Original Stock Research Articles

Analysis of migration of screwed acetabular components following revision arthroplasty of the hip joint. Results of single-image roentgen analysis

Out of 57 revised acetabular components, which were regularly checked, 47 had been replaced by a cemented Müller's acetabular reinforcement ring resp. a cementless Müller's Sl-shell with flange. Both types of cups are anchored in the acetabular roof with cancellous bone screws (tab. 1). 42 cases with radiograph series permitted a detailed analysis with the EBRA-method, a computer aided method for the evaluation of acetabular spatial migration based on standard radiographs of the pelvis. The clinical results were very satisfying (tab. 6). The screwed acetabular components migrated little, although, some essential displacements of the center of rotation (in relation to the anatomical position) had to be accepted. As was recognizable with today's inaccurate methods of measuring the center of the head, the displacement too far towards cranial influenced the migration tendency less than an excessive lateralisation. Especially satisfying is the fact, that no increased migration was observed after reconstruction bone grafting of severe acetabular defects, provided that at least a partly direct contact between the acetabular component and the original bone stock was obtained. For the first time EBRA shall be introduced here as a method which shows the migration and the spatial inclination of the acetabular cup in a vector chart.

Excystation of the metacercarial cysts of Echinostoma caproni in a frozen and thawed trypsin–bile salts–cysteine medium

Saxton et al. (2008) recently described the use of a trypsin– bile salts–cysteine (TBC) medium to excyst the metacercarial cysts of Echinostoma caproni and Echinostoma trivolvis. The medium was prepared as described by Irwin et al. (1984) to excyst Himasthla leptosoma, except that bile salts were substituted for sodium taurocholate. The medium was used fresh by combining two solutions, A and B, just before use. Solution A consisted of trypsin and bile salts, whereas solution B consisted of the reductant L-cysteine. Details of the formulation and use of this medium were described by Saxton et al. (2008). A frozen and thawed TBC medium has not been used previously for work on E. caproni, although brief mention of this medium for the excystation of E. trivolvis was given by Saxton et al. (2008). The life cycle of this echinostome is maintained in at least six laboratories (see Toledo and Fried 2005), and encysted metacercariae of this echinostome are usually available for teaching and research purposes. One of us (BF) supplies colleagues with encysted metacercariae of this echinostome, and other workers mentioned in Toledo and Fried (2005) also provide this echinostome to colleagues. Some workers request BF to supply a medium for excystation of cysts of E. caproni. In the past, a frozen trypsin and bile (TB) medium of Fried and Roth (1974) was sent to investigators on dry ice to be used for the excystation of E. caproni. As explained by Saxton et al. (2008), the inability to get certain batches of the original trypsin stocks made it difficult to prepare and supply an effective TB medium. The newer TBC medium described in Saxton et al. (2008) has now replaced the old TB medium. Because of the advantages of making up large amounts of medium, e.g. 100 ml, and freezing it for long times, e.g., up to 2 years (see Fried 1994), we recently initiated work to describe the efficacy of a frozen and thawed TBC medium. The purpose of this report is to provide the results of our studies on excysting E. caproni metacercarial cysts in a frozen and thawed TBC medium. Cysts of E. caproni were obtained from the kidney/ pericardium of experimentally infected Biomphalaria glabrata snails and used within 1 to 14 days after removal from the snails (Fried and Huffman 1996). Cysts were placed, 25 to 30, in a 3.5-cm diameter Petri dish containing 3 ml of the frozen and thawed medium. The TBC medium was prepared as described in Saxton et al. (2008), and then 5 ml of solution A and 5 ml of solution B were frozen individually at either −10°C or −60°C for 24 h, 1 week, or 4 weeks before defrosting the medium and then combining solutions A and B. Defrosting of the medium was done under tap water at 22–24°C. Just before use, the two solutions were combined, and since no particulate matter was seen in the thawed medium, filtration was not necessary. The Petri dish containing the cysts was placed in an incubator at 41±0.5°C for up to 60 min. In preliminary trials, observations made at 60 min revealed a very high (approaching 100%) percentage of excystation. In subsequent trials, to determine the rate of excystation in this medium, observations were made on 25 to 30 cysts per datum point at 15, 20, 25, and 30 min. As seen in Fig. 1, excystation approached 100% within 30 min, and the rate of excystation was greatest between 15 and 20 min. Parasitol Res (2008) 102:809–810 DOI 10.1007/s00436-007-0850-y

Aluminium, Tau and Alzheimer's Disease

I would like to bring to the attention of your readers fundamental flaws in both the methodology and philosophy of a paper recently published in JAD [13]. The most significant problems concern the former and they seriously undermine both the interpretation of the results and the conclusions drawn by the authors. For example, Fig. 1 purports to demonstrate the effects of AlCl3 on tau aggregation in vitro. What these experiments actually demonstrate is that AlCl3 inhibited the heparin-induced aggregation of tau. When one considers the extraordinarily high concentrations of AlCl3 used in these experiments (0.2–20.0 mM) compared to those of tau (10 μM) and heparin (10 μM) and the well known ability for aluminium hydroxide to adsorb and precipitate the highly polyanionic heparin [3,16,17], (it is not a coincidence that aluminium is a major contaminant of parenteral heparin solutions [2,9]) it should have come as no surprise to find that super-saturated solutions of AlCl3 precipitated heparin and inhibited its induction of the assembly of tau filaments in vitro. However, to test the influence of aluminium upon heparininduced aggregation of tau the authors needed to ensure that heparin was present to a significant excess, at least ten times the concentration of AlCl3. There can be no good reason for designing experiments in which the ratio of total aluminium to tau was at its minimum 20 and at its maximum 2000! There can be no physiological significance to such experiments and I urge the authors to repeat these experiments in the presence of a significant excess of heparin (or another inducer of tau polymerisation which will not bind aluminium) and using stoichiometric ratio’s of aluminium to tau of no more than 10. Only then will the authors actually address the hypothesis that they set out to test. Unfortunately this was not the only significant oversight in the chosen methods. The remainder of the experiments use aluminium which the authors describe as aluminium maltolate. However, their method of preparing Almaltolate will not result in Al-maltolate and nor do they provide any evidence that what they have in their stock solutions is Al-maltolate. The decision to prepare their maltol solution in phosphate-buffered saline (PBS) ensured that they introduced a minimum of 5 mM inorganic phosphate into the Al-maltolate stocks and this would have ensured that a significant proportion of the total aluminium would have been precipitated at pH 7.4 as mixed hydroxyphosphates. In addition if the dilutions of this stock solution, used in particular for the experiments reported in Fig. 2, were made with PBS (which includes 10 mM inorganic phosphate), as it appeared they were, then this would have ensured that approximately all of the aluminium would be precipitated as aluminium hydroxyphosphates in these treatments. Thus the N2a cells were not exposed to the designated concentrations of Al-maltolate but to unspecified concentrations of aluminium hydroxyphosphates in the presence of maltol. These problems will also influence the intraperitoneal injections of aluminium reported in Table 1 and Fig. 3 where one is also left wondering how you can produce a 50 mM Al-maltolate stock from an original stock which was only 25 mM? One final word of caution concerning experiments with aluminium and tau is that aluminium catalyses both phosphorylation [12] and phosphoincorporation [1] of proteins, including tau, and considering the role played by phosphorylation in the aggregation of tau one

Peptide Impurities in Commercial Synthetic Peptides and Their Implications for Vaccine Trial Assessment

The advent of T-cell assay methodologies that are amenable to high throughput coupled with the availability of large libraries of overlapping peptides have revolutionized the fields of vaccine efficacy testing and cellular immune response assessment. Since T-cell assay performance is critically dependent upon the quality and specificity of the stimulating peptides, assurance of high-quality and reliable input peptides is an important aspect of assay validation. Herein, we demonstrate that individual peptides from large human immunodeficiency virus (HIV)-based peptide library sets obtained directly from two independent custom peptide suppliers contained contaminating peptides capable of giving false-positive results, which were consistent with nominal antigen-specific CD8+ T-cell responses. In-depth investigation of the cellular response in terms of responding CD8+ T-cell frequency and human leukocyte antigen (HLA) restriction led to the conclusion that one set of HIV type 1 (HIV-1)-derived peptides was contaminated with a peptide from human cytomegalovirus (HCMV), which is commonly used in cellular immunology research applications. Analytical characterization of the original stock of the suspect HIV-1 peptide confirmed the presence of approximately 1% by weight of the HCMV peptide. These observations have critical implications for quality assurance (QA) and quality control (QC) of peptides used in clinical trials where cellular immune-based assays are important end-point determinants. We propose a simple schema of biological QA/QC protocols to augment the standard biochemical QA/QC analyses as a means to circumvent this and other problems that can affect cellular immune-based assay outcome and interpretation.

Congenicity and genetic polymorphism in cloned lines derived from a single isolate of a rodent malaria parasite

Many of the most commonly studied lines of the rodent malaria parasite Plasmodium yoelii yoelii originated from a single parasite isolate designated 17X. Amongst these lines, however, are parasites that exhibit variation in genotype and phenotype (e.g. growth rate). We describe here the results of a comparative genetic analysis between cloned lines of 17X that differ in growth rate, using nucleotide sequences of specific genes and patterns of genome-wide amplified fragment length polymorphism (AFLP). Our findings indicate that the original stock of 17X comprises two unrelated genotypes. Genotype-1 is represented by parasites with a slow growth phenotype (e.g. 17X (NIMR)) and a fast growth phenotype (e.g. 17XYM). Within this genotype, there are also genomic differences manifest as a small number of AFLP bands that differentiate the fast- and slow-growing lines from each other. The other genotype, genotype-2, is represented only by parasites with a slow growth phenotype (e.g. 17XA).

Regulation of IRF-3-dependent Innate Immunity by the Papain-like Protease Domain of the Severe Acute Respiratory Syndrome Coronavirus

Severe acute respiratory syndrome coronavirus (SARS-CoV) is a novel coronavirus that causes a highly contagious respiratory disease, SARS, with significant mortality. Although factors contributing to the highly pathogenic nature of SARS-CoV remain poorly understood, it has been reported that SARS-CoV infection does not induce type I interferons (IFNs) in cell culture. However, it is uncertain whether SARS-CoV evades host detection or has evolved mechanisms to counteract innate host defenses. We show here that infection of SARS-CoV triggers a weak IFN response in cultured human lung/bronchial epithelial cells without inducing the phosphorylation of IFN-regulatory factor 3 (IRF-3), a latent cellular transcription factor that is pivotal for type I IFN synthesis. Furthermore, SARS-CoV infection blocked the induction of IFN antiviral activity and the up-regulation of protein expression of a subset of IFN-stimulated genes triggered by double-stranded RNA or an unrelated paramyxovirus. In searching for a SARS-CoV protein capable of counteracting innate immunity, we identified the papain-like protease (PLpro) domain as a potent IFN antagonist. The inhibition of the IFN response does not require the protease activity of PLpro. Rather, PLpro interacts with IRF-3 and inhibits the phosphorylation and nuclear translocation of IRF-3, thereby disrupting the activation of type I IFN responses through either Toll-like receptor 3 or retinoic acid-inducible gene I/melanoma differentiation-associated gene 5 pathways. Our data suggest that regulation of IRF-3-dependent innate antiviral defenses by PLpro may contribute to the establishment of SARS-CoV infection.

Complex network-based time series analysis

Recent works show that complex network theory may be a powerful tool in time series analysis. We propose in this paper a reliable procedure for constructing complex networks from the correlation matrix of a time series. An original stock time series, the corresponding return series and its amplitude series are considered. The degree distribution of the original series can be well fitted with a power law, while that of the return series can be well fitted with a Gaussian function. The degree distribution of the amplitude series contains two asymmetric Gaussian branches. Reconstruction of networks from time series is a common problem in diverse research. The proposed strategy may be a reasonable solution to this problem.

Attention with virus contaminated cell lines

Although (or probably because) quality control efforts are continuously increasing in animal cell technology, sometimes surprising news on contaminated cell lines are arriving. Recently a Japanese group (Li et al. in J. Virol., doi:10.1128/JVI.00807-07, published on-line ahead of print on 8 August 2007) working on the development of the production of hepatitis E virus-like particles by infecting High Five insect cells (BTI-TN-5B1-4 (Tn5)) with recombinant baculovirus has observed the appearance of unknown viral particles with diameter of 35 nm containing RNA. The study established that these unknown viral particles were nodaviral particles and that they belong to the genus Alphanodavirus. The infection of the Tn5 cells with recombinant baculovirus induced the production of infectious nodaviral particles in parallel to the production of the recombinant protein. The preoccupying fact is that this nodavirus was latently present in the ‘High Five’ cells and that other freshly purchased ampoules equally contained cells with latent nodavirus infection. In principle, the presence of latent virus per se might not be a problem, however, in the case of nodaviruses their presence can be an issue because 1st there is a serious risk of contamination by this virus when virus-like particles for vaccine purposes or recombinant proteins for therapeutic purposes are produced using the mentioned cell system, and 2nd nodaviruses (known as viruses infecting insects and fishes) are unique in being able to infect suckling mice and suckling hamsters (Garzon et al. Arch. Virol. 113 (1990) 165, Scherer & Hurlbut. Am. J. Epidemiol. 86 (1967) 271, Scherer et al. Am. J. Trop. Med. Hyg. 17 (1968) 120) with resulting paralysis and death, although no alphanodavirus infections of humans have been reported. Today nobody knows if the original stock of these cells was contaminated thus we do not know if all established subcultures and all derived subclones of the ‘High Five’ cells also contain latent nodavirus or not. Therefore, the authors (Li et al.) of the paper further indicated that all cell lines derived from the insect Tn5 cell line should be examined for the presence of such nodaviruses, and that, because of the ability of nodaviruses to establish latent and inapparent infections, all insect cell lines should be screened routinely for the presence of virus. What does this mean to the producer of biologicals using ‘High Five’ cells as cell substrate? In the case (the worst case scenario has to be assumed here), that the original stock of the ‘High Five’ cells was already contaminated and that these cells are used for the production of recombinant proteins for human use or virus like particles for vaccination purposes, either the downstream processing protocol has to be able to eliminate any nodavirus present or potentially present, or, as a total elimination cannot unequivocally be proven, a supplementary virus inactivation step should be added to the purification protocol. Else, ‘High Five’ should not be further considered for production of biological substances for human use. How is the situation for other insect cell lines? Schneider’s cell line 1 (Drosophila melanogaster cells): a similar infection by a nodavirus has been reported previously for a sub clone of this cell line (Friesen et al. J. Virol. 35 (1980) 741). Sf9 cells: With respect to Sf9 cells, Li et al. (J. Virol. doi:10.1128/JVI.00807-07) did not find any indication for the presence of a latent nodavirus infection. No information is available for other insect cell lines. And for mammalian cell lines? With respect to mammalian cells, many virus contaminations have been observed during the past and more details can be found in Merten (Cytotechnology 39 (2002) 91). As a conclusion, I would like to ask any ‘cell culturist’ to follow the recommendations of Li et al. (J. Virol. doi:doi:10.1128/JVI.00807-07) and to be cautious because almost any animal cell is a potential virus producer. Although routine virus testing is a must and a valuable means for reducing the risk of using virus contaminated cell lines, it does not provide absolute safety because of the possibility of new emerging viruses and the permanently existing risk of contaminations by adventitious agents and viruses. Thus the users of animal cells as well as the producers of biotech products by using animal cells have to be attentive to this possible threat and they have to assure the absence of adventitious agents/viruses by any means.

Assessing genetic variation and population structure of invasive North American beaver (Castor Canadensis Kuhl, 1820) in Tierra Del Fuego (Argentina)

The North American beaver (Castor Canadensis) was introduced into Isla Grande de Tierra del Fuego, Argentina in 1946 as a potential source of wild fur. The species showed high growth potential, reaching close to 100,000 individuals from an original founding stock of 25 females and 25 males. Beavers adapted rapidly to their new environment and became invasive, providing an excellent model of successful adaptation of introduced populations to a new habitat. In this study, we used polymorphic mitochondrial (mt) DNA to evaluate genetic variation in the introduced beaver population from Tierra del Fuego. Nucleotide variation in partial sequences of Cytochrome b (500 bp) and 12S rRNA (421 bp) genes and the main non-coding D-loop region (521 bp) were analyzed. Our study allowed to identify 10 different mtDNA lineages in the invasive population, none of them shared among the source populations. The pattern observed is a consequence of cessation of gene flow following expansion of the founding beaver population since the time of its introduction. This approach contributes to the understanding of effects of genetic changes on survival ability and reproductive success of invasive species. It also has important management implications to invasive species.

ESTRUS SYNCHRONIZATION OF JERSY CATTLE UNDER ARID LAND ENVIRONMENT

The objective of the present study was to eval-uate the effect of using one method of estrus syn-chronization programs on Jersy cattle reproductive performance under arid land environment, by ap-plying a specific doses of prostaglandin F2α (two injections of 5ml for cow), to increase the repro-ductive efficiency of the animals, through regulat-ing time of pregnancy and parturition. Forty non-pregnant, healthy cows were taken randomly from the original stock of Hada Al Sham Research sta-tion which belong to king Abdul Aziz University and were classified into two groups, treatment and control groups. Results obtained showed that: es-trus synchronization program using two injections of prostaglandin F2α showed that, statistically, there is no significant difference in the plasma progesterone concentration between treated and control groups. Jersy cows treated with prosta-glandin F2α showed estrus in a shorter period compared to the control group. The percentage of animals showed estrus was 75 ٪ in treated group, compared with 65% in control group which showed 84 ٪. The pregnancy rate in treated group was 86.66 ٪, versus 69.23٪ in the control group. Service period length (SPL) was 97 days for the treatedgroup, compared to 104 days for the control group. There is a significant (P0.01) difference in the plasma progesterone concentration between both groups during pregnancy, which was higher in the treated group.- The differences in the plasma progesterone con-centration between both groups after parturition were not significant. Estrus synchronization in the Kingdom of Saudi Arabia under arid land environment was considered as an application of new technology to improve reproductive effi-ciency of animals, and to regulate time of breed-ing and parturition in the herd. This will lead to a great important in the management of the ani-mal production branches.

Synergistic antiproliferative effects of KIT tyrosine kinase inhibitors on neoplastic canine mast cells

Aggressive mast cell (MC) tumors are hematopoietic neoplasms characterized by uncontrolled growth of MC and resistance to conventional drugs. In most cases, the tyrosine kinase (TK) receptor KIT is involved in malignant cell growth. Therefore, several KIT TK-targeting drugs are currently being tested for their ability to block growth of neoplastic MC. We examined the effects of four TK inhibitors (imatinib, midostaurin, nilotinib, and dasatinib) on C2 canine mastocytoma cells, as well as primary neoplastic canine MC. As assessed by (3)H-thymidine incorporation experiments, all TK inhibitors produced dose-dependent inhibition of proliferation in C2 cells with the following IC(50) values: imatinib: 269 +/- 180 nM, midostaurin: 157 +/- 35 nM, nilotinib: 55 +/- 24 nM, dasatinib: 12 +/- 3 nM. Growth-inhibitory effects of TK inhibitors were also observed in primary neoplastic mast cells, although IC(50) values for each drug varied from patient to patient, with midostaurin being the most potent agent in all samples tested. In consecutive experiments, we were able to show that TK inhibitors cooperate with each other in producing growth inhibition in C2 cells with synergistic effects observed with most drug combinations. In flow cytometry and TUNEL assay experiments, growth-inhibitory effects of TK inhibitors were found to be associated with cell-cycle arrest and apoptosis. Together, these data show that several TK-targeting drugs induce apoptosis and inhibit proliferation in canine mastocytoma cells in vitro, and that synergistic drug interactions can be obtained. Clinical trials are now warranted to explore whether these TK inhibitors also counteract growth of neoplastic cells in vivo in patients with aggressive MC tumors.

Impact of Dual Infections on Chemotherapeutic Efficacy in BALB/c Mice Infected with Major Genotypes ofTrypanosoma cruzi

The aim of this work was to investigate the impact of dual infections with stocks of Trypanosoma cruzi major genotypes on benznidazole (BZ) treatment efficacy. For this purpose, T. cruzi stocks representative of the genetic T. cruzi lineages, displaying different susceptibilities to BZ, belonging to the major T. cruzi genotypes broadly dispersed in North and South America and important in Chagas' disease epidemiology were used. Therapeutic efficacy was observed in 27.8% of the animals treated. Following BZ susceptibility classification, significant differences were observed in dual infections on the major genotype level, demonstrating that combinations of genotypes 19+39 and genotypes 19+32 led to a shift in the expected BZ susceptibility profile toward the resistance pattern. Analysis on the T. cruzi stock level demonstrated that 9 out of 24 dual infections shifted the expected BZ susceptibility profile compared with the respective single infections, including shifts toward lower and higher BZ susceptibilities. Microsatellite identification was able to identify a mixture of T. cruzi stocks in 7.7% of the T. cruzi isolates from infected and untreated mice (6.9%) and infected and treated but not cured mice (9.0%), revealing in some mixtures of BZ-susceptible and -resistant stocks that the T. cruzi stock identified after BZ treatment was previously susceptible in single infections. Considering the clonal structure and evolution of T. cruzi, an unexpected result was the identification of parasite subpopulations with distinct microsatellite alleles in relation to the original stocks observed in 12.2% of the isolates. Taken together, the data suggest that mixed infections, already verified in nature, may have an important impact on the efficacy of chemotherapy.

Incidence of hepatitis virus infection and severe liver dysfunction in patients receiving chemotherapy for solid tumors

19611 Background: Hepatitis virus infection through virus reactivation has a high risk of mortality in patients with solid malignancies receiving chemotherapy. Methods: We examined the incidence of both hepatitis B virus (HBV) and hepatitis C virus (HCV) infection and severe liver dysfunction (alanine aminotransferase >ten times the normal upper limit and total bilirubin >5 mg/dl) during chemotherapy in 171 patients with solid tumor. Results: Six patients (3.5%) were infected with HCV and 17 patients (9.9%) were infected with HBV. One patients (0.5%) were infected with both HCV and HCV. There were severe liver dysfunction in 29 (16.9%) all patients. HCV- or HBV-infected patients showed severe liver dysfunction at a significantly higher incidence than non-infected patients (7/22 (31%) vs. 18/149 (12%), p<0.047). Furthermore, the incidence of severe liver dysfunction in HCV-infected patients was significantly higher than in HBV- infected patients (6/8 (75.0%) vs. 18/149 (18.2%), p<0.01). Three of eight HBV infected patients were initially negative for hepatitis B surface antigen (HBsAg) by latex agglutination and became positive for HBsAg during chemotherapy. Furthermore, all three patients developed severe liver dysfunction and two developed fatal fulminant hepatitis. From an examination of the original stock of serum samples before chemotherapy, two patients were found to be positive for HBV-DNA by polymerase chain reaction (PCR). Although post-transfusion HBV infection was suspected in the one remaining patient, the cause of HBV infection could not be clarified due to the impossibility of examination in blood donors. Conclusions: Since HBV-infected patients develop severe liver dysfunction at a higher incidence than either patients not infected with virus or HCV-infected patients before chemotherapy for hematological malignancies, it is recommended that HBV- DNA should be tested by PCR to detect HBV marker-negative carriers and liver function tests should be carefully monitored. No significant financial relationships to disclose.

Bond graph and finite element analyses of temperature distribution in a hot rolling process: A comparative study

During the process of hot rolling, a metal is given its final shape by plastically deforming the original stock. This paper shows how variables, specifically the temperature, at each point in the deformation zone can be modelled using a multielement bond graph approach. Low-carbon steel has been considered and the modelling is described for single-pass hot rolling. Surface and centre temperature distributions are shown, and simulation results are found to be in good agreement between the two modelling techniques of bond graphs and finite element analysis.

Mycoplasma contamination and viral immunomodulatory activity: Dendritic cells open Pandora's box

During in vitro investigations on the interaction of classical swine fever virus (CSFV) – an immunosuppressive viral pathogen – with monocyte-derived dendritic cells (MoDC) a soluble factor with a strong anti-proliferative activity for T lymphocytes was found. This activity, with an inhibitory dilution 50% (ID 50) of 10 3–10 7, was induced after virus infection of monocytes differentiating into DC. UV-inactivation of the supernatants and blocking experiments with a monoclonal antibody against the E2 envelope protein of CSFV initially indicated a virus-dependency. However, further investigations including filtration and centrifugation experiments as well as antibiotic treatment demonstrated the involvement of mycoplasma. This was confirmed by a Hoechst 33258 staining, PCR and mycoplasma cultures— Mycoplasma hyorhinis was identified as the contaminant. Elucidation of a mycoplasma presence occurred under conditions in which the original virus stocks prepared in SK6 cells were negative for mycoplasma using the above tests. Moreover, conventional passage of the virus on the SK6 cells used for this purpose did not reveal any mycoplasma. It was the passage of virus in MoDC rather than SK6 cells that was required to expose the contamination. Three passages of the anti-proliferative supernatants on MoDC cultures increased the ID 50 10 3-fold; only when these MoDC-derived supernatants were employed was the mycoplasma contaminant also detectable on SK6 cells. In conclusion, these data demonstrate that regular testing of cell lines and virus stocks for mycoplasma does not necessarily identify their presence, and that application of passage in MoDC cultures could prove an aid for identifying initially undetectable levels of mycoplasma contamination.

Oxidative Degradation of Athabasca Bitumen, Fuel Oil, and Used Transformer Oil

Oxidative cracking of bitumen, waxy fuel oil, and used transformer oils were carried out individually in an autoclave with 0.6 wt% of hydroquinone as a catalyst. The cracking process is conducted at 410°C in an atmosphere of oxygen gas of 0.15 MPa, for 30 min. The identification and quantitative determination of both the liquids and gases obtained during the cracking process are achieved using packed and capillary gas chromatography (GC) connected with suitable detectors. It was found that the degraded liquid products obtained have a higher percentage of lower hydrocarbons compared to the original feed stocks. Several analytical parameters including API gravity, calorific value, viscosity, density, pour point, etc., were used to evaluate the liquid product obtained. Also, the calorific values of the liberated gases were calculated and compared with that of natural gas. The cracked oil products were distilled and compared to their corresponding petroleum fractions. The cracked fractions have the same characteristics as their corresponding petroleum fractions with the exception of some properties that depend on the aromatic, naphthenic, and waxy nature of the virgin oil.

The importance of stocking age in the enhancement of River Kymijoki salmon (Salmo salar)

Finnish Game and Fisheries Research Institute, Helsinki, FinlandSummaryHatchery-reared Atlantic salmon parr and smolts are regularlyreleasedintotheRiverKymijoki,SouthernFinland,toenhancethe local river and coastal fisheries. In 1988–1994, a series ofmicro- and Carlin-tagging experiments were carried out toexamine the influence of stocking age on the stocking results.Five age groups were compared: 1-year and 2-year-old smolts,and 1-summer, 1-year and 2-summer-old parr. The aim was todetermine the most profitable way of producing salmon forfishing in the River Kymijoki. Stocking age had a stronginfluence onthestocking results, measuredastheproportion ofadult recoveries. The most favourable results were obtainedusing 2-year-old smolts (survival index 100), followed by1-year-old smolts (52), 2-summer-old parr (51), 1-year-old parr(37) and 1-summer-old parr (24). Available data on rearingcosts suggest that 2-year-old smolts were also the mosteconomically profitable choice, followed by 1-year-old parr,1-year-old smolts and 1-summer-old parr. The most expensiveway of producing salmon was by stocking 2-summer-old parr.IntroductionThe reduction of the original wild salmon stock of the RiverKymijoki in the eastern Baltic Sea started in the early 1920s, inconjunction with increasing industrial pollution, dredging, logfloating and damming. Eventually, in the early 1950s, RiverKymijoki salmon were driven to extinction, putting an end tothe once flourishing salmon fisheries in the river and in theadjacent coastal areas (Ja¨rvi, 1932).The possibility of restoring the salmon stock of the RiverKymijoki began to improve in the early 1970s, when logfloating ended and the treatment of industrial wastes becamemore effective. First attempts to reintroduce salmon into theriver were carried out in 1974 and regular releases of hatchery-reared fish began in 1979. The extinct original stock of the riverwas replaced by an imported salmon strain from the RiverNeva, Russia.The remaining maximal natural smolt production capacityin the River Kymijoki has been estimated at 100 000 smoltsper year (Mikkola et al., 1990), which is 40% of the pastoriginal production of 250 000 smolts (Sjo¨blom et al., 1974).However, river stretches suitable for salmon reproduction aremostly located above the lowest dams and are only accessibleto spawning migrants via fish ladders in years with a highwater discharge. The continuously accessible river stretches arecapable of producing only up to 3 000 smolts per year.Due to the limited and uncertain potential to revive naturalreproduction, the principal goal of the management of RiverKymijoki salmon has been to revive and maintain the localsalmon fishery in the river and at sea by regular stocking ofhatchery-reared smolts in the estuary and parr into suitablenursery areas in the river. The smolts have been either 2- or1-year-olds on release, and parr have been 1-summer, 1-year or2-summers old.In 1988–1994, two series of tagging experiments were carriedout to examine the influence of stocking age on stockingresults. The aim was to determine the most profitable way ofproducing salmon for fishing in the River Kymijoki.Material and methods

Achievements in forest tree genetic improvement in Australia and New Zealand 7: Maritime pine and Brutian pine tree improvement programs in Western Australia

Summary Maritime pine (Pinus pinaster) is an important plantation species in Western Australia. The area now planted is about 50000 ha, but this will increase significantly because of the planned establishment of more than 150000 ha in medium- rainfall areas of the wheat belt to reduce salinity while providing a commercial tree crop. A breeding program was begun in 1957 in Western Australia to ameliorate defects in P. pinaster for plantation wood production on impoverished sands in high-rainfall areas of the Swan Coastal Plain. The priority was to improve stem straightness while maintaining dominant vigour; reducing branch angle and branch size were secondary requirements. Eighty-three progeny trials covering 160 ha with 186 100 trees were planted from 1965 to 1991, and 25 ha of clonal seed orchards were established. The program has provided substantial gains in tree growth, and stem and branching form, since 1971. The new cultivar available for deployment to tree farms is about 80% more productive than the original stock, as well as being much straighter and smaller limbed. A second phase of the breeding program started in 1996. This was designed to take the developed, diverse breeding population to new sites in medium-rainfall areas of the wheat belt, and to test the suitability of the genotypes available for deployment. Over the subsequent decade some 32 progeny trials testing 843 families with 81 380 progeny were established on an area of 55 ha. Tolerance to drought and strong apical dominance on fertile, medium-rainfall sites were identified as new traits important to the breeding objective. New seed orchards were developed for these major traits. Brutian pine (Pinus brutia) has potential for high-evaporation, medium-low-rainfall areas because of its inherent ability to survive severe water stress and display apical dominance. The breeding of this species was stepped up in 1999 using old progeny trials at Yanchep as a base population. The objective was to improve the early growth and establishment of the species, and to examine its potential as a hybrid with P. pinaster.

Long Term Serial Repitching and the Genetic and Phenotypic Stability of Brewer's Yeast

Two brewing yeast strains, one employed for the production of an ale type product and the other used solely for bottle conditioning, were serially repitched over a period of one year. Subsequently each yeast culture was compared to the original stocks for a variety of phenotypic and genotypic characteristics. Fermentation performance was assessed in terms of flocculation capacity and the time required to achieve attenuation in 150 barrel fermentation vessels, while the propensity for the population to accumulate variants was assessed by analysing giant colony morphology. Changes to the genome were monitored by DNA fingerprinting of each yeast culture using RAPD-PCR and RFLP. Although some colony morphology variation was observed between fresh and old ale yeast cultures, there were no detectable genetic changes or alterations in fermentation characteristics to either yeast strain over the course of serial repitching. It is suggested that although some brewing yeast strains are susceptible to genetic drift, others are more resilient and can remain stable over extended periods of time. The propensity to produce variants may therefore play a significant role in determining the number of times a strain may be serially repitched, or its suitability for beer fermentations.

Bond graph modelling of temperature distribution in a steel plate during multi-stand rolling

In a multi-stand rolling process, the final thickness of the strip is achieved through plastic deformation of the original stock by a series of counter-rotating rollers. In this work, a bond graph model for four stand rolling process has been developed for predicting temperature distribution. The model can predict temperature on the surface of the plate as well as inside the material. Extensive simulation studies have been performed for various parametric conditions.