Generation of reference cell lines, media, and a process platform for CHO cell biomanufacturing

Due to the favorable attributes of Chinese hamster ovary (CHO) cells for therapeutic proteins and antibodies biomanufacturing, companies generate proprietary cells with desirable phenotypes. One key attribute is the ability to stably express multi-gram per liter titers in chemically defined media. Cell, media, and feed diversity has limited community efforts to translate knowledge. Moreover, academic, and nonprofit researchers generally cannot study "industrially relevant" CHO cells due to limited public availability, and the time and knowledge required to generate such cells. To address these issues, a university-industrial consortium (Advanced Mammalian Biomanufacturing Innovation Center, AMBIC) has acquired two CHO "reference cell lines" from different lineages that express monoclonal antibodies. These reference cell lines have relevant production titers, key performance outcomes confirmed by multiple laboratories, and a detailed technology transfer protocol. In commercial media, titers over 2 g/L are reached. Fed-batch cultivation data from shake flask and scaled-down bioreactors is presented. Using productivity as the primary attribute, two academic sites aligned with tight reproducibility at each site. Further, a chemically defined media formulation was developed and evaluated in parallel to the commercial media. The goal of this work is to provide a universal, industrially relevant CHO culture platform to accelerate biomanufacturing innovation.

A rapid ethnography of itinerant teachers of the deaf

A rapid ethnographic study of 10 itinerant teachers in two school districts and 21 other professionals working with the itinerants was conducted. Rapid ethnography starts with the same assumptions about culture as conventional ethnography. However, it is not constrained by the assumption of cultural ignorance on the investigator's part. Thus, it enables better-directed data collection. Interviews with the itinerants and other professionals, direct observation of itinerants at work, and archival data permitted the authors to generate a list of themes reflecting results of other studies which focused on specific skills for itinerant teaching. While knowledge of specific skills cannot be ignored, the study shows that effective itinerants are ones who, through a personality trait, extensive experience, or a specific value system, can generate a positive composite image of their role as itinerants and are then able to interact on the basis of that image.

Nonsurgical treatment of acute iatrogenic renal artery injuries occurring after renal artery angioplasty and stenting

OBJECTIVE

The objective of this study was to determine the success of the nonsurgical treatment of acute iatrogenic renal artery injuries that occur after renal artery angioplasty and stenting at a tertiary referral center.

MATERIALS AND METHODS

During a 5-year period, 212 patients (308 renal arteries) underwent percutaneous transluminal angioplasty or stent dilatation of the renal artery. Through a retrospective review of medical and radiology records, we determined that 13 of these patients suffered iatrogenic renal artery injuries.

RESULTS

The renal arterial complication rates were 4.2% per artery treated and 6.1% per patient treated. All 13 patients were successfully treated nonsurgically. Five patients with acute rupture of the renal artery were treated immediately with balloon tamponade or with placement of an additional stent or stent-graft. Six patients suffered acute thrombotic occlusion; five were successfully treated with thrombolysis, and one was successfully treated without thrombolysis by the placement of an additional stent. Presumed distal guidewire perforation caused subcapsular hematoma in one patient and a perirenal and pararenal hematoma in another; both were successfully treated with conservative management. During the clinical follow-up period (mean period, 19 months), one patient required long-term hemodialysis. No other patients required additional treatment.

CONCLUSION

The nonsurgical treatment of acute iatrogenic renal artery injuries occurring after renal artery angioplasty and stenting can be successful and may obviate additional surgery.

Transjugular intrahepatic portosystemic shunt for bleeding stomal varices associated with chronic portal vein occlusion: long-term angiographic, hemodynamic, and clinical follow-up

The efficacy of the transjugular intrahepatic portosystemic shunt procedure (TIPS) in controlling refractory hemorrhage from stomal varices at the mucocutaneous junction has been previously described, but the durability of this procedure for this indication is unknown. Conservative therapy may be unsuccessful in preventing recurrent hemorrhage. Some authors believe that portosystemic shunting is the treatment of choice for patients with bleeding stomal varices who are good surgical candidates, because of the low incidence of recurrent bleeding and the longest survival. We report the 39-month angiographic and hemodynamic follow-up, and the 48-month clinical follow-up of a patient with refractory hemorrhage from stomal varices and coexistent chronic portal vein occlusion successfully treated with a TIPS procedure.

The expression of cytokines and their receptors in normal and mildly reactive human brain

There are many inflammatory diseases of the brain such as AIDS, other viral encephalitides and multiple sclerosis all of which are probably influenced by both systemic and focal CNS cytokine release. We have studied the expression of a wide range of pro- and anti-inflammatory cytokines and their receptors, beta2-microglobulin, and MHC Class II, using immunocytochemistry on cryostat sections of normal and mildly reactive human brain. The aim was to try to determine the cytokine 'baseline' expression in normal human brain and the results obtained indicated very low expression of various cytokines and their receptors, mainly by microglia and macrophages with some endothelial expression.

Prevalence of Alzheimer plaques in AIDS

OBJECTIVES

Both genetic and environmental risk factors for Alzheimer's disease have been identified. The best established environmental risk factor, head trauma, is thought to act through the triggering of an inflammatory response. Another stimulus to an inflammatory response in the brain is AIDS. Whether there is an increased prevalence of beta/A4 amyloid deposits in the form of argyrophilic plaques in the brains of patients with AIDS has therefore been investigated.

METHODS

The prevalence of argyrophilic amyloid plaques in the cerebral cortex of frontal and temporal lobes was compared in 97 cases of AIDS dying at ages 30-69 years with that in 125 age matched, non-HIV infected controls.

RESULTS

In the control group, and in AIDS, the prevalence of plaques increased with age (p=0.005 and 0.048 respectively). There was a significantly greater prevalence of argyrophilic plaques in the AIDS group as a whole (29%) (p < 0.004) and in those in the fourth decade (18%) (p < 0.014) than in control subjects (13% and 0% respectively).

CONCLUSION

There is a predisposition to argyrophilic plaque formation in the brain in AIDS. The findings support the view that a stimulus to an inflammatory response in the brain favours argyrophilic plaque formation. The clinical relevance of our findings is, as yet, unclear.

Five-year follow-up of prophylactic vena cava filters in high-risk trauma patients

OBJECTIVE

To assess the short- and long-term outcomes of vena cava filter (VCF) placement for prophylaxis against pulmonary embolism in patients at high risk due to trauma.

DESIGN AND SETTING

Case series at a level I trauma center.

PATIENTS

Patients were considered for prophylactic VCF placement if they met 1 of the injury criteria--spinal cord injuries with neurologic deficit, severe fractures of the pelvis or long bone (or both), and severe head injury--and had a contraindication to anticoagulation.

INTERVENTION

Vena cava filters were placed percutaneously by the interventional radiologists when the acute trauma condition was stabilized following admission.

MAIN OUTCOME MEASURES

Filter tilt of 14 degrees or more, strut malposition, insertion-related deep vein thrombosis, pulmonary embolism, or inferior vena cava patency.

RESULTS

There were 132 prophylactic VCFs placed. A 3.1% rate of insertion-related deep vein thrombosis occurred, all of which were asymptomatic. Filter tilt occurred in 5.5% of patients and strut malposition in 38%. Three cases of pulmonary embolism (1 fatal) occurred in a prophylactic VCF, and all patients had either filter tilt or strut malposition. The risk of pulmonary embolism developing was higher in those patients with filter tilt or strut malposition than in those who did not have these complications (6.3% vs 0%; P=.05; Fisher exact test). The 1-, 2-, and 3-year inferior vena cava patency rates (+/-SD) were 97%+/-3%.

CONCLUSIONS

Prophylactic VCF can be placed safely with an acceptable rate of insertion-related deep vein thrombosis and long-term inferior vena cava patency. Patients with prophylactic VCF remain at risk for pulmonary embolism if the filter is tilted 14 degrees or more or has strut malposition. In such patients, consideration should be given to placing a second filter.

Arterial embolization in the chest

Transcatheter therapy is an effective technique in the treatment of vascular abnormalities in the chest. Pulmonary arteriovenous malformations, associated with the clinical sequellae of dyspnea, stroke, brain abscess, and hemoptysis, can be treated by transcatheter embolization with metallic coils or occlusion balloons. The results of treatment are excellent, with improvement seen in symptoms and physiologic parameters. The bronchial arteries and systemic nonbronchial collateral arteries supplying the tracheobronchial tree are most frequently involved in massive hemoptysis, a serious disorder with associated high rates of morbidity and mortality. Transcatheter embolization of these arteries is both safe and effective, requiring a thorough understanding of the arterial anatomy and technique of embolization.

Cerebral white matter damage in HIV infection demonstrated using beta-amyloid precursor protein immunoreactivity

We have examined brain sections from 55 autopsy cases of AIDS for the prevalence and severity of axonal damage, assessed using beta-amyloid precursor protein (beta APP) immunoreactivity as a marker of such damage. The cases were subdivided into cases with HIV encephalitis with multinucleated giant cells (MGC), cases with other specific pathology, such as cerebral toxoplasmosis or lymphoma, cases with non-specific pathology and cases with no pathology. Significantly more foci containing beta APP+ axons were found in cases with HIV encephalitis with MGC (80%) and in cases with other specific pathology (58%) than in those with non-specific (30%) or no pathology (30%). The prevalence and abundance of beta APP+ axons generally paralleled the severity of pallor of myelin staining of cerebral white matter in cases without other specific pathology but in 4 cases without any pallor of myelin staining beta APP+ axons were present, suggesting that it may be a more sensitive marker of some forms of white matter damage in HIV infection than myelin pallor. Foci of beta APP+ axons were found in subcortical and deep white matter but did not convincingly co-localise with foci of demonstrable HIV infection as indicated by the presence of MGC and HIV p24 immunoreactivity. In contrast, they showed an approximately perivascular distribution at some sites in all of the disease categories studied. We consider this localisation to be more suggestive of a vascular pathogenetic mechanism of deep white matter damage in HIV infection than a mechanism dependent on diffusion of local myelinotoxic products from foci of cerebral HIV infection.

Macrophages and microglia in HSV-1 infected mouse brain

We have examined the macrophage and microglial cell response in mouse brains during the course of acute herpes simplex encephalitis produced by intranasal inoculation of virus. Macrophage infiltration and a microglial cell reaction were detected from 24 h after initial detection of HSV-1 antigen in brain. Macrophage infiltration was confined to focal areas of infection but the microglial cell reaction occurred in a more widespread distribution. Following disappearance of viral antigen, with resolution of the acute infection, macrophage infiltration and a focal microglial cell reaction remained for several weeks, providing a marker of sites of previous infection.

Oligodendrocyte reactions and cell proliferation markers in human demyelinating diseases

We have carried out immunocytochemical reactions using antibodies to markers of oligodendrocytes, astrocytes, microglia and proliferating cells (PCNA) in sections of human brain in a variety of demyelinating conditions and human immunodeficiency virus (HIV) infection. In the acute phases of demyelinating diseases we found marked reactive changes in oligodendrocytes with hyperplasia and an increased cytoplasmic reaction using antibodies to enzymes involved in myelin formation. Proliferative responses were implied by the hyperplasia and the common finding of clusters of two or three adjacent oligodendrocytes at sites of acute myelin damage. This was borne out by studies using the PCNA antibody which gave negative reactions in normal brain but positive reactions in acute demyelination. Double staining for PCNA and cell markers showed that cells that had entered the cell proliferation cycle were to be found among astrocytes, microglia/macrophages and oligodendrocytes. In chronic demyelinating conditions, numbers of oligodendrocytes were reduced and cells in the proliferative cycle were not present, suggesting that the reactive potential of oligodendrocytes or their precursors and their capacity to respond to demyelination is limited.

Prophylactic vena cava filter insertion in severely injured trauma patients: indications and preliminary results

Pulmonary embolism (PE) remains a significant problem in trauma patients. A 5-year review at this institution revealed 25 PEs (seven fatal) in 2525 admitted trauma patients (1% incidence). Three groups of high-risk patients were identified: (1) those with severe head injury and coma; (2) those with spinal cord injuries with neurologic deficit; and (3) those with pelvic and long bone fractures. The relative risk of PE in these high-risk patients was 21 to 54 times that of the general trauma population. Beginning in July 1991, as prophylaxis against PE, vena cava filters (VCF) were inserted in patients whose injuries placed them in a high-risk group. Thirty-four patients had VCFs inserted percutaneously in the radiology suite without complications. On follow-up examination, 17.6% developed documented lower extremity deep vein thrombosis. There were no PEs. Overall, the incidence of PE in the general trauma population was significantly decreased from 1% to 0.25% (p < 0.05; chi 2). We conclude that insertion of VCFs in high-risk trauma patients is safe and efficacious in decreasing the incidence of PE.

Sensory and sympathetic ganglia in HIV-1 infection: immunocytochemical demonstration of HIV-1 viral antigens, increased MHC class II antigen expression and mild reactive inflammation

Sensory and sympathetic ganglia from 12 cases of human immunodeficiency virus type 1 (HIV-1) infection, all but one without clinical evidence of peripheral nerve disease, were studied immunocytochemically for their content of lymphocytes, macrophages, MHC Class II antigens and HIV-1 and cytomegalovirus antigens. They were compared with ganglia from 7 normal and peripheral nerve disease control cases. Compared with normal controls, many of the ganglia from the majority of HIV-1-infected subjects contained more T lymphocytes and macrophages and enhanced MHC class II expression. A few also showed occasional neuronal degeneration which was not present in the normal controls. In 7 cases HIV-1 gp41 envelope protein and/or p24 core protein antigens were detected in intraganglionic macrophages. Sensory ganglia contained more gp41 HIV-1 antigen than sympathetic ganglia. There was no clear correlation between detection of HIV-1 antigens in ganglia and in the CNS. Detection of HIV-1 antigens in ganglia was more common in cases of HIV-1 infection that had progressed to clinical AIDS by the time of death (71%) than in those that had not done so (40%). It is concluded that there is commonly a mild ganglionitis which is asymptomatic in the absence of detailed clinical testing and frequently associated with local presence of HIV-1 antigens in sensory and sympathetic ganglia in AIDS.

Central pontine myelinolysis in a patient with AIDS

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Immunocytochemical characteristics of small cell lung carcinoma associated with the Lambert-Eaton myasthenic syndrome

The Lambert-Eaton myasthenic syndrome (LEMS) is characterized by the presence of IgG antibodies to motor nerve terminals, and associates with small cell lung carcinoma in more than 60% of cases. We have carried out a comparative immunocytochemical study on small cell lung carcinoma (SCLC) in five LEMS cases and six non-LEMS cases, using antibodies to tumor markers, MHC Class I and II, macrophages and lymphocytes. The authors found a reduced expression of the 200Kd neurofilament antigen and of MHC Class I antigens in the LEMS cases as well as a greater infiltration of activated macrophages. It is suggested that these findings are consistent with the view that SCLC antigenic determinants trigger the autoantibody response in SCLC-LEMS.

Fate of oligodendrocytes in HIV-1 infection

The brains of 22 HIV-1-infected cases and 11 controls, matched for age and sex, were studied with immunocytochemical reactions specific for oligodendrocytes, astrocytes, microglia and HIV-1. In HIV-1 infection, mild degrees of myelin damage were associated with an increase in oligodendrocyte numbers, a change that was reversed in the presence of severe damage. Severity of myelin damage correlated with the extent of astrocytic and microglial reactions expressed in a semi-quantitative manner. HIV-1 p24 antigen was detected in all cases with severe myelin damage and a smaller proportion of cases with lesser degrees of myelin damage. It is concluded that, in HIV-1 infection, oligodendrocytes undergo an initial reactive hyperplasia which may represent an attempt to repair myelin damage.

Immunocytochemical study of macrophages and microglial cells and extracellular matrix components in human CNS disease. 1. Gliomas

We have used an immunocytochemical approach to investigate the inter-relationships between astrocytes, macrophages and microglia and the extracellular matrix components fibronectin and laminin, in 27 gliomas. Using recently available markers to macrophages and microglia (monoclonals Mac387, KP1 and the lectin RCA-1) and antisera to GFAP, fibronectin and laminin, we have described the reactions of these cells and the extracellular matrix. We found RCA-1 to be the superior marker for detecting most macrophages and microglia. There were more macrophages and microglia in high-grade gliomas than in low-grade. RCA-1 also reacted with endothelial cells in normal and reactive brain but showed markedly less affinity for endothelium in an close to gliomas. A possible role for the extracellular matrix in the astrocyte, macrophage and microglial reactions is discussed in the broader context of their role in the immune response.

Immunocytochemical study of macrophages and microglial cells and extracellular matrix components in human CNS disease. 2. Non-neoplastic diseases

For comparison with an earlier paper on gliomas (Morris and Esiri, J. Neurol. Sci., 101 (1991) 47-58), we have used an immunocytochemical approach to examine the reactions of astrocytes, macrophages and microglia and alterations to the extracellular matrix components fibonectin and laminin in 15 cases of non-neoplastic CNS disease. We compared recently available markers for the detection of macrophages and microglia (monoclonals Mac387, KP1 and the lectin RCA-1) and also used antisera to GFAP, fibronectin and laminin. RCA-1 was the superior marker for detecting macrophages and microglia but it also reacted with endothelial cells in normal and reactive brain. The numbers of macrophages and microglia were highly variable, depending on the type of lesion. Fibronectin and laminin were largely confined to the vasculature and leptomeninges. The relationship between the extracellular matrix and the astrocyte, macrophage and microglial reactions is discussed.

Acute experimental osteomyelitis and abscesses: detection with MR imaging versus CT

Acute experimental osteomyelitis and abscesses were induced in the proximal tibia and surrounding soft tissues, respectively, in 67 New Zealand white rabbits. Fifty-three rabbits were injected with a Staphylococcus aureus solution and 26, with sterile saline in tibial medullae and/or surrounding soft tissues. Contrast material-enhanced computed tomography (CT) and magnetic resonance (MR) imaging were performed 7 days after inoculation. Immediately after imaging, the animals were killed and necropsy was performed. MR imaging was more sensitive than CT in the detection of osteomyelitis (94% vs 66%, P less than .025) and abscesses (97% vs 52%, P less than .001). MR imaging was equally specific as CT in the exclusion of osteomyelitis (93% vs 97%, chi 2 = 0) but less specific than CT in the exclusion of abscesses (77% vs 100%, P less than .025). The overall accuracy of MR imaging was somewhat, although not significantly, greater than that of CT in the detection of both osteomyelitis (93% vs 80%) and abscesses (87% vs 75%).

Immunocytochemical techniques in stereotactic biopsy

Conventional neuropathological stains, immunocytochemistry and cell culture can be performed on small tissue fragments obtained by stereotactic biopsy. A simple processing technique is described with particular attention to immunocytochemistry. The results of this technique are described for 34 specimens obtained from patients with low- and high-grade gliomas, lymphomas, pineal tumour and benign processes. The application of immunocytochemical techniques is of value in achieving a definitive diagnosis in the small tissue fragments obtained by stereotactic biopsy.

Mononuclear cell infiltration in central portions of human astrocytomas

The mononuclear cell infiltration in the central portion of human low- and high-grade astrocytomas has been examined using monoclonal antibodies to cell surface differentiation antigens. There was no significant difference between the number of T cells, B cells, or macrophages. The OKT8+ (suppressor/cytotoxic) T cell population was the major lymphocyte subset in the infiltrates. There was, however, indirect evidence for a proportion of the total OKT8+ cells being natural killer cells. Overall, there was a significant difference in the number of macrophages compared to the total lymphoid cell population. Several cell types seem to play an equal role in the cellular and humoral immune response within the center of the tumors, as distinct from that occurring at the periphery.

Immunocytochemistry of intracranial meningiomas

Fifty meningiomas of four major histological types have been examined by immunocytochemical methods applied to formalin fixed paraffin embedded material and using readily available commercial antisera. The expression of GFAP, S100, NSE, vimentin, cytokeratin, fibronectin and desmoplakin was investigated. The majority of tumours contained NSE (86%) and S100 (78%), and all irrespective of histological type, contained vimentin and fibronectin. The epithelial marker cytokeratin was found in 56% of cases, but showed only focal expression. The relevance of these findings to histogenesis and metabolism is discussed and it is suggested that intermediate filament typing provides valuable information on meningiomas structure and function. The possible role of NSE and S100 in meningeal neoplasm is discussed.

Cross reactivity of anti-epithelial membrane antigen monoclonal for reactive and neoplastic glial cells

An anti-epithelial membrane antigen monoclonal (Clone E29) was used as part of a panel of antisera in the investigation of primary CNS and metastatic tumours. In contrast to others, definite and often strongly positive cross-reactivity has been demonstrated on glial cells. The material consisted of fourteen astrocytomas, two ependymomas, six cerebral metastases and two cases of gliosis.

Comparison of smear and imprint techniques for rapid diagnosis in neuro-oncology

The smear and imprint techniques were applied to brain tumor biopsy specimens and the resultant preparations compared for preservation of architecture and cell morphology. The imprint gave excellent detail of cell morphology and good preservation of architecture, especially in soft tumors. The method has enabled a rapid diagnosis to be made in 100 cases of intracranial lesions and is a valuable complement to smear and cryostat sections.

Thyroid stimulating and gonadotrophic hormones in pituitary adenomas without clinical or serological abnormality

Forty-three chromophobe adenomas have been examined immunocytochemically for their hormonal content. Twelve cases with full pre-operative normal serum hormonal levels were found to have many positive cells within the tumour for thyroid stimulating hormone (TSH), follicle stimulating hormone (FSH) and luteinizing hormone (LH). The specificity of the immunoreactive product within the tissue was checked by immunoabsorption. It is suggested that a non-secreted biologically inactive glycoprotein hormone is produced by tumour clones.

Immunocytochemistry of folliculo-stellate cells of normal and neoplastic human pituitary gland

Five normal human pituitaries and 20 pituitary neoplasms were investigated by immunocytochemical methods. Glial fibrillary acidic protein and S100 have been shown in the anterior lobe of the pituitary. Both these markers were present in the folliculo-stellate cell. Evidence is presented for the presence of a transitional folliculo-stellate cell which is immunoreactive for S100. The role of the folliculo-stellate cell is discussed.

Reed-Sternberg/lymphocyte rosette: lymphocyte subpopulations as defined by monoclonal antibodies

The Reed-Sternberg cell/lymphocyte rosette characteristic of Hodgkin's disease tissue and cell suspensions was investigated with monoclonal antibodies on fresh viable cell suspensions prepared from nine cases of Hodgkin's disease. The biopsy material comprised six spleens and three lymph nodes. The majority of the rosetting lymphocytes were T cells, primarily of the helper subset. Some of the attached lymphocytes were suppressor T cells. In addition, a few of the rosetting lymphocytes around Reed-Sternberg cells were B cells.

The lectin binding affinity of Reed-Sternberg cells

Reed-Sternberg cells from ten cases of Hodgkin's disease were examined by the direct immunofluorescence technique, for their affinity for nine lectins. The surrounding lymphocytes and monocytes of HD tissue were also assessed for their ability to bind lectins. RS cells showed considerable heterogeneity of reaction. Overall, there was a marked decrease in the binding of most of the lectins studied in HD cases as compared to normal peripheral blood mononuclear cells. This was particularly evident for RCA, PHA and PNA binding. It is suggested that there is a defect in carbohydrate metabolism, with fewer lectin-binding sites on both RS cells and on the mononuclear cell populations in Hodgkin's disease. Further quantitative work is required to verify this.

The reaction of xenogeneic and monoclonal antisera with Reed-Sternberg cells

Xenogeneic antisera have been prepared against human monocytes, B lymphocytes and T lymphocytes. The reactivity of these antisera against a variety of normal and neoplastic cells is described. Reed-Sternberg cells from three cases of Hodgkin's disease failed to react with xenogeneic anti-T and anti-monocyte sera, but reacted with an anti-B serum. A further three cases were examined with monoclonal antibodies. Negative results were obtained with monoclonal anti-T and positive results were given by monoclonal antibodies directed against DR and HLA antigens.

Binding of the chymotrypsin substrate, tryptophan methyl ester, by rat alpha-fetoprotein

We studied how tryptophan methyl ester and related compounds inhibit binding of estrone to rat alpha-fetoprotein and find that: (a) like chymotrypsin, alpha-fetoprotein binds tryptophan esters with higher affinity than tryptophan or its amides; (b) the affinity of alpha-fetoprotein for tryptophan methyl ester is 3.7 . 10(-4) M, which is close to the affinity of chymotrypsin (10(-4) M); (c) alpha-fetoprotein binding of tryptophan methyl ester is stereoselective and pH dependent. All of these observations suggest that there is a specific interaction between alpha-fetoprotein and the chymotrypsin substrate, tryptophan methyl ester, and that rat alpha-fetoprotein contains a site with some structural similarities to the catalytic site in chymotrypsin. Since we also find that tryptophan methyl ester is a competitive inhibitor of estrone binding to alpha-fetoprotein, it is possible that the protease substrate binding site on alpha-fetoprotein is spatially close to the estrone binding site.

Detection of bovine viruses in fetal bovine serum used in cell culture

This investigation employed a viral screening method detect endogenous bovine virus contaminants in commercially supplied fetal bovine serum. Fifty-one lots of fetal bovine serum from 14 suppliers were examined. Over 30% of the lots tested were found to contain bovine viruses; they included bovine virus diarrhea virus, parainfluenza type3-like virus, bovine herpesvirus-1, bovine enterovirus type 4, and an unidentified cytopathogenic agent. Of the 51 lots, 20 had been pretested by the suppliers and were considered to be free of known viral contaminants. Our viral screening methods revealed that five of these pretested lots, or 25%, contained endogenous bovine viruses.