CCM was capable of differentiating horses developing experimental laminitis from controls. Lamellar malate, pyruvate, aconitate and glycolate, and plasma malate alone were identified as the source of differentiation between OFT and CON groups. These results highlighted clear discriminators between OFT and CON horses, suggesting that changes in energy metabolism occur locally in the lamellar tissue during laminitis development. The biological significance of these alterations requires further investigation.

Administration of fenoldopam in critically ill small animal patients with acute kidney injury: 28 dogs and 34 cats (2008-2012)

OBJECTIVE

To describe the clinical features and outcomes of critically ill dogs and cats with acute kidney injury (AKI) receiving fenoldopam infusions compared to patients with AKI that did not receive fenoldopam.

DESIGN

Retrospective clinical study from May 1, 2008 until June 1, 2012.

SETTING

Private emergency and specialty referral hospital.

ANIMALS

Client-owned dogs (28) and cats (34) with AKI that received fenoldopam compared with similar patients with AKI (30 dogs and 30 cats) that did not.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The medical records of 62 critically ill dogs and cats with AKI that received fenoldopam were reviewed. Presenting clinical signs, physical examination findings, and primary and secondary disease processes were identified in all patients. The mean number of days on fenoldopam was 1.5 days (range 0.3-4.0 days) for dogs and 1.9 days (range 1.0-4.0 days) for cats. Eleven of 28 (39%) dogs survived to discharge and 13 of 34 (38%) of the cats survived to discharge. Of the animals in the group receiving fenoldopam that died, the majority (84%) were euthanized. Potential adverse reactions were evaluated, with hypotension being the most commonly encountered adverse effect (7% of fenoldopam group [FG] dogs and 23% of FG cats). When compared with patients with AKI that did not receive fenoldopam, no significant differences were found between the groups with regards to survival, length of hospital stay, adverse effects, or changes in creatinine, BUN, or sodium concentrations except that patients receiving fenoldopam were significantly more likely to have received other renally active medications.

CONCLUSIONS

In this study of patients with AKI, fenoldopam administration at 0.8 μg/kg/min in dogs and 0.5 μg/kg/min in cats appeared relatively safe but was not associated with improvement in survival to discharge, length of hospital stay, or improvement in renal biochemical parameters when compared to patients with AKI not receiving fenoldopam.

The prevalence and impact of Fusarium head blight pathogens and mycotoxins on malting barley quality in UK

Fusarium head blight (FHB) caused by Fusarium and Microdochium species can significantly affect the yield of barley grain as well as the quality and safety of malt and beer. The present study provides new knowledge on the impacts of the FHB pathogen complex on the malting and brewing quality parameters of naturally infected barley. Quantitative real-time PCR and liquid chromatography double mass spectrometry were used to quantify the predominant FHB pathogens and Fusarium mycotoxins, respectively, in commercially grown UK malting barley samples collected between 2007 and 2011. The predominant Fusarium species identified across the years were F. poae, F. tricinctum and F. avenaceum. Microdochium majus was the predominant Microdochium species in 2007, 2008, 2010 and 2011 whilst Microdochium nivale predominated in 2009. Deoxynivalenol and zearalenone quantified in samples collected between 2007 and 2009 were associated with F. graminearum and F. culmorum, whilst HT-2 and T-2, and nivalenol in samples collected between 2010 and 2011 correlated positively with F. langsethiae and F. poae, respectively. Analysis of the regional distribution and yearly variation in samples from 2010 to 2011 showed significant differences in the composition of the FHB species complex. In most regions (Scotland, the South and North of England) the harvest in 2010 had higher concentrations of Fusarium spp. than in 2011, although no significant difference was observed in the Midlands between the two years. Microdochium DNA was significantly higher in 2011 and in the North of England and Scotland compared to the South or Midlands regions. Pathogens of the FHB complex impacted negatively on grain yield and quality parameters. Thousand grain weight of malting barley was affected significantly by M. nivale and M. majus whilst specific weight correlated negatively with F. avenaceum and F. graminearum. To determine the impact of sub-acute infections of the identified Fusarium and Microdochium species on malting and brewing quality of naturally infected samples, selected malting barley cultivars (Optic, Quench and Tipple) were micromalted and subjected to malt and wort analysis of key quality parameters. F. poae and M. nivale decreased germinative energy and increased water sensitivity of barley. The fungal biomass of F. poae and F. langsethiae correlated with increased wort free amino nitrogen and with decreased extract of malt. DNA of M. nivale correlated with increased malt friability as well as decreased wort filtration volume. The findings of this study indicate that the impact of species such as the newly emerging F. langsethiae, as well as F. poae and the two non-toxigenic Microdochium species should be considered when evaluating the quality of malting barley.

Low multiplicity infection of insect cells with a recombinant baculovirus: The cell yield concept

In vitro infection of insect cells with baculoviruses is increasingly considered a viable means for the production of biopesticides, recombinant veterinary vaccines, and other recombinant products. Batch fermentation processes traditionally employ intermediate to high multiplicities of infection necessitating two parallel scale-up processes-one for cells and one for virus. In this study, we consider the use of multiplicities of infection as low as 0.0001 plaque-forming units per cell, a virus level low enough to enable infection of even large reactors (e.g., 10 m(3)) directly from a frozen stock. Using low multiplicities in the Sf9/beta-gal-AcNPV system, recombinant protein titers comparable with the maximum titer observed in high multiplicity infections were achieved. Cultures yielding the maximum titer were characterized by reaching a maximum cell density between 3 and 4 x 10(9) cell L(-1). This optimal cell yield did not depend on the multiplicity of infection, supporting the existing view that batch cultures are limited by availability of substrate. Up to a certain cell density, product titer will increase almost linearly with availability of biocatalyst, that is, cells. Beyond this point any further cell formation comes at the expense of final product titer. Low multiplicity infections were found not to cause any significant dispersion of the protein production process. Hence, product stability is not a major issue of concern using low multiplicities of infection. The sensitivity to initial conditions and disturbances, however, remains an issue of concern for the commercial use of low multiplicity infections. (c) 1996 John Wiley & Sons, Inc.

TRI12 based quantitative real-time PCR assays reveal the distribution of trichothecene genotypes of F. graminearum and F. culmorum isolates in Danish small grain cereals

Quantitative real-time PCR assays, based on polymorphisms in the TRI12 gene of the trichothecene pathway, were developed to identify and quantify the trichothecene genotypes producing 3-acetyl-deoxynivalenol (3ADON), 15-acetyl-deoxynivalenol (15ADON) or nivalenol (NIV) in the Fusarium graminearum species complex, Fusarium culmorum, Fusarium cerealis and Fusarium pseudograminearum. These assays were applied on a total of 378 field samples of cereal grain of wheat, barley, triticale, rye and oats collected from 2003 to 2007 to study the trichothecene genotype composition in Danish cereals. The three genotypes, 3ADON, 15ADON and NIV were found in all five cereal species, great annual variation in the occurrence of the trichothecene genotypes was evident with considerable variation between the samples. 3ADON was the dominant genotype in barley, triticale, rye and oats while 15ADON was most dominant in wheat. The NIV genotype was found at low levels in most samples. Study of genotype composition within the Danish F. graminearum and F. culmorum population was based on principal component analysis (PCA). PCA revealed that the dominating genotype of F. graminearum in wheat is 15ADON. For barley, the PCA analysis indicated that the F. graminearum population consisted of all three genotypes, and in triticale, the F. graminearum population consisted mainly of 15ADON genotype. F. culmorum/F. cerealis showed correlation to the NIV genotype in wheat and triticale but not in barley. F. culmorum/F. cerealis also showed some correlation to 3ADON especially in wheat and triticale. Selected wheat and barley samples from 1957 to 2000 showed low amounts of F. graminearum and F. culmorum in general but with a dominance of the 3ADON genotype. 15ADON was not detected in these samples, except for very low amounts in the sample representing the years from 1997 to 2000. Detection of low amounts of the 15ADON genotype in these historical samples and the relatively high amounts of 15ADON genotype in 2003 and following years correspond well with the occurrence of F. graminearum and indicates that the 15ADON genotype was introduced along with F. graminearum around 2000. The amounts of the 3ADON and 15ADON genotypes correlated well with the total amount of DON whereas the amounts of NIV genotype correlated well with the amount of NIV in wheat and triticale but not in barley where the results indicate that Fusarium poae may also contribute to the NIV content.

Compartment syndrome: pathophysiology, clinical presentations, treatment, and prevention in human and veterinary medicine

OBJECTIVE

To review the human and veterinary literature pertaining to all forms of compartment syndrome (CS).

DATA SOURCES

Data sources included scientific reviews and original research publications from the human and veterinary literature.

HUMAN DATA SYNTHESIS

While CS affecting the extremities has been recognized in people for decades, other forms of CS in the abdominal and thoracic cavities are recently gaining more attention. The role of CS in critically ill people is a rapidly growing area of interest. More research on prevention and treatment of CS is being conducted in people because some studies have found mortality rates as high as 80% for those suffering from these conditions.

VETERINARY DATA SYNTHESIS

While a significant amount of experimental studies of CS have been performed on small animals, there is a marked lack of primary veterinary studies. The majority of the veterinary literature includes case reports and series, and many of these studies were published over a decade ago. However, the increased recognition of CS in people has sparked an interest in veterinary critical care medicine and this has been demonstrated by the recent increased evaluation of compartment pressures in veterinary patients.

CONCLUSIONS

CS is a complex clinical condition where increased pressure within a compartment can cause significant adverse effects within the compartment as well as throughout the body. Systemic inflammatory responses and local ischemia-reperfusion elements can contribute to the detrimental effects seen in CS. This cascade of events results in increased mortality rates and contributes to the development of CS elsewhere. A better understanding of CS will help veterinarians improve patient care and outcome. Future studies on incidence, prevention, and treatment of CSs in the critical care patient are needed in veterinary medicine.

Fusarium head blight of cereals in Denmark: species complex and related mycotoxins

Quantitative real-time polymerase chain reaction differentiating 10 Fusarium spp. and Microdochium nivale or M. majus was applied to a total of 396 grain samples of wheat, barley, triticale, oat, and rye sampled across Denmark from 2003 to 2007, along with selected samples of wheat and barley from 1957 to 2000, to determine incidence and abundance of individual Fusarium spp. The mycotoxins deoxynivalenol (DON), nivalenol, zearalenone, T-2, and HT-2 were quantified using liquid chromatography-double mass spectrometry. Major differences in the Fusarium species complex among the five cereals as well as great yearly variation were seen. Fusarium graminearum, F. culmorum, and F. avenaceum were dominant in wheat, with DON as the dominant mycotoxin. F. langsethiae, F. culmorum, and F. avenaceum were dominant in barley and oat, leading to relatively high levels of the mycotoxins T-2 and HT-2. F. graminearum, F. culmorum, and F. avenaceum dominated in triticale and rye. The nontoxigenic M. nivale/majus were present in significant amounts in all cereal species. Wheat and barley samples from 1957 to 1996 exhibited no or very low amounts of F. graminearum, indicating a recent increase of this pathogen. Biomass and mycotoxin data exhibited good correlations between Fusarium spp. and their corresponding mycotoxins under field conditions.

Manufactured RBC--rivers of blood, or an oasis in the desert?

Red blood cell (RBC) transfusion is an essential practice in modern medicine, one that is entirely dependent on the availability of donor blood. Constraints in donor supply have led to proposals that transfusible RBC could be manufactured from stem cells. While it is possible to generate small amounts of RBC in vitro, very large numbers of cells are required to be of clinical significance. We explore the challenges facing large scale manufacture of RBC and technological developments required for such a scenario to be realised.

Delayed hypercalcemia after non-oliguric acute renal failure associated with rhabdomyolysis

Alterations in the calcium metabolism are a characteristic paraclinical finding in patients with oliguric acute renal failure associated with rhabdomyolysis. A 20-year-old male operated on under general anesthesia developed non-oliguric acute renal failure due to malignant hyperthermia with rhabdomyolysis (urine myoglobin greater than 20,000 nmol/l; reference range less than 0.85 nmol/l). On the 20th postoperative day hypercalcemia was found, reaching a maximum serum level of 3.74 mmol/l (reference range 2.18-2.65 mmol/l) on the 27th postoperative day. Delayed hypercalcemia in non-oliguric acute renal failure associated with rhabdomyolysis has not been reported previously. This case suggests that prolonged control of the serum calcium level should be performed in patients with rhabdomyolysis, even in the absence of oliguria.

Class switch recombination in selective IgA-deficient subjects

Selective IgA deficiency is a common immunodeficiency in Caucasians, but the molecular basis of the disorder remains elusive. To address this issue we examined the molecular events leading to IgA production. Naive IgD positive B cells were purified from four donors with IgA deficiency and four control donors, all Caucasians. Stimulation of B cells from IgA-deficient donors with the cytokines transforming growth factor (TGF)-beta, interferon (IFN)-gamma or interleukin (IL)-10 in the presence of anti-CD40 antibodies showed reduced expression of both activation-induced cytidine deaminase (AID) and alpha germline transcripts (GLT) compared to controls. It was possible, however, to induce AID and alpha GLT when stimulating the cells with anti-CD40 antibody and TGF-beta in the combination with IL-10. Moreover, in anti-CD40 antibody-stimulated cultures, addition of IL-10 or IL-10 + TGF-beta in combination, induced IgA production, albeit lower than found in B cells from controls. The B cells from the IgA-deficient subjects were less effective in differentiating into CD138(+) X-box binding protein 1 (XBP-1)(+) plasma cells when stimulated with TGF-beta, IFN-gamma or IL-10. Interestingly, when adding IL-4 to TGF-beta alone or in combination with IL-10, the immunoglobulin production in B cells from IgA-deficient donors was comparable with those of normal controls. These data show that in healthy subjects in vitro IgA production can be up-regulated by addition of IL-10 to CD40-stimulated B cells, whereas a similar B cell differentiation does not occur in IgA-deficient subjects. Addition of IL-4, however, reverts this abnormality.

Method for the generation and cultivation of functional three-dimensional mammary constructs without exogenous extracellular matrix

During puberty, pregnancy, lactation and post-lactation, breast tissue undergoes extensive remodelling and the disruption of these events can lead to cancer. In vitro studies of mammary tissue and its malignant transformation regularly employ mammary epithelial cells cultivated on matrigel or floating collagen rafts. In these cultures, mammary epithelial cells assemble into three-dimensional structures resembling in vivo acini. We present a novel technique for generating functional mammary constructs without the use of matrix substitutes.

Bioreactors for hematopoietic cell culture

Hematopoietic cell culture, or ex vivo expansion of hematopoietic cells, is an enabling technology with many potential applications in bone-marrow transplantation, immunotherapy, gene therapy, and the production of blood products. Hematopoietic cultures are complex, with many different cell types of different stages of development present at any given point in time and never in steady state. Moreover, these cells interact strongly with each other and the environment through cytokines (growth factors) and adhesion molecules, as well as through their metabolism. Despite these significant challenges, cell products produced in bioreactors have shown promise in recent phase 1 clinical trials.

Hemin reconstitutes proton extrusion in an H(+)-ATPase-negative mutant of Lactococcus lactis

H(+)-ATPase is considered essential for growth of Lactococcus lactis. However, media containing hemin restored the aerobic growth of an H(+)-ATPase-negative mutant, suggesting that hemin complements proton extrusion. We show that inverted membrane vesicles prepared from hemin-grown L. lactis cells are capable of coupling NADH oxidation to proton translocation.

Osmolarity effects on observed insect cell size after baculovirus infection are avoided using growth medium for sample dilution

Rates of cell size increase are an important measure of success during the baculovirus infection process. Batch and fed batch cultures sustain large fluctuations in osmolarity that can affect the measured cell volume if this parameter is not considered during the sizing protocol. Where osmolarity differences between the sizing diluent and the culture broth exist, biased measurements of size are obtained as a result of the cell osmometer response. Spodoptera frugiperda (Sf9) cells are highly sensitive to volume change when subjected to a change in osmolarity. Use of the modified protocol with culture supernatants for sample dilution prior to sizing removed the observed error during measurement.

Lag-burst kinetics in phospholipase A(2) hydrolysis of DPPC bilayers visualized by atomic force microscopy

The lag-burst phenomenon in the phospholipase A(2) mediated hydrolysis of phospholipid bilayers is for the first time demonstrated in an atomic force microscopy (AFM) study. Simultaneous AFM measurements of the degree of bilayer degradation and the physical-chemical state of the membrane reveals growing nanoscale indentations in the membrane during the lag phase. It is argued that these indentations are domains of hydrolysis products (lysoPC/PC) which eventually trigger the burst. The rate of the rapid hydrolysis following the burst is found to be proportional to the length of the edge between membrane adsorbed and desorbed to the mica base. The observed maximal rate of membrane degradation is approx. 0.2 mmol lipid/min/mol lipase in solution.

Stoichiometric modeling of Clostridium acetobutylicum fermentations with non-linear constraints

A stoichiometric model of Clostridium acetobutylicum and related strains has been previously derived. The stoichiometric matrix of the model contains a singularity which has prevented the calculation of a unique set of fluxes which describe the primary metabolic activity. To resolve the singularity, we have developed a non-linear constraint relating the acetate and butyrate uptake fluxes. Subsequently, we developed a software package utilizing a model independent heuristic global optimization approach to solve the resultant non-linear problem. We have validated the use of the non-linear constraint by correlating calculated butyrate production pathway flux profiles with measured intracellular pH profiles. Finally, we examined a controlled batch fermentation to determine that the acid formation pathways play critical roles throughout solventogenesis. The broader usefulness of reformulating the stoichiometric model as a constrained minimization problem is discussed.

Population balance model of in vivo neutrophil formation following bone marrow rescue therapy

In this paper, we develop a simple four parameter population balance model of in vivo neutrophil formation following bone marrow rescue therapy. The model is used to predict the number and type of neutrophil progenitors required to abrogate the period of severe neutropenia that normally follows a bone marrow transplant. The estimated total number of 5 billion neutrophil progenitors is consistent with the value extrapolated from a human trial. The model provides a basis for designing ex vivo expansion protocols.

Characterization of hematopoietic cell expansion, oxygen uptake, and glycolysis in a controlled, stirred-tank bioreactor system

Cultures of umbilical cord blood and mobilized peripheral blood mononuclear cells were carried out in a stirred bioreactor with pH and dissolved oxygen control. Expansion of total cells and colony-forming units granulocyte-macrophage was greatly enhanced by the use of a cell-dilution feeding protocol (as compared to a cell-retention feeding protocol). The specific oxygen consumption rate (qO2) for these cultures ranged from 1.7 x 10(-8) to 1.2 x 10(-7) micromol/(cell.h). The maximum in qO2 for each culture closely corresponded with the maximum percentage of progenitor or colony-forming cells (CFCs) present in the culture. The maximum qO2 values are slightly less than those reported for hybridomas, while the lowest qO2 values are somewhat greater than those reported for mature granulocytes. Examination of the ratio of lactate production to oxygen consumption in these cultures suggests that post-progenitor cells of the granulomonocytic lineage obtain a greater portion of their energy from glycolysis than do CFCs. The different metabolic profiles of CFCs and more mature cells suggest that monitoring the uptake or production of oxygen, lactate, and other metabolites will allow estimation of the content of several cell types in culture.

Effect of percutaneous ethanol injection therapy versus suppressive doses of L-thyroxine on benign solitary solid cold thyroid nodules: a randomized trial

The results of studies using suppressive doses of L-T4 on benign solitary solid cold thyroid nodules have been conflicting. Recently, intranodular injection of absolute ethanol has been proposed as an effective treatment, but has been evaluated only in uncontrolled studies. Our objective was to evaluate the effect of two alternative medical treatment modalities, percutaneous ethanol injection therapy and L-T4, on the benign solitary solid cold thyroid nodule. In a prospective randomized clinical trial, 50 euthyroid patients with a single solid colloid thyroid nodule causing local discomfort were assigned to a single intranodular injection of sterile 98% ethanol (n = 25) or suppressive doses of L-T4 (n = 25). We aimed at an ethanol dose of 20-50% of the pretreatment nodular volume. The initial daily dose of L-T4 was 1.5 microg/kg BW and was adjusted monthly during the first 6 months to reduce serum TSH to subnormal levels (<0.40 mU/L). Thyroid nodule volume and total thyroid volume were assessed by ultrasound, and thyroid function was determined by routine assays before and during follow-up. Symptom scores before and at 12 months were evaluated by a questionnaire rating pressure symptoms and cosmetic symptoms. The median ethanol dose given was 21% [95% confidence interval (CI), 18;25] of the pretreatment nodule volume. In this group, the median reduction in nodule volume was 47% (CI, 33;57; P < 0.0001) compared to 9% (CI, -7;22; P = 0.09) in the L-T4 group. The difference between the two treatment regimens was statistically significant (P < 0.0001). The median reduction in perinodular thyroid volume was 20% (CI, 11;31; P = 0.03) in the L-T4 group, whereas no change was seen in the ethanol group (-2.5%; CI, -18;11; P = 0.9). Fourteen of 25 (56%) patients treated with ethanol injection and 8 of 25 (32%) treated with L-T4 had complete relief of symptoms at 12 months of follow-up (P = 0.09). No major side-effects were seen in either group. Percutaneous ethanol injection therapy administered as a single small dose results in a satisfactory clinical response in approximately 50% of patients by halving the nodule volume. The thyroid nodule-reducing effect of L-T4 suppressive therapy is insignificant, but a subjective satisfactory clinical response is seen in a subgroup of patients, probably explained by the concomitant reduction of perinodular thyroid volume.

Phage-display libraries of murine and human antibody Fab fragments

We provide efficient and detailed procedures for construction, expression, and screening of comprehensive libraries of murine or human antibody Fab fragments displayed on the surface of filamentous phage. In addition, protocols for producing and using ultra-electrocompetent cells, for producing Fab phages from libraries, and for selecting antigen binders by panning are presented. The latter protocol includes a procedure for trypsin elution of bound phage.

Phage display used for gene cloning of human recombinant antibody against the erythrocyte surface antigen, rhesus D

A novel phage display system has been developed for PCR amplification and cloning of the Fab fragments of human immunoglobulin genes. Using this system, we have cloned an antibody from a mouse-human hybridoma cell line directed against the erythrocyte antigen rhesus D. Intact erythrocytes were used for absorption of the Fab phages. Soluble Fab fragments produced from the cloned material showed identical performance to the parental antibody in agglutination assays. Gel filtration confirmed that the Fab fragment consists of a kappa-Fd heterodimer. The successful use of intact cells for selection of specific Fab phages demonstrates that it is possible to by-pass purification of the antigen of interest. Comparison with published germline sequences demonstrated that the immunoglobulin coding regions had the highest homology to the VH 1.9III and V kappa Hum kappa v325 germline genes, respectively.

Relationship between oxygen uptake rate and time of infection of Sf9 insect cells infected with a recombinant baculovirus

Oxygen uptake rates (OUR) of Sf9 insect cells propagated in a serum-free medium (SF900II, Gibco) and of cells infected with a recombinant AcNPV were investigated before and after infection in a laboratory-scale bioreactor. The volumetric OURs of uninfected and exponentially growing cells were found to be proportional to the cell density. For infected cultures, the specific OUR of cells increased immediately after addition of virus and a maximum of 1.3 times the value of uninfected cells was noted for all the cultures between 8 to 30 hours post infection, which coincides with the period at which most viral replication and the majority of DNA synthesis takes place. It was observed that the rate of rise in the specific OUR decreased as the cell density at the time of infection increased, which meant that the later the infection, the later the maximum sOUR was observed. We therefore suggest that OUR measurement can be used to reflect the efficiency of a batch infection. Carbohydrate and amino acid consumption rates from an infected run were analysed in an effort to identify substrate(s) that may be used at increased rates to fuel the rise in oxygen demand observed early in the infection cycle. No observable rise in the consumption rates of glucose or glutamine, which are the major energy sources for animal cells, were seen after infection but an increase in the consumption rates of some amino acids suggests that infected Sf9 cells may utilise amino acids at an enhanced rate for energy post infection.

Increase in lactoferrin and elastase alpha-1-proteinase inhibitor complexes but lack of complement activation and IL-6 response following thoracic surgery

Polymorphonuclear neutrophil (PMN) stimulation and degranulation can be mediated by the cytokines and by complement activation. The aim of the present study was to measure TNF alpha, IL-1 alpha, IL-6 and C3d in relation to postoperative increase in lactoferrin and elastase alpha-1-proteinase inhibitor (E alpha-1-PI) levels. Eleven patients undergoing thoracic surgery took part in the study. Blood leucocytes, E alpha-1-PI, lactoferrin and C3d were measured preoperatively, at the end of surgery and postoperatively, at 4 h and on day 1, 2, 3 and 5. TNF alpha, IL-1 alpha and IL-6 were measured preoperatively, at the end of surgery and postoperatively, at 4 h, and on days 1 and 5. The leucocyte count, lactoferrin and E alpha-1-PI levels increased significantly postoperatively (P < 0.01). There was no significant change in C3d values. Plasma IL-6 levels were unchanged in the postoperative period. Plasma TNF alpha and IL-1 alpha were detectable at low levels in only two and four patients, respectively.

CONCLUSION

The postoperative increase in blood levels of PMN lactoferrin and E alpha-1-PI complexes observed in the present study was not accompanied by complement activation, or increased blood levels of IL-6.

Avoiding rapid growth at high cell densities: a potentially important optimisation criterion for hybridoma cultures

Inhibition caused by rapid changes in the environment has earlier been observed in hybridoma cultures following deliberate step-changes in the culture environment. This paper presents evidence of similar effects occurring during the normal span of continuous cultures fed enriched medium at low dilution rates (0.002-0.005 1/h). The effect of this observation on optimisation is discussed. In continuous culture at a dilution rate of 0.013 1/h, a viable cell density of 4 x 10(9) cells/l was achieved by gradually increasing the nutrient concentration in the feed medium. The MAb titre was 200 mg/l representing a 6-fold increase compared to batch culture and a 2-fold increase compared to continuous culture using standard medium.

Accuracy of the endpoint assay for virus titration

The statistics of estimators used with the endpoint assay for virus titration were investigated. For a standard assay with 10 wells/dilution, the graphical estimator traditionally used was found to produce estimates with significant positive bias and a relatively low accuracy. Furthermore, the graphical estimator was found to be inconsistent. A superior estimator based on the maximum likelihood principle was developed. The results are discussed in relation to the choice between the endpoint titration assay and the plaque assay, and an alternative two-stage assay is presented.

Rapid estimation of serum myoglobin concentration during rhabdomyolysis with a latex-agglutination test (Rapi-Tex)

A latex-agglutination test (Rapi-Tex) was used for semiquantitative estimation of myoglobin concentration in 89 serum samples obtained from ten patients undergoing lower-limb arterial embolectomy. Each serum sample was tested with Rapi-Tex both undiluted and after 1:50 dilution with saline. The myoglobin concentration was additionally measured with enzyme-immunoassay. In the undiluted samples there were five 'false negative' Rapi-Tex results--two in the myoglobin concentration interval 0-300 micrograms and three in the samples with myoglobin exceeding 25,000 micrograms/l--and four 'false positive' results. None of the diluted samples gave rise to false classification. Using 1:50 diluted serum, the negative predictive value of the Rapi-Tex test for identification of a myoglobin concentration greater than 5,000 micrograms/l was 0.99 (95% confidence limits 0.94-1.00), and the positive predictive value was 1.00 (0.61-1.00). Rapi-tex is concluded to be a useful emergency test for severe hypermyoglobinemia.

The effect of n-3 polyunsaturated fatty acids on lipids, platelet function, coagulation, fibrinolysis and monocyte chemotaxis in patients with hypertension

We have studied the effect of dietary supplementation with 4 g of n-3 polyunsaturated fatty acids (n-3 PUFA) daily for 6 wk on plasma lipids, haemostasis and monocyte chemotaxis in 10 patients with untreated hypertension. Total cholesterol, LDL-cholesterol, HDL-cholesterol and triglycerides did not change, but the ratio of total to HDL-cholesterol was significantly reduced after the fish oil supplement. Platelet function was unaltered by intake of n-3. Plasma fibrinogen and fibronectin decreased after supplementation with n-3 PUFA, while the effects on fibrinolysis were equivocal. Monocyte chemotaxis was reduced by the supplement. These data lend support to a role for an increased intake of n-3 PUFA in the management of patients with hypertension.

Plasma 6-keto-PGF1 alpha, thromboxane B2 and PGE2 during diabetic ketoacidosis

In 10 patients admitted to hospital with diabetic ketoacidosis plasma prostanoids 6-keto-PGF alpha, thromboxane B2 and PGE2 were studied before treatment and following recovery. During ketoacidosis the median plasma 6-keto-PGF1 alpha and PGE2 were significantly increased compared to those of a normal reference group: 5.2 pg/ml and 3.9 pg/ml versus 1.7 pg/ml and 0.4 pg/ml (p less than 0.01 and p less than 0.05). In response to therapy both prostanoids decreased significantly towards a normal level, 6-keto-PGF1 alpha: 0.5 pg/ml p less than 0.01 and PGE2: 0.08 p less than 0.05 respectively. The changes in plasma 6-keto-PGF1 alpha were negatively correlated to changes in pH, rho: -0.7788 p = 0.0135, whereas the changes in PGE2 were positively correlated to serum creatinine at admittance, rho: 0.6976, p = 0.0368 and to the amount of intravenous fluid and insulin used during treatment, rho: 0.7500 p = 0.0126 and rho: 0.8424, p = 0.0023 respectively. Plasma thromboxane B2 concentrations were not elevated and did not change after treatment of the ketoacidosis.

Serum creatine kinase-B activity in patients with chronic lower-limb ischemia and after leg amputation

Serum creatine kinase-B (CK-B) activity was measured and electrocardiograms (ECG) recorded before and after operation in two groups of ten orthopedic patients. Group I underwent lower-limb amputation because of severe, chronic ischemia of the leg and group II (controls) had knee prosthesis implantation or knee ligament surgery. In group I the number of patients with CK-B activities exceeding the discrimination value (0.25 muka-tal/l) for acute myocardial infarction preoperatively and 2, 24, 48, 72 hours, and at 7 days postoperatively were, respectively, three, three, five, three, two and nil. In Group II the serum CK-B activity remained below the myocardial infarction discrimination value in all patients at all times. No ECG abnormalities indicating myocardial infarction appeared in any patient of either group. The study indicates that severe, chronic lower-limb ischemia and amputation of the leg may cause elevation of non-cardiac CK-B activity in serum that can interfere with enzymatic recognition of acute myocardial infarction.

Serum and urinary phosphate during and after prolonged muscular ischaemia in non-exercising men and women

Serum inorganic phosphate (Pi) concentrations and urinary Pi excretions were measured in nine patients undergoing abdominal aortic bypass grafting (group I) and in nine patients undergoing lower limb arterial embolectomy (group II). In group I, serum Pi concentrations were normal until 24 h after reperfusion, when they decreased, reaching their nadir at 48 h (median Pi 0.45 mmol 1(-1). The urinary phosphate clearance relative to the creatinine clearance (Cp/Cc) increased 5 min after reperfusion reaching a maximal median value (0.454) in the 2-24-h collection period. In group II, eight patients had a normal and one had a subnormal serum Pi before reperfusion. None developed hypo- or hyperphosphataemia and the Cp/Cc remained unchanged. Daily urinary Pi excretion was higher in group I than in group II (P less than 0.03). The authors concluded that the regional muscular ischaemia in non-exercising men and women was not associated with hyperphosphataemia. The possible influence of major surgery and anaesthesia on phosphate homeostasis should be considered.

Complement and leukocyte changes during major vascular surgery

To gain further insight into the effects of major vascular surgery involving the abdominal aorta on complement and leukocytes, serial measurements of leukocyte and differential counts, plasma concentrations of C3d, and granulocyte elastase bound to alpha1 proteinase inhibitor (E-alpha1PI) were made after aorta declamping in a group of patients not receiving blood or plasma. In the hours after declamping, lymphocyte count decreased, whereas an increase was noticed in leukocytes, neutrophils, and plasma E-alpha1PI. Complement activation was not found. Previous reports on complement activation during aortic surgery probably reflect the administration of blood and plasma during the surgical procedures. Whether aortic cross-clamping or interaction between granulocytes and the aortic prothesis is responsible for the release of lysosomal enzymes during the procedure warrants further studies.

Plasma IgG, IgG subclasses and acute-phase proteins in children with recurrent acute otitis media

Quantitation of IgG, IgG subclasses and acute-phase proteins was performed in plasma samples from 156 children, aged 2 to 162 months, with varying degrees of otitis proneness. None of the children had acute otitis media or had received any antibiotics 3 weeks before the examination. Children with recurrent acute otitis media (rAOM) had significantly higher levels of total IgG, IgG1, and significantly lower levels of IgG2 than healthy children (p less than 0.02, p less than 0.0003, and p less than 0.03, respectively). However, the low levels of IgG2 found in the rAOM children could at least, to some extent, be explained by the observation that these children were somewhat younger than the healthy children. Except for recurrent episodes of common colds, children suffering from secretory otitis media (SOM) most often show no clinical signs of inflammatory events. Nevertheless, children with SOM had raised levels of plasma IgG1, indicating recurrent polyclonal stimulation of the immune apparatus, which seems to be less pronounced than that of rAOM children. Levels of acute-phase proteins, haptoglobin, orosomucoid and alpha 1-antitrypsin were evenly distributed in the children investigated, reflecting that they had no acute illness at the time of plasma sampling.

Non-cardiac creatine kinase-B activity in serum after abdominal aortic bypass surgery

Serum creatine kinase (CK) and creatine kinase isoenzyme MB (CK-B) were measured and electrocardiogram (ECG) recorded preoperatively and 24, 48 and 72 hours and 7 days after abdominal aortic bypass grafting in ten patients. No ECG abnormality indicating acute myocardial infarction (AMI) appeared and no patient had chest pain. CK-B was below the discrimination value for AMI in all cases preoperatively, but increased significantly after the operation to a maximal median value of 15 (range 5-32) U/l at 48 hours. The time-activity curve of CK paralleled that of CK-B, reaching a maximal median value of 814 (range 289-1972) U/l at 48 hours. On day 7 CK and CK-B had normalized. The CK-B activity relative to CK activity remained below 6% in all patients. Elevated serum CK-B activity should be utilized with caution for the diagnosis of perioperative AMI in patients undergoing aortic bypass grafting.

Nasopharyngeal secretory immunoglobulins in children with recurrent acute otitis media and secretory otitis media

Secretory IgA (SIgA) and secretory IgM (SIgM), total IgA and total IgM were measured in plasma and nasopharyngeal secretions (NPS) from young children with different degrees of otitis proneness. Significantly higher levels of plasma IgM and lower levels of NPS-SIgM were found in children with recurrent episodes of acute otitis media (rAOM) compared with children suffering from secretory otitis media (SOM) and healthy controls. Both plasma IgA and NPS-SIgA were evenly distributed in the three groups of children investigated, and in most children the levels of NPS-SIgA exceeded plasma IgA levels. Plasma SIgA was significantly increased in children with rAOM and SOM, probably resulting from frequent occurrence of inflammatory events at the nasopharyngeal level. No correlation could be demonstrated between NPS-SIgA and plasma IgA, or between NPS-SIgM and plasma IgM. Also, for both NPS-SIgA and NPS-SIgM, there was no correlation with age. A negative correlation was observed between the transudation index of albumin to the nasopharynx and the ratio of NPS-SIgA to total NPS-IgA. A ratio of 1 (100%) corresponded to a transudation index of 8%. The ratios of NPS-SIgA to total NPS-IgA varied considerably and a range of 39%-88% could only to some extent be explained by transudation of plasma IgA to NPS. The results of the present study show that the children with rAOM and SOM are well furnished with locally produced SIgA antibodies at the nasopharyngeal level. In children with SOM, the nasopharyngeal hypofunction in the case of low NPS-SIgM seems to be less pronounced compared with that of otitis-prone children.

Severe hypophosphatemia following elective abdominal aortic bypass grafting

Serum phosphate levels and urinary phosphate excretion were investigated in ten patients undergoing elective abdominal aortic bypass grafting. The abdominal aorta was cross-clamped peroperatively for 50-95 min. The median serum phosphate was within reference range (0.80-1.55 mmol/l) during cross-clamping and for the first 24 hours after revascularization of the lower limbs. At 48 hours there was statistically significant fall in the serum phosphate level in all patients, with median reaching a nadir of 0.49 mmol/l. At 72 hours this level had risen to 0.69 mmol/l, and reference range had been regained 7 days postoperatively. The median urinary phosphate excretion (mmol) was 38.4 during the first 24 postoperative hours, and 34.7 and 10.0 on the 2 subsequent days. The median ratio of urinary phosphate to creatinine clearance was, respectively, 0.47, 0.37, 0.09 and 0.08 on postoperative days 1, 2, 3 and 7. The study indicated that patients undergoing aortic bypass grafting with protracted regional muscular ischemia may constitute a risk group with respect to development of severe postoperative hypophosphatemia.

Myoglobin and creatine phosphokinase in serum during and after aortic bypass grafting

In 10 patients undergoing aortic bypass grafting with peroperative aortic cross-clamping we measured the levels of myoglobin and creatine phosphokinase. The duration of peroperative lower limb arterial clamping ranged from 50 min to 95 min. No significant increase in either serum myoglobin or in serum creatine phosphokinase was found during lower limb arterial clamping or for the first two hours after release of ischemia. Both parameters reached a maximum value at 24 hours after release of ischemia, with a median serum myoglobin concentration of 565 micrograms/l (range: 132-2688 micrograms/l) and a median serum creatine phosphokinase activity of 457 U/l (range: 190-1602 U/l). The increase in serum myoglobin and creatine phosphokinase was not associated with the duration of lower limb arterial clamping. Renal impairment was not found in these patients, as evaluated by the serum concentration of beta 2-microglobulin.

Comparisons between CK-B and other clinical indicators of cardiac contusion following multiple trauma

The activity of creatine kinase (CK) and creatine kinase B(CK-B) was measured in 17 patients with injuries to multiple organ systems, including the chest. The patients were closely observed for clinical signs of disturbed cardiac function by means of serial ECG, continuous monitoring of cardiac rhythm, daily cardiac auscultation, serial chest roentgenography and monitoring of central hemodynamic parameters. No statistically significant difference in CK and CK-B activity was found between the group of patients with normal cardiac function and the group with disturbed cardiac function. The CK-B activity was markedly elevated, but CK-B activity relative to CK activity was normal in both groups during the first 7 days after the trauma. The authors conclude that the significance of these enzymes' serum activity, measured with the immunoinhibition method, is diagnostically doubtful not only as regards cardiac contusions, but also in other cardiopathy preceding or following major trauma.