Sheep may not be an important zoonotic reservoir for Cryptosporidium and Giardia parasites

Little is known of the prevalence of Cryptosporidium and Giardia parasites in sheep and the genotypes that they harbor, although potentially sheep may contribute significantly to contamination of watersheds. In the present study, conducted in Western Australia, a total of 1,647 sheep fecal samples were screened for the presence of Cryptosporidium and Giardia spp. using microscopy, and a subset (n = 500) were screened by PCR and genotyped. Analysis revealed that although both parasites were detected in a high proportion of samples by PCR (44% and 26% for Giardia and Cryptosporidium spp., respectively), with the exception of one Cryptosporidium hominis isolate, the majority of isolates genotyped are not commonly found in humans. These results suggest that the public health risk of sheep-derived Cryptosporidium and Giardia spp. in catchment areas and effluent may be overestimated and warrant further investigation.     

Electron microscopy of the slime moldPhysarum polycephalum

Summary Electron micrographs of fixed sections of the plasmodium of the classic protoplasmic material,Physarum polycephalum, are presented. Numerous round nuclei having well-defined membranes and containing one to three dense nucleoli were especially prominent in the plasmodium. In the surrounding cytoplasm, many irregular membrane-limited bodies were evident, some containing tiny rod-like elements and others with inner structures resembling mitochondria. In addition, there can be seen many small dense granules plus various vacuoles and other inclusions.     

Comparison of verdeluz orange G and modified Gallego stains

Tumors of the oral cavity include combinations of hard and soft tissues that may be difficult to identify using routine hematoxylin and eosin (H & E) staining. Although combination stains can demonstrate hard and soft tissues, trichrome stains, such as VanGieson and Masson, cannot differentiate dental hard tissues, such as dentin, cementum and osteoid. Modified Gallegos (MGS) and verdeluz orange G-acid fuchsin (VOF) stains can differentiate components of teeth. We used 10 tissue sections of decalcified bone and 10 pathologic tissue sections that contained different calcified tissues including peripheral ossifying fibroma, odontoma, central ossifying fibroma and cemento-ossifying fibroma. Sections were stained with H & E, VOF or MGS. H and E stained both hard tissues pink. VOF stained bone purple-red, cementum red and collagen blue. MGS stained bone green-blue, cementum red and collagen blue. VOF staining intensity and differentiation was better than MGS staining. VOF staining demonstrated hard tissue components distinctly and exhibited good contrast with the surrounding connective tissue. VOF also is a simple, single step, rapid staining procedure.     

Many type IIs restriction endonucleases interact with two recognition sites before cleaving DNA.

Type IIs restriction endonucleases recognize asymmetric DNA sequences and cleave both DNA strands at fixed positions, typically several base pairs away from the recognition site. These enzymes are generally monomers that transiently associate to form dimers to cleave both strands. Their reactions could involve bridging interactions between two copies of their recognition sequence. To examine this possibility, several type IIs enzymes were tested against substrates with either one or two target sites. Some of the enzymes cleaved the DNA with two target sites at the same rate as that with one site, but most cut their two-site substrate more rapidly than the one-site DNA. In some cases, the two sites were cut sequentially, at rates that were equal to each other but that exceeded the rate on the one-site DNA. In another case, the DNA with two sites was cleaved rapidly at one site, but the residual site was cleaved at a much slower rate. In a further example, the two sites were cleaved concertedly to give directly the final products cut at both sites. Many type IIs enzymes thus interact with two copies of their recognition sequence before cleaving DNA, although via several different mechanisms.     

Structure of Shigella sonnei lipid A

The detailed chemical structure of lipid A of Shigella sonnei phase II was elucidated. The lipid A backbone consists of a β-1,6-linked glucosamine disaccharide substituted with (mono) phosphates both at C-1 and C-4′. This was shown by selective degradation followed by ³¹P-NMR studies. C-4 and C-6′ were found to contain unsubstituted hydroxyl groups, the latter being the point of attachment of KDO as reported for other enterobacterial lipids A.The amino groups of the glucosamine disaccharide are substituted by 3-hydroxy fatty acids: 3-O-(14:0) 14:0 at the non-reducing glucosamine and 3-O-(12:0) 14:0 at the reducing glucosamine. In contrast to earlier reports, no ethanolamine or phosphodiester linkages were found in lipid A.     

Anatomically based lower limb nerve model for electrical stimulation

Background  

Functional Electrical Stimulation (FES) is a technique that aims to rehabilitate or restore functionality of skeletal muscles using external electrical stimulation. Despite the success achieved within the field of FES, there are still a number of questions that remain unanswered. One way of providing input to the answers is through the use of computational models.