Dry Rehydratable Film Method for Rapid Enumeration of Coliforms in Foods (3M™ Petrifilm™ Rapid Coliform Count Plate): Collaborative Study

A rehydratable dry-film plating method for coliforms in foods, the 3M™ Petrifilm™ Rapid Coliform Count plate method, was compared with the U.S. Food and Drug Administration's Bacteriological Analytical Manual method for nondairy foods and the American Public Health Association's Standard Methods for the Examination of Dairy Products (SMEDP) method for dairy foods. Six food types, vanilla ice cream, cheddar cheese, fresh refrigerated uncooked pasta, wheat flour, prepared frozen macaroni and cheese, and frozen hash browns, were analyzed for coliforms by 11 collaborating laboratories. For each food product tested, the collaborators received 8 blind samples consisting of a control sample and 3 levels of inoculated sample, each in duplicate. The mean log counts for the methods were comparable. The repeatability and reproducibility variances of the Petrifilm Rapid Coliform Count method at 14 and 24 h were not significantly different from those of the standard methods.

Petrifilm™ Rapid S. aureus Count Plate Method for Rapid Enumeration of Staphylococcus aureus in Selected Foods: Collaborative Study

A rehydratable dry-film plating method for Staphylococcus aureusin foods, the 3M™ Petrifilm™ Rapid S. aureus Count Plate method, was compared with AOAC® Official MethodSM 975.55 (Staphylococcus aureus in Foods). Nine foods—instant nonfat dried milk, dry seasoned vegetable coating, frozen hash browns, frozen cooked chicken patty, frozen ground raw pork, shredded cheddar cheese, fresh green beans, pasta filled with beef and cheese, and egg custard—were analyzed for S. aureus by 13 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample and 3 levels of inoculated test sample, each in duplicate. The mean log counts for the methods were comparable for pasta filled with beef and cheese; frozen hash browns; cooked chicken patty; egg custard; frozen ground raw pork; and instant nonfat dried milk. The repeatability and reproducibility variances of the Petrifilm Rapid S. aureus Count Plate method were similar to those of the standard method.

GPCRomics: GPCR Expression in Cancer Cells and Tumors Identifies New, Potential Biomarkers and Therapeutic Targets

G protein-coupled receptors (GPCRs), the largest family of targets for approved drugs, are rarely targeted for cancer treatment, except for certain endocrine and hormone-responsive tumors. Limited knowledge regarding GPCR expression in cancer cells likely has contributed to this lack of use of GPCR-targeted drugs as cancer therapeutics. We thus undertook GPCRomic studies to define the expression of endoGPCRs (which respond to endogenous molecules such as hormones, neurotransmitters and metabolites) in multiple types of cancer cells. Using TaqMan qPCR arrays to quantify the mRNA expression of ∼340 such GPCRs, we found that human chronic lymphocytic leukemia (CLL) cells/stromal cells associated with CLL, breast cancer cell lines, colon cancer cell lines, pancreatic ductal adenocarcinoma (PDAC) cells, cancer associated fibroblasts (CAFs), and PDAC tumors express 50 to >100 GPCRs, including many orphan GPCRs (which lack known physiologic agonists). Limited prior data exist regarding the expression or function of most of the highly expressed GPCRs in these cancer cells and tumors. Independent results from public cancer gene expression databases confirm the expression of such GPCRs. We propose that highly expressed GPCRs in cancer cells (for example, GPRC5A in PDAC and colon cancer cells and GPR68 in PDAC CAFs) may contribute to the malignant phenotype, serve as biomarkers and/or may be novel therapeutic targets for the treatment of cancer.

GPR68, a proton-sensing GPCR, mediates interaction of cancer-associated fibroblasts and cancer cells

The microenvironment of pancreatic ductal adenocarcinoma (PDAC) is characterized by a dense fibrotic stroma (desmoplasia) generated by pancreatic cancer-associated fibroblasts (CAFs) derived from pancreatic stellate cells (PSCs) and pancreatic fibroblasts (PFs). Using an unbiased GPCRomic array approach, we identified 82 G-protein-coupled receptors (GPCRs) commonly expressed by CAFs derived from 5 primary PDAC tumors. Compared with PSCs and PFs, CAFs have increased expression of GPR68 (a proton-sensing GPCR), with the results confirmed by immunoblotting, The Cancer Genome Atlas data, and immunohistochemistry of PDAC tumors. Co-culture of PSCs with PDAC cells, or incubation with TNF-α, induced GPR68 expression. GPR68 activation (by decreasing the extracellular pH) enhanced IL-6 expression via a cAMP/PKA/cAMP response element binding protein signaling pathway. Knockdown of GPR68 by short interfering RNA diminished low pH-induced production of IL-6 and enhancement of PDAC cell proliferation by CAF conditioned media. CAFs from other gastrointestinal cancers also express GPR68. PDAC cells thus induce expression by CAFs of GPR68, which senses the acidic microenvironment, thereby increasing production of fibrotic markers and IL-6 and promoting PDAC cell proliferation. CAF-expressed GPR68 is a mediator of low-pH-promoted regulation of the tumor microenvironments, in particular to PDAC cell-CAF interaction and may be a novel therapeutic target for pancreatic and perhaps other types of cancers.-Wiley, S. Z., Sriram, K., Liang, W., Chang, S. E., French, R., McCann, T., Sicklick, J., Nishihara, H., Lowy, A. M., Insel, P. A. GPR68, a proton-sensing GPCR, mediates interaction of cancer-associated fibroblasts and cancer cells.

Abstract C156: GPCRs as potential therapeutic targets in pancreatic cancer-associated fibroblasts

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a dense fibrotic stromal matrix, composed of activated fibroblasts (PFs)/stellate cells (PSCs), immune/inflammatory cells and other cell types. This unique tumor microenvironment is increasingly recognized as a key mediator of PDAC progression and drug resistance. Targeting the tumor stroma may thus be a therapeutic approach for PDAC. Pancreatic cancer-associated fibroblasts (CAFs), myofibroblast-like cells that produce extracellular matrix proteins, are responsible for the desmoplasia in PDAC. PSCs and PFs are the key progenitors of CAFs. Blocking the activity of CAFs may be a means to improve the therapy and prognosis of PDAC. We hypothesized that G protein-coupled receptors (GPCRs) expressed by pancreatic CAFs are potential therapeutic targets for PDAC. To begin to test this hypothesis, we used an unbiased GPCRomic array approach to identify and quantify the GPCRs expressed by pancreatic CAFs. We discovered that 104 GPCRs have shared expression in CAFs from the primary tumors of five patients; 35 of those GPCRs had at least a 2-fold increased expression in CAFs compared to both PSCs and PFs. An orphan GPCR that we term Orphan 1 is one of the most highly up-regulated GPCRs in CAFs. We found that: 1) co-culture of PSCs with a PDAC cell line (ASPC-1) increases expression of fibrotic markers and Orphan 1 GPCR; 2) Transfection of Orphan 1 GPCR in PSCs increases the expression of fibrotic markers; 3) siRNA knockdown of Orphan 1 in CAFs decreases fibrotic marker expression and cytokine secretion. We conclude that GPCRomics can identify GPCRs that regulate pancreatic CAFs. One such GPCR, Orphan 1, contributes to pro-fibrotic activities in CAFs and is a potential therapeutic target to blunt the fibrosis associated with pancreatic cancer.

Citation Format: Shu Zhou, Sarah Chang, Thalia McCann, Randall French, Andrew M. Lowy, Paul A. Insel. GPCRs as potential therapeutic targets in pancreatic cancer-associated fibroblasts. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C156.

Peers experience of delivering a problem-solving programme to enhance antipsychotic medication adherence for individuals with schizophrenia

ACCESSIBLE SUMMARY

No research has been conducted into the experience of peer support in improving adherence with oral antipsychotic medication for consumers with schizophrenia. Altruism influences peers to participate in peer support. Engagement in peer support can be challenging and rewarding for peers, and helps improve their own confidence and well-being.

ABSTRACT

Many consumers with schizophrenia are reluctant to take their prescribed antipsychotic medications; however, non-adherence can lead to relapse. The aim of this study was to evaluate peers' perspectives of their participation in a problem-solving peer support programme to enhance adherence in consumers who are reluctant to take antipsychotic medication. Peers contacted consumers by a weekly telephone call for 8 weeks, and used a problem-solving approach to inform their discussion about medication adherence. Semi-structured qualitative interviews were used to evaluate peers' perspectives of their involvement in the programme. Three main themes were abstracted from the data: motivation to participate in the study, experience of peer support programme, and rewards and challenges of the peer experience. Helping others was an important motivator for peers in agreeing to participate in the study. Telephone delivery was a convenient way to deliver the peer support programme. However, at times, it was difficult to contact consumers by telephone and this caused some frustration. Despite these difficulties, peers recognized that being involved in the programme increased their confidence and made them feel worthwhile. The findings have implications for the use of peer support as an adjunct intervention to promote medication adherence in consumers with schizophrenia.

Abstract A57: GPCRs as potential therapeutic targets in pancreatic cancer-associated fibroblasts

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a dense fibrotic stromal matrix, composed of activated fibroblasts/stellate cells, inflammatory cells and other cell types. This unique tumor microenvironment has been increasingly recognized as a key mediator of PDAC progression and drug resistance. Thus, targeting the tumor stroma may be a novel therapeutic approach for PDAC. We hypothesized that G protein-coupled receptors (GPCRs) expressed by pancreatic cancer-associated fibroblasts (CAFs) may be potential therapeutic targets for PDAC. To begin to test this hypothesis, we used an unbiased GPCRomic array approach to identify and quantify the GPCRs expressed by pancreatic CAFs. We found 104 GPCRs, whose expression was shared in CAFs obtained from the primary tumors of five patients. Among those GPCRs, 35 had at least two-fold higher expression in the CAFs compared to normal pancreatic fibroblasts and included GPCRs that link to each of the major classes of G proteins. RT-PCR analysis of the 10 most up-regulated GPCRs correlated well (r2=0.82) with the data from the GPCR array. We conclude that: 1) GPCRomic array analysis can identify and quantify the profile of GPCRs expressed by pancreatic CAFs; 2) the CAF-expressed profile differs from that of normal pancreatic fibroblasts and 3) GPCRs expressed by CAFs may have functional roles and be novel therapeutic targets for PDAC.

Citation Format: Shu Zhou, Thalia McCann, Randall French, Andrew Lowy, Paul Insel. GPCRs as potential therapeutic targets in pancreatic cancer-associated fibroblasts. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr A57.

G Protein-Coupled Receptor (GPCR) Expression in Native Cells: "Novel" endoGPCRs as Physiologic Regulators and Therapeutic Targets

G protein-coupled receptors (GPCRs), the largest family of signaling receptors in the human genome, are also the largest class of targets of approved drugs. Are the optimal GPCRs (in terms of efficacy and safety) currently targeted therapeutically? Especially given the large number (∼ 120) of orphan GPCRs (which lack known physiologic agonists), it is likely that previously unrecognized GPCRs, especially orphan receptors, regulate cell function and can be therapeutic targets. Knowledge is limited regarding the diversity and identity of GPCRs that are activated by endogenous ligands and that native cells express. Here, we review approaches to define GPCR expression in tissues and cells and results from studies using these approaches. We identify problems with the available data and suggest future ways to identify and validate the physiologic and therapeutic roles of previously unrecognized GPCRs. We propose that a particularly useful approach to identify functionally important GPCRs with therapeutic potential will be to focus on receptors that show selective increases in expression in diseased cells from patients and experimental animals.

Social climate of acute old age psychiatry inpatient units: staff perceptions within the context of patient aggression

Patient aggression occurs in old age psychiatry and is contrary to their recovery and to the well-being of staff. A favourable social climate can contribute to a reduction in aggression. The aim of this study was to examine the perceptions of clinical staff about the social climate of acute old age psychiatry inpatient units. Eighty-five clinicians were recruited from these facilities. They completed a survey questionnaire about the social climate or ward atmosphere of inpatient units. The findings showed that, to some extent, respondents' perceived patient cohesion and mutual support were evident, units were perceived somewhat positively as safe environments for patients and staff, and the ward climate helped meet patients' therapeutic needs. Overall, clinicians were somewhat positive about the social climate of the units, and this has implications for the perception of aggression in old age psychiatry inpatient settings. As there is a direct relationship between social climate and aggression, clinicians should consider adopting a broad-based, person-centred approach to the promotion of a favourable social climate in old age psychiatry inpatient settings.

Monitoring the response of canine hyperadrenocorticism to trilostane treatment by assessment of acute phase protein concentrations

BACKGROUND

Acute phase proteins (APPS) include haptoglobin (Hp), C-reactive protein (CRP) and serum amyloid A (SAA). Increased Hp concentrations may be induced by endogenous or exogenous glucocorticoids in dogs.

OBJECTIVES

To assess whether control of hyperadrenocorticism (HAC) affects the concentrations of Hp, CRP, SAA, alkaline phosphatase (ALKP) and cholesterol, to determine whether these analytes can be used to assess control of HAC following trilostane treatment, and whether a combination of these tests offers a valid method of assessing disease control.

METHODS

Hp, CRP, SAA, ALKP and cholesterol were assessed in 11 dogs with spontaneous HAC before and after treatment with trilostane. Adequate control of HAC was defined as post-ACTH cortisol less than 150 nmol/l.

RESULTS

Significant reductions in Hp, ALKP, cholesterol and SAA (P<0.05) but not of CRP were found after control of HAC. Only Hp, cholesterol and ALKP were moderately informative (Se & Sp>0.7) of disease control when compared to adrenocorticotropin or corticotropin (ACTH) stimulation test. SAA and CRP were unhelpful (Se & Sp<0.7). The analysis of the combination of the analytes did not improve the correlation with ACTH stimulation test.

CLINICAL RELEVANCE

Relying on these analytes does not provide additional information over ACTH stimulation test results when assessing control of HAC treated with trilostane.

Pre-biopsy PSA and biopsy gleason sum; evaluating the independence of two independent variables

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Background: Traditionally PSA, Gleason sum and Clinical Stage are considered independent predictors of outcome for prostate cancer. The purpose of this study is to investigate a codependence between prostate specific antigen (PSA) and Gleason sum and whether this relationship has evolved during the PSA era. Methods: The Columbia Urologic Oncology Database was reviewed and 2,522 patients were identified who underwent radical prostatectomy from 1988 to 2005; a retrospective cohort of 1,786 patients with complete data was included. Patients were stratified by Gleason sum into groups with Gleason sum <7, =7 and >7. PSA was correlated to Gleason sum to examine a possible relationship between the two variables. Two-sample t-tests with 95% confidence intervals were utilized to determine differences between groups and were confirmed by ANOVA techniques. A Cox regression model using an interaction term between PSA and Gleason sum was fit to determine if an interaction exists between the two variables. Patients were further stratified into two cohorts by median year of surgery (1998) and the PSA-Gleason sum relationship was evaluated over time. Results: Median patient age was 61.9 years. 1,081 patients were identified with Gleason sum <7. 540 patients had a Gleason sum =7. 165 patients had a Gleason sum >7. The mean PSA values were 6.05, 6.89 and 8.41 for <7, =7 and >7 groups respectively. Differences between the means were statistically significant and validated by the ANOVA technique (p < 0.001). A Cox regression model validated PSA, Gleason sum and clinical stage as independent predictors of outcome. The addition of an interaction term into the Cox regression model between PSA and Gleason sum demonstrated a significant interaction effect between PSA and Gleason sum (p < 0.001). The relationship remained between PSA and Gleason sum within the pre and post 1998 groups (p < 0.001). Conclusions: PSA and Gleason sum are highly interrelated variables, although they each carry additional information that significantly contributes to the prediction of biochemical failure (PSA ≥0.2 ng/ml). For an individual patient, the higher the initial PSA the higher the risk of having a high Gleason sum on biopsy. This relationship has remained constant over the PSA era.

No significant financial relationships to disclose.

Sampling Broad Habitat change to assess biodiversity conservation action in Northern Ireland

A habitat monitoring programme, the Northern Ireland Countryside Survey, carried out by the University of Ulster for the Department of the Environment for Northern Ireland, is described. It was based on a random sample of quarter kilometer grid squares, stratified by multivariate land classification. Estimates of change in habitat area between 1987-1992 and 1998 are presented and used to assess policy-related priorities for biodiversity conservation action in widespread habitats in Northern Ireland (NI). The basis of the assessment is Broad Habitats, a classification developed as part of the United Kingdom (UK) Biodiversity Action Plan. Improved Grassland, Neutral Grassland and Bog Broad Habitats occupy the largest area of NI, which holds a large proportion of the UK Neutral Grassland and Fen Marsh and Swamp Broad Habitat resource. The greatest net area increases with time were in Improved Grassland (33%), Coniferous Woodland (12%) and Broadleaved, Mixed and Yew Woodland (9%). The greatest net area decreases were in Neutral Grassland (-32%), Arable and Horticulture (-25%), Fen, Marsh and Swamp (-19%), Bog (-8%) and Calcareous Grassland (-7%). These changes are a function of agriculture, public and private forestry, building construction and peat cutting for fuel. The Key biodiversity issue is seminatural Broad Habitat loss, in particular, Neutral Grassland and Fen, Marsh and Swamp, highlighting the lack of effective action for protecting biodiversity in the countryside as a whole. The extent to which current land use is shown to be driving change, indicates that biodiversity conservation action through implementing landscape-scale agri-environment measures could deliver major biodiversity gains. The reliable information on recent changes, provided by the Northern Ireland Countryside Survey, has been used to guide conservation planning. Future re-survey will allow the effectiveness of the conservation strategy as it applies to the countryside as a whole, to be determined. As decisions on land use increasingly have a strong European dimension, concerted action for protecting biodiversity in the countryside as a whole is needed. This would be promoted by a structured sampling approach, based on standard habitat mapping procedures.

Cytokines increase neonatal cardiac myocyte calcium concentrations: the involvement of nitric oxide and cyclic nucleotides

Neonatal rat cardiac myocytes were treated with cytokines, with or without the nitric oxide synthase (NOS) inhibitors N-monomethyl-L-arginine (LNMMA) and N-nitro-L-arginine methyl ester (LNAME), and systolic and diastolic calcium levels were measured by fluorescence spectrophotometry and confocal microscopy. Time-dependent changes following interferon-gamma (IFN-gamma) treatment revealed a continuing increase in intracellular calcium, which was reduced with LNMMA, but not with LNAME. Increases in calcium also occurred with interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), but not to the extent seen with IFN-gamma. Increased cyclic guanosine monophosphate (cGMP) was involved in the results described with short-term (2 hr) TNF-alpha and long-term (18 hr) IFN-gamma treatments. Short-term exposure to IFN-gamma produced an increase in cyclic adenosine monophosphate (cAMP) and also an initial increase in the myocyte-bearing rate, with calcium levels either (i) subsequently returning to control levels while maintaining a fast beating rate or (ii), retaining a high systolic calcium level, but beating at control rates. Treatment with both IL-1beta and IFN-gamma stabilized the beating rate of the cells on some occasions. Shortening of myocytes increased with isoproterenol and following treatment with IFN-gamma, while isoproterenol stimulation of IFN-gamma-treated cells revealed increased contractile activity after short, but not long, treatment. LNMMA, but not reduced the increased contractile response with short-term IFN-gamma treatment. Our findings suggest that TNF-alpha acts via a cGMP-dependent pathway, whereas the actions of IFN-gamma involve adenylate cyclase, and possibly a NO-forming mechanism and cGMP pathway as well. It is also apparent that the two NO inhibitors function via different mechanisms or that LNMMA has a direct effect on the calcium-signaling pathway.

The validity of spot urine samples for low-level occupational mercury exposure assessment and relationship to porphyrin and creatinine excretion rates

Hg and porphyrin levels in single void urine specimens (spot samples) were compared with calculated 24-hr urine levels in 35 (20 [correction of 25] male and 15 female) practicing dentists who had been occupationally exposed to low levels of elemental Hg. The study aimed to: 1) determine the individual variability for Hg and porphyrin concentrations in spot samples over a 24-hr period; 2) test for the presence of diurnal variation in urinary Hg and porphyrin concentrations; and 3) determine the time of day at which a spot sample would give a Hg concentration closest to the 24-hr average concentration. Results confirmed previous reports of a first-order diurnal pattern with a mid-morning peak for Hg concentration (P < .001). A second-order model best described creatinine excretion (P = .0089), with peaks at about 5:00 and 19:00. The use of creatinine adjustment for Hg concentration significantly reduced the intraindividual variation around the diurnal curve. No diurnal patterns were found for any of the porphyrins examined. We recommend that, for small clinical studies using urinary Hg concentration, 24-hr sampling would be ideal, but that for mass screenings and cross-sectional studies, spot samples may be useful because they correlate fairly well with 24-hr averages (creatinine adjusted, r = 0.61; unadjusted, r = 0.74). Because of the existence of diurnal variation, for all cases using serial sampling attention should be paid to time of day.

Gender and age differences in food cognition

Results from three studies relevant to a model of food cognition based on the evaluative dimensions pleasure, health, and convenience are reported. In the first study, discriminant analyses of the evaluative ratings (n = 248) of 35 meals and snacks yielded significant gender and age differences on the pleasure and health dimensions. Separate factor analyses of the pleasure and health ratings revealed that males and females grouped foods differently on these criteria. The factor analysis of convenience ratings suggested that males and females perceive the meaning of convenience differently. In the second study, 336 college students rated 27 meals on the three evaluative dimensions and also indicated their preferences for each meal. Multiple regression analyses showed that preferences could be significantly predicted, and other results showed that as compared to males, females give higher health, pleasure and convenience ratings to healthy meals. The third study employed a modified free association technique to investigate gender and age differences in the meanings of nine familiar foods. Data from 96 males and females aged 18 to 86 revealed a substantial variety of significant age and gender differences for specific foods. It is suggested that taken together, these results indicate important cognitive and affective sources for gender and age-related food attitudes.

Hypnotically induced pseudomemories: Sampling their conditions among hypnotizable subjects

Three studies are reported in a program of research that investigated a range of parameters affecting individual differences in the incidence of hypnotically induced pseudomemory among hypnotizable subjects. Study 1 replicated Laurence and Perry's (1983b) base rates for hypnotically induced pseudomemory response among hypnotizable subjects; in Study 2 the same response was analyzed under more strictly controlled stimulus conditions. Study 3 was an investigation of the impact of a broader range of stimulus events on response and a more sensitive test of the hypothesis that individual differences in pseudomemory effects are tied essentially to the social context of hypnosis. In all three studies, independent groups of subjects were tested who were highly responsive to hypnotic suggestion. Data indicated that the incidence of pseudomemory response was stable and consistent when stringent criteria of scoring were adopted. Also, for some subjects, real and suggested memories were maintained at one and the same time when hypnotically induced memory was examined in different test settings, suggesting that pseudomemories do not permanently overlay real experience. Overall, contextual factors appeared to play a major role among susceptible subjects in determining the nature and incidence of hypnotically induced pseudomemories.

Development of a purified cholera toxoid. III. Refinements in purification of toxin and methods for the determination of residual somatic antigen

The addition of an ultrafiltration step to the purification procedures previously described for cholera toxin (Rappaport et al., (1974) permitted the preparation of highly purified antigenic toxoids essentially free of somatic antigen(s). The purity of such toxoids is established: (i) by the absence of more than about one part limulus amebocyte lysate (LAL)-positive endotoxin per 10(5) parts toxoid and (ii) by the inability of the toxoids to elicit a significant rise in rabbit vibriocidal antibody. The antigenicity of the toxoids is demonstrated by their ability to produce the same high levels of rabbit serum antitoxin as are produced by comparable toxoids containing small amounts of somatic antigen. The results also indicate that amounts of somatic antigen of the order of less than or equal to 1 mug/100 mug of toxoid do not exert an adjuvant effect on the toxoid, at least with respect to circulating antitoxin. Other data show that, where present, the ability of somatic antigen to elicit vibriocidal antibody is influenced by the immunization schedule employed and that a correlation exists between the LAL-determined endotoxin content of the toxoids and their ability to stimulate vibriocidal antibody. Somatic antigen-free toxoids, purified and tested by the refinements herein described, were prepared for use in the National Institutes of Health sponsored field trials, and data pertaining to their purity and antigenic properties are presented.

Development of a purified cholera toxoid. II. Preparation of a stable, antigenic toxoid by reaction of purified toxin with glutaraldehyde

Evidence is presented which confirms that cholera toxoids obtained by reaction of purified toxin with Formalin possess the ability to partially reactivate both in vivo and in vitro. At the same time, conditions are presented for the preparation of stable, antigenic cholera toxoids by reaction of purified toxin with glutaraldehyde. Treatment of purified cholera toxin with approximately 200 mol of glutaraldehyde per mol of toxin at pH 7.8 reproducibly resulted in the preparation of toxoids which: (i) possessed less than 20 bluing doses per 100 mug; (ii) did not reactivate in vivo or in vitro; (iii) precipitated with, and neutralized antitoxin; (iv) elevated prolonged serum antitoxin in immunized rabbits; (v) protected immunized guinea pigs against toxin skin challenge; and (vi) lent themselves to enhanced antigenicity by means of an in situ adjuvant system which may be suitable for man. Acrylamide gel electrophoresis and molecular sieve chromatography of a series of glutaraldehyde-derived toxoids suggested that the reaction products consisted of monomeric and polymeric species and that the proportion of higher-molecular-weight species was determined by the relative concentrations of toxin and glutaraldehyde. The results suggested a relationship between complete and irreversible elimination of toxicity and the formation of higher-molecular-weight toxoids.