Inulin crystal initiation via a glucose-fructose cross-link of adjacent polymer chains: atomic force microscopy and static molecular modelling.

Semi-crystalline microparticles of inulin (MPI) have clinical utility as potent human vaccine adjuvants but their relevant surface structure and crystal assembly remain undefined. We show inulin crystal surfaces to resemble multi-layered, discoid radial spherulites resulting from very rapid formation of complex tertiary structures, implying directed crystal initiation. Physical and in silico molecular modelling of unit cells confirm steric feasibility of initiation by hydrogen-bonded cross-linking of terminal glucose to a fructose of another chain, mimicking bonding in sucrose crystals. A strong, chelate-like dual H-bond is proposed to compel the known antiparallel alignment of inulin chains. Such cross-linking would require one extra fructose per chain in the native inulin crystal, as observed. Completion of five H-bonded internal ring-domains would 'lock in' each new 6-fructose structural unit of each antiparallel helix pair to create a new isoform. All known properties of inulin isoforms follow readily from these concepts.

Banking North American buffalo semen.

The purpose of this study was to develop a procedure to collect and preserve semen from wood bison (Bison bison athabascae) and plains bison (Bison bison bison). Semen samples from three wood and three plains bison bulls were collected by electroejaculation from June through October. In addition, sperm was collected from the cauda epididymis of seven plains bison. Semen was cryopreserved using two commercially available cryopreservation media, an egg yolk-based medium (Triladyl), and a medium free of products of animal origin (Andromed). Sperm morphology and motility were recorded on fresh and post-thawed semen samples. Total sperm motility was not different between plains and wood bison for the months of June (50%), July (69%) and October (54%). However, total sperm motility for wood bison was higher (P<0.05) than plains bison for the months of August and September (August: 80% vs 55%; September: 73% vs 40%). Plains and wood bison did not differ in mean total and mean progressive motility (35 and 15%, respectively) of frozen-thawed sperm samples. The post-thaw motility of Triladyl-treated sperm was higher (P<0.05) than Andromed-treated sperm (35% vs 13%, respectively). Interestingly, post-thawed epididymal spermatozoa had higher total motility (P<0.05) than post-thawed electroejaculated sperm when cryopreserved with a medium free of products of animal origin (Andromed; 35% vs 9%, respectively). In conclusion, we used electroejaculation to collect high quality bison semen, and cryopreserved it for future needs.

Chronic renal failure among farm families in cascade irrigation systems in Sri Lanka associated with elevated dietary cadmium levels in rice and freshwater fish (Tilapia).

Chronic renal failure (CRF), in the main agricultural region under reservoir based cascade irrigation in Sri Lanka has reached crisis proportion. Over 5,000 patients in the region are under treatment for CRF. The objective of this study is to establish the etiology of the CRF. Concentrations of nine heavy metals were determined in sediments, soils of reservoir peripheries, water and Nelumbo nucifera (lotus) grown in five major reservoirs that supply irrigation water. All five reservoirs carried higher levels of dissolved cadmium (Cd), iron (Fe) and lead (Pb). Dissolved Cd in reservoir water ranged from 0.03 to 0.06 mg/l. Sediment Cd concentration was 1.78-2.45 mg/kg. No arsenic (As) was detected. Cd content in lotus rhizomes was 253.82 mg/kg. The Provisional Tolerable Weekly Intake (PTWI) of Cd based on extreme exposure of rice is 8.702-15.927 microg/kg body weight (BW) for different age groups, 5-50 years. The PTWI of Cd due to extreme exposure of fish is 6.773-12.469 microg/kg BW. The PTWI on a rice staple with fish is 15.475-28.396 microg/kg BW. The mean urinary cadmium (UCd) concentration in CRF patients of age group 40-60 years was 7.58 microg Cd/g creatinine and in asymptomatic persons UCd was 11.62 microg Cd/g creatinine, indicating a chronic exposure to Cd. The possible source of Cd in reservoir sediments and water is Cd-contaminated agrochemicals. The CRF prevalent in north central Sri Lanka is a result of chronic dietary intake of Cd, supported by high natural levels of fluoride in drinking water, coupled with neglecting of routine de-silting of reservoirs for the past 20 years.