Excitation dynamics in Photosystem I trapped in TiO2 mesopores.

Excitation decay in closed Photosystem I (PSI) isolated from cyanobacterium Synechocystis sp. PCC 6803 and dissolved in a buffer solution occurs predominantly with a ~ 24-ps lifetime, as measured both by time-resolved fluorescence and transient absorption. The same PSI particles deposited in mesoporous matrix made of TiO2 nanoparticles exhibit significantly accelerated excitation decay dominated by a ~ 6-ps component. Target analysis indicates that this acceleration is caused by ~ 50% increase of the rate constant of bulk Chls excitation quenching. As an effect of this increase, as much as ~ 70% of bulk Chls excitation is quenched before the establishment of equilibrium with the red Chls. Accelerated quenching may be caused by increased excitation trapping by the reaction center and/or quenching properties of the TiO2 surface directly interacting with PSI Chls. Also properties of the PSI red Chls are affected by the deposition in the TiO2 matrix: they become deeper traps due to an increase of their number and their oscillator strength is significantly reduced. These effects should be taken into account when constructing solar cells' photoelectrodes composed of PSI and artificial matrices.

[PCR-based diagnosis of mucormycosis in tissue samples]. / PCR-Diagnostik von Mukormykosen aus Gewebeschnitten.

Mucormycosis is characterized by a rapid, often fatal progression. Early diagnosis of invasive mucormycosis is the key for timely therapeutic intervention and improved survival. Contrary to the more prevalent aspergillosis, effective antifungal therapy of mucormycosis is mainly limited to amphotericin B. Given the importance to guide the timely initiation of amphotericin B and possible surgical intervention, rapid and specific identification of fungal hyphae is essential. Conventional histopathology depends on abundance and morphology of the fungi as well as on the skills of the personnel, and usually shows an accuracy of 80 %. PCR assays targeting fungal ribosomal genes to identify Mucorales at least at genus level increase sensitivity, allow a rapid identification as well as detection of double mold infections. Thus, PCR assays are beneficial to complement existing approaches. They are recommended to rapidly specify tissue diagnosis and accurate identification of fungi. This will help to guide effective therapy and thereby, survival will increase. Retrospective analyses of mucormycosis by PCR help to evaluate therapeutic interventions and will optimize treatment options.

Antagonistic Effects of Point Mutations on Charge Recombination and a New View of Primary Charge Separation in Photosynthetic Proteins.

Light-induced electron-transfer reactions were investigated in wild-type and three mutant Rhodobacter sphaeroides reaction centers with the secondary electron acceptor (ubiquinone QA) either removed or permanently reduced. Under such conditions, charge separation between the primary electron donor (bacteriochlorophyll dimer, P) and the electron acceptor (bacteriopheophytin, HA) was followed by P+HA- → PHA charge recombination. Two reaction centers were used that had different single amino-acid mutations that brought about either a 3-fold acceleration in charge recombination compared to that in the wild-type protein, or a 3-fold deceleration. In a third mutant in which the two single amino-acid mutations were combined, charge recombination was similar to that in the wild type. In all cases, data from transient absorption measurements were analyzed using similar models. The modeling included the energetic relaxation of the charge-separated states caused by protein dynamics and evidenced the appearance of an intermediate charge-separated state, P+BA-, with BA being the bacteriochlorophyll located between P and HA. In all cases, mixing of the states P+BA- and P+HA- was observed and explained in terms of electron delocalization over BA and HA. This delocalization, together with picosecond protein relaxation, underlies a new view of primary charge separation in photosynthesis.

PCR based identification and discrimination of agents of mucormycosis and aspergillosis in paraffin wax embedded tissue.

BACKGROUND: Invasive fungal infections are often diagnosed by histopathology without identification of the causative fungi, which show significantly different antifungal susceptibilities. AIMS: To establish and evaluate a system of two seminested polymerase chain reaction (PCR) assays to identify and discriminate between agents of aspergillosis and mucormycosis in paraffin wax embedded tissue samples. METHODS: DNA of 52 blinded samples from five different centres was extracted and used as a template in two PCR assays targeting the mitochondrial aspergillosis DNA and the 18S ribosomal DNA of zygomycetes. RESULTS: Specific fungal DNA was identified in 27 of 44 samples in accordance with a histopathological diagnosis of zygomycosis or aspergillosis, respectively. Aspergillus fumigatus DNA was amplified from one specimen of zygomycosis (diagnosed by histopathology). In four of 16 PCR negative samples no human DNA was amplified, possibly as a result of the destruction of DNA before paraffin wax embedding. In addition, eight samples from clinically suspected fungal infections (without histopathological proof) were examined. The two PCR assays detected a concomitant infection with Absidia corymbifera and A fumigatus in one, and infections with Rhizopus arrhizus and A fumigatus in another two cases. CONCLUSIONS: The two seminested PCR assays described here can support a histopathological diagnosis of mucormycosis or aspergillosis, and can identify the infective agent, thereby optimising antifungal treatment.

Eosinophilic meningomyelitis in toxocariasis: case report and review of the literature.

Toxocariasis is a worldwide-occurring parasitic infection leading to tissue damage in various organs due to wandering Toxocara larvae (visceral larva migrans). More than 40 cases of CNS involvement in children and immunocompetent adults have been documented in detail to date. Here, we present evidence of eosinophilic meningomyelitis in an adult without known risk factors and with positive Toxocara antibody response in CSF, but not in blood. Toxocariasis has to remain among the differential diagnosis in patients with eosinophilic CNS infection even if serological tests in blood are negative. Adult cases seem to be more frequent than previously thought (about 60%).

A fluorometric assay to monitor mitogenic stimulation of human lymphocytes.

A fluorometric assay using Hoechst 33342 to measure DNA in cell culture has been applied to detect mitogenic stimulation of human lymphocytes. Mononuclear cells from the peripheral blood of healthy donors and of HIV infected patients were stimulated with mitogens (PHA and ConA, respectively) in serum-free culture medium (5 x 10(4) or 1 x 10(5) cells/well) and incubated with Hoechst 33342. Fluorescence intensities were read using an automated fluorescence reader against the dye solution as a blank. The stimulation index (fluorescence units of stimulated vs. unstimulated cell culture) was calculated and compared to the stimulation index obtained in the [3H]thymidine assay. A sensitivity of 94.6% and a specificity of 97.4% was observed for the fluorometric assay. The intra-assay variability (12.3-15.6%) and the interassay variability (9.6-21.8%) were calculated using 1 x 10(5) cells/culture for PHA stimulation. We recommend the inexpensive and rapid fluorometric Hoechst 33342 assay as an alternative procedure, for monitoring mitogen induced stimulation of human lymphocytes in the diagnosis of immunodeficiencies.

Common surface epitope of Bartonella bacilliformis and Chlamydia psittaci.

A serosurvey revealed intense cross-reactivity between Bartonella bacilliformis and Chlamydia psittaci. One of the cross-reacting Bartonella antigens was identified as lipopolysaccharide which reacted with Bartonella as well as with Chlamydia serum antibodies. A monoclonal Bartonella antibody bound to Bartonella lipopolysaccharide as well as to the surfaces of Bartonella bacilliformis and Chlamydia psittaci. It was thus demonstrated that Chlamydia psittaci carries a surface epitope identical to an epitope of Bartonella lipopolysaccharide. The lipopolysaccharide was preliminarily characterized by polyacrylamide gel electrophoresis and by a lectin-binding assay. The lipopolysaccharides of Bartonella bacilliformis and Chlamydia psittaci are not identical.

Case report: Nitazoxanide treatment failure in chronic isosporiasis.

We report a 60-year-old immunocompetent patient with chronic biliary isosporiasis who failed to respond to orally administered cotrimoxazole prophylaxis and orally administered treatment with nitazoxanide, a 5-nitrothiazole benzamide compound. Severe malabsorption was regarded as responsible for the subtherapeutic levels of nitazoxanide in plasma and bile, resulting in treatment failure. Intravenously administered cotrimoxazole stopped the shedding of Isospora belli oocysts in bile within 5 days, excluding initially suspected resistance to cotrimoxazole. Patients with malabsorption and cholangitis due to Coccidia such as Isospora belli and Cryptosporidium spp. or due to protozoa that cause microsporidiasis seem to be predisposed to fail to respond to otherwise effective treatment.

Shaping public policy from the perspective of a data builder.

During the past six decades, data analysis and research studies have been instrumental in shaping public and private health care policy. Policymakers obtain the knowledge they need for making policy decisions through exposure to and examination of data generated through research studies, experimentation, demonstrations, and analyses. In this article, U.S. hospital care policy has been divided into phases. As the development of health care policy has progressed in each phase, decisionmakers have consistently increased their reliance on data.

Aspergillus antigen and PCR assays in bone marrow transplanted children.

Screening for Aspergillus antigen and DNA has been introduced for the early diagnosis of invasive aspergillosis (IA) in adults, but data in children at risk are scarce. Seventeen 1-108 month-old children were screened for Aspergillus antigenaemia by a commercial assay before and after bone marrow transplantation (BMT). Seventy-one serum samples were examined retrospectively by a novel nested PCR assay. Results of both assays were correlated with clinical, radiological and microbiological findings used for the definition of invasive aspergillosis by the European Organisation for Research and Treatment of Cancer (EORTC). Three cases of probable or possible IA were defined, and in 14 children invasive aspergillosis was ruled out. In 10 children, Aspergillus antigen was detected in at least two consecutive serum samples, a microbiological EORTC criteria of IA. Specific DNA was detected in 8 antigen-positive and 2 antigen-negative sera. A positive predictive value of 20% was calculated for both assays. Hence, a high rate of positive results of antigen Elisa and PCR assays in BMT children are due to transient antigenaemia and fungaemia without clinical relevance. According to our data, prospective studies in well defined pediatric patients are urgently needed to determine the value of serial Aspergillus PCR assays for the early diagnosis of invasive aspergillosis in children at risk.

Comparison of viability assays for Cryptosporidium parvum oocysts after disinfection.

In order to test various viability assays for Cryptosporidium parvum oocysts were used to infect HCT-8 cells in vitro or baby mice. Infected cells were either stained with fluorescent anti-Cryptosporidium-antibody or lysed and subjected to C. parvum-specific PCR after 48 h. Titrations with infective oocysts were performed and compared to oocysts disinfected with Neopredisan for 2 h at varying concentrations. Caecal smears and histological sections from infected animals were examined in parallel. The number of foci of parasite development in vitro after immunofluorescent staining correlated well with the infection dose. PCR was less quantifiable and the results were not always reproducible, especially when low infection doses were used. Disinfection resulted in a dose-dependent reduction of oocyst infectivity when compared to the controls in all three assays. The infection of cells cultured in vitro with oocysts of C. parvum provides a suitable tool for the estimation of viability after treatment with chemical disinfectants. Immunofluorescence is easy to perform and gives quantitative results, while PCR-based detection of parasite DNA, although possible, requires the use of more sophisticated tools for quantification.

[Headache after a stay in the Dominican Republic]. / Kopfschmerzen nach Aufenthalt in der Dominikanischen Republik.

CASE HISTORY: In a 27-year-old female German patient severe headache and wandering paresthesias appeared one week after returning from a holiday in the Dominican Republic. After 3 weeks of ongoing symptoms she was admitted to our hospital with the suspicion of an inflammatory or infectious disease of the central nervous system. Upon admission slight stiffness of the neck, fever (38.2 C) and paresthesias of the right elbow and the right thigh were noticed. LABORATORY FINDINGS: Cerebrospinal fluid (CSF) revealed an eosinophilic pleocytosis. In the acute phase of the disease, antibodies against nematodes were found in CSF, without corresponding antibody-reactivity in serum. In the course levels of nematode antibodies in CSF increased and antibody-reactivity in serum was observed. Thorough investigation for other infectious or inflammatory causes of eosinophilic meningitis revealed no abnormalities. DIAGNOSIS, TREATMENT AND COURSE: Symptoms, onset within the typical incubation period and the eosinophilic meningitis lead to the diagnosis of a suspected Angiostrongyliasis. Successful treatment was achieved with a combination of oral albendazole and corticosteroids given for 4 weeks. CONCLUSION: Infection with larvae of Angiostrongylus cantonensis is one of the main causes of eosinophilic meningitis worldwide. Human infection can occur after ingestion of intermediate hosts or contaminated vegetables. Angiostrongyliasis has been endemic to Southeast Asia and the Pacific Basin and only recently cases from the Caribbean have been described. Headache, paresthesias and the finding of an eosinophilic meningitis in patients returning from tropical or subtropical regions should lead to the suspicion and eventually the treatment of an Angiostrongyliasis.

Successful treatment of disseminated mucormycosis with a combination of liposomal amphotericin B and posaconazole in a patient with acute myeloid leukaemia.

The combination of resection of infected tissue and antifungal therapy is the treatment of choice in mucormycosis. In disseminated mucormycosis, where surgery is impossible, the mortality is almost 90%. We report the first case of disseminated mucormycosis that was cured with a combination therapy of liposomal amphotericin B and posaconazole without surgical intervention.

Diagnosis of invasive aspergillosis and mucormycosis in immunocompromised patients by seminested PCR assay of tissue samples.

Aspergillosis and mucormycosis are the most common mold infections in patients with hematological malignancies. Infections caused by species of the genus Aspergillus and the order Mucorales require different antifungal treatments depending on the in vitro susceptibility of the causative strain. Cultures from biopsy specimens frequently do not grow fungal pathogens, even from histopathologically proven cases of invasive fungal infection. Two seminested PCR assays were evaluated by amplifying DNA of zygomycetes and Aspergillus spp. from organ biopsies of 21 immunocompromised patients. The PCR assays correctly identified five cases of invasive aspergillosis and six cases of mucormycosis. They showed evidence of double mold infection in two cases. Both assays were negative in five negative controls and in two patients with yeast infections. Sequencing of the PCR products was in accordance with culture results in all culture-positive cases. In six patients without positive cultures but with positive histopathology, sequencing suggested a causative organism. Detection of fungal DNA from biopsy specimens allows rapid identification of the causative organism of invasive aspergillosis and mucormycosis. The use of these PCR assays may allow guided antifungal treatment in patients with invasive mold infections.

[Parasitic diseases in pediatric cancer patients]. / Parasitosen bei pädiatrisch-onkologischen Patienten.

Parasitic infections are rare events in pediatric oncology. Transmission routes and diseases of most parasites do not differ significantly from those seen in otherwise healthy children. However, latent asymptomatic infections with Cryptosporidium spp., Leishmania spp., Strongyloides stercoralis and Toxoplasma gondii might exacerbate during immunosuppression. Screening in asymptomatic patients is often unsuccessful due to the low sensitivity of available assays except in toxoplasmosis. This article provides the recommendations of the Infectious Diseases Working Party of the German Society for Pediatric Infectious Diseases (DGPI) and the German Society for Pediatric Hematology/Oncology (GPOH) for the appropriate diagnostic procedures and antiparasitic treatment immunocompromised patients.

Building the science base for public health practice.

This article explores the need for and current state of the science base in public health practice. In addition, it discusses how the National Public Health Performance Standards Program will help build the science base in the future and how this can have a positive effect on public health practice and community health status.

A decade of progress in academic/practice linkages.

Almost a decade has passed since the release of recommendations of the Public Health Faculty/Agency Forum, a national effort designed to expand academic/practice linkages. Has anyone really cared? Has anything really changed? Indeed, the academic community in particular has responded by integrating more public health practice into teaching, research, and service. This article explores where progress has been made and where continuing efforts still are needed. In addition, potential ways to continue enhancing academic/practice linkages are discussed.

Schistosomiasis in German children.

UNLABELLED: Reports on schistosomiasis in children growing up in Europe are rare despite increased travel activity. We report on eight male and three female German children aged 50 months to 15 years with schistosomiasis. Six children were asymptomatic, whereas two presented with typical signs of Katayama fever. Persisting haematuria, headache with eosinophilia and pyelonephritis were observed in one child each. An exposure was reported for six of the children. Two were examined solely because schistosomiasis was diagnosed in a family member. All had antibodies against schistosomal antigens in at least two of three screening tests. However, schistosomal ova (Schistosoma haematobium) were detected in urine and faecal specimens from only three children. A tumour-like lesion of the bladder was found by ultrasound in only one of the children who also exhibited haematuria. Neither eosinophilia nor elevated IgE levels were constant findings. Six to 12 months after praziquantel treatment, parasitological and ultrasound checks were negative and levels of specific antibodies decreased. However, 2 years later, elevated antibody levels were detected in one girl without evidence of any new exposure. She became antibody-negative 1 year after a second course of treatment. CONCLUSION: In contrast to residents of endemic areas, parasitological and ultrasound examinations seem to be inferior to immunodiagnostics in children from non-endemic areas at temporary risk for schistosomiasis.