Impact of UV radiation on DOM transformation on molecular level using FT-ICR-MS and PARAFAC.

Dissolved organic matter (DOM) is an omnipresent constituent of natural water bodies. Reuse and transformation of DOM compounds in the water column is driven by physicochemical and biological processes leading to the production of refractory DOM. Typically, breakdown of DOM chemical compounds into smaller or more condensed fragments is triggered by ultraviolet (UV) radiation. Here, we present a study on the photodegradation of DOM produced during an incubation experiment with a natural microbial community. At the end of the first incubation without UV irradiation, the samples from 3 mesocosms were filtered to remove microbes and particles and continuously exposed to UV radiation (280-365 nm). We investigated DOM in depth via monitoring of dissolved organic carbon (DOC) concentrations, DOM molecular characterization by Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) and excitation emission matrix spectroscopy (EEMS). Analysis of variance indicated no significant differences in the DOC concentration between treatments. Main peaks in the fluorescent DOM (FDOM) were photo-bleached by UV radiation, and an increase in the fluorescent intensity of selected peaks was observed on irradiated samples toward the end of the experiment. Parallel factor analysis (PARAFAC) indicated the presence of three main components in all treatments: C1 (Marine humic M), C2 (Bacterial produced humic C), C3 (Tyrosine), and an additional component in the dark incubation of mesocosm 3, C4 (Tryptophan). Despite an intensive filtration protocol through 0.7, 0.2 and 0.1 µm filters, low bacterial abundances were determined (<2.5 × 10-3 cells mL-1). We observed a direct correlation between structural indices and the intensity of PARAFAC components. Average double bond equivalent and aromaticity were strongly positively correlated with PARAFAC components C1 and C2 for one or more mesocosm. Moreover, FT-ICR-MS showed that under the tested conditions, the refractory character of the DOM assessed as the similarity to a deep ocean DOM reference did not increase on molecular level. Thus, mechanisms other than photochemical transformations of relatively recent DOM are likely necessary to facilitate long-term stability of DOM in the oceans.

The pattern of malaria infection in under-fives in Ile-Ife, Nigeria.

Over 90% of the burden of malaria occurs in sub-Saharan Africa. Children, especially under-fives, are the most vulnerable. In Nigeria, Africa's most populous nation, it accounts for 25 and 30% of infant and childhood deaths, respectively. One hundred and seventy-six children who fulfilled clinical and parasitological criteria for the diagnosis of malaria, 26.4% of all under-fives, who presented to the Seventh Day Adventist Hospital in Ile-Ife during the months of May to September 2005 were studied to identify the factors that were associated with severe malaria in the target population. The proportion of children with severe malaria in the study was 17%, while the case-fatality rate was 3.5%. Of the 17 variables examined, high malaria parasite density, non-use of mosquito-bite preventive measures and poverty remained independently and significantly associated with an increased risk for severe malaria. Progress in stemming the burden of malaria depends on accurate knowledge and understanding of the epidemiology and control of the disease in the affected populations.

Anemia in young children of the Muynak District of Karakalpakistan, Uzbekistan: prevalence, type, and correlates.

OBJECTIVES: This study examined prevalence and correlates of anemia in the Muynak District of Uzbekistan, an area of rapidly changing social and economic conditions following the collapse of the Soviet Union. METHODS: Questionnaire data and blood samples were collected on a random sample of 433 children aged 1 through 4 years. RESULTS: The prevalence of anemia ranged from 89% in 1-year-olds to 48% in 4-year-olds. Correlates for anemia included younger age, a communal water source, and a history of pica. CONCLUSIONS: Anemia is a widespread problem in young children in this district. An aggressive attempt to reverse this problem is needed.

An analysis of 2846 industrial illnesses and injuries seen in a family practice.

We analyzed 2846 industrial illnesses and injuries in 2430 patients seen in a family practice with a large occupational medicine component over a three-and-a-half-year period. Of the 268 medical diagnoses made, back injuries and cumulative trauma disorders to the upper extremities comprised the majority. A large number of pesticide and chemical exposures were also seen. Consultations were obtained in 16.7% of the cases and 61.7% of the cases were closed as resolved. There were 17 patients hospitalized and no deaths. We recommend that family practice residents be trained in the procedures and laws of the workers' compensation system as well as in treating specific occupational health problems.