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At least 199 records · Page 11Linked to original sources
PubMed1992

Anaplasmosis in Uganda. I. Use of dried blood on filter paper and serum samples for serodiagnosis of anaplasmosis--a comparative study.

The suitability of blood collected on filter papers in comparison with corresponding conventional serum samples in the diagnosis of bovine anaplasmosis was studied using the Complement Fixation Test (CFT), DOT-ELISA, Western immunoblot and Rapid Card Agglutination Test (RCAT). Dried blood on Whatman filter paper no. 1 was eluted in 1.8 ml of PBS 0.05% Tween 20 given an initial dilution of 1:100. The reactivity in both DOT-ELISA and Western immunoblotting was similar to that obtained with the sera diluted 1:100. Filter paper samples gave lower reactivity in all the tests as compared with corresponding serum samples. There was no significant difference in the reactivity between the eluates from filter papers stored at room temperature and those stored at 4 degrees C. Storage at room temperature did not significantly affect reactivity for up to 6 months. Eluates from filter papers stored for 6 months at room temperature continued to give similar reactivity to those from freshly prepared filter papers in both DOT-ELISA and Western blot, and in the Rapid Card Agglutination Test. It is concluded that collecting blood on filter papers is a suitable technique for large-scale screening and for seroepidemiological studies on anaplasmosis, and offers many advantages especially in developing countries where transport and cold chain facilities are a major constraint.

Anaplasmosis↗
PubMed1997

Preinduction cervical ripening: prostaglandin E2 gel vs hygroscopic mechanical dilator.

OBJECTIVES: To evaluate the efficacy and safety of hygroscopic mechanical dilators (Dilapan) for ripening the pregnant cervix prior to induction of labour at or near term and to compare it with an intracervical PGE2 gel (Prepidil). METHODS: One hundred and eighty-five women (69 nulliparae, 116 multiparae) at term with singleton pregnancies in cephalic presentation, who were scheduled for induction of labour in the labour ward at the National University Hospital, but had an unfavourable cervical score were randomized into 2 groups by random number table. In group 1 (Prepidil), 0.5 mg of PGE2 in 2.5 ml of triacetin gel was inserted into the endocervical canal. In women in group 2 (Dilapan) upto a maximum of 4 hygroscopic dilators were placed in the endocervical canal. If labour did not ensue at the end of 12 hours of ripening, the cervical score was assessed, amniotomy was performed and oxytocin commenced. Neonatal and obstetric outcome was compared, statistical analysis performed using Chi-square, and t-tests. RESULTS: Significantly more women in the group who received Dilapan for cervical ripening required amniotomy and oxytocin for induction of labour > 12 hours after priming compared with the group who received Prepidil (p < 0.001). Operative delivery for no progress and fetal distress respectively was similar in the 2 groups. The number of cases of hyperstimulation were higher in the Prepidil group but did not result in an increased incidence of operative deliveries for fetal distress. There was one neonatal death and one case of neonatal sepsis in the Dilapan group. Uterine rupture occurred in 1 woman who received Prepidil. CONCLUSION: Dilapan, a mechanical method of cervical ripening is as effective as the more widely accepted mode of ripening with an endocervical PGE2 gel in achieving vaginal delivery. Dilapan would be useful for cervical priming prior to induction of labour in places where prostaglandins are not available because of cost and the need for a cold chain.

Adult↗
PubMed2004

The genetic basis for measles vaccine failure.

The US measles epidemics of 1989-1991 included a series of outbreaks resulting from vaccine failure. A series of studies was launched aimed at elucidating the mechanisms of this vaccine failure. A meta-analysis of the literature examining epidemics in vaccinated populations was conducted, which showed that the secondary vaccine failure rate (development of the disease despite an initial or primary vaccine success) is no more than 0.2%. The overwhelming proportion of measles vaccine failure was due to primary vaccine failure (failure to ever generate antibody from antigenic stimulation). This comparison of two geographically distinct communities revealed that 10% of children previously vaccinated against measles lacked antibody on follow-up and that these vaccine failures clustered in families. A study of monozygotic and dizygotic twins revealed a high degree of heritability of measles vaccine antibody level. Subsequent studies found associations with both class I and class II alleles in these population-based studies. In the future, detection of the specific peptides that interact with human leukocyte antigen (HLA) molecules may serve as the basis for improved vaccines and address vaccine failure that results from cold-chain problems, immaturity of the immune system, malnutrition and maternal immunity.

Antibody Formation↗
PubMed1989

Bovine ephemeral fever.

Ephemeral fever remains a viral disease of considerable importance to many countries including Australia. The virus has been only partly characterised and still awaits final classification. Although BEF virus was first thought to contain 6 structural proteins there is increasing evidence to suggest that it contains the 5 proteins characteristic of the Rhabdoviridae. Although BEF is thought to be arthropod borne, the vector has yet to be identified but it is clear from the distribution of BEF that more than one vector is capable of transmitting the disease. Despite rigorous investigation of the clinical signs and the pathology of ephemeral fever, little progress has been made on the pathogenesis of the disease. This has been partly due to the difficulty of propagating BEF virus in vitro and the inability to define the site of replication. However, there is mounting evidence to suggest that BEF is immunopathologic in nature and that the clinical expression of the disease is influenced by the release of one or more mediators of inflammation. The disease is characterised by a number of haematological and biochemical changes and early and prolonged treatment with phenylbutazone is capable of reversing a number of these changes. The intravenous administration of calcium can now be considered a justifiable addition to the treatment regimen together with prolonged phenylbutazone therapy. The vaccines currently available are prepared from either live attenuated or killed virus and may be less than reliable. There appears to be a need for a reliable, inexpensive, cold-chain independent alternative vaccine.

Animals↗
PubMed1991

Reported measles immunisation and serological immunity in children attending general practitioners.

To determine the feasibility of serological testing for measles immunity in children attending general practitioners and to assess the validity of establishing immune status by reported immunisation history compared with serology, a cross-sectional descriptive study was conducted in general practices in the Illawarra area south of Sydney, New South Wales. Participants were 234 children under 15 years attending general practitioners. 87 per cent of children were reported to have been immunised against measles, but 46 per cent of these children were seronegative for measles antibody using an ELISA test on finger-prick blood. This could not be explained by inaccurate reporting of immunisation. No causes other than failure to seroconvert or inadequate specificity of the test on the blood samples were evident. Failure to seroconvert as a result of inadequate adherence to cold chain requirements is a possibility that needs further investigation. The results further question whether a single vaccination is adequate to achieve the public health aims of measles immunisation programs.

Adolescent↗
PubMed2021

Affordable oral health care: dental biofilm disruption using chloroplast made enzymes with chewing gum delivery.

Current approaches for oral health care rely on procedures that are unaffordable to impoverished populations, whereas aerosolized droplets in the dental clinic and poor oral hygiene may contribute to spread of several infectious diseases including COVID-19, requiring new solutions for dental biofilm/plaque treatment at home. Plant cells have been used to produce monoclonal antibodies or antimicrobial peptides for topical applications to decrease colonization of pathogenic microbes on dental surface. Therefore, we investigated an affordable method for dental biofilm disruption by expressing lipase, dextranase or mutanase in plant cells via the chloroplast genome. Antibiotic resistance gene used to engineer foreign genes into the chloroplast genome were subsequently removed using direct repeats flanking the aadA gene and enzymes were successfully expressed in marker-free lettuce transplastomic lines. Equivalent enzyme units of plant-derived lipase performed better than purified commercial enzymes against biofilms, specifically targeting fungal hyphae formation. Combination of lipase with dextranase and mutanase suppressed biofilm development by degrading the biofilm matrix, with concomitant reduction of bacterial and fungal accumulation. In chewing gum tablets formulated with freeze-dried plant cells, expressed protein was stable up to 3&#xa0;years at ambient temperature and was efficiently released in a time-dependent manner using a mechanical chewing simulator device. Development of edible plant cells expressing enzymes eliminates the need for purification and cold-chain transportation, providing a potential translatable therapeutic approach. Biofilm disruption through plant enzymes and chewing gum-based delivery offers an effective and affordable dental biofilm control at home particularly for populations with minimal oral care access.

Biofilms↗
PubMed2026

Amplification of RNA for identification of Zika and HCV in whole blood.

Direct RNA amplification from whole blood is fundamentally limited by rapid enzymatic degradation and inhibitory matrix effects. Here, we present a blood drying protocol that enables sensitive and robust RNA detection without the need for extraction, purification, or cold-chain logistics. Using whole blood, the platform achieves high detection sensitivity, down to 10 copies per microliter for Zika virus and 1 international unit per microliter for hepatitis C virus (HCV). We further demonstrate that the protocol can be scaled to larger blood volumes and achieve single-copy sensitivity without any sample loss. This is accomplished through thermal treatments of the sample combined with a primer-limited reverse transcription step, which together stabilize RNA within a dried blood matrix and permit spatially resolved enzymatic amplification. The system supports multiplexed detection from a single sample, enabling simultaneous identification of multiple targets. Separately, we introduce a concept wherein the very few copies of the preserved RNA within the matrix can be accessed repeatedly for molecular analysis. Furthermore, we demonstrated the detection of Zika and HCV using a portable fluorometer for point-of-care (POC) uses. With lyophilized reagents and minimal instrumentation such as a heater and an inexpensive portable fluorometer, this platform enables robust, reusable, and field-deployable diagnostics, advancing toward truly accessible on-site RNA testing in urgent care or low-resource settings from whole blood.

Humans↗
PubMed2007

Use of capillary blood samples as a new approach for diagnosis of Dengue virus infection.

We evaluated the use of capillary blood samples stored on filter papers for diagnosis of dengue virus infection. Venous and capillary blood samples were collected from 130 patients suspected of having dengue fever. We compared the performances of standard reference methods using capillary blood samples absorbed onto filter papers versus venous blood samples. The resulting sensitivity, specificity, and positive predictive value of tests performed on filter paper compared to those performed on venous blood samples were 81.6% (62/76; 95% confidence interval [CI], 74.9% to 88.3%), 90.7% (49/54; 95% CI, 85.7% to 95.7%), and 92.5% (62/67; 95% CI, 86.2% to 98.8%), respectively. During the acute phase of dengue virus infection (day 1 to day 4), the tests performed on capillary blood samples had a sensitivity of 88.5% (95% CI, 82.0% to 95.0%) and a specificity of 93.8% (95% CI, 88.9% to 98.7%). During the convalescent phase of infection, this method allowed the viral serotype to be determined for 4 of 15 (27%) dengue virus-infected patients for whom virological diagnosis using venous samples was negative. Capillary blood samples could therefore be a good alternative for the diagnosis of dengue virus infection in tropical areas. Indeed, these samples are convenient for storage and transport without the need for a cold chain and simplify the collection of samples from children. Moreover, our results suggest that viral particles persist longer in capillary blood than in peripheral blood. Analysis of the viability of viral particles under these conditions may give new insights into the physiopathology of dengue virus infection and the transmission of dengue virus during outbreaks.

Aedes↗
PubMed1988

Stability of St. Louis encephalitis viral antigen detected by enzyme immunoassay in infected mosquitoes.

The use of enzyme immunoassay to detect St. Louis encephalitis (SLE) viral antigen in vector mosquitoes enhances the effectiveness of surveillance because infected mosquitoes can be identified more rapidly than with conventional virus isolation systems and because it is a simple and accessible procedure. Infectivity among mosquitoes experimentally infected with SLE virus was lost within 24 h after the mosquitoes were stored at 27 degrees C and 80% relative humidity; however, viral antigen remained stable under these conditions and could be detected by enzyme immunoassay 2 weeks later. Desiccation further extended the period during which antigen could be detected to 6 weeks. Absorbances were higher in infected mosquitoes stored at 27 degrees C than in mosquitoes frozen continuously. Absorbances in infected mosquitoes also increased after repeated freezing and thawing and sonication. Both phenomena may be related to the release of antigen from decaying or disrupted cells. The relative stability of SLE viral antigen at ambient temperatures lends flexibility to schemes which use direct antigen detection to identify vectors. Surveillance systems can be designed without regard to collecting living mosquitoes, and a cold chain in unnecessary to preserve specimens, thus reducing the cost of surveillance and expanding the geographic areas to which it is accessible.

Animals↗
PubMed2001

Measles vaccine coverage and immune response in children of Caiabi and Metuktire Indian tribes living in malarial endemic area: Parque indígena do Xingu, Central Brazil.

Measles vaccination efficiency was evaluated in children from two Indian tribes - Caiabi and Metuktire - living in the Amazon region, in the Parque Indigena do Xingu (PIX). The population sample, selected at random, made up 37 Caiabi and 28 Metuktire children, aged from 20-75 months (40%). For operational and epidemiological reasons, measles vaccine is given from 6 months of age. The average age of children when they received the vaccine was 11.5 months for the first dose and 20 months for the second. The search for IgG antibodies against measles virus and Plasmodium falciparum was made through immunofluorescence assay (IFA). Measles vaccine coverage has reached 60% at 12 months of age and 92% at 18 months, whereas post-vaccine serum conversion was 95% in Caiabi children (geometric mean of titres (GMT) 126) and 89% in Metuktire (GMT 109). The difference in GMT is not statistically significant. Seventy-three per cent of Caiabi children (GMT 101) and 100% of Metuktire children (GMT135) were plasmodium antibody positive, showing they had been exposed to malarial infection. Despite the differences detected, the immune response to measles vaccine was satisfactory in both groups, with a positive percentage consistent with that achieved in non-malarial areas in Americas. The results show the efficiency of a vaccination programme in an indigenous area despite the difficulties in reaching the villages and maintaining the cold chain, and also despite the malaria endemicity.

Animals↗
PubMed2005

A mass vaccination campaign targeting adults and children to prevent typhoid fever in Hechi; expanding the use of Vi polysaccharide vaccine in southeast China: a cluster-randomized trial.

BACKGROUND: One of the goals of this study was to learn the coverage, safety and logistics of a mass vaccination campaign against typhoid fever in children and adults using locally produced typhoid Vi polysaccharide (PS) and group A meningococcal PS vaccines in southern China. METHODS: The vaccination campaign targeted 118,588 persons in Hechi, Guangxi Province, aged between 5 to 60 years, in 2003. The study area was divided into 107 geographic clusters, which were randomly allocated to receive one of the single-dose parenteral vaccines. All aspects regarding vaccination logistics, feasibility and safety were documented and systematically recorded. Results of the logistics, feasibility and safety are reported. RESULTS: The campaign lasted 5 weeks and the overall vaccination coverage was 78%. On average, the 30 vaccine teams gave immunizations on 23 days. Vaccine rates were higher in those aged < or = 15 years (90%) than in adolescents and young adults (70%). Planned mop-up activities increased the coverage by 17%. The overall vaccine wastage was 11%. The cold chain was maintained and documented. 66 individuals reported of adverse events out of all vaccinees, where fever (21%), malaise (19%) and local redness (19%) were the major symptoms; no life-threatening event occurred. Three needle-sharp events were reported. CONCLUSION: The mass immunization proved feasible and safe, and vaccine coverage was high. Emphasis should be placed on: injection safety measures, community involvement and incorporation of mop-up strategies into any vaccination campaign. School-based and all-age Vi mass immunizations programs are potentially important public health strategies for prevention of typhoid fever in high-risk populations in southern China.

Adolescent↗
PubMed2005

Application of direct agglutination test (DAT) and fast agglutination screening test (FAST) for sero-diagnosis of visceral leishmaniasis in endemic area of Minas Gerais, Brazil.

BACKGROUND: The direct agglutination test (DAT) has proved to be a very important sero-diagnostic tool combining high levels of intrinsic validity and ease of performance. Otherwise, fast agglutination screening test (FAST) utilises only one serum dilution making the test very suitable for the screening of large populations. RESULTS: We have tested FAST and DAT for the detection anti-Leishmania antibodies in serum samples from patients with American visceral (AVL) and cutaneous leishmaniases (ACL) in Minas Gerais State, Brazil. The DAT on serum and blood samples of confirmed AVL patients found all samples positive at a serum dilution of > or = 1:800. This dilution was subsequently used as cut off value in the study. The blood and serum samples of these confirmed patients could also be clearly read in FAST using a 1:100 dilution with the same high sensitivity. DAT and FAST were not able to detect significant amounts of antibodies in samples from ACL patients and are not suitable for the diagnosis of this manifestation of the disease. CONCLUSION: We suggest that both DAT and FAST are very practical diagnostic tools for the sero-diagnosis of AVL under rural conditions as both serological tests do not require sophisticated equipment, a cold chain and are very simple to perform.

Journal Article↗
PubMed2006

Lessons and implications from a mass immunization campaign in squatter settlements of Karachi, Pakistan: an experience from a cluster-randomized double-blinded vaccine trial [NCT00125047].

OBJECTIVE: To determine the safety and logistic feasibility of a mass immunization strategy outside the local immunization program in the pediatric population of urban squatter settlements in Karachi, Pakistan. METHODS: A cluster-randomized double blind preventive trial was launched in August 2003 in 60 geographic clusters covering 21,059 children ages 2 to 16 years. After consent was obtained from parents or guardians, eligible children were immunized parenterally at vaccination posts in each cluster with Vi polysaccharide or hepatitis A vaccine. Safety, logistics, and standards were monitored and documented. RESULTS: The vaccine coverage of the population was 74% and was higher in those under age 10 years. No life-threatening serious adverse events were reported. Adverse events occurred in less than 1% of all vaccine recipients and the main reactions reported were fever and local pain. The proportion of adverse events in Vi polysaccharide and hepatitis A recipients will not be known until the end of the trial when the code is broken. Throughout the vaccination campaign safe injection practices were maintained and the cold chain was not interrupted. Mass vaccination in slums had good acceptance. Because populations in such areas are highly mobile, settlement conditions could affect coverage. Systemic reactions were uncommon and local reactions were mild and transient. Close community involvement was pivotal for information dissemination and immunization coverage. CONCLUSION: This vaccine strategy described together with other information that will soon be available in the area (cost/effectiveness, vaccine delivery costs, etc) will make typhoid fever control become a reality in the near future.

Journal Article↗
PubMedDate not supplied

A novel device for the non-invasive measurement of free hemoglobin in blood bags.

The production of red blood cell concentrates from human donors is a very expensive procedure and human resources are in short supply. Under perfect storage conditions at a temperature of 2-6 degrees C, a blood bag must be used within 35-49 days (in Germany). Visual inspection of the bag for apparent hemolysis by a blood bank physician is a crucial but subjective quality control assessment. Since an interruption of the cold chain cannot be definitely ruled out, bags are often disposed of prematurely for safety reasons. There is currently no method of testing a closed blood bag with respect to hemolysis for its suitability to be used in a transfusion. The proposed optical measuring device is a hemoglobin sensor which determines the free hemoglobin in standard erythrocyte concentrates without opening the bag. The optical measurements are done on the flexible tube connected to the main bag. The optical measurements were evaluated using standard hemoglobin solutions with an accuracy of 0.005 g/dL. These investigations show that in the future each blood bag can be tested non-invasively for its content of free hemoglobin. This will contribute to decreasing the wastage rate of red blood cell concentrates.

Blood Chemical Analysis↗
PubMed2001

Bacterial ghosts as carrier and targeting systems.

Bacterial ghosts are empty cell envelopes originating from Gram-negative bacteria. They have a natural outer surface make-up which provides them with the original targeting functions of the bacteria they are derived from and are thus able to bind to and/or are taken up by specific cells or tissues of animal, human or plant origin. The extended bacterial ghost system represents a platform technology for creating new qualities in non-living carriers which can be used for the specific targeting of drugs, DNA or other compounds to overcome toxic or non-desired obstacles. Freeze dried bacterial ghosts are stable without the requirement of a cold chain and can be effectively administered orally and aerogenically as drug carriers. The new system is an alternative to liposomes and may have an advantage due to its higher specificity for targeting specific tissues, its easy method of production and its versatility in entrapping and packaging various compounds in different compartments of the carriers.

Animals↗
PubMed2006

Bacterial ghosts as a novel advanced targeting system for drug and DNA delivery.

Although there are powerful drugs against infectious diseases and cancer on the market, delivery systems are needed to decrease serious toxic and noncurative side effects. In order to enhance compliance, several delivery systems such as polymeric micro- and nanoparticles, liposomal systems and erythrocyte ghosts have been developed. Bacterial ghosts representing novel advanced delivery and targeting vehicles suitable for the delivery of hydrophobic or water-soluble drugs, are the main focus of this review. They are useful nonliving carriers, as they can carry different active substances in more than one cellular location separately and simultaneously. Bacterial ghosts combine excellent natural or engineered adhesion properties with versatile carrier functions for drugs, proteins and DNA plasmids or DNA minicircles. The simplicity of both bacterial ghost production and packaging of drugs and/or DNA makes them particularly suitable for the use as a delivery system. Further advantages of bacterial ghost delivery vehicles include high bioavailability and a long shelf life without the need of cold-chain storage due to the possibility to freeze-dry the material.

Animals↗
PubMed2006

Noninvasive delivery technologies: respiratory delivery of vaccines.

This paper reviews the developments in noninvasive methods of drug delivery, with a focus on the delivery of vaccines via the respiratory tract. Recent results indicate that the respiratory system, and the nasal mucosa in particular, provide a valuable target site for immunisation against respiratory and mucosal pathogens. Vaccine delivery via the nasal and pulmonary routes each present distinct sets of performance requirements. Current delivery systems in development for both routes are reviewed herein. The storage and respiratory delivery of drugs and vaccines in powder form has been shown to provide improved stability and extended retention time in the respiratory mucosa. These features, in addition to the noninvasive nature of respiratory delivery, can provide benefits to public health vaccination campaigns, facilitating mass vaccination without the high cost of maintaining cold-chain storage.

Administration, Inhalation↗
PubMed2004

Lassa fever vaccine.

Lassa fever remains a serious challenge to public health in West Africa threatening both local residents in rural areas and those who serve them, particularly medical care providers. Given the ecology of the rodent host and conditions in the endemic area, a vaccine is mandatory for control. The challenge is to overcome the scientific, political and economic obstacles to producing a human use vaccine candidate. There are some scientific issues to resolve. It is known that the G-protein confers protection but we do not know its duration. If the N-protein is also included there may be a better duration of protection but it is unclear whether the N-protein as a vaccine may possibly enhance the infection. The original vaccinia vector must be replaced by new vectors, chimeras or by delivering DNA in some format. A live vaccine is attractive because it can confer protection in a single shot. A killed vaccine is more stable, particularly for distribution in the tropics but usually requires repeated shots. For practical reasons a live vaccine format should probably be pursued, which could then be combined with a yellow fever vaccine, using the same cold chains, since this disease occupies the same endemic areas in West Africa. Lassa vaccine initiatives have suffered from a lack of funding in the past but bioterrorism has brought new resources to Lassa virus science. Adequate funding and applications of new vaccine technologies give hope that we may soon see a vaccine in clinical trials. However, the difficulty of conducting trials in endemic areas and lack of political stability remain serious problems.

Africa, Western↗