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Search Results: 1 - 10 of 40 matches for " RICHARDUS KASWADJI "
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Growth and Extracellular Carbonic Anhydrase Activity of Zooxanthellae Symbiodinium sp. in Response of Zinc Enrichment
HAYATI Journal of Biosciences , 2011,
Abstract: Coral reef communities contain a wide variety of mutualistic associations none more important than the relationship between corals and their symbiotic dinoflagellates of the genus Symbiodinium sp., commonly referred to as zooxanthellae. The function of Zinc (Zn) as cofactor of several enzyme systems such as extracellular carbonic anhydrase (extracellular CA) which catalyzes the interconversion of HCO3- and CO2. Concentrations of dissolved Zn in oligothropic waters are often very low therefore may limit the growth of zooxanthellae and their ability to fix CO2 from seawater via the carbonic anhydrase. The aim of this research is to investigate the effect of various concentrations of Zn on the growth and extracellular CA activity in zooxanthellae. Cell density was monitored daily by enumeration with hemocytometer-type chamber (0.1 mm). Extracellular CA was measured in homogenized intact whole cell by a pH drift assay. Results revealed that Zn status strongly influences the growth rate and extracelullar CA activity in zooxanthellae. The specific growth rate and cell density increased two-fold whilst extracelullar CA activity increased 10.5 times higher than that in control with increasing concentrations of Zn from 0 to 80 nM, but decreased when Zn was over 80 nM. Under a concentration of 80 nM was not Zn limited culture, consequently the growth rate of zooxanthellae not dependent on CO2 concentration yet offset by extracelullar CA activity.
Bintang Marhaeni1*, Ocky Karna Radjasa 2, Dietriech G. Bengen1 dan Richardus.F.Kaswadji1
Journal of Coastal Development , 2010,
Abstract: Seagrasses have been known to produce secondary metabolites that have important ecological roles, including preventing from pathogen infections and fouling organisms. A research aimed at screening the potential of bacterial symbionts of seagrass Enhalus sp. was performed. Bacterial symbionts including endophytes and epiphytes were isolated from the seagrass, and marine biofilm-forming bacteria were isolated from the fiber and wooden panels from the surrounding colonies. A total of 17 epiphyte and 6 endophyte isolates were obtained, however more biological activity was found among endophytes (100%) compared to epiphytes (47%) against biofilm-forming bacteria. In addition, bacterial endophytes inhibited more biofilm-forming bacteria than epiphytes. Interestingly more isolates were obtained from rough surfaces both from fiber and wooden panels than smoothe surfaces. Bacterial symbionts of seagrass Enhalus sp., in particular its endophytes show potential source as natural marine antifoulants
Monitoring of risk perceptions and correlates of precautionary behaviour related to human avian influenza during 2006 - 2007 in the Netherlands: results of seven consecutive surveys
Onno de Zwart, Irene K Veldhuijzen, Jan Richardus, Johannes Brug
BMC Infectious Diseases , 2010, DOI: 10.1186/1471-2334-10-114
Abstract: Seven web-based surveys were conducted including 3,840 respondents over a one-year period. Time trends were analyzed with linear regression analyses. Multivariate analysis was used to study determinants of precautionary behaviour.While infection with AI was considered a very severe health problem with mean score of 4.57 (scale 1 - 5); perceived vulnerability was much lower, with a mean score of 1.69. While perceived severity remained high, perceived vulnerability decreased slightly during a one-year period covering part of 2006 and 2007. Almost half of the respondents (46%) reported taking one or more preventive measures, with 36% reporting to have stayed away from (wild) birds or poultry. In multivariate logistic regression analysis the following factors were significantly associated with taking preventive measures: time of the survey, higher age, lower level of education, non-Dutch ethnicity, vaccinated against influenza, higher perceived severity, higher perceived vulnerability, higher self efficacy, lower level of knowledge, more information about AI, and thinking more about AI. Self efficacy was a stronger predictor of precautionary behaviour for those who never or seldom think about AI (OR 2.3, 95% CI 1.9 - 2.7), compared to those who think about AI more often (OR 1.5, 95% CI 1.2 - 1.9).The fact that perceived severity of AI appears to be high and remains so over time offers a good point of departure for more specific risk communications to promote precautionary actions. Such communications should aim at improving knowledge about the disease and preventive actions, and focus on perceived personal vulnerability and self efficacy in taking preventive measures.Infectious diseases are once again among the major public health challenges. The SARS epidemic of 2003 showed not only that there are new unknown viruses which can have severe health consequences, but also made clear how fast a disease can spread globally, what the societal and economic impact can be, as we
The spatial distribution of leprosy cases during 15 years of a leprosy control program in Bangladesh: An observational study
EAJ Fischer, D Pahan, SK Chowdhury, JH Richardus
BMC Infectious Diseases , 2008, DOI: 10.1186/1471-2334-8-126
Abstract: The houses of 11,060 leprosy cases registered in the control area during a 15-year period (1989–2003) were traced back, added to a geographic database (GIS), and plotted on digital maps. We looked for clusters of cases in space and time. Furthermore, relationships with the proximity to geographic features, such as town center, roads, rivers, and clinics, were studied.Several spatio-temporal clusters were observed for voluntarily reported cases. The cases within and outside clusters did not differ in age at detection, percentage with multibacillary leprosy, or sex ratio. There was no indication of the spread from one point to other parts of the district, indicating a spatially stable endemic situation during the study period. The overall risk of leprosy in the district was not associated with roads, rivers, and leprosy clinics. The risk was highest within 1 kilometer of town centers and decreased with distance from town centers.The association of a risk of leprosy with the proximity to towns indicates that rural towns may play an important role in the epidemiology of leprosy in this district. Further research on the role of towns, particularly in rural areas, is warranted.New cases of leprosy are currently found primarily in tropical regions [1,2], but the distribution within these regions is not uniform. Sixty eight percent of newly detected cases in 2005 were found in Southeast Asia, 80% of which were detected in India. In the same year, another 13% of all cases worldwide were found in Brazil. The Southeast Asian region and Brazil together accounted for 81% of all cases of leprosy detected in 2006 [2].Within highly endemic regions, the occurrence of leprosy is also not uniformly distributed [3-5]. The distribution of leprosy in the Brazilian state of Ceará reflects socioeconomic differences within the state [4,6], whereas the explanation for the uneven distribution in another Brazilian state, S?o Paulo thought to be migratory movement towards the urban and developi
The spatial distribution of leprosy in four villages in Bangladesh: An observational study
EAJ Fischer, D Pahan, SK Chowdhury, L Oskam, JH Richardus
BMC Infectious Diseases , 2008, DOI: 10.1186/1471-2334-8-125
Abstract: Using geographic information systems, we created digital maps of four villages in a highly endemic area in northwest Bangladesh. The villages were surveyed three times over four years. The spatial pattern of the compounds – a small group of houses – was analyzed, and we looked for spatial clusters of leprosy cases.The four villages had a total population of 4,123. There were 14 previously treated patients and we identified 19 new leprosy patients during the observation period. However, we found no spatial clusters with a probability significantly different from the null hypothesis of random occurrence.Spatial analysis at the microlevel of villages in highly endemic areas does not appear to be useful for identifying clusters of patients. The search for clustering should be extended to a higher aggregation level, such as the subdistrict or regional level. Additionally, in highly endemic areas, it appears to be more effective to target complete villages for contact tracing, rather than narrowly defined contact groups such as households.Identifying individuals with increased exposure to Mycobacterium leprae, the causative agent of leprosy, enhances the possibility of prevention or early diagnosis. Several studies have shown that household members and neighbors have an increased risk of leprosy [1-3], making them desirable targets for interventions such as preventive treatment [2,4]. A study in Indonesia identified spatial clusters of cases on islands with extremely high incidence [1]. Spatial information can be used to improve the discovery of new cases and other interventions in high incidence areas [5].In the Nilphamari district in Bangladesh, household members and close neighbors have an increased risk of contracting leprosy when compared with neighbors of neighbors and social contacts [2]. However, new cases among neighbors of neighbors and social contacts were still over three times more likely than in the general population [2,6]. Because neighbors of neighbors an
The severe acute respiratory syndrome epidemic in mainland China dissected
Wuchun Cao,Sake J. De Vlas,Jan H. Richardus
Infectious Disease Reports , 2011, DOI: 10.4081/idr.2011.e2
Abstract: This paper provides a review of a recently published series of studies that give a detailed and comprehensive documentation of the severe acute respiratory syndrome (SARS) epidemic in mainland China, which severely struck the country in the spring of 2003. The epidemic spanned a large geographical extent but clustered in two areas: first in Guangdong Province, and about 3 months later in Beijing with its surrounding areas. Reanalysis of all available epidemiological data resulted in a total of 5327 probable cases of SARS, of whom 343 died. The resulting case fatality ratio (CFR) of 6.4% was less than half of that in other SARS-affected countries or areas, and this difference could only partly be explained by younger age of patients and higher number of community acquired infections. Analysis of the impact of interventions demonstrated that strong political commitment and a centrally coordinated response was the most important factor to control SARS in mainland China, whereas the most stringent control measures were all initiated when the epidemic was already dying down. The long-term economic consequence of the epidemic was limited, much consumption was merely postponed, but for Beijing irrecoverable losses to the tourist sector were considerable. An important finding from a cohort study was that many former SARS patients currently suffer from avascular osteo-necrosis, as a consequence of the treatment with corticosteroids during their infection. The SARS epidemic provided valuable information and lessons relevant in controlling outbreaks of newly emerging infectious diseases, and has led to fundamental reforms of the Chinese health system. In particular, a comprehensive nation-wide internet-based disease reporting system was established.
Behavioral and Psychosocial Interventions for HIV Prevention in Floating Populations in China over the Past Decade: A Systematic Literature Review and Meta-Analysis
Xiaona Liu, Vicki Erasmus, Qing Wu, Jan Hendrik Richardus
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0101006
Abstract: Background Floating populations have been repeatedly characterized as “the tipping point” for the HIV epidemic in China. This study aims to systematically summarize and assess the effectiveness of HIV prevention interventions in floating populations in China over the past decade. Methods We conducted a systematic search in three international databases for literature published between 2005 and 2012 with condom use as the primary outcome, and knowledge about HIV transmission and prevention and stigma towards HIV-infected individuals as secondary outcomes. The impact of interventions on changing the primary and secondary outcomes was calculated by risk difference (RD). We also performed subgroup analyses and meta-regression based on different study characteristics, using Stata 12.0, for the primary outcome. Results Sixteen studies (out of 149) involved 19 different programs and a total of 10,864 participants at entry from 11 provinces in China. The pooled effect estimate of all studies indicated that people participating in HIV-related interventions were 13% more likely to use condoms (95%CI: 0.07, 0.18), however, the effects on increasing condom use exhibited significant heterogeneity across programs (P<0.01, I2 = 0.93). The meta-regression results suggest that interventions have been significantly less successful in changing condom use in more recent studies (β, 0.14; 95%CI: 0.01, 0.27), adjusted for sexual relationship, study design and follow-up period. Regarding the secondary outcomes, HIV-related interventions were successful at improving knowledge about HIV transmission and prevention (RD, ?0.26; 95%CI: ?0.36, ?0.16 and RD, ?0.25; 95%CI: ?0.33, ?0.16, respectively), and decreasing stigma (RD, 0.18; 95%CI: 0.09, 0.27). Conclusions The included studies between 2005 and 2012 indicate that HIV prevention interventions among Chinese floating populations in the past decade were only marginally effective at increasing condom use, but relatively successful at increasing HIV knowledge and decreasing stigma. To avert new infections, novel sexual risk-reduction interventions taking into account the changing socio-economic and cultural situation of Chinese floating populations are urgently needed.
Two Immigrants with Tuberculosis of the Ear, Nose, and Throat Region with Skull Base and Cranial Nerve Involvement
Renate A. Richardus,Jeroen C. Jansen,Stefan C. A. Steens,Sandra M. Arend
Case Reports in Medicine , 2011, DOI: 10.1155/2011/675807
Abstract: We report two immigrants with tuberculosis of the skull base and a review of the literature. A Somalian man presented with bilateral otitis media, hearing loss, and facial and abducens palsy. Imaging showed involvement of both mastoid and petrous bones, extending via the skull base to the nasopharynx, suggesting tuberculosis which was confirmed by characteristic histology and positive auramine staining, while Ziehl-Neelsen staining and PCR were negative. A Sudanese man presented with torticollis and deviation of the uvula due to paresis of N. IX and XI. Imaging showed a retropharyngeal abscess and lysis of the clivus. Histology, acid-fast staining, and PCR were negative. Both patients had a positive Quantiferon TB Gold in-tube result and improved rapidly after empiric treatment for tuberculosis. Cultures eventually yielded M. tuberculosis. These unusual cases exemplify the many faces of tuberculosis and the importance to include tuberculosis in the differential diagnosis of unexplained problems.
Preventing Nerve Function Impairment in Leprosy: Validation and Updating of a Prediction Rule
Ron P. Schuring,Jan H. Richardus,Ewout W. Steyerberg,David Pahan,William R. Faber,Linda Oskam
PLOS Neglected Tropical Diseases , 2008, DOI: 10.1371/journal.pntd.0000283
Abstract: Background To validate and update a prediction rule for estimating the risk of leprosy-related nerve function impairment (NFI). Methodology/Principal Findings Prospective cohort using routinely collected data, in which we determined the discriminative ability of a previously published rule and an updated rule with a concordance statistic (c). Additional risk factors were analyzed with a Cox proportional hazards regression model. The population consisted of 1,037 leprosy patients newly diagnosed between 2002 and 2003 in the health care facilities of the Rural Health Program in Nilphamari and Rangpur districts in northwest Bangladesh. The primary outcome was the time until the start of treatment. An NFI event was defined as the decision to treat NFI with corticosteroids after diagnosis. NFI occurred in 115 patients (13%; 95% confidence interval 11%–16%). The original prediction rule had adequate discriminative ability (c = 0.79), but could be improved by substituting one predicting variable: ‘long-standing nerve function impairment at diagnosis’ by ‘anti-PGL-I antibodies’. The adjusted prediction rule was slightly better (c = 0.81) and identified more patients with NFI (80%) than the original prediction rule (72%). Conclusions/Significance NFI can well be predicted by using the risk variables ‘leprosy classification’ and ‘anti-PGL-I antibodies’. The use of these two variables that do not include NFI offer the possibility of predicting NFI, even before it occurs for the first time. Surveillance beyond the treatment period can be targeted to those most likely to benefit from preventing permanent disabilities.
The Long Term Effect of Current and New Interventions on the New Case Detection of Leprosy: A Modeling Study
Egil A. J. Fischer,Sake J. de Vlas,J. Dik F Habbema,Jan Hendrik Richardus
PLOS Neglected Tropical Diseases , 2011, DOI: 10.1371/journal.pntd.0001330
Abstract: Background Although the number of newly detected leprosy cases has decreased globally, a quarter of a million new cases are detected annually and eradication remains far away. Current options for leprosy prevention are contact tracing and BCG vaccination of infants. Future options may include chemoprophylaxis and early diagnosis of subclinical infections. This study compared the predicted trends in leprosy case detection of future intervention strategies. Methods Seven leprosy intervention scenarios were investigated with a microsimulation model (SIMCOLEP) to predict future leprosy trends. The baseline scenario consisted of passive case detection, multidrug therapy, contact tracing, and BCG vaccination of infants. The other six scenarios were modifications of the baseline, as follows: no contact tracing; with chemoprophylaxis; with early diagnosis of subclinical infections; replacement of the BCG vaccine with a new tuberculosis vaccine ineffective against Mycobacterium leprae (“no BCG”); no BCG with chemoprophylaxis; and no BCG with early diagnosis. Findings Without contact tracing, the model predicted an initial drop in the new case detection rate due to a delay in detecting clinical cases among contacts. Eventually, this scenario would lead to new case detection rates higher than the baseline program. Both chemoprophylaxis and early diagnosis would prevent new cases due to a reduction of the infectious period of subclinical cases by detection and cure of these cases. Also, replacing BCG would increase the new case detection rate of leprosy, but this effect could be offset with either chemoprophylaxis or early diagnosis. Conclusions This study showed that the leprosy incidence would be reduced substantially by good BCG vaccine coverage and the combined strategies of contact tracing, early diagnosis, and treatment of infection and/or chemoprophylaxis among household contacts. To effectively interrupt the transmission of M. leprae, it is crucial to continue developing immuno- and chemoprophylaxis strategies and an effective test for diagnosing subclinical infections.
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