Características clínicas, métodos diagnósticos y evolución de la criptococosis extrameníngea en personas viviendo con VIH / Clinical features, diagnosis methods and evolution in non meningeal cryptococcosis in people living with VIH

La criptococosis es una micosis grave que se manifiesta, en el 90% de los casos, como una meningoencefalitis, especialmente en las personas con VIH. El objetivo de este estudio es describir los casos de criptococosis extrameníngea en personas viviendo con VIH y conocer cuántas de estas padecen compromiso meníngeo concomitante. Además, determinar la relación con el título de antígeno polisacárido capsular de Cryptococcus en suero. Se realizó un estudio retrospectivo, observacional y analítico. Se incluyeron personas viviendo con VIH cuyo diagnóstico inicial de criptococosis se había realizado a partir de muestras extrameníngeas en el período comprendido entre 2012 y 2019. Los pacientes se dividieron en dos grupos. Grupo 1, pacientes sin compromiso meníngeo; Grupo 2, aquellos que finalmente tenían compromiso del SNC. De un total de 531 criptococosis registradas en ese período, se incluyeron 113 pacientes (21%), de los cuales en 58 se comprobó el compromiso meníngeo. No se observaron diferencias significativas en cuanto a la mortalidad entre ambos grupos.Ninguno de los pacientes con antigenemia por LFA (antígeno capsular en suero por inmunocromatografía) positiva, pero con antigenemia por aglutinación de partículas de látex (AL) negativa, tuvo compromiso meníngeo. Se observó que títulos de antígeno para Cryptococcus en suero por AL mayor o igual a 1/100 se correlacionaron con un aumento de 30 veces en la posibilidad de padecer meningitis. En todos los casos se debe descartar el compromiso del SNC. La AL sigue siendo una prueba útil y complementaria, debido a que en los casos con AL negativa no se observó compromiso meníngeo

Cryptococcosis is a serious mycosis that manifests itself, in 90% of cases, as meningoencephalitis, especially in AIDS patients. The objective of this study is to describe the extra-meningeal cases of cryptococcosis in people living with HIV and to know how many of them suffer from concomitant meningeal involvement. Also, to determine its relationship with the Cryptococcus capsular polysaccharide antigen titer in serum.A retrospective, observational and analytical study was carried out. HIV-positive patients whose initial diagnosis had been made from extrameningeal samples in the period between 2012 and 2019 were included. The patients were divided into 2 groups. Group 1: patients without meningeal involvement; group 2: those who finally had CNS involvement.Of a total of 531 cryptococcosis registered in this period, 113 patients (21%) were included, of whom meningeal involvement was confirmed in 58. No significant differences were observed in terms of mortality in both groups.None of the patients with positive LFA antigenemia (Capsular antigen detection by lateral Flow assay) but negative latex particle agglutination (LA) antigenemia had meningeal involvement. LFA was found to be highly sensitive and allows early diagnosis, but it does not replace other diagnostic procedures.Serum Cryptococcus antigen titers for by LA greater than or equal to 1/100 were found to correlate with a 30-fold increase in the likelihood of meningitis.In all cases, CNS involvement must be ruled out. LA continues to be a useful and complementary test, because in cases with negative LA, no meningeal involvement was observed

Estudo piloto de avaliação de um teste rápido imunocromatográfico para o diagnóstico de sífilis gestacional / Pilot evaluation of a rapid immunochromatographic test for the diagnosis of gestational syphilis

A sífilis gestacional é um problema global de saúde pública e é uma das mais comuns causas de efeitos adversos durante a gravidez devido à ausência ou inadequação do tratamento. Estabelecer um diagnóstico de sífilis durante o pré-natal, evita a transmissão de Treponema pallidum para a criança. Objetivo: o objetivo deste estudo foi avaliar o desempenho de OL Syphilis (OrangeLife, Brasil), um teste imunocromatográfico rápido, para o diagnóstico de sífilis gestacional. Métodos: Um total de 185 mulheres grávidas no pré-natal foram avaliadas por sífilis OL. Os resultados foram comparados com os métodos tradicionais: Laboratório de Pesquisa de Doenças Venéreas e Reaginas de Plasma Rápido (VDRL e RPR) como ensaios de seleção e FTA-ABS como teste confirmatório. Resultados: A prevalência de sífilis nessa população foi de 6,49% (IC 3,40 a 11,06%). A sensibilidade do teste rápido (TR) foi de 91,67% (IC95% 61,52 a 99,79%) e a especificidade foi de 100% (95%IC 97,89 a 100%). O PPV foi 100% (95%CI 71,51 a 100%) e o VPL foi de 99,43 (95%CI 96,84 a 100%). O acordo medido pelo coeficiente Kappa foi de 0,954 (IC95% 0,863 a 1,000). Conclusão: O teste OL Syphilis poderia ser usado no rastreio de mulheres grávidas, fornecendo diagnóstico rápido, aumentando a probabilidade de ter a doença diagnosticada e oportuna, evitando as consequências devastadoras da sífilis congênita.

Gestational syphilis is a global public health problem and one of the most common causes of adverse effects during pregnancy due to absence or inadequacy of treatment. Establishing a diagnosis of syphilis during prenatal care prevents the transmission of Treponema pallidum to the child. Objective: The objective of this study was to evaluate the performance of OL Syphilis (OrangeLife, Brazil), a rapid immunochromatographic test for gestational syphilis diagnosis. Methods: A total of 185 pregnant women in prenatal care were evaluated by OL Syphilis. The results were compared by traditional methods: Venereal Disease Research Laboratory and Rapid Plasma Reagin (VDRL and RPR) for screening and fluorescent treponemal antibody absorption test (FTA-Abs) for confirmation. Results: The prevalence of syphilis in this population was 6.49% (95%CI 3.40 to 11.06%). Rapid Test (RT) sensitivity was 91.67% (95%CI 61.52 to 99.79%) and specificity was 100% (95%CI 97.89 to 100%). Positive predictive value was 100% (95%CI 71.51 to 100%) and Negative predictive value was 99.43% (95%CI 96.84 to 100%). The agreement measured by Kappa coefficient was 0.954 (95%CI 0.863 to 1.000). Conclusion: The OL Syphilis test could be used for screening pregnant women, thus providing rapid diagnosis, increasing the probability of diagnosis and timely treatment, and preventing the devastating consequences of congenital syphilis.

Point-of-Care Testing for Infectious Diseases: Past, Present, and Future.

Point-of-care (POC) diagnostics provide rapid actionable information for patient care at the time and site of an encounter with the health care system. The usual platform has been the lateral flow immunoassay. Recently, emerging molecular diagnostics have met requirements for speed, low cost, and ease of use for POC applications. A major driver for POC development is the ability to diagnose infectious diseases at sites with a limited infrastructure. The potential use in both wealthy and resource-limited settings has fueled an intense effort to build on existing technologies and to generate new technologies for the diagnosis of a broad spectrum of infectious diseases.

Update on Malaria Diagnostics and Test Utilization.

Malaria is a potentially life-threatening disease requiring rapid diagnosis and treatment. Although microscopic examination of thick and thin blood films remains the gold standard for laboratory diagnosis, rapid antigen tests and nucleic acid amplification methods may also play a useful role in detection of acute infection. This review discusses the advantages and disadvantages of the commonly used diagnostic methods and provides important practice points for optimal malaria test utilization.

The role of rk39 serologic test in the diagnosis of visceral leishmaniasis in a Tertiary Hospital, Northern Ethiopia.

BACKGROUND: The study is done in Ayder Referral Hospital in Northern Ethiopia. Ethiopia is one of the countries where visceral leishmaniasis (VL) is endemic. Diagnosis of VL in Ethiopia is primarily based on rK39 immunochromatographic (rk39-ICT) strip. This test has been shown to have variable sensitivity and specificity in different countries. Hence the objective of the study is to determine the sensitivity and specificity of rk39-ICT in the diagnosis of VL in our set up. The study participants were VL suspected patients admitted to the hospital. A cross sectional study design was used. The study was conducted from January 14, 2013 to June 26, 2015. The rK39-ICT strip used was the InBios brand. Ethical clearance was obtained from the IRB of the college and written consent was obtained from the individual patients. RESULTS: A total of 62 VL suspects were involved in the study. The mean age was 26.3 years (SD = 6.94 years) with a median age of 25.5 years. Sixty-one (98.4%) of the patients was males. The rK39-ICT was positive in 50 (80.6%) of the patients. Splenic aspiration was positive in 44 (71%) of the patients. In 37 (59.7%) of the patients both rK39 and splenic aspiration were positive. Thirteen (21%) of the patients had positive rK39 but negative splenic aspiration. Five (8.1%) of the patients had both negative rK39 and splenic aspiration however seven (11.3%) of the patients had rk39 negative but splenic aspiration positive. The sensitivity, specificity, positive predictive value and the negative predictive value of rK39-ICT, taking splenic aspiration as a gold standard test, is 84.1% (95% CI 69.9-93.4%), 27.8% (95% CI 9.7-53.5%), 74.0% (95% CI 60-85.4%) and 41.7% (95% CI 15.2-72.3%) respectively. CONCLUSION: Sensitivity of rK39-ICT is low and its specificity is poor in our set up. Significant number of patients with confirmed VL did not have travel history to endemic areas. We recommend that the rK39-ICT needs improvement for clinical use in our set up and case definition for visceral leishmaniasis in Ethiopia needs to be revisited.

Community health workers adherence to referral guidelines: evidence from studies introducing RDTs in two malaria transmission settings in Uganda.

BACKGROUND: Many malaria-endemic countries have implemented national community health worker (CHW) programmes to serve remote populations that have poor access to malaria diagnosis and treatment. Despite mounting evidence of CHWs' ability to adhere to malaria rapid diagnostic tests (RDTs) and treatment guidelines, there is limited evidence whether CHWs adhere to the referral guidelines and refer severely ill children for further management. In southwest Uganda, this study examined whether CHWs referred children according to training guidelines and described factors associated with adherence to the referral guideline. METHODS: A secondary analysis was undertaken of data collected during two cluster-randomized trials conducted between January 2010 and July 2011, one in a moderate-to-high malaria transmission setting and the other in a low malaria transmission setting. All CHWs were trained to prescribe artemisinin-based combination therapy (ACT) and recognize symptoms in children that required immediate referral to the nearest health centre. Intervention arm CHWs had additional training on how to conduct an RDT; CHWs in the control arm used a presumptive diagnosis for malaria using clinical signs and symptoms. CHW treatment registers were reviewed to identify children eligible for referral according to training guidelines (temperature of ≥38.5 °C), to assess whether CHWs adhered to the guidelines and referred them. Factors associated with adherence were examined with logistic regression models. RESULTS: CHWs failed to refer 58.8% of children eligible in the moderate-to-high transmission and 31.2% of children in the low transmission setting. CHWs using RDTs adhered to the referral guidelines more frequently than CHWs not using RDTs (moderate-to-high transmission: 50.1 vs 18.0%, p = 0.003; low transmission: 88.5 vs 44.1%, p < 0.001). In both settings, fewer than 20% of eligible children received pre-referral treatment with rectal artesunate. Children who were prescribed ACT were very unlikely to be referred in both settings (97.7 and 73.3% were not referred in the moderate-to-high and low transmission settings, respectively). In the moderate-to-high transmission setting, day and season of visit were also associated with the likelihood of adherence to the referral guidelines, but not in the low transmission setting. CONCLUSIONS: CHW adherence to referral guidelines was poor in both transmission settings. However, training CHWs to use RDT improved correct referral of children with a high fever compared to a presumptive diagnosis using sign and symptoms. As many countries scale up CHW programmes, routine monitoring of reported data should be examined carefully to assess whether CHWs adhere to referral guidelines and take remedial actions where required.

A qualitative study of health professionals' uptake and perceptions of malaria rapid diagnostic tests in Burkina Faso.

BACKGROUND: Since 2012, rapid diagnostic tests (RDT) for malaria have been in use nationwide in Burkina Faso. The objective is to strengthen health professionals' diagnostic capabilities and promote good therapeutic practices. A qualitative study was conducted to learn about the adoption of this tool in the natural context of a national scale-up policy. METHODS: This study involved five health centres in two health districts. Twenty-eight individual interviews were conducted in 2013 with health professionals and members of the health district management teams. Health professionals' RDT use and drug prescription practices were observed during 278 curative care consultations over 5 weeks. RESULTS: Health professionals assessed the use of RDT positively as it allowed them to reach clear and accurate diagnoses and above all to deliver appropriate, rational care. However, the introduction of RDTs did not really change their diagnostic practices or prescribing practices for artemisinin-based combination therapy (ACT). They continued to rely predominantly on symptoms in establishing their diagnoses because of doubts regarding the reliability of the tests and the occasional stockouts of RDTs experienced by the health centres. Patients with negative RDT results continued to receive anti-malarial treatments. However, the situation remains quite heterogeneous. CONCLUSION: The use of RDTs points to the co-existence of official standards and different standards applied in practice. Setting up regular supervision activities provided an opportunity to observe and understand the various obstacles encountered by health professionals and to monitor how official directives are put into practice. For efficient use of RDTs and their results, health professionals need information and directives that are up-to-date and standardized.

Health workers' compliance to rapid diagnostic tests (RDTs) to guide malaria treatment: a systematic review and meta-analysis.

BACKGROUND: The World Health Organization recommends malaria to be confirmed by either microscopy or a rapid diagnostic test (RDT) before treatment. The correct use of RDTs in resource-limited settings facilitates basing treatment onto a confirmed diagnosis; contributes to speeding up considering a correct alternative diagnosis, and prevents overprescription of anti-malarial drugs, reduces costs and avoids unnecessary exposure to adverse drug effects. This review aims to evaluate health workers' compliance to RDT results and factors contributing to compliance. METHODS: A PROSPERO-registered systematic review was conducted to evaluate health workers' compliance to RDTs in sub-Saharan Africa, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies published up to November 2015 were searched without language restrictions in Medline/Ovid, Embase, Cochrane Central Register of Controlled Trials, Web of Science, LILACS, Biosis Previews and the African Index Medicus. The primary outcome was health workers treating patients according to the RDT results obtained. RESULTS: The literature search identified 474 reports; 14 studies were eligible and included in the quantitative analysis. From the meta-analysis, health workers' overall compliance in terms of initiating treatment or not in accordance with the respective RDT results was 83% (95% CI 80-86%). Compliance to positive and negative results was 97% (95% CI 94-99%) and 78% (95% CI 66-89%), respectively. Community health workers had higher compliance rates to negative test results than clinicians. Patient expectations, work experience, scepticism of results, health workers' cadres and perceived effectiveness of the test, influenced compliance. CONCLUSIONS: With regard to published data, compliance to RDT appears to be generally fair in sub-Saharan Africa; compliance to negative results will need to improve to prevent mismanagement of patients and overprescribing of anti-malarial drugs. Improving diagnostic capacity for other febrile illnesses and developing local evidence-based guidelines may help improve compliance and management of negative RDT results. TRIAL REGISTRATION: CRD42015016151 (PROSPERO).

[Urine antigen testing: Indication and contribution to the treatment of community-acquired pneumonia]. / Antigénuries: indications de prescription et apports thérapeutiques dans les pneumonies aiguës communautaires.

Urinary antigen tests are quick and simple tests helping to provide an etiological diagnosis in community-acquired pneumonia. However, their prescription is sometimes excessive and performed in unjustified situations. The therapeutic benefit is limited. Indeed, studies show that appropriate antibiotic therapy based on the result of urinary antigen tests does not improve the cost and the patient survival compared to empirical antibiotic therapy. One must be careful before antibiotic therapy reduction based on the sole negative result of urinary antigen test. Legionella urinary antigen test is the most commonly method used for the diagnosis of legionellosis but must be prescribed in a specific clinical context. Streptococcus pneumoniae urinary antigen test is especially interesting in the epidemiological surveillance of pneumococcal community-acquired pneumonia.

Ultrasensitive immunochromatographic assay for the simultaneous detection of five chemicals in drinking water.

In this paper, we describe the development of a multicomponent lateral-flow assay based on an antibody-antigen reaction for the rapid and simultaneous detection of trace contaminants in water, including a heavy metal, algal toxin, antibiotic, hormone, and pesticide. The representative analytes chosen for the study were lead (Pb(II), microcystin-leucine-arginine (MC-LR), chloramphenicol (CAP), testosterone (T), and chlorothalonil (CTN). Five different antigens were immobilized separately in five test lines on a nitrocellulose membrane. The monoclonal antibodies specifically recognized the corresponding antigens, and there was no cross-reactivity between the antibodies in the detection assay. Samples or standards containing the five analytes were preincubated with the freeze-dried colloidal-gold-labeled monoclonal antibody conjugates to improve the sensitivity of the assay. The results were obtained within 20min with a paper-based sensor. The cut-off values for the strip test were 4ng/mL for Pb(II), 1ng/mL for MC-LR, 0.1ng/mL for CAP, 5ng/mL for T, and 5ng/mL for CTN. The assay was evaluated using spiked water samples, and the accuracy and reproducibility of the results were good. In summary, this lateral-flow device provides an effective and rapid method for the onsite detection of multiple contaminants in water samples, with no treatment or devices required.

Feasibility and acceptability of rapid HIV test screening (DEPIVIH) by French family physicians.

BACKGROUND: In France, around 50,000 people were unaware of their HIV positivity at the end of 2008. The latest guidelines recommend routine screening of all adults. Family physicians have been identified as key persons for this new policy. Rapid HIV tests (RHT) have been proposed as an alternative to conventional blood tests. OBJECTIVES: The authors assessed the feasibility and acceptability of RHT test based screening in French community practice. METHOD: We made a prospective interventional study of the BioMerieux VIKIA(®) HIV 1/2 RHT among French family physicians. Data on the RHT was posted in the physician's waiting room. RESULTS: Sixty-two French physicians, mostly family practitioners, included 383 patients with a mean age of 36.2 years, from June to October 2010. Twenty-two percent (83) of these patients had never been tested for HIV. The RHT was proposed and 382 tests were accepted and performed (acceptability rate of 99.7%). Sixty-five percent of the tests were made on the patient's request. The tested population represented 1.5% of consulting patients during the study period (feasibility rate). Patients were quite satisfied but physicians less so. Test steps and capillary blood sampling were the main source of difficulty mentioned. At the end of the study, 59% of physicians were ready to continue using RHT in their daily practice. CONCLUSION: Routine RHT screening in community practice is feasible and well accepted by patients. It was the first screening test for 22% of our patients. Its feasibility was limited by capillary blood sampling technique and time constraints during consultation.

ROCS: a reproducibility index and confidence score for interaction proteomics studies.

BACKGROUND: Affinity-Purification Mass-Spectrometry (AP-MS) provides a powerful means of identifying protein complexes and interactions. Several important challenges exist in interpreting the results of AP-MS experiments. First, the reproducibility of AP-MS experimental replicates can be low, due both to technical variability and the dynamic nature of protein interactions in the cell. Second, the identification of true protein-protein interactions in AP-MS experiments is subject to inaccuracy due to high false negative and false positive rates. Several experimental approaches can be used to mitigate these drawbacks, including the use of replicated and control experiments and relative quantification to sensitively distinguish true interacting proteins from false ones. METHODS: To address the issues of reproducibility and accuracy of protein-protein interactions, we introduce a two-step method, called ROCS, which makes use of Indicator Prey Proteins to select reproducible AP-MS experiments, and of Confidence Scores to select specific protein-protein interactions. The Indicator Prey Proteins account for measures of protein identifiability as well as protein reproducibility, effectively allowing removal of outlier experiments that contribute noise and affect downstream inferences. The filtered set of experiments is then used in the Protein-Protein Interaction (PPI) scoring step. Prey protein scoring is done by computing a Confidence Score, which accounts for the probability of occurrence of prey proteins in the bait experiments relative to the control experiment, where the significance cutoff parameter is estimated by simultaneously controlling false positives and false negatives against metrics of false discovery rate and biological coherence respectively. In summary, the ROCS method relies on automatic objective criterions for parameter estimation and error-controlled procedures. RESULTS: We illustrate the performance of our method by applying it to five previously published AP-MS experiments, each containing well characterized protein interactions, allowing for systematic benchmarking of ROCS. We show that our method may be used on its own to make accurate identification of specific, biologically relevant protein-protein interactions, or in combination with other AP-MS scoring methods to significantly improve inferences. CONCLUSIONS: Our method addresses important issues encountered in AP-MS datasets, making ROCS a very promising tool for this purpose, either on its own or in conjunction with other methods. We anticipate that our methodology may be used more generally in proteomics studies and databases, where experimental reproducibility issues arise. The method is implemented in the R language, and is available as an R package called "ROCS", freely available from the CRAN repository http://cran.r-project.org/.

Extension of the selection of protein chromatography and the rate model to affinity chromatography.

The rational selection of optimal protein purification sequences, as well as mathematical models that simulate and allow optimization of chromatographic protein purification processes have been developed for purification procedures such as ion-exchange, hydrophobic interaction and gel filtration chromatography. This paper investigates the extension of such analysis to affinity chromatography both in the selection of chromatographic processes and in the use of the rate model for mathematical modelling and simulation. Two affinity systems were used: Blue Sepharose and Protein A. The extension of the theory developed previously for ion-exchange and HIC chromatography to affinity separations is analyzed in this paper. For the selection of operations two algorithms are used. In the first, the value of η, which corresponds to the efficiency (resolution) of the actual chromatography and, Σ, which determines the amount of a particular contaminant eliminated after each separation step, which determines the purity, have to be determined. It was found that the value of both these parameters is not generic for affinity separations but will depend on the type of affinity system used and will have to be determined on a case by case basis. With Blue Sepharose a salt gradient was used and with Protein A, a pH gradient. Parameters were determined with individual proteins and simulations of the protein mixtures were done. This approach allows investigation of chromatographic protein purification in a holistic manner that includes ion-exchange, HIC, gel filtration and affinity separations for the first time.

Affinity liquid chromatography method for the quantification of immunoglobulin G in bovine colostrum powders.

An affinity liquid chromatography (LC) method for the determination of bovine immunoglobulin G (IgG), using protein G coupled to an agarose support, was modified to permit the quantification of IgG in colostrum-based powders. Sample preparation included pH adjustment to 4.6 to precipitate casein and denatured whey protein. The method was applied to a range of colostrum powders and was compared with the alternative independent methods of surface plasmon resonance immunoassay, radial immunodiffusion, and reversed-phase LC. The method was rapid, and performance parameters included a working range of 10-150 microg IgG and precision relative standard deviation values of <10%.

Nitroproteins from a human pituitary adenoma tissue discovered with a nitrotyrosine affinity column and tandem mass spectrometry.

The aim of this study was to characterize endogenous nitroproteins, and those proteins that interact with nitroproteins, in a human pituitary nonfunctional adenoma so as to clarify the role of protein nitration in adenomas. A nitrotyrosine affinity column (NTAC) was used to preferentially enrich and isolate endogenous nitroproteins and nitroprotein-protein complexes from a tissue homogenate that was prepared from a human pituitary nonfunctional pituitary adenoma. The preferentially enriched endogenous nitroproteins and nitroprotein-protein complexes were subjected to trypsin digestion, desalination, and tandem mass spectrometry analysis. Nine nitroproteins (Rho-GTPase-activing protein 5, leukocyte immunoglobulin-like receptor subfamily A member 4 precursor, zinc finger protein 432, cAMP-dependent protein kinase type I-beta regulatory subunit, sphingosine-1-phosphate lyase 1, centaurin beta 1, proteasome subunit alpha type 2, interleukin 1 family member 6, and rhophilin 2) and three proteins (interleukin 1 receptor-associated kinase-like 2, glutamate receptor-interacting protein 2, and ubiquitin) that interacted with nitroproteins were discovered. The nitration site of each nitroprotein was located onto the functional domain where nitration occurred, and each nitroprotein was related to a corresponding functional system. Those data indicate that protein nitration might be an important molecular event in the formation of a human pituitary nonfunctional adenoma.

Automation of protein purification for structural genomics.

A critical issue in structural genomics, and in structural biology in general, is the availability of high-quality samples. The additional challenge in structural genomics is the need to produce high numbers of proteins with low sequence similarities and poorly characterized or unknown properties. 'Structural-biology-grade' proteins must be generated in a quantity and quality suitable for structure determination experiments using X-ray crystallography or nuclear magnetic resonance (NMR). The choice of protein purification and handling procedures plays a critical role in obtaining high-quality protein samples. The purification procedure must yield a homogeneous protein and must be highly reproducible in order to supply milligram quantities of protein and/or its derivative containing marker atom(s). At the Midwest Center for Structural Genomics we have developed protocols for high-throughput protein purification. These protocols have been implemented on AKTA EXPLORER 3D and AKTA FPLC 3D workstations capable of performing multidimensional chromatography. The automated chromatography has been successfully applied to many soluble proteins of microbial origin. Various MCSG purification strategies, their implementation, and their success rates are discussed in this paper.

Statistical calculation of detection limits for DNA adducts using the 32P-postlabeling assay with a standard addition procedure.

The 32P-postlabeling assay is widely used for the analysis of DNA adducts. Some adducts can be detected with very high sensitivity but quantification can be unreliable, particularly if it is based only on comparison with unmodified nucleotides (relative adduct labeling, RAL values). Furthermore, guidelines to calculate detection limits for adduct concentrations are lacking. This is particularly important for human biomonitoring studies of environmental exposures, where a low adduct level can remain undetected. Reports of null results of toxicity studies should always include a limit of detection, indicating the effect magnitude that would have produced, with a given probability of false negative (type II error), a statistically significant increase (type I error). Here, we report on a procedure based on t-statistics to calculate two types of detection limits, the "critical level (CL)" and the "detection level (DL)". The first is the size of the difference between exposed and controls required to achieve statistical significance. The second is the size of the difference that will be detected with a chosen probability of a false negative. For the degrees of freedom (d.f.) to be used for the t-values, a general formula is given so that different standard deviations and group sizes of control and exposed groups can be handled. A sample calculation of the whole procedure is shown, using the null data for the formation of a particular adduct in lung DNA of styrene-treated mice, analyzed by 32P-postlabeling. The procedure takes into account: (i) TLC-specific background radioactivity; (ii) variability within the control and exposed groups; and (iii) confidence limits for the factor to convert 32P-radioactivity to amounts of adduct. The latter step incorporates the variance of the differences between the samples and replicates spiked with adduct standard. A statement such as follows is the result: the concentration of the alpha-isomer adduct of styrene 7,8-oxide at the O(6)-position of guanine in mouse lung DNA would have to be at least 12 adducts per 10(8) nucleotides to be detected in the given experiment on a 5% level (type I error), with a probability of 5% to miss an existing effect (type II error).

Process characterization for metal-affinity chromatography of an Fc fusion protein: a design-of-experiments approach.

The utility of a design-of-experiments approach was investigated for process characterization of a metal-affinity chromatographic purification process for an Fc fusion protein. This approach gave a better understanding of some of the key process variables as well as robustness for this step in the purification process. Single-variable experiments were employed to screen some of the potentially important variables in this step. Ranges for these variables were set based on prior experience in clinical manufacturing with similar processes. Following these experiments, a fractional factorial study was employed to further investigate the most important variables and their interactions. Key operational variables that had an impact on step yield and eluate purity were identified. In addition, the study helped identify a worst-case scenario for the step purity and helped assure that the rest of the process would successfully purify the product. This paper demonstrates the utility of a design-of-experiments approach for the characterization and validation of process chromatography steps in downstream processing. In addition, this study emphasizes the utility of robustness studies early in process development and establishes a strategy for future robustness studies.

Capsaicin induces cystatin S-like substances in submandibular saliva of the rat.

Irritating dietary substances such as tannin and papain have been reported to alter the morphology of salivary glands and their secretions. Such alterations can be one line of protection from toxic or irritating substances in food. We investigated the effects of dietary capsaicin (a pungent ingredient of hot red pepper) on the rat submandibular gland and its secretions. Several groups of animals were offered either control diets or diets containing capsaicin (from 0.0001 to 0.1%) for seven days. Higher concentrations suppressed food consumption for two days, after which only the highest concentration continued to reduce intake. The relative weight of the salivary glands in capsaicin-diet groups increased in a dose-dependent fashion, and new proteins appeared in the submandibular saliva. Chromatographic and electrophoretic properties of these proteins were identical or similar to those of isoproterenol-induced proteins. After affinity chromatography of the new protein fraction on a Cm-papain Sepharose 4B column, SDS-electrophoresis of the eluate revealed three major bands (15,500, 16,500, and 28,000 kDa). Hydrolysis of N-benzoyl-D,L-arginine-p-nitroanilide by papain (a cysteine protease) decreased in the presence of the new protein fraction, suggesting that these proteins have cystatin-like activity (inhibition of cysteine protease). Denervation of the glossopharyngeal nerve suppressed induction of these proteins. The results suggest that dietary capsaicin induces cystatin S-like substances in submandibular saliva by stimulating the reflex arc involving the glossopharyngeal nerve. These proteins likely facilitate ingestion of diets containing the irritating substance.