The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Marcel Hommel - One of the best experts on this subject based on the ideXlab platform.
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detection of leishmanial antigen in the urine of patients with visceral leishmaniasis by a Latex agglutination test
American Journal of Tropical Medicine and Hygiene, 2005Co-Authors: Shyam Sundar, Marcel Hommel, Michael L. Chance, S AgrawalAbstract:Diagnosis of visceral leishmaniasis (VL) is usually done by demonstration of parasites in tissue smears. However, obtaining these smears may be risky, painful, and difficult. Antibody-based diagnostics are limited by their inability to predict active disease. In this study, a new Latex agglutination test (KAtex), which detects parasite antigen in freshly voided and boiled urine, was evaluated in patients with VL before the start (n 382) and at the end of treatment (n 273); 185 healthy controls from leishmaniasis-endemic region were also studied. The KAtex result was positive in 87% (95% confidence interval (CI) 83.3-90.3). However, at the end of treatment only 3% (95% CI 1.6-6.2) patients were positive. The specificity of the test was 99% and 2 of 185 healthy controls tested positive. Positive and negative predictive values were 0.994 and 0.788, respectively. KAtex is a promising test, and in a simplified and improved format it could be applied meaningfully in the diagnosis of VL.
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evaluation of a urinary antigen based Latex agglutination test in the diagnosis of kala azar in eastern nepal
Tropical Medicine & International Health, 2004Co-Authors: Suman Rijal, Marleen Boelaert, Sharada Regmi, B M S Karki, Rupa Singh, François Chappuis, Marcel Hommel, Michael L. Chance, D. Jacquet, Philippe DesjeuxAbstract:BACKGROUND We evaluated the diagnostic accuracy as well as the reproducibility of the urine Latex agglutination test 'KAtex' in the diagnosis of kala-azar in patients recruited at a tertiary care centre in Dharan, Nepal, between November 2000 and January 2002. METHODS All patients presenting with fever of 2 weeks or more and splenomegaly were consecutively enrolled. Bone marrow and - if negative - spleen aspirates were examined for Leishmania donovani. Serum and urine samples were taken in duplicate for the Direct Agglutination Test (DAT) and KAtex. The reference laboratory determined sensitivity and specificity of KAtex. Reproducibility between both laboratories was assessed. RESULTS KAtex was performed on urine from 155 parasitologically confirmed kala-azar and 77 non-kala-azar cases (parasitology and DAT-negative). KAtex showed a sensitivity of 47.7% (74/155, 95% CI: 39.7-55.9) and a specificity of 98.7% (76/77, 95% CI: 93.0-100.0). Reproducibility of KAtex showed a kappa of 0.684 (P < 0.001, n = 232). CONCLUSION KAtex evaluation showed high specificity, low sensitivity and moderate reproducibility. A urine test for kala-azar could become a real breakthrough in kala-azar management if its reproducibility and sensitivity could be further improved.
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field evaluation of Latex agglutination test for detecting urinary antigens in visceral leishmaniasis in sudan
Eastern Mediterranean Health Journal, 2003Co-Authors: Sayda Elsafi, Marleen Boelaert, Michael L. Chance, A Abdelhaleem, Awad Hammad, I Elbasha, A Omer, H G Kareem, Marcel HommelAbstract:: A Latex agglutination test to detect urinary antigens for visceral leishmaniasis (VL) was studied. In 204 patients with suspected VL, KAtex had a sensitivity of 95.2% with good agreement with microscopy smears but poor agreement with 4 different serology tests. It was also positive in 2 confirmed VL cases co-infected with HIV. In all K4tex-positive confirmed cases actively followed up after treatment, the test became negative 1 month after completion of treatment. While IC4tex had a specificity of 100% in healthy endemic and non-endemic controls, the direct agglutination test (DAT) was positive in 14% of the KAtex-negative healthy endemic controls. KAtex is a simple addition to the diagnostics of VL particularly at field level and as a complementary test for the diagnosis of VL in smear-negative cases with positive DAT results.
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Latex agglutination test for the detection of urinary antigens in visceral leishmaniasis
Acta Tropica, 2001Co-Authors: Zamil J Attar, Sayda Elsafi, James Carney, Ahmed A Azazy, Maha Elhadi, Cibele Dourado, Michael L. Chance, Marcel HommelAbstract:This paper describes a new Latex agglutination test ('KATEX') for the detection of leishmanial antigen in the urine of patients with visceral leishmaniasis. In preliminary laboratory trials, using urine collected from well-defined cases and controls from Brazil, Yemen and Nepal, the test had 100% specificity and a sensitivity between 68 and 100%. When used in a time-course experiment in cotton rats infected with Leishmania donovani, the test became positive 1 week after inoculation and antigen levels in urine declined rapidly after chemotherapy (the test was negative before the end of the course of treatment). Finally, in an integrated study performed in Sudan, KATEX was compared to microscopy and four different serological tests in a group of 73 patients having presented with clinical manifestations suggestive of visceral leishmaniasis. Compared to microscopy, KATEX performed better than any single serological test in predicting positivity and a particularly good result was obtained by combining KATEX and the direct agglutination test (DAT).
Robert G Hamilton - One of the best experts on this subject based on the ideXlab platform.
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natural rubber Latex skin testing reagents safety and diagnostic accuracy of nonammoniated Latex ammoniated Latex and Latex rubber glove extracts
The Journal of Allergy and Clinical Immunology, 1996Co-Authors: Robert G Hamilton, Franklin N AdkinsonAbstract:Abstract Background: Nonammoniated Latex, ammoniated Latex, and rubber glove extracts are the only sources of natural rubber (Hevea brasiliensis) Latex that have potential for use as skin testing reagents in the diagnosis of Latex allergy. Their diagnostic sensitivity and specificity as skin test reagents are unknown. Objective: We conducted a phase 1/2 clinical study to examine the safety and diagnostic accuracy (sensitivity and specificity) of nonammoniated Latex, ammoniated Latex, and rubber glove extracts as skin test extracts to identify the most efficacious source material for future skin test reagent development. Methods: Twenty-four adults not allergic to Latex, 19 adults with hand dermatitis or pruritus, and 59 adults with a Latex allergy were identified by clinical history. All provided blood and then received puncture skin tests and intradermal skin tests with nonammoniated Latex, ammoniated Latex, and rubber glove extracts from Malaysian H. brasiliensis Latex by use of sequential titration. A glove provocation test and IgE anti-Latex RAST were used to clarify positive history–negative skin test response and negative history–positive skin test response mismatches. Results: All three extracts were biologically safe and sterile. After normalization to 1 mg/ml of total protein, all three extracts produced equivalent diagnostic sensitivity and specificity in puncture skin tests and intradermal skin tests at various extract concentrations. Optimal diagnostic accuracy was safely achieved at 100 μg/ml for puncture skin tests and 1 μg/ml for intradermal skin tests (e.g., nonammoniated Latex: puncture skin test sensitivity 96%, specificity 100%; intradermal skin test sensitivity 93%, specificity 96%). The presence of IgE antibody in skin was highly correlated with IgE anti-Latex in serum (nonammoniated Latex: r = 0.98, p r = 0.94, p r = 0.96, p Conclusions: Equivalent diagnostic sensitivity and specificity were observed with the nonammoniated Latex, ammoniated Latex, and rubber glove extract skin test reagents after normalization for total protein; nonammoniated Latex may be considered the reagent of choice on the basis of practical quality control and reproducibility considerations. (J ALLERGY CLIN IMMUNOL 1996;98:872-83.)
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Natural rubber Latex skin testing reagents: safety and diagnostic accuracy of nonammoniated Latex, ammoniated Latex, and Latex rubber glove extracts.
The Journal of allergy and clinical immunology, 1996Co-Authors: Robert G Hamilton, N F AdkinsonAbstract:Nonammoniated Latex, ammoniated Latex, and rubber glove extracts are the only sources of natural rubber (Hevea brasiliensis) Latex that have potential for use as skin testing reagents in the diagnosis of Latex allergy. Their diagnostic sensitivity and specificity as skin test reagents are unknown. We conducted a phase 1/2 clinical study to examine the safety and diagnostic accuracy (sensitivity and specificity) of nonammoniated Latex, ammoniated Latex, and rubber glove extracts as skin test extracts to identify the most efficacious source material for future skin test reagent development. Twenty-four adults not allergic to Latex, 19 adults with hand dermatitis or pruritus, and 59 adults with a Latex allergy were identified by clinical history. All provided blood and then received puncture skin tests and intradermal skin tests with nonammoniated Latex, ammoniated Latex, and rubber glove extracts from Malaysian H. brasiliensis Latex by use of sequential titration. A glove provocation test and IgE anti-Latex RAST were used to clarify positive history-negative skin test response and negative history-positive skin test response mismatches. All three extracts were biologically safe and sterile. After normalization to 1 mg/ml of total protein, all three extracts produced equivalent diagnostic sensitivity and specificity in puncture skin tests and intradermal skin tests at various extract concentrations. Optimal diagnostic accuracy was safely achieved at 100 micrograms/ml for intradermal skin tests (e.g., nonammoniated Latex: puncture skin test sensitivity 96%, specificity 100%; intradermal skin test sensitivity 93%, specificity 96%). The presence of IgE antibody in skin was highly correlated with IgE anti-Latex in serum (nonammoniated Latex: r = 0.98, p < 0.001; ammoniated Latex: r = 0.94, p < 0.001; rubber glove extract: r = 0.96, p < 0.001). All five available subjects with a positive history, negative skin test response, and absence of IgE antibody in serum had a negative glove provocation test response, indicating no clinical evidence of Latex allergy. No systemic or large local allergic reactions were observed with puncture skin tests or intradermal skin tests. Equivalent diagnostic sensitivity and specificity were observed with the nonammoniated Latex, ammoniated Latex, and rubber glove extract skin test reagents after normalization for total protein; nonammoniated Latex may be considered the reagent of choice on the basis of practical quality control and reproducibility considerations.
Xaver Baur - One of the best experts on this subject based on the ideXlab platform.
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Latex allergen elimination in natural Latex sap and Latex gloves by treatment with alkaline potassium hydroxide solution
Allergy, 1997Co-Authors: Xaver Baur, J. Rennert, Z. ChenAbstract:Antigenic proteins in Latex products can cause type I allergy. We investigated the effects of potassium hydroxide (KOH) solution on the allergenicity of proteins in natural Latex sap and Latex gloves by using an EAST competitive inhibition immunoassay and skin prick test. Latex sap was mixed with KOH solution at different concentrations and incubated over various periods of time at room temperature. Latex gloves were washed in KOH solution for different times at 30°C and 90°C. Our immunoassay results for the subsequently extracted Latex proteins demonstrated a KOH concentration-, temperature-, and lime-dependent decrease in allergenicily, finally resulting in complete loss of IgE-binding activity. In the skin prick test, we found only four weakly positive reactions to proteins extracted from KOH-washed gloves in 30 Latex-sensitized patients. In addition, up to 97% of the aqueous extractable protein content could be removed from Latex gloves by washing in KOH solution under certain conditions. These results suggest that antigenic proteins in natural Latex sap and Latex gloves can be changed by treatment with KOH solution, which is followed by a loss of their capability to bind specific IgE antibodies from most Latex-sensitized patients.
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Latex allergen database
Electrophoresis, 1997Co-Authors: Anton Posch, Gerhard Leubner-metzger, Colin H. Wheeler, Arnd Petersen, Michael J. Dunn, Zhiping Chen, Xaver BaurAbstract:Two-dimensional (2-D) electrophoresis followed by immunoblotting and N-terminal protein microsequencing were used to characterize and identify the IgE-reactive proteins of Hevea Latex that are the main cause of the Latex type I allergy affecting especially health care workers and spina bifida children. This approach generated a comprehensive Latex allergen database, which facilitated the integration of most of the Latex allergen data presented in the literature. The major Latex allergens Hev b 1, Hev b 3, Hev b 6 and Hev b 7 have been localized on our 2-D maps. Moreover, we were able to identify six previously undescribed IgE-binding Latex proteins, namely enolase, superoxide dismutase, proteasome subunit C5, malate dehydrogenase, triosephosphate isomerase and endochitinase. The generated Latex 2-D maps will provide valuable information to develop strategies for the isolation of the novel IgE binding proteins in order to study the frequency of sensitization among both risk groups. Detailed knowledge of all proteins involved in Latex allergy will allow better diagnosis of Latex allergy and to monitor the success of prevention strategies that are needed to reduce the high prevalence of Latex allergy among both risk groups.
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Latex allergen elimination in natural Latex sap and Latex gloves by treatment with alkaline potassium hydroxide solution.
Allergy, 1997Co-Authors: Xaver Baur, J. Rennert, Zhiping ChenAbstract:Antigenic proteins in Latex products can cause type I allergy. We investigated the effects of potassium hydroxide (KOH) solution on the allergenicity of proteins in natural Latex sap and Latex gloves by using an EAST competitive inhibition immunoassay and skin prick test. Latex sap was mixed with KOH solution at different concentrations and incubated over various periods of time at room temperature. Latex gloves were washed in KOH solution for different times at 30 degrees C and 90 degrees C. Our immunoassay results for the subsequently extracted Latex proteins demonstrated a KOH concentration-, temperature-, and time-dependent decrease in allergenicity, finally resulting in complete loss of IgE-binding activity. In the skin prick test, we found only four weakly positive reactions to proteins extracted from KOH-washed gloves in 30 Latex-sensitized patients. In addition, up to 97% of the aqueous extractable protein content could be removed from Latex gloves by washing in KOH solution under certain conditions. These results suggest that antigenic proteins in natural Latex sap and Latex gloves can be changed by treatment with KOH solution, which is followed by a loss of their capability to bind specific IgE antibodies from most Latex-sensitized patients.
Daniel Epron - One of the best experts on this subject based on the ideXlab platform.
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In situ 13CO2 labelling of rubber trees reveals a seasonal shift in the contribution of the carbon sources involved in Latex regeneration
Journal of Experimental Botany, 2020Co-Authors: Ornuma Duangngam, Dorine Desalme, Philippe Thaler, Poonpipope Kasemsap, Jate Sathornkich, Duangrat Satakhun, Chompunut Chayawat, Nicolas Angeli, Pisamai Chantuma, Daniel EpronAbstract:Rubber trees (Hevea brasiliensis) are the main source of natural rubber, extracted from Latex, which exudes from the trunk after tapping. Tapped trees require large amounts of carbon (C) to regenerate the Latex after its collection. Knowing the contribution of C sources involved in Latex biosynthesis will help in understanding how rubber trees face this additional C demand. Whole crown 13CO2 pulse labelling was performed on 4-year-old rubber trees in June, when Latex production was low, and in October, when it was high. 13C content was quantified in the foliage, phloem sap, wood, and Latex. In both labelling periods, 13C was recovered in Latex just after labelling, indicating that part of the carbohydrate was directly allocated to Latex. However, significant amounts of 13C were still recovered in Latex after 100 d and the peak was reached significantly later than in phloem sap, demonstrating the contribution of a reserve pool as a source of Latex C. The contribution of new photosynthates to Latex regeneration was faster and higher when Latex metabolism was well established, in October, than in June. An improved understanding of C dynamics and the source–sink relationship in rubber tree is crucial to adapt tapping system practices and ensure sustainable Latex production.
Lishan Hsieh - One of the best experts on this subject based on the ideXlab platform.
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comparison of Latex specific ige binding among nonammoniated Latex ammoniated Latex and Latex glove allergenic extracts by elisa and immunoblot inhibition
The Journal of Allergy and Clinical Immunology, 1996Co-Authors: Akira Akasawa, Lishan HsiehAbstract:Abstract BACKGROUND: Nonammoniated Latex, ammoniated Latex, and Latex glove extracts have been used as source materials for the preparation of allergenic extracts for the diagnosis of Latex allergy. These materials showed different patterns of protein bands and immunoreactive bands. However, their IgE–reactive repertoires were not compared. OBJECTIVE: The goals of this study were to compare the IgE reactivity and to define the common IgE–reactive epitopes among three Latex allergenic extracts. METHODS: Two serum pools were obtained from adults and children with Latex allergy to evaluate the IgE reactivity among three Latex extracts. IgE reactivity and IgE–reactive proteins were compared by inhibition ELISA and inhibition immunoblot methods, respectively. RESULTS: In this study inhibition curves were similar for nonammoniated Latex and ammoniated Latex but were different when the Latex glove extracts were used. Several protein bands of ammoniated Latex and Latex glove extracts could not be inhibited by the nonammoniated Latex. The ammoniated Latex and Latex glove extracts were able to remove all the Latex-specific IgE from the serum. CONCLUSION: The IgE–reactive proteins differ among different Latex extracts. Ammoniated Latex and Latex glove extracts contain more complete immunoreactive repertoires for detecting IgE antibodies. Our study provides useful information for selecting the Latex extract. (J ALLERGY CLIN IMMUNOL 1996;97:1116-20.)
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Comparison of Latex–specific IgE binding among nonammoniated Latex, ammoniated Latex, and Latex glove allergenic extracts by ELISA and immunoblot inhibition
The Journal of Allergy and Clinical Immunology, 1996Co-Authors: Akira Akasawa, Lishan HsiehAbstract:Abstract BACKGROUND: Nonammoniated Latex, ammoniated Latex, and Latex glove extracts have been used as source materials for the preparation of allergenic extracts for the diagnosis of Latex allergy. These materials showed different patterns of protein bands and immunoreactive bands. However, their IgE–reactive repertoires were not compared. OBJECTIVE: The goals of this study were to compare the IgE reactivity and to define the common IgE–reactive epitopes among three Latex allergenic extracts. METHODS: Two serum pools were obtained from adults and children with Latex allergy to evaluate the IgE reactivity among three Latex extracts. IgE reactivity and IgE–reactive proteins were compared by inhibition ELISA and inhibition immunoblot methods, respectively. RESULTS: In this study inhibition curves were similar for nonammoniated Latex and ammoniated Latex but were different when the Latex glove extracts were used. Several protein bands of ammoniated Latex and Latex glove extracts could not be inhibited by the nonammoniated Latex. The ammoniated Latex and Latex glove extracts were able to remove all the Latex-specific IgE from the serum. CONCLUSION: The IgE–reactive proteins differ among different Latex extracts. Ammoniated Latex and Latex glove extracts contain more complete immunoreactive repertoires for detecting IgE antibodies. Our study provides useful information for selecting the Latex extract. (J ALLERGY CLIN IMMUNOL 1996;97:1116-20.)
