Is non-union of tibial shaft fractures due to nonculturable bacterial pathogens? A clinical investigation using PCR and culture techniques

BACKGROUND

Non-union continues to be one of the orthopedist's greatest challenges. Despite effective culture methods, the detection of low-grade infection in patients with non-union following tibial fracture still presents a challenge. We investigated whether "aseptic" tibial non-union can be the result of an unrecognized infection.

METHODS

A total of 23 patients with non-union following tibial shaft fractures without clinical signs of infection were investigated. Intraoperative biopsy samples obtained from the non-union site were examined by means of routine culture methods and by polymerase chain reaction (PCR) for the detection of 16 S ribosomal RNA (rRNA). Control subjects included 12 patients with tibial shaft fractures.

RESULTS

23 patients (8 women and 15 men; mean age: 47.4 years) were included into this study. Preoperative C-reactive protein levels (mean: 20.8 mg/l) and WBC counts (mean: 8,359/μl) in the study group were not significantly higher than in the control group. None of the samples of non-union routine cultures yielded microorganism growth. Bacterial isolates were found by conventional culturing methods in only 1 case of an open fracture from the control group. In this case, PCR yielded negative results. 16 S rRNA was detected in tissue specimens from 2 patients (8.7%) with non-union. The analysis of these variable species-specific sequences enabled the identification of specific microorganisms (1x Methylobacterium species, 1x Staphylococcus species). Both PCR-positive patients were culture-negative.

CONCLUSIONS

The combination of microbiological culture and broad-range PCR seems to substantially add to the number of microbiological diagnoses obtained and may improve the clinician's ability to tailor therapy to the individual patient's needs.

Amendments to sterility test requirements for biological products. Final rule

The Food and Drug Administration (FDA) is amending the sterility test requirements for biological products. This rule provides manufacturers of biological products greater flexibility, as appropriate, and encourages use of the most appropriate and state-of-the-art test methods for assuring the safety of biological products. FDA is taking this action as part of its ongoing efforts to comprehensively review and, as necessary, revise its regulations related to biological products.

Identification of Candida dubliniensis in a diagnostic microbiology laboratory

Candida dubliniensis is an emerging yeast pathogen isolated mainly from immunocompromised patients. As molecular tests are currently unsuitable for use in routine diagnostic laboratories, we compared a variety of phenotypic techniques for differentiating C. albicans and C. dubliniensis. The tests included: colony colour on CHROMagar Candida medium; growth at 37 degrees C and 45 degrees C; ability to produce germ tubes and chlamydospores; and the Auxacolor system. The organisms included 105 isolates previously identified as C. albicans, 10 reference strains of C. albicans, 2 reference strains of C. dubliniensis and 102 fresh clinical isolates identified as C. albicans. None of the tests alone was satisfactory but a combination of 3 tests may be suitable for presumptive identification of C. dubliniensis.

ED(27) trophoblast-like cells isolated from first-trimester chorionic villi are genetically identical to HeLa cells yet exhibit a distinct phenotype

ED(27) trophoblast-like cells were prepared from human chorionic villus samples obtained at 9 weeks gestation and have been grown continuously in vitro without phenotypic drift for nearly a decade. These cells express many trophoblast markers, including cytokeratin, placental alkaline phosphatase (PLAP), secretion of 17beta-estradiol, and a microvillous apical surface. The ED(27) cell line is a useful model system for studies of placental cell biology and has been distributed to laboratories world-wide. However, experiments to investigate their relationship to primary villous cytotrophoblast have shown that these cells do not secrete detectable amounts of human chorionic gonadotropin in culture and, when digested with trypsin, disperse into individual cells. Furthermore, immunocytochemical studies demonstrated that, unlike villous cytotrophoblasts, ED(27) cells were immunoreactive with monoclonal antibodies recognizing some HLA Class I antigens. This was not HLA-G, however, as would be expected if these cells originated from extravillous cytotrophoblasts, but rather classical HLA-A, B which is thought not to be expressed by any trophoblast subpopulations. These inconsistencies prompted us to question the authenticity of the continuous cell line as it now exists. Genetic haplotype analysis using the polymerase chain reaction (PCR) revealed that ED(27) was genetically identically to the HeLa cell line. Inasmuch as HeLa cells have never been grown in the laboratory (DAK), the only possible origin of HeLa cell contamination of ED(27) cells was the WISH cell line, and further PCR analysis revealed that this cell line was also genetically identical to HeLa. Like ED(27) cells, HeLa cells and WISH cells synthesized small amounts of estrogen and were found to express PLAP and antigens recognized by the monoclonal antibodies ED822, directed against the syncytiotrophoblast, and J1B5 directed against villous cytotrophoblast. These results point out the need for adherence to rigorous and consistent quality control measures to assure the authenticity of cell lines used as in vitro model systems.

Responsibility for truth in research

For over half a century, cell cultures derived from animals and humans have served researchers in various fields. To this day, cross-contamination of cultures has plagued many researchers, often leading to mistaken results, retractions of results, cover-ups and some out-and-out falsification of data and results following inadvertent use of the wrong cells. Also, during years of examining cultures for purity we learned that many virologists were not too concerned about the specificity of the cultures they used to propagate the particular virus under study as long as the substrate (whatever it might have been) gave optimal virus yield. Polio virus propagates in primate cells, and much research has involved cells from man and various species of primates. In the 1950s a large number of chimpanzees were held in captivity in Africa for extensive studies of the efficacy of polio vaccine in production at the Wistar Institute in Philadelphia and elsewhere. Chimpanzee tissues, particularly kidneys, were thus readily available and could have also provided substrates for polio virus production, since little was known about the purity of substrates and little attention was paid to their specificity at that time.

Gastroenterology-urology devices; classification of tissue culture media for human ex vivo tissue and cell culture processing applications. Final rule

The Food and Drug Administration (FDA) is classifying tissue culture media for human ex vivo tissue and cell culture processing applications into class II (special controls). The special control that will apply to this device is a guidance document entitled "Class II Special Controls Guidance Document: issue Culture Media for Human Ex Vivo Tissue and Cell Culture Processing Applications; Final Guidance for Industry and FDA Reviewers." The agency is taking this action in response to a petition submitted under the Federal Food, Drug, and Cosmetic Act (the act) as amended by the Medical Device Amendments of 1976, the Safe Medical Devices Act of 1990, and the Food and Drug Administration Modernization Act of 1997. The agency is classifying these devices into class II (special controls) in order to provide a reasonable assurance of the safety and effectiveness of the devices.

ASTM lights the way for tissue engineered medical products standards: jump start for combination medical products that restore biological function of human tissues

Everybody hopes for better health and restoration of impaired bodily function, and now that hope is illuminated by the promise of powerful biological tools that make human cells grow and replace human tissue. ASTM Committee F04 on Medical and Surgical Materials and Devices is taking the lead by defining some of those tools as standards that can be used for the development, production, testing, and regulatory approval of medical products.

A systematic approach to the validation of process control parameters for monoclonal antibody production in fed-batch culture of a murine myeloma

A systematic approach to the validation of control ranges of control parameters for a cell culture process producing a monoclonal antibody is described. Specifically, the structure and functional activity of a monoclonal IgG1 antibody produced at the outer limits of numerical ranges of fed-batch culture control parameters such as pH and temperature were examined, with the aim of providing assurance that antibody produced under varying culture conditions was of consistent quality based on a carefully defined set of specifications. An experimental design was created using a half-fractional factorial design for fed-batch culture incorporating half of the thirty two possible combinations of five selected control parameters at high and low levels. Statistical analysis of all data gathered from the study allowed an assessment of the effects of the process control parameters at either high or low outer limits on fed-batch culture response variables such as growth rate and specific antibody productivity. Measured values for the responses of growth rate and specific antibody productivity throughout this study ranged from 0.22-0.44 d(-1) and 6.4-32 microg monoclonal antibody/10(6) cells/d respectively. Analytical characterisation of monoclonal antibody purified from each fed-batch culture considered the purity, structure and biological activity of the glycoprotein. All antibody preparations were identical to each other and to the current antibody reference standard or control. Glycosylation analysis of certain samples from the study demonstrated that the distribution of glycoforms of the antibody was not affected by the varying process control conditions of the fed-batch cultures.

Simplified method to generate large quantities of dendritic cells suitable for clinical applications

The present study describes the optimization of an in vitro culture method for generating large amounts of dendritic cells (DC) in serum-free conditions from leukapheresis containing a mixed population of peripheral blood mononuclear cells (PBMC) which are cultured in the presence of GM-CSF and IL-13. Initial comparisons between the generation of DC from bulk and monocyte-enriched leukapheresis products showed that the presence of lymphocytes during the culture favors the differentiation of monocytes into DC. DC yields obtained from mixed mononuclear cell cultures were between 38 and 54% higher than yields obtained from monocyte-enriched cultures. Both types of cultures resulted in the generation of DC with an immature phenotype (CD83- and high phagocytic activity), which have been previously shown to be good stimulators for T cell responses. DC yields of bulk cultures in serum-free conditions were significantly higher than those obtained in the presence of 2% human serum. The cytokines of the supernatants of serum-free cultures comprised a significant content of pro-inflammatory cytokines such as IL-1, IL-12 and TNF-alpha. Maturation of DC generated by this method can be induced by treatment with double-stranded RNA, LPS or TNF-alpha, resulting in enhanced surface expression of CD80, CD86, CD40, CD83 and MHC molecules on the DC. The methodology described here offers the possibility for generating large amounts of clinical grade DC from bulk leukapheresis products, thus avoiding DC precursor purification steps, and thereby minimizing the risks of contamination. This culture process may be applied to cell-based therapeutic approaches for the treatment of cancer or chronic viral infections.

Generation of useful cell culture data

As the need for viable and interpretable cell culture systems increases, it is not sufficient to simply be successful at growing cells in vitro. Rather, vigilance is required to obtain repeatable data from these systems, especially if mechanistic or developmental experimental designs are attempted. We suggest that all aspects of basic cell culture are as important as growing cells. We offer the papers of this issue to help the cell scientist scrutinize and identify problems in many of these important areas, including obtaining tissue, eliminating microbial contamination, formulating a defined medium, isolating specific cell types from tissue and then using them for in vitro studies, cloning cells, selecting and developing methods for cell culture analyses, and recognizing abnormal cell culture activity.

Comparison of basic methods in clinical studies and in vitro tissue and cell culture studies reported in three anaesthesia journals

Tissue and cell culture (in vitro) studies reported in the 1997 issues of the British Journal of Anaesthesia, Anesthesia and Analgesia, and Anesthesiology were compared with groups of clinical studies selected at random from the same issues. Comparisons were of some basic aspects of study design and reporting that might lead to bias. The aspects examined were sample size, randomization and reporting of exclusions and withdrawals. Two groups of 53 articles were compared: sample size was smaller in in vitro than in clinical studies (median 6 vs 19); randomization was reported in five in vitro studies and in 37 studies; and failures were reported in two in vitro studies and in 43 clinical studies. This hinders interpretation of reported tissue and cell culture studies. Where possible, tissue and cell culture studies should be conducted, reported and assessed for publication to standards equivalent to those for clinical studies.

Tissue culture of retinal pigment epithelium following isolation with a gelatin matrix technique

Prior to transplantation of the retinal pigment epithelium, it is necessary to develop techniques to harvest viable retinal pigment epithelium as an organized monolayer. Unfortunately, current techniques result in contraction of the harvested monolayer and coiling of the cell sheets, which hinders successful transplantation. The purpose of this study was to develop a method for harvesting retinal pigment epithelium from eye cups and from tissue culture prior to transplantation. Passage 1 porcine retinal pigment epithelium and native retinal pigment epithelium from fresh porcine eye cups were pretreated with 0.25% edetic acid for 12 minutes and coated with a 100 micron layer of 12% gelatin. Patches of the retinal pigment epithelial cell monolayer were harvested and transferred to culture plates, and cell viability and the ability of the transferred cells to proliferate in culture was determined. Our results demonstrated that retinal pigment epithelium can be harvested from tissue culture and eye cups as an organized monolayer with high efficiency (94.7 +/- 3.5% and 99.7 +/- 0.3% harvesting rates, respectively) and high cell viability (91.3 +/- 2.9% and 89.4 +/- 4.3%, respectively). Cells harvested from tissue culture plates divided and became confluent within 10 to 14 days. Cells harvested from eye cups maintained a differentiated phenotype and migrated outward from the margin of the exoplant. There was no contraction of the retinal pigment epithelial monolayer isolated from either substrate. Thus, we were able to harvest retinal pigment epithelium as an organized monolayer from tissue culture plates and freshly enucleated eyes with edetic acid and gelatin. The harvested cells were viable and proliferated without contraction of the monolayer in vitro.

Solid tissue culture for cytogenetic analysis: a collaborative survey for the Association of Clinical Cytogeneticists

AIMS

To survey the diagnostic service provided by UK laboratories for the culture of solid tissue samples (excluding tumours) and in particular to examine the variation in culture success rates and the problems of maternal cell overgrowth.

METHODS

Twenty seven laboratories took part in a collaborative survey during 1992. Each laboratory submitted data on up to a maximum of 60 consecutive specimens (n = 1361) over a six month period.

RESULTS

Skin specimens, the largest category received (n = 520), were the most problematic (51% success rate). Culture success rates were significantly lower (43%) when skin specimens (n = 140) were transported dry to the laboratory. Success rates for skin specimens also varied, depending on the origin of the specimen, from 18% for intra-uterine deaths (IUD) (n = 94) to 85% for neonatal deaths (n = 33) and 83% for live patients (n = 54). Culture of selected extra-fetal tissues from IUD, stillbirths and following elective termination of pregnancy (TOP) gave comparable success rates to those achieved for skin samples from neonatal deaths and live births. Skewed sex ratios, female > male, were identified for products of conception (POC) (n = 298) and placental biopsy specimens (n = 97).

CONCLUSIONS

By appropriate selection, transport and processing of tissues, and in particular by avoiding relying solely on skin samples from IUD, stillbirths and TOP, an increase in culture success rates for solid tissue samples submitted for cytogenetic analysis could be achieved. The high risk of maternal cell contamination from POC and placental biopsy specimens was also identified in this survey.

Issues of biological assays for viral vaccines

The major test materials in viral vaccine production are seed virus, cell substrate and vaccine. The seed virus should be clearly identified as to source strain and its freedom from adventitious agents. The cell substrate to be used for the production of vaccine is generally tested following the recommendation that appeared in "Points to Consider in the Characterization of Cell Line Used to Produce Biologicals". It should be noted that a shift in emphasis has taken place from the earlier versions of the "Points to Consider". The tests for vaccine include bulk and final container tests. These tests, in principle, are performed following 21 CFR 600-680. In vitro and in vivo tests for detecting adventitious viruses are complementary; hence, both types of tests are desirable. Some of the practical points to consider in designing and performing the tests for adventitious viruses are discussed.

Overview of a quality assurance/quality control compliance program consistent with FDA regulations and policies for somatic cell and gene therapies: a four year experience

Somatic cell and gene therapy involve the application of biological technologies to an individual patient through the use of living cells which provide a therapeutic benefit (Aliski, 1991). Various forms of cellular and gene therapies are being developed and evaluated in an increasing number of clinical trials for congenital and acquired disorders. The potential and progress of these therapeutic applications have resulted in an increasing effort by the Food and Drug Administration (FDA) to develop the regulatory framework under which these therapeutic approaches would insure safety and efficacy, the primary mandate of the FDA. Over five years ago Cellcor began to define the parameters, specifications, and conditions relevant to a Quality Assurance/Quality Control (QA/QC) program that has evolved to insure safety and maximize the efficacy of applications of the company's ex vivo technology, autolymphocyte therapy. Autolymphocyte therapy is an outpatient form of somatic cell immunotherapy based upon the infusion of T cells that have been activated ex vivo using a combination of previously generated autologous cytokines and an anti-CD3 monoclonal antibody. We have been able to demonstrate the feasibility for the safe, controlled, and consistent preparation and delivery of a cellular therapy by application of relevant GMP regulations. This presentation reviews aspects of this program and chronicles our experience which at present amounts to over 4400 in fusions for over 700 patients. This program provides a high degree of assurance that a cellular therapy program can be carried out in a multisite mode involving hundreds of patients through the strict adherence to cGMP as set forth in existing regulations.(ABSTRACT TRUNCATED AT 250 WORDS)

The applicability of the cumulative embryo score system for embryo selection and quality control in an in-vitro fertilization/embryo transfer programme

The cumulative embryo score system involves three aspects of relevance in pregnancy achievement during in-vitro fertilization (IVF) and embryo transfer: cleavage rates, morphological qualities and the number of embryos transferred. The scores of 602 IVF/embryo transfer trials were calculated and analysed to determine the system's relationship to pregnancy rate, pregnancy outcome and the incidence of twin and triplet pregnancies. The system was also applied to cycles where endotoxins were either present in or absent from culture medium, in order to evaluate its validity in quality control analyses. Pregnancy rates were found to increase from 4%, with scores between 1 and 10, to 35% in the 41-50 group. The score of 20 was the criterion for separating patients into poor and good pregnancy prognosis groups (P = 0.00001). Biochemical abortions occurred more frequently with scores < 20 (P = 0.00978), but a similar relationship was not found in clinical abortion rates (P = 0.62206). Birth rates below and above a score of 20 (2.8 and 19.2%, respectively) differed significantly (P = 0.0005). The scores of twins overlapped extensively with those of singleton births, but those of all triplets were > 40. The system did not reflect a correlation between embryo quality and the presence of endotoxins in culture medium.

Safe biotechnology (5). Recommendations for safe work with animal and human cell cultures concerning potential human pathogens

The benefits of using animal or human cell cultures have been clearly demonstrated in diagnostic and therapeutic research and in their application for manufacturing. Cell cultures serve as a tools for the production of vaccines, receptors, enzymes, monoclonal antibodies and recombinant DNA-derived proteins. They represent an integral part of drug development for which corresponding facilities, equipment and manufacturing processes are required. Although the cells themselves offer no particular risk to workers in laboratories and production areas or to the environment, the cell cultures may be contaminated with viruses, mycoplasma, bacteria, yeast and fungi or might contain endogenous viruses. The containment level for animal and human cells is therefore determined by the risk class of these agents. The history of animal and human cell cultures has proved that they can be handled safely. The recommendations in this publication concern the safe handling of cell cultures (tissue explants, primary cell cultures) and permanent cell lines of animal and human origin. A classification system of safety precautions has been elaborated according to the potential for contamination with the pathogenic agents involved.

The importance of cell physiology to the performance of animal cell bioreactors

This report has pointed out the following: (1) the new animal cell products that will be produced commercially will have large dollar markets and will, together with cost containment and competitive pressures, place a greater emphasis on the reduction of the cost of production through the selection of appropriate culture technology; (2) the benefits to be gained by working with basic biological processes in animal cell culture that will increase cell density, cell productivity, and product quality; (3) the need to work with reactor technologies that can affect the basic biology of the cell in these positive ways; (4) it appears worthwhile to explore immobilized, high cell density culture technologies as a possible means to achieve the objectives by affecting the basic regulation of the cell through fundamental cell/cell environment biological processes.

Evaluation of two ELISA's for detecting Chlamydia trachomatis from endocervical swabs

Two enzyme immunoassays (EIAs) detecting Chlamydia trachomatis from endocervical swabs, Syva MicroTrak (MT) and Abbott Chlamydiazyme (CZ), were compared with a tissue culture (TC) standard. Initially, 8% (100 of 1250) of specimens were TC positive, yielding sensitivities of 94% (94 of 100) for MT and 79% (79 of 100) for CZ with identical 98% specificities (1129 of 1150 for MT and 1130 of 1150 for CZ). Discrepant specimens were retested by both EIAs and assayed for elementary bodies (EBs) by a fluorescent antibody test. After discrepancy analysis, 9.5% (118) of 1240 patients were either TC or EB positive, yielding sensitivities of 94.1% for MT (111 of 118) and 79.7% for CZ (94 of 118) with identical specificities of 100% (1122 of 1122). These results indicate that the MT is significantly more sensitive (p less than 0.05, McNemar test) than CZ in detecting C. trachomatis from endocervical swabs.

Safety and economic aspects of continuous mammalian cell culture

Mammalian cell cultures are the most appropriate host cells for recombinant DNA derived products if complex protein structures have to be synthesized in their native form. Due to their physiological behaviour they grow either adherent or in suspension. For the attachment of adherent cells, microcarriers or wire springs can be applied to increase the internal surface of the bioreactor. Both systems provide a simplified media exchange but, however, show some limitations in scale up. In contrast, suspension culture systems as homogeneous systems independent of any carrier have not shown any limitation in scale up. Because most cell lines which are of commercial interest grow in suspension, this technology is best advanced and used in batch and continuous mode. Although mammalian cell cultures are sensitive to hydrodynamic shear forces, technologies for deep tank production are developed which allow stirrer tip speed of up to 1.5 m s-1 sufficient for oxygen uptake, suspension of cells and homogeneous supply with nutrients. For long term bioprocesses without selection pressure it has to be considered that transformed cell lines might show genetic instability due to their variations of chromosomes. In addition, sterile technology becomes an important factor in long term bioprocesses. The decision as to which cell culture system should be chosen, whether batch or continuous processes should be applied essentially is based on the capital investment, the amount of material to be produced, genetic stability of the production cell line, reliability of sterile technology and the flexibility required in the production plant. Under the assumption that 20 kg of a protein have to be produced per year and the same product concentrations in the harvest fluid are reached in the batch process and for instance in the chemostat, it can be considered that the capital investment for one 10,000 l batch process and a 2 x 2,000 l continuous process, necessary to produce the amount of material, is comparable. Risk of microbial contamination or technical failure can be considered to be fairly low in the batch process. The economic risk for long term bioprocess in the chemostat can be expected to be medium and high in the perfusion system which is in the large scale not technically fully satisfactory. In addition, due to the longer down time period after contaminations and the start up of the continuous process, the annual yield of the batch process can be considered to be higher.(ABSTRACT TRUNCATED AT 400 WORDS)

In vitro fabrication of bioartificial mucosa for reconstruction of oral mucosa: basic research and clinical application

Bioartificial mucosa can be fabricated with living cells in vitro and used for mucosal grafting. In this report, we describe our culturing methods for preparation of bioartificial mucosa and its morphological characteristics. Bioartificial mucosa has bilayered components, namely, mucosal epithelium and submucosal tissue. Submucosal tissue was composed of fibroblasts and type I collagen lattice. Mucosal epithelium was formed by an epithelial segment grafted on the submucosal tissue surface. Between epithelial and submucosal tissues, basement membrane was observed under a transmission electron microscope. In animal experiments, the bioartificial mucosa was well vascularized and survived completely without immunological rejections. Based on the findings from these animal experiments, we applied this bioartificial mucosa to humans and succeeded in reconstructing their mucosal defects. We also present an overview of the problems relevant to the use of such methods.

[Establishing three dimensional tumors in vitro and the reaction of the lymphokine-activated killer cells (LAK) to the three dimensional tumors]

In this study, we attempted to develop a technique, by which three-dimensional tumors were produced from two cultured head and neck tumor cell lines (Hep2, KB) and a colon adenocarcinoma cell line (HT29) using fibrinogen, thrombin, and double layered agar system. The three-dimensional tumor was large enough to perform the histologic study, which showed no significant histologic difference in comparison with the histologic findings of the xenografted tumor on nude mice. Furthermore, we applied this assay model to evaluate the antitumor effect of lymphokine activated killer (LAK) cells on the three-dimensional tumor produced by the technique. When tumor cells were cocultured with LAK cells, the damage of the three-dimensional structure due to the degeneration of tumor cells was observed. These findings suggest that the three-dimensional tumor may be useful to evaluate the antitumor effect of LAK cells in term of head and neck solid tumors.

Establishment of primary cultures of pulp cells from bovine permanent incisors

A primary culture method was established by comparing the different effects of four methods of enzymatic separation--trypsin, collagenase with and without trypsin pretreatment, and a trypsin-collagenase mixture--and five media: DMEM, DMEM and Ham's F 12 mixture, F 12, RPMI 1640 and Medium 199. The trypsin pretreatment/collagenase method was most preferable considering the high number of isolated cells, satisfactory adhesion, good growth and a single population at subconfluence. DMEM and the DMEM/F-12 mixture resulted in the best adhesion, cell growth and cell number at confluence. Primary cells separated by the trypsin pretreatment/collagenase method and cultured in DMEM were responsive to parathyroid hormone at the proliferating stage and had higher alkaline phosphatase activity than cells cultured from gingiva and mucosa after reaching confluence. The long-term cultured cells formed nodules that were slightly mineralized. These results indicate that the cultured pulp cells had properties characteristic of pulp cells in vivo. This enzymatic separation method may be useful in studies of the regulation of pulp metabolism and odontoblast differentiation.

Sensitivity of chromosomal mosaicism detection by different tissue culture methods

In the field of prenatal cytogenetic diagnosis, two tissue culture methodologies are currently in use: the flask method, which examines mixed populations of cells, and the in situ method, which examines distinct colonies of cells. These two methods provide inherently different levels of sensitivity which can be made comparable by adjusting the number of cells examined depending on the methodology used and the number of colonies formed per ml of specimen. Assuming that there are 2 colonies per ml of amniotic fluid in a 20 ml specimen, in order to detect 10, 20, and 30 per cent mosaicism with 95 per cent confidence, 29, 14, and 9 colonies should be examined respectively by the in situ method. Similarly, 50, 17, and 10 cells must be analysed by the flask method.

Process validation for cell culture-derived pharmaceutical proteins

Principles of process validation are extremely powerful tools in assurance of product quality. They are especially useful for reducing those risks not easily measured routinely during production. When combined with effective process and facility design principles, characterization of cell banks and products, appropriate lot release tests, and adherence to cGMP, safe cell culture biologicals can be prepared in a reliable manner.

[Presence of mycoplasmas in cell cultures in Argentina]

The presence of mycoplasmas in cell cultures used for virus propagation in Argentine laboratories, was studied. Samples were obtained from laboratories located in the city of Buenos Aires and provinces of Córdoba and Buenos Aires. The fluorescent stain Hoechst 33258, which specifically binds to DNA, was used for mycoplasma testing. Thirty three (65%) of 51 analyzed cell cultures (48 established lines and 3 primary cultures), were found contaminated despite that all laboratories were well equipped to work under sterile conditions. The high rate of infection observed let us conclude that the risk to work with mycoplasma contaminated cultures was not properly appreciated.

Standardization of tissue culture conditions for spontaneous thymidine-2-14C incorporation by unstimulated normal human peripheral lymphocytes: circadian rhythm of DNA synthesis

The rate of DNA synthesis by human lymphocytes was studied in vitro by measuring unstimulated thymidine-2-14C incorporation (spontaneous lymphocyte blastogenesis; SLB). Freezing lymphocytes and extracting DNA after thawing did not alter the radioactive label count rate and was as efficient as extracting DNA immediately after culture. Omission of fetal calf serum also did not alter the rate of DNA synthesis. Standards established as optimal for studies of SLB were: cell concentration, 1.0 times 10(6)/ml/tube; 14C-TdR concentration, 0.4 mjCi/tube; duration of incubation, 8 hr. In sets of identical samples obtained by specimen division, the variation in counts was 6%. To achieve reproducibility of results; it was essential to count the lymphocytes, and then to ensure that each tube contained almost precisely known numbers of cells. Diurnal variations in the rate of DNA synthesis by circulating lymphocytes of healthy men were measured in vitro by SLB at 2-hr intervals for 24 hr. Leukocyte counts, hematocrit, hemoglobin, plasma cortisol, and body temperature were monitored concurrently. The DNA synthesis rate varied in a 24-hr cycle with peaks at 10 A.M. and 11:00 P.M.., depressions at 4 A.M. and 4 P.M. The rate was correlated with body temperature and hematocrit level, and inversely related to the absolute eosinophil count.

Mycoplasmas and cell cultures

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Substitution of 4-(2-hydroxyethyl)-1-piperazineethane sulfonic acid (HEPES) for bicarbonate in protein-free animal cell culture medium: application to vaccinia virus quantitation and fluorogenic acetylesterase assay in living LM cells

The buffer 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) at 15 mM has been substituted for sodium bicarbonate in the protein-free medium used for the growth of LM mouse fibroblasts. Cells have been cultivated in spinner flasks for up to 6 months with continuous aeration from an air line. The generation time was similar to that of parallel bicarbonate-buffered cells. Cotton-plugged shaken Erlenmeyer flasks produced the same results. HEPES-buffered cells have been grown in cotton-plugged prescription bottles and in glass and plastic Petri dishes in an ordinary humidified incubator. Vaccinia virus plaque production was slightly reduced in cells grown and overlaid with HEPES medium compared to bicarbonate medium. There was little difference in plaque count on cells grown in bicarbonate and overlaid with HEPES medium. These results indicate that HEPES buffer could be used routinely for cell and virus growth in aerated systems where CO2 is not limiting. Acetylesterase (EC. 3.1.1.6), measured by the fluorometric breakdown of fluorescein diacetate by living cells, was lower in HEPES than in bicarbonate-buffered medium, indicating an effect of HEPES on the cell membrane. The ability of HEPES to withstand autoclaving also renders it useful as a buffer for currently available autoclavable Eagle's medium.

Standardization of human diploid fibroblast cultivation: centrifugation procedure

The effect of varying centrifugal forces on the growth rate, longevity, and adsorption on glass of human embryonic diploid lung fibroblasts was studied. Cells centrifuged at 120, 500, or 1,500 x g at each passage had similar growth rates but their longevity decreased slightly with increasing force. These forces had no influence on the proportion of cells attaching to the glass. When the material in the first supernatant was recentrifuged at 2,000 x g for 30 min and added to the cells precipitated in the first centrifugation, the longevity of these cells was increased by several cell divisions. Cells which were not centrifuged but added directly from the cell suspension in trypsin to the new culture grew at a slightly slower rate than the centrifuged cells and became senescent at an earlier time. However, the noncentrifuged cells adsorbed to glass better than those centrifuged.